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1

Physical conditions for the r-process  

SciTech Connect

Recent works show that the r-process can proceed by competition between neutron capture and {beta}-decay in low temperature environments (< 5 Multiplication-Sign 10{sup 8} K; cold r-process) where photo-disintegration plays no role. This is in contrast to the traditional picture of the r-process in high temperature environments ({approx} 1 Multiplication-Sign 10{sup 9} K; hot r-process) where the (n, {gamma})-({gamma}, n) equilibrium holds. In this study, we explore nucleosynthesis calculations based on a site-independent model to elucidate the physical conditions leading to cold and hot r-processes.

Wanajo, S.; Tachibana, T.; Goriely, S. [Technische Universitaet Muenchen, Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching and Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Senior High School of Waseda University, Nerima, Tokyo 177-0044 (Japan); Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, C.P. 226, B-1050 Brussels (Belgium)

2012-11-12

2

Nuclear fissions in R and r-cooling processes  

Microsoft Academic Search

The initial condition for the r-cooling process is determined using a model of the dynamical r-process. All nuclides with Z of at least 80 on the neutron-rich side of the beta-stable line are assumed to have finite probabilities for spontaneous fission, neutron-induced fission, and beta-decay-induced fission. Rates for beta decay, neutrino energy loss, beta-decay-induced fission, and delayed neutron emission are

T. Ohnishi

1978-01-01

3

Ris-R-1582(EN) Innovation Process  

E-print Network

Risø-R-1582(EN) Innovation Process By Andrei Kolodovski for Risø Risø National Laboratory Roskilde Denmark December 2006 #12;Author: Andrei Kolodovski for Risø Title: Innovation Process Department: Risø system - Report provides innovation methodology to establish common understanding of the process concepts

4

r-Process in Neutron Star Mergers.  

PubMed

The production site of the neutron-rich heavy elements that are formed by rapid neutron capture (the r-process) is still unknown despite intensive research. Here we show detailed studies of a scenario that has been proposed earlier by Lattimer & Schramm, Symbalisty & Schramm, Eichler et al., and Davies et al., namely the merger of two neutron stars. The results of hydrodynamic and full network calculations are combined in order to investigate the relevance of this scenario for r-process nucleosynthesis. Sufficient material is ejected to explain the amount of r-process nuclei in the Galaxy by decompression of neutron star material. Provided that the ejecta consist of matter with a proton-to-nucleon ratio of Ye approximately 0.1, the calculated abundances fit the observed solar r-pattern excellently for nuclei that include and are heavier than the A approximately 130 peak. PMID:10525469

Freiburghaus; Rosswog; Thielemann

1999-11-10

5

Neutron capture in the r-process  

SciTech Connect

Recently we have shown that neutron capture rates on nuclei near stability significantly influence the r-process abundance pattern. We discuss the different mechanisms by which the abundance pattern is sensitive to the capture rates and identify key nuclei whose rates are of particular im- portance. Here we consider nuclei in the A = 130 and A = 80 regions.

Surman, Rebecca [Union College; Mclaughlin, Gail C [North Carolina State University; Mumpower, Matthew [North Carolina State University; Hix, William Raphael [ORNL; Jones, K. L. [University of Tennessee, Knoxville (UTK)

2010-01-01

6

Nuclear correlations and the r-process  

E-print Network

We show that long-range correlations for nuclear masses have a significant effect on the synthesis of heavy elements by the r-process. As calculated by Delaroche et al. [1], these correlations suppress magic number effects associated with minor shells. This impacts the calculated abundances before the third r-process peak (at mass number A~195), where the abundances are low and form a trough. This trough and the position of the third abundance peak are strongly affected by the masses of nuclei in the transition region between deformed and spherical. Based on different astrophysical environments, our results demonstrate that a microscopic theory of nuclear masses including correlations naturally smoothens the separation energies, thus reducing the trough and improving the agreement with observed solar system abundances.

Arcones, A

2011-01-01

7

Nuclear correlations and the r-process  

E-print Network

We show that long-range correlations for nuclear masses have a significant effect on the synthesis of heavy elements by the r-process. As calculated by Delaroche et al. [1], these correlations suppress magic number effects associated with minor shells. This impacts the calculated abundances before the third r-process peak (at mass number A~195), where the abundances are low and form a trough. This trough and the position of the third abundance peak are strongly affected by the masses of nuclei in the transition region between deformed and spherical. Based on different astrophysical environments, our results demonstrate that a microscopic theory of nuclear masses including correlations naturally smoothens the separation energies, thus reducing the trough and improving the agreement with observed solar system abundances.

A. Arcones; G. F. Bertsch

2011-12-04

8

Nuclear correlations and the r process.  

PubMed

We show that long-range correlations for nuclear masses have a significant effect on the synthesis of heavy elements by the rprocess. As calculated by Delaroche etal. [Phys. Rev. C 81, 014303 (2010)], these correlations suppress magic number effects associated with minor shells. This impacts the calculated abundances before the third r-process peak (at mass number A?195), where the abundances are low and form a trough. This trough and the position of the third abundance peak are strongly affected by the masses of nuclei in the transition region between deformed and spherical. Based on different astrophysical environments, our results demonstrate that a microscopic theory of nuclear masses including correlations naturally smoothens the separation energies, thus reducing the trough and improving the agreement with observed solar system abundances. PMID:22587238

Arcones, A; Bertsch, G F

2012-04-13

9

History Preserving Process Graphs R.J. van Glabbeek*  

E-print Network

History Preserving Process Graphs R.J. van a class of process graphs obeying the restriction * *that any state not only uniquely characterizes graph can be unfolded into such a graph. These histor* *y preserving process graphs capture

Pratt, Vaughan

10

Fission Properties for R-Process Nuclei  

SciTech Connect

We present a systematics of fission barriers and fission lifetimes for the whole landscape of superheavy elements (SHE), i.e., nuclei with Z 100. The fission lifetimes are also compared with the -decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parametrizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bimodal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.

Erler, J. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany/UTK/ORNL; Langanke, K. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys./Frankfurt Inst. Advanced Studies, Germany; Loens, H. P. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Martinez-Pinedo, G. [GSI-Darmstadt/Tech. Univ. Darmstadt, Inst. Phys.; Reinhard, P.-G. [Inst. fur Theoretische Physik II, Univ. Erlangen-Numberg, Germany

2012-01-01

11

Fission properties for r-process nuclei  

E-print Network

We present a systematics of fission barriers and fission lifetimes for the whole landscape of super-heavy elements (SHE), i.e. nuclei with Z>100. The fission lifetimes are also compared with the alpha-decay half-lives. The survey is based on a self-consistent description in terms of the Skyrme-Hartree-Fock (SHF) approach. Results for various different SHF parameterizations are compared to explore the robustness of the predictions. The fission path is computed by quadrupole constrained SHF. The computation of fission lifetimes takes care of the crucial ingredients of the large-amplitude collective dynamics along the fission path, as self-consistent collective mass and proper quantum corrections. We discuss the different topologies of fission landscapes which occur in the realm of SHE (symmetric versus asymmetric fission, regions of triaxial fission, bi-modal fission, and the impact of asymmetric ground states). The explored region is extended deep into the regime of very neutron-rich isotopes as they are expected to be produced in the astrophysical r process.

J. Erler; K. Langanke; H. P. Loens; G. Martnez-Pinedo; P. -G. Reinhard

2011-12-05

12

Sensitivity studies for the weak r process: neutron capture rates  

SciTech Connect

Rapid neutron capture nucleosynthesis involves thousands of nuclear species far from stability, whose nuclear properties need to be understood in order to accurately predict nucleosynthetic outcomes. Recently sensitivity studies have provided a deeper understanding of how the r process proceeds and have identified pieces of nuclear data of interest for further experimental or theoretical study. A key result of these studies has been to point out the importance of individual neutron capture rates in setting the final r-process abundance pattern for a main (A ? 130 peak and above) r process. Here we examine neutron capture in the context of a weak r process that forms primarily the A ? 80 r-process abundance peak. We identify the astrophysical conditions required to produce this peak region through weak r-processing and point out the neutron capture rates that most strongly influence the final abundance pattern.

Surman, R., E-mail: surmanr@union.edu [Department of Physics and Astronomy, Union College, Schenectady, NY 12308 (United States); Mumpower, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Sinclair, R.; Jones, K. L. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States)] [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Hix, W. R. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States) [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); McLaughlin, G. C. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)] [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

2014-04-15

13

Sensitivity studies for the weak r process: neutron capture rates  

NASA Astrophysics Data System (ADS)

Rapid neutron capture nucleosynthesis involves thousands of nuclear species far from stability, whose nuclear properties need to be understood in order to accurately predict nucleosynthetic outcomes. Recently sensitivity studies have provided a deeper understanding of how the r process proceeds and have identified pieces of nuclear data of interest for further experimental or theoretical study. A key result of these studies has been to point out the importance of individual neutron capture rates in setting the final r-process abundance pattern for a `main' (A 130 peak and above) r process. Here we examine neutron capture in the context of a `weak' r process that forms primarily the A 80 r-process abundance peak. We identify the astrophysical conditions required to produce this peak region through weak r-processing and point out the neutron capture rates that most strongly influence the final abundance pattern.

Surman, R.; Mumpower, M.; Sinclair, R.; Jones, K. L.; Hix, W. R.; McLaughlin, G. C.

2014-04-01

14

Prospects for understanding the astrophysical r-process  

SciTech Connect

This paper discusses several recent advances toward a deeper understanding of the still unknown astrophysical site for rapid (r-process) neutron capture nucleosynthesis. The physical constraints on the r-process from the input nuclear data are highlighted and the particular importance of the recent measurements of beta-decay lifetimes along the r-process path is discussed. Astronomical observations of s- and r-process elemental abundances on metal poor halo stars are also discussed, in the context of models for the galactic chemical evolution of heavy-element abundances, as a constraint on the nature of the r-process. On the basis of these constraints it is suggested that the most likely source for the r-process may be from the ejection of core material from low-mass type II supernovae. 27 refs., 1 fig.

Mathews, G.J.; Cowan, J.J.

1988-07-01

15

The Rare Earth Peak : An Overlooked r-Process Diagnostic  

E-print Network

The astrophysical site or sites responsible for the r-process of nucleosynthesis still remains an enigma. Since the rare earth region is formed in the latter stages of the r-process it provides a unique probe of the astrophysical conditions during which the r-process takes place. We use features of a successful rare earth region in the context of a high entropy r-process (S>100k_B) and discuss the types of astrophysical conditions that produce abundance patterns that best match meteoritic and observational data. Despite uncertainties in nuclear physics input, this method effectively constrains astrophysical conditions.

M. Mumpower; G. McLaughlin; R. Surman

2012-02-08

16

Nuclear fissions in r and r -cooling processes  

Microsoft Academic Search

The effect of nuclear fissions occurring during ther-cooling stage is investigated. The initial conditions for ther-cooling process are derived from the final conditions of the dynamicalr-process. Neutron-excess nuclides in the region ofZ?80 are all assumed to have finite probabilities for spontaneous fission, neutron-induced fission and -decay-induced fission. For the evaluation of the rates for delayed neutron emission, -decay-induced fission and

Teruaki Ohnishi

1978-01-01

17

R-Process in Collapsing O/Ne/Mg Cores  

E-print Network

Several circumstantial arguments point to the formation of the third r-process peak at A about 190, near platinum, in stars of mass of about 8-10 solar masses: 1) The delayed production of europium with respect to iron imposes a time scale that restricts the progenitor stars to less than about 10 solar masses; 2) the r-process demands a dominant robust mechanism at least for barium and above, since the relative abundance pattern of those r-process elements in low-metallicity stars is consistent with the solar pattern; 3) stars of about 8-10 solar masses produce nearly identical degenerate O/Ne/Mg cores that collapse due to electron capture; and 4) the resulting low-mass cores may produce both an r-process in a prompt explosion and a subsequent r-process in a neutrino driven wind. The prompt explosion of an O/Ne/Mg core yields low entropy and low electron fraction, and hence may produce a reasonable r-process peak at A about 190 as well as all of the r-process elements with Z greater than 56. The possible differences in the neutrino-driven wind and associated r-process due to the low-mass neutron stars expected in this mass range are also discussed.

J. Craig Wheeler; John J. Cowan; Wolfgang Hillebrandt

1997-11-22

18

Sensitivity studies for the main r process: ?-decay rates  

NASA Astrophysics Data System (ADS)

The pattern of isotopic abundances produced in rapid neutron capture, or r-process, nucleosynthesis is sensitive to the nuclear physics properties of thousands of unstable neutron-rich nuclear species that participate in the process. It has long been recognized that the some of the most influential pieces of nuclear data for r-process simulations are ?-decay lifetimes. In light of experimental advances that have pushed measurement capabilities closer to the classic r-process path, we revisit the role of individual ?-decay rates in the r process. We perform ?-decay rate sensitivity studies for a main (A > 120) r process in a range of potential astrophysical scenarios. We study the influence of individual rates during (n, ?)-(?, n) equilibrium and during the post-equilibrium phase where material moves back toward stability. We confirm the widely accepted view that the most important lifetimes are those of nuclei along the r-process path for each astrophysical scenario considered. However, we find in addition that individual ?-decay rates continue to shape the final abundance pattern through the post-equilibrium phase, for as long as neutron capture competes with ? decay. Many of the lifetimes important for this phase of the r process are within current or near future experimental reach.

Mumpower, M.; Cass, J.; Passucci, G.; Surman, R.; Aprahamian, A.

2014-04-01

19

Sensitivity studies for the main r process: ?-decay rates  

SciTech Connect

The pattern of isotopic abundances produced in rapid neutron capture, or r-process, nucleosynthesis is sensitive to the nuclear physics properties of thousands of unstable neutron-rich nuclear species that participate in the process. It has long been recognized that the some of the most influential pieces of nuclear data for r-process simulations are ?-decay lifetimes. In light of experimental advances that have pushed measurement capabilities closer to the classic r-process path, we revisit the role of individual ?-decay rates in the r process. We perform ?-decay rate sensitivity studies for a main (A > 120) r process in a range of potential astrophysical scenarios. We study the influence of individual rates during (n, ?)-(?, n) equilibrium and during the post-equilibrium phase where material moves back toward stability. We confirm the widely accepted view that the most important lifetimes are those of nuclei along the r-process path for each astrophysical scenario considered. However, we find in addition that individual ?-decay rates continue to shape the final abundance pattern through the post-equilibrium phase, for as long as neutron capture competes with ? decay. Many of the lifetimes important for this phase of the r process are within current or near future experimental reach.

Mumpower, M.; Cass, J.; Passucci, G.; Aprahamian, A. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Surman, R. [Department of Physics and Astronomy, Union College, Schenectady, New York 12308 (United States)] [Department of Physics and Astronomy, Union College, Schenectady, New York 12308 (United States)

2014-04-15

20

Neutron Capture Rates and r-PROCESS Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Simulations of r-process nucleosynthesis require nuclear physics information for thousands of neutron-rich nuclear species from the line of stability to the neutron drip line. While arguably the most important pieces of nuclear data for the r-process are the masses and ? decay rates, individual neutron capture rates can also be of key importance in setting the final r-process abundance pattern. Here we consider the influence of neutron capture rates in forming the A ~ 80 and rare earth peaks.

Surman, R. A.; Mumpower, M. R.; McLaughlin, G. C.; Sinclair, R.; Hix, W. R.; Jones, K. L.

2013-03-01

21

Neutrinos, Fission Cycling, and the r-process  

E-print Network

It has long been suggested that fission cycling may play an important role in the r-process. Fission cycling can only occur in a very neutron rich environment. In traditional calculations of the neutrino driven wind of the core-collapse supernova, the environment is not sufficiently neutron rich to produce the r-process elements. However, we show that with a reduction of the electron neutrino flux coming from the supernova, fission cycling does occur and furthermore it produces an abundance pattern which is consistent with observed r-process abundance pattern in halo stars. Such a reduction can be caused by active-sterile neutrino oscillations or other new physics.

J. Beun; G. C. McLaughlin; R. Surman; W. R. Hix

2006-07-26

22

Managing a Dispersed Product Development Process John R. Hauser  

E-print Network

Managing a Dispersed Product Development Process By Ely Dahan and John R. Hauser October 2000 for Innovation in Product Development at M.I.T. #12;i Managing a Dispersed Product Development Process Table of Contents THE CHALLENGE OF A DISPERSED PRODUCT DEVELOPMENT PROCESS................................1 PRODUCT

Gabrieli, John

23

Impact of nuclear fission on r-process nucleosynthesis and origin of solar r-process elements  

NASA Astrophysics Data System (ADS)

Binary neutron star mergers (NSMs) are expected to be main production sites of r-process elements. Their ejecta are extremely neutron-rich (Ye<0.1), and the r-process path proceeds along the neutron drip line and enters the region of fissile nuclei. In this situation, although superheavy nuclei may be synthesized and the r-process path may reach the island of stability, those are sensitive to theoretical models of nuclear masses and nuclear fission. In this study, we carry out r-process nucleosynthesis simulations in the NSMs. Our new nuclear reaction network code include new theoretical models of nuclear masses and nuclear fission. Our r-process simulation of a binary NSM shows that the final r-process elemental abundances exhibit flat pattern for A110-160, and several fission cycling operate in extremely neutron-rich conditions of the NSM. We find that the combination of the NSMs and the magnetorotational supernovae can reproduce the solar r-process elements. We discuss the validity of this interpretation.

Shibagaki, Shota; Kajino, Toshitaka; Mathews, Grant J.; Chiba, Satoshi

2015-02-01

24

Galactic r-process production: The inhomogeneous approach  

E-print Network

The origin of elements made by the rapid neutron-capture process (r-process) is not fully understood. Different sources have been proposed, e.g., core-collapse supernovae and neutron star mergers. Old metal-poor stars carry the signature of the astrophysical r-process source(s). Europium is the most indicative element to trace the r-process production, since it is mostly made by the r-process and it is easy to observe compared to other heavy r-process elements. In this work we simulate the evolution of europium in our Galaxy with the inhomogeneous chemical evolution model ICE, and we compare our results with spectroscopic observations. We test the most important parameters affecting the chemical evolution of the r-process element Eu: (a) for neutron star mergers the coalescence time scale of the merger and the probability to experience a neutron star merger event after two supernova explosions occurred and formed a double neutron star system ) and (b) for the sub-class of magneto-rotationally driven Supernova...

Wehmeyer, B; Thielemann, F -K

2015-01-01

25

Barium from a mini r-process in supernovae  

NASA Technical Reports Server (NTRS)

McCulloch and Wasserburg (1978) have reported nonlinear isotopic anomalies in barium for two Ca-Al-rich inclusions of the Allende carbonaceous chondrite, known as EK-1-4-1 and C-1. In an attempt to account for these anomalies, it has been proposed that Ba from an r-process of nucleosynthesis, containing Ba-135 and Ba-137, was injected into the primeval color system but was not totally homogenized. Questions arise in connection with the relations of Xe isotopes in carbonaceous chondrites. This has prompted Heymann and Dziczkaniec (1979, 1980, 1981) to study the formation of r-Xe, r-Kr, and r-Te by the mini r-process which is thought to occur in the O, Ne-rich shells of Type II supernovae. Lee et al. (1979) have studied the formation of r-Ba, r-Nd, and r-Sm by the same process. Certain differences regarding the approaches used by Lee et al. and by Heymann and Dziczkaniec make it necessary to restudy the work of Lee et al. Attention is given to the survival probabilities of nuclear species of interest, taking into accounts the elements Cs, Ba, I, and Xe.

Heymann, D.

1983-01-01

26

Improving PIN Processing API Security R. Focardi and F. Luccio  

E-print Network

machine) network. This API controls access to the tamper-resistant Hardware Security Modules where PINImproving PIN Processing API Security R. Focardi and F. Luccio Universit`a di Venezia, Italy propose a countermeasure for a class of known attacks on the PIN processing API used in the ATM (cash

Focardi, Riccardo

27

Facilitating Change Through a Simplified R and D Process.  

ERIC Educational Resources Information Center

The paper suggests the application of a research and development (R and D) process in an ongoing project at the National Technical Institute for the Deaf. Four phases/stages of the process are discussed: research, development, implementation, and maintenance. It is pointed out that the objective of the project has been to train normal hearing

Osguthorpe, Russell T.; Bishop, Milo E.

28

Sensitivity studies for the main r process: nuclear masses  

SciTech Connect

The site of the rapid neutron capture process (r process) is one of the open challenges in all of physics today. The r process is thought to be responsible for the creation of more than half of all elements beyond iron. The scientific challenges to understanding the origin of the heavy elements beyond iron lie in both the uncertainties associated with astrophysical conditions that are needed to allow an r process to occur and a vast lack of knowledge about the properties of nuclei far from stability. One way is to disentangle the nuclear and astrophysical components of the question. On the nuclear physics side, there is great global competition to access and measure the most exotic nuclei that existing facilities can reach, while simultaneously building new, more powerful accelerators to make even more exotic nuclei. On the astrophysics side, various astrophysical scenarios for the production of the heaviest elements have been proposed but open questions remain. This paper reports on a sensitivity study of the r process to determine the most crucial nuclear masses to measure using an r-process simulation code, several mass models (FRDM, Duflo-Zuker, and HFB-21), and three potential astrophysical scenarios.

Aprahamian, A.; Mumpower, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Bentley, I. [Department of Chemistry and Physics, St. Mary's College, Notre Dame, IN 46556 (United States)] [Department of Chemistry and Physics, St. Mary's College, Notre Dame, IN 46556 (United States); Surman, R. [Department of Physics and Astronomy, Union College, Schenectady, NY 12308 (United States)] [Department of Physics and Astronomy, Union College, Schenectady, NY 12308 (United States)

2014-04-15

29

The r-process nucleosynthesis: Nuclear physics challenges  

SciTech Connect

About half of the nuclei heavier than iron observed in nature are produced by the socalled rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved and for which essentially no experimental data exist. The present contribution emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Their impact on the r-abundance distribution resulting from the decompression of neutron star matter is discussed.

Goriely, S. [Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles Campus de la Plaine, CP 226, 1050 Brussels (Belgium)

2012-10-20

30

Fission Cycling in a Supernova r-process  

E-print Network

Recent halo star abundance observations exhibit an important feature of consequence to the r-process: the presence of a main r-process between the second and third peaks which is consistent among halo stars. We explore fission cycling and steady-beta flow as the driving mechanisms behind this feature. The presence of fission cycling during the r-process can account for nucleosynthesis yields between the second and third peaks, whereas the presence of steady-beta flow can account for consistent r-process patterns, robust under small variations in astrophysical conditions. We employ the neutrino-driven wind of the core-collapse supernova to examine fission cycling and steady-beta flow in the r-process. As the traditional neutrino-driven wind model does not produce the required very neutron-rich conditions for these mechanisms, we examine changes to the neutrino physics necessary for fission cycling to occur in the neutrino-driven wind environment, and we explore under what conditions steady-beta flow is obtained.

J. Beun; G. C. McLaughlin; R. Surman; W. R. Hix

2007-07-30

31

Neutrino-nucleus interaction and supernova r-process nucleosynthesis  

E-print Network

We discuss various neutrino-nucleus interactions in connection with the supernova r-process nucleosynthesis, which possibly occurs in the neutrino-driven wind of a young neutron star. These interactions include absorptions of electron neutrinos and antineutrinos on free nucleons, electron-neutrino captures on neutron-rich nuclei, and neutral-current interactions of heavy-flavor neutrinos with alpha particles and neutron-rich nuclei. We describe how these interactions can affect the r-process nucleosynthesis and discuss the implications of their effects for the physical conditions leading to a successful supernova r-process. We conclude that a low electron fraction and/or a short dynamic time scale may be required to give the sufficient neutron-to-seed ratio for an r-process in the neutrino-driven wind. In the case of a short dynamic time scale, the wind has to be contained during the r-process. Possible mechanisms which can give a low electron fraction or contain the wind are discussed.

Y. -Z. Qian

1996-11-13

32

Rosens (M,R) system in process algebra  

PubMed Central

Background Robert Rosens Metabolism-Replacement, or (M,R), system can be represented as a compact network structure with a single source and three products derived from that source in three consecutive reactions. (M,R) has been claimed to be non-reducible to its components and algorithmically non-computable, in the sense of not being evaluable as a function by a Turing machine. If (M,R)-like structures are present in real biological networks, this suggests that many biological networks will be non-computable, with implications for those branches of systems biology that rely on in silico modelling for predictive purposes. Results We instantiate (M,R) using the process algebra Bio-PEPA, and discuss the extent to which our model represents a true realization of (M,R). We observe that under some starting conditions and parameter values, stable states can be achieved. Although formal demonstration of algorithmic computability remains elusive for (M,R), we discuss the extent to which our Bio-PEPA representation of (M,R) allows us to sidestep Rosens fundamental objections to computational systems biology. Conclusions We argue that the behaviour of (M,R) in Bio-PEPA shows life-like properties. PMID:24237684

2013-01-01

33

The r-Process in Black Hole Winds  

E-print Network

All the current r-process scenarios relevant to core-collapse supernovae are facing severe difficulties. In particular, recent core-collapse simulations with neutrino transport show no sign of a neutron-rich wind from the proto-neutron star. In this paper, we discuss nucleosynthesis of the r-process in an alternative astrophysical site, "black hole winds", which are the neutrino-driven outflow from the accretion torus around a black hole. This condition is assumed to be realized in double neutron star mergers, neutron star - black hole mergers, or hypernovae.

Shinya Wanajo; Hans-Thomas Janka

2010-06-11

34

The r-, s-, and p-Processes in Nucleosynthesis  

NASA Technical Reports Server (NTRS)

A goal of this paper is to review the recent progress astrophysicists, astronomers, and physicists have made in the r-, s-, and p-processes in nucleosynthesis and to point out the problems that remain in our understanding of the formation of the heavy nuclei. Another, perhaps deeper, goal is to to seek some understanding of why there are three major processes available to nature for synthesis of heavy elements.

Meyer, Bradley S.

1994-01-01

35

On the Site of the Weak rProcess Component #  

E-print Network

of Physics and Astronomy, University of Oklahoma, Norman, OK, 73019 Abstract. There is increasingly strong140, the signature of which is unambiguously imprinted upon the abun dance patterns of the most metal deficient halo While the general nature of the rprocess and its contributions to the abun dances of heavy elements

Cowan, John

36

Extinct Radioactivities and the R-Process Jet  

NASA Technical Reports Server (NTRS)

All extinct radioactive species in the solar nebula were injected from a core-collapse supernova. I discuss primarily the products expected from an r-process jet in this supernova, and various supporting astrophysical observations. Additional information is contained in the original extended abstract.

Cameron, A. G. W.

2001-01-01

37

Sensitivity to masses in the r-process  

NASA Astrophysics Data System (ADS)

The rapid neutron capture process is thought to produce over 50% of the elements beyond iron and still remains, in many ways, a mystery. Questions about the site, conditions and whether it is a single process are outstanding open questions. The process is affected by the astrophysics of the scenario and the nuclear physics of the nuclei involved in the process. Simulations of the r-process require large sets of data such as cross sections, separation energies and decay rates. Clearly, it would be desirable if all of these data sets to be observed and experimentally proven, but since we are looking toward extremely neutron rich nuclei, perilously close to the drip line, we must use many theoretical values. Using an r-process simulation written by Bradley Meyer in 1993, we have been able to see the effects of changing the mass models (and therefore the separation energies) on the final abundances. The input includes the Finite Range Droplet Model, the ETFSI, Duflo-Zucker, and F0 models. By comparing these theoretical models against each other and against known masses, we hope to be able to suggest key regions for further mass measurements.

Brett, Sam; Aprahamian, Ani

2009-10-01

38

?-decay spectroscopy for the r-process nucleosynthesis  

SciTech Connect

Series of decay spectroscopy experiments, utilizing of high-purity Ge detectors and double-sided silicon-strip detectors, have been conducted to harvest the decay properties of very exotic nuclei relevant to the r-process nucleosynthesis at the RIBF. The decay properties such as ?-decay half-lives, low-lying states, ?-delayed neutron emissions, isomeric states, and possibly Q{sub ?} of the very neutron-rich nuclei are to be measured to give significant constraints in the uncertainties of nuclear properties for the r-process nucleosynthesis. Recent results of ?? spectroscopy study using in-flight fission of {sup 238}U-beam will be presented together with our future perspectives.

Nishimura, Shunji [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Collaboration: RIBF Decay Collaborations

2014-05-09

39

Assessment of advanced coal-gasification processes. [AVCO high throughput gasification in process; Bell High Mass Flux process; CS-R process; and Exxon Gasification process  

SciTech Connect

This report represents a technical assessment of the following advanced coal gasification processes: AVCO High Throughput Gasification (HTG) Process, Bell Single - Stage High Mass Flux (HMF) Process, Cities Service/Rockwell (CS/R) Hydrogasification Process, and the Exxon Catalytic Coal Gasification (CCG) Process. Each process is evaluated for its potential to produce SNG from a bituminous coal. In addition to identifying the new technology these processes represent, key similarities/differences, strengths/weaknesses, and potential improvements to each process are identified. The AVCO HTG and the Bell HMF gasifiers share similarities with respect to: short residence time (SRT), high throughput rate, slagging and syngas as the initial raw product gas. The CS/R Hydrogasifier is also SRT but is non-slagging and produces a raw gas high in methane content. The Exxon CCG gasifier is a long residence time, catalytic fluidbed reactor producing all of the raw product methane in the gasifier.

McCarthy, J.; Ferrall, J.; Charng, T.; Houseman, J.

1981-06-01

40

Probabilities of delayed processes for nuclei involved in the r-process  

SciTech Connect

Delayed fission, along with induced and spontaneous fission, is responsible for the suppression of the production of superheavy elements both during the r-process and after its completion. Beta-decay strength functions are required for calculating delayed fission. In the present study, respective strength functions are calculated by relying on the theory of finite Fermi systems and by predominantly employing nuclear masses and fission barriers predicted by a generalized Thomas-Fermi model. The probabilities for delayed fission and for the emission of delayed neutrons are calculated for a number of isotopes. On the basis of calculations performed in order to determine the probabilities for delayed processes, it is shown that some of the delayed-fission probabilities calculated thus far were substantially overestimated. The application of these new results to calculating the r-process may change substantially both the r-process path and the yields of superheavy nuclei.

Panov, I. V., E-mail: Igor.Panov@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation); Korneev, I. Yu.; Lutostansky, Yu. S. [National Research Center Kurchatov Institute (Russian Federation)] [National Research Center Kurchatov Institute (Russian Federation); Thielemann, F.-K. [University of Basel, Institute of Physics (Switzerland)] [University of Basel, Institute of Physics (Switzerland)

2013-01-15

41

Nuclear properties far from stability and the R-process  

Microsoft Academic Search

Within the waiting-point assumption, we have investigated the influence of nuclear properties far from stability on the prediction of solar-system r-process abundance (Nr,⊙) distributions. When using data sets for masses and ?-decay quantities from the Finite-Range Droplet Model (FRDM) and the Extended Thomas-Fermi plus Strutinski Integral (ETFSI) method, local deficiencies in the Nr,⊙ fits around A≊115 and 175 cannot be

Karl-Ludwig Kratz

1995-01-01

42

Predictions for nuclear properties along the r-process path  

SciTech Connect

The uniformity of different nuclear regions as a function of the number of valence protons and neutrons (counted from the nearest closed shell) has been exploited for the parameterization of calculations for nuclei far from stability within the IBA model. Predictions are given for low lying levels, E2 transition rates, and binding energies for nuclei in the r-process path in the A = 150 and A = 190 mass regions. 6 refs., 6 figs.

Aprahamian, A.

1987-10-15

43

Space - A unique environment for process modeling R&D  

NASA Technical Reports Server (NTRS)

Process modeling, the application of advanced computational techniques to simulate real processes as they occur in regular use, e.g., welding, casting and semiconductor crystal growth, is discussed. Using the low-gravity environment of space will accelerate the technical validation of the procedures and enable extremely accurate determinations of the many necessary thermophysical properties. Attention is given to NASA's centers for the commercial development of space; joint ventures of universities, industries, and goverment agencies to study the unique attributes of space that offer potential for applied R&D and eventual commercial exploitation.

Overfelt, Tony

1991-01-01

44

Cerebellar rTMS disrupts predictive language processing  

PubMed Central

Summary The human cerebellum plays an important role in language, amongst other cognitive and motor functions [1], but a unifying theoretical framework about cerebellar language function is lacking. In an established model of motor control, the cerebellum is seen as a predictive machine, making short-term estimations about the outcome of motor commands. This allows for flexible control, on-line correction, and coordination of movements [2]. The homogeneous cytoarchitecture of the cerebellar cortex suggests that similar computations occur throughout the structure, operating on different input signals and with different output targets [3]. Several authors have therefore argued that this motor model may extend to cerebellar nonmotor functions [35], and that the cerebellum may support prediction in language processing [6]. However, this hypothesis has never been directly tested. Here, we used the Visual World paradigm [7], where on-line processing of spoken sentence content can be assessed by recording the latencies of listeners' eye movements towards objects mentioned. Repetitive transcranial magnetic stimulation (rTMS) was used to disrupt function in the right cerebellum, a region implicated in language [8]. After cerebellar rTMS, listeners showed delayed eye fixations to target objects predicted by sentence content, while there was no effect on eye fixations in sentences without predictable content. The prediction deficit was absent in two control groups. Our findings support the hypothesis that computational operations performed by the cerebellum may support prediction during both motor control and language processing. PMID:23017990

Lesage, Elise; Morgan, Blaire E.; Olson, Andrew C.; Meyer, Antje S.; Miall, R. Chris

2012-01-01

45

Novel technique for constraining r-process (n,$?$) reaction rates  

E-print Network

A novel technique has been developed, which will open exciting new opportunities for studying the very neutron-rich nuclei involved in the r-process. As a proof-of-principle, the $\\gamma$-spectra from the $\\beta$-decay of $^{76}$Ga have been measured with the SuN detector at the National Superconducting Cyclotron Laboratory. The nuclear level density and $\\gamma$-ray strength function are extracted and used as input to Hauser-Feshbach calculations. The present technique is shown to strongly constrain the $^{75}$Ge($n,\\gamma$)$^{76}$Ge cross section and reaction rate.

A. Spyrou; S. N. Liddick; A. C. Larsen; M. Guttormsen; K. Cooper; A. C. Dombos; D. J. Morrissey; F. Naqvi; G. Perdikakis; S. J. Quinn; T. Renstrm; J. A. Rodriguez; A. Simon; C. S. Sumithrarachchi; R. G. T. Zegers

2014-08-27

46

Novel technique for constraining r-process (n, ?) reaction rates.  

PubMed

A novel technique has been developed, which will open exciting new opportunities for studying the very neutron-rich nuclei involved in the r process. As a proof of principle, the ? spectra from the ? decay of ^{76}Ga have been measured with the SuN detector at the National Superconducting Cyclotron Laboratory. The nuclear level density and ?-ray strength function are extracted and used as input to Hauser-Feshbach calculations. The present technique is shown to strongly constrain the ^{75}Ge(n,?)^{76}Ge cross section and reaction rate. PMID:25526121

Spyrou, A; Liddick, S N; Larsen, A C; Guttormsen, M; Cooper, K; Dombos, A C; Morrissey, D J; Naqvi, F; Perdikakis, G; Quinn, S J; Renstrm, T; Rodriguez, J A; Simon, A; Sumithrarachchi, C S; Zegers, R G T

2014-12-01

47

MODISTools - downloading and processing MODIS remotely sensed data in R.  

PubMed

Remotely sensed data - available at medium to high resolution across global spatial and temporal scales - are a valuable resource for ecologists. In particular, products from NASA's MODerate-resolution Imaging Spectroradiometer (MODIS), providing twice-daily global coverage, have been widely used for ecological applications. We present MODISTools, an R package designed to improve the accessing, downloading, and processing of remotely sensed MODIS data. MODISTools automates the process of data downloading and processing from any number of locations, time periods, and MODIS products. This automation reduces the risk of human error, and the researcher effort required compared to manual per-location downloads. The package will be particularly useful for ecological studies that include multiple sites, such as meta-analyses, observation networks, and globally distributed experiments. We give examples of the simple, reproducible workflow that MODISTools provides and of the checks that are carried out in the process. The end product is in a format that is amenable to statistical modeling. We analyzed the relationship between species richness across multiple higher taxa observed at 526 sites in temperate forests and vegetation indices, measures of aboveground net primary productivity. We downloaded MODIS derived vegetation index time series for each location where the species richness had been sampled, and summarized the data into three measures: maximum time-series value, temporal mean, and temporal variability. On average, species richness covaried positively with our vegetation index measures. Different higher taxa show different positive relationships with vegetation indices. Models had high R (2) values, suggesting higher taxon identity and a gradient of vegetation index together explain most of the variation in species richness in our data. MODISTools can be used on Windows, Mac, and Linux platforms, and is available from CRAN and GitHub (https://github.com/seantuck12/MODISTools). PMID:25558360

Tuck, Sean L; Phillips, Helen Rp; Hintzen, Rogier E; Scharlemann, Jrn Pw; Purvis, Andy; Hudson, Lawrence N

2014-12-01

48

MODISTools downloading and processing MODIS remotely sensed data in R  

PubMed Central

Remotely sensed data available at medium to high resolution across global spatial and temporal scales are a valuable resource for ecologists. In particular, products from NASA's MODerate-resolution Imaging Spectroradiometer (MODIS), providing twice-daily global coverage, have been widely used for ecological applications. We present MODISTools, an R package designed to improve the accessing, downloading, and processing of remotely sensed MODIS data. MODISTools automates the process of data downloading and processing from any number of locations, time periods, and MODIS products. This automation reduces the risk of human error, and the researcher effort required compared to manual per-location downloads. The package will be particularly useful for ecological studies that include multiple sites, such as meta-analyses, observation networks, and globally distributed experiments. We give examples of the simple, reproducible workflow that MODISTools provides and of the checks that are carried out in the process. The end product is in a format that is amenable to statistical modeling. We analyzed the relationship between species richness across multiple higher taxa observed at 526 sites in temperate forests and vegetation indices, measures of aboveground net primary productivity. We downloaded MODIS derived vegetation index time series for each location where the species richness had been sampled, and summarized the data into three measures: maximum time-series value, temporal mean, and temporal variability. On average, species richness covaried positively with our vegetation index measures. Different higher taxa show different positive relationships with vegetation indices. Models had high R2 values, suggesting higher taxon identity and a gradient of vegetation index together explain most of the variation in species richness in our data. MODISTools can be used on Windows, Mac, and Linux platforms, and is available from CRAN and GitHub (https://github.com/seantuck12/MODISTools). PMID:25558360

Tuck, Sean L; Phillips, Helen RP; Hintzen, Rogier E; Scharlemann, Jrn PW; Purvis, Andy; Hudson, Lawrence N

2014-01-01

49

Nucleon-Alpha Particle Disequilibrium and Short-Lived r-Process Radioactivities  

NASA Technical Reports Server (NTRS)

r-Process yields can be extremely sensitive to expansion parameters when a persistent disequilibrium between free nucleons and alpha particles is present. This may provide a natural scenario for understanding the variation of heavy and light r-process isotopes in different r-process events. Additional information is contained in the original extended abstract.

Meyer, B. S.; Clayton, D. D.; Chellapilla, S.; The, L.-S.

2002-01-01

50

Mass measurements along the r-process path at CARIBU  

NASA Astrophysics Data System (ADS)

The CARIBU facility is now operational and a large body of new mass measurements around the N=82 waiting point has been accumulated. The masses of over 70 neutron-rich isotopes from the heavy Californium fission peak have been measured with the CPT Penning trap mass spectrometer yielding a typical accuracy of 10 keV/c2. The most neutron-rich masses show significant deviations from either masses measured by other means when available or from extrapolated values from the last Atomic Mass Evaluation when no measurements where available. The system used for these measurements will be briefly described and an analysis of the modification to the delay for the r-process in this region when taking into accounts the new masses will be presented.

Savard, Guy; Clark, Jason; van Schelt, Jon; Lascar, Dan; Levand, Anthony; Zabransky, Bruce; Sharma, Kumar

2012-10-01

51

Supernovae versus Neutron Star Mergers as the Major r-Process Sources.  

PubMed

I show that recent observations of r-process abundances in metal-poor stars are difficult to explain if neutron star mergers (NSMs) are the major r-process sources. In contrast, such observations and meteoritic data on 182Hf and 129I in the early solar system support a self-consistent picture of r-process enrichment by supernovae (SNe). While further theoretical studies of r-process production and enrichment are needed for both SNe and NSMs, I emphasize two possible direct observational tests of the SN r-process model: gamma rays from the decay of r-process nuclei in SN remnants and surface contamination of the companion by SN r-process ejecta in binaries. PMID:10790073

Qian

2000-05-01

52

Supernovae versus Neutron Star Mergers as the Major r-Process Sources  

E-print Network

I show that recent observations of r-process abundances in metal-poor stars are difficult to explain if neutron star mergers (NSMs) are the major r-process sources. In contrast, such observations and meteoritic data on Hf182 and I129 in the early solar system support a self-consistent picture of r-process enrichment by supernovae (SNe). While further theoretical studies of r-process production and enrichment are needed for both SNe and NSMs, I emphasize two possible direct observational tests of the SN r-process model: gamma rays from decay of r-process nuclei in SN remnants and surface contamination of the companion by SN r-process ejecta in binaries.

Y. -Z. Qian

2000-03-16

53

Higgs boson mass effects in the process ?+R(L)?-R(L)-->W+LW-L  

NASA Astrophysics Data System (ADS)

The process ?+R(L)?-R(L)-->W+LW-L is studied with a view to discern the Higgs boson mass effects. The helicity amplitudes are evaluated retaining muon mass terms and cancellation of possible bad high energy behavior is discussed. The results are examined in the context of the equivalence theorem. The Higgs boson mass effects in the differential cross section (d?/d cos ?), total cross section (?), and forward-backward asymmetry (AFB) are presented for two cases: (i) mH<2mW and (ii) mH>2mW. Near the WL pair production threshold, both d?/d cos ? and ? increase with an increase in s for case (ii), while this trend is absent for case (i). Near resonance (s~mH), d?/d cos ? does not show an appreciable dependence on ?. For case (i) AFB is always positive, while for case (ii) AFB changes sign from negative to positive at s=mH. The AFB decreases with an increase in mH for any s>mH.

Singhal, J. K.; Singh, Sardar

2001-07-01

54

The impact of global nuclear mass model uncertainties on $r$-process abundance predictions  

E-print Network

Rapid neutron capture or `$r$-process' nucleosynthesis may be responsible for half the production of heavy elements above iron on the periodic table. Masses are one of the most important nuclear physics ingredients that go into calculations of $r$-process nucleosynthesis as they enter into the calculations of reaction rates, decay rates, branching ratios and Q-values. We explore the impact of uncertainties in three nuclear mass models on $r$-process abundances by performing global monte carlo simulations. We show that root-mean-square (rms) errors of current mass models are large so that current $r$-process predictions are insufficient in predicting features found in solar residuals and in $r$-process enhanced metal poor stars. We conclude that the reduction of global rms errors below $100$ keV will allow for more robust $r$-process predictions.

M. Mumpower; R. Surman; A. Aprahamian

2014-11-14

55

Explorations of the r-Processes: Comparisons between Calculations and Observations of Low-Metallicity Stars  

E-print Network

Abundances of heavier elements (barium and beyond) in many neutron-capture-element-rich halo stars accurately replicate the solar system r-process pattern. However, abundances of lighter neutron-capture elements in these stars are not consistent with the solar system pattern. These comparisons suggest contributions from two distinct types of r-process synthesis events -- a so called main r-process for the elements above the 2nd r-process peak and a weak r-process for the lighter neutron-capture elements. We have performed r-process theoretical predictions to further explore the implications of the solar and stellar observations. We find that the isotopic composition of barium and the elemental Ba/Eu abundance ratios in r-process-rich low metallicity stars can only be matched by computations in which the neutron densities are in the range 23< log n_n < 28, values typical of the main r-process. For r-process conditions that successfully generate the heavy element pattern extending down to A=135, the relative abundance of I129 produced in this mass region appears to be at least 90% of the observed solar value. Finally, in the neutron number density ranges required for production of the observed solar/stellar 3rd r-process-peak (A~200), the predicted abundances of inter-peak element hafnium (Z=72, A~180) follow closely those of 3rd-peak elements and lead. Hf, observable from the ground and close in mass number to the 3rd r-process-peak elements, might also be utilized as part of a new nuclear chronometer pair, Th/Hf, for stellar age determinations.

Karl-Ludwig Kratz; Khalil Farouqi; Bernd Pfeiffer; James W. Truran; Christopher Sneden; John J. Cowan

2007-03-05

56

Realistic fission model and the r-process in neutron star mergers  

SciTech Connect

About half of heavy elements are considered to be produced by the rapid neutron-capture process, r-process. The neutron star merger is one of the viable candidates for the astrophysical site of r-process nucleosynthesis. Nuclear fission reactions play an important role in the r-process of neutron star mergers. However theoretical predictions about fission properties of neutron-rich nuclei have some uncertainties. Especially, their fission fragment distributions are totally unknown and the phenomenologically extrapolated distribution was often applied to nucleosynthesis calculations. In this study, we have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions. We discuss the effects on the r-process in neutron star mergers from the nuclear fission of heavy neutron-rich actinide elements. We also discuss how variations in the fission fragment distributions affect the abundance pattern.

Shibagaki, S.; Kajino, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8850 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556, U.S.A. and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2014-05-09

57

Neutron-capture elements in the s- and r-process-rich stars: Constraints on neutron-capture nucleosynthesis processes  

E-print Network

The chemical abundances of the very metal-poor double-enhanced stars are excellent information for setting new constraints on models of neutron-capture processes at low metallicity. These stars are known as s+r stars, since they show enhancements of both s-process and r-process elements. The observed abundance ratios for the double-enhanced stars can be explained by those of stars that were polluted by an AGB star and subsequently accreted very significant amounts of r-process material out of an AIC (accretion-induced collapse) or Type 1.5 supernova. In this paper we present for the first time an attempt to fit the elemental abundances observed in the s- and r-rich, very metal-poor stars using a parametric model and suggest a new concept of component coefficients to describe the contributions of the individual neutron-capture processes to double-enhanced stars. We find that the abundance ratios of these stars are best fitted by enrichments of s- and r-process material. The overlap factor in the AGB stars where the observed s-process elements were produced lies between 0.1 and 0.81. Taking into account the dependence of the initial-final mass relations on metallicity, this wide range of values could possibly be explained by a wide range of core-mass values of AGB stars at low metallicity. The component coefficient of the r-process is strongly correlated with the component coefficient of the s-process for the double-enhanced stars. This is significant evidence that the r-process material in double-enhanced stars comes from an AIC or Type 1.5 supernova.

Bo Zhang; Kun Ma; Guide Zhou

2006-05-14

58

r-Process Nucleosynthesis in Black Hole-Neutron Star Mergers  

SciTech Connect

Compact object mergers have long been speculated to be a possible site of r-process nucleosynthesis. While most attention has been focused on the cold decompression of neutron star matter ejected from the merger, other sites within the merger likely contribute to its nucleosynthetic output. Here we consider hot outflows from the accretion disk that forms around the black hole following a black hole- neutron star merger. We begin with the results of a three-dimensional numerical merger model and carefully calculate the neutrino and antineutrino fluxes emitted from the accretion disk. We find that neutrino interactions on free nucleons in the outflowing material result in neutron excesses such that at least a weak r-process is produced and in some cases a main r-process as well. Additionally, we find that the weak r-process pattern calculated for certain trajectories compares favorably to the pattern observed in a weak r-process-enhanced halo star.

Surman, Rebecca [Union College; Mclaughlin, Gail C [North Carolina State University; Ruffert, Maximilian [University of Edinburgh; Janka, Hans-Thomas [Max Planck Institut fur Astrophysik (MPA), Germany; Hix, William Raphael [ORNL

2008-01-01

59

DETECTION OF THE SECOND r-PROCESS PEAK ELEMENT TELLURIUM IN METAL-POOR STARS ,  

SciTech Connect

Using near-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, we detect neutral tellurium in three metal-poor stars enriched by products of r-process nucleosynthesis, BD +17 3248, HD 108317, and HD 128279. Tellurium (Te, Z = 52) is found at the second r-process peak (A Almost-Equal-To 130) associated with the N = 82 neutron shell closure, and it has not been detected previously in Galactic halo stars. The derived tellurium abundances match the scaled solar system r-process distribution within the uncertainties, confirming the predicted second peak r-process residuals. These results suggest that tellurium is predominantly produced in the main component of the r-process, along with the rare earth elements.

Roederer, Ian U. [Carnegie Observatories, Pasadena, CA 91101 (United States); Lawler, James E. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Cowan, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Frebel, Anna [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Ivans, Inese I. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Schatz, Hendrik [Department of Physics and Astronomy, Michigan State University, E. Lansing, MI 48824 (United States); Sobeck, Jennifer S. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Sneden, Christopher [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)

2012-03-15

60

Sensitivity studies for r-process nucleosynthesis in three astrophysical scenarios  

E-print Network

In rapid neutron capture, or r-process, nucleosynthesis, heavy elements are built up via a sequence of neutron captures and beta decays that involves thousands of nuclei far from stability. Though we understand the basics of how the r-process proceeds, its astrophysical site is still not conclusively known. The nuclear network simulations we use to test potential astrophysical scenarios require nuclear physics data (masses, beta decay lifetimes, neutron capture rates, fission probabilities) for all of the nuclei on the neutron-rich side of the nuclear chart, from the valley of stability to the neutron drip line. Here we discuss recent sensitivity studies that aim to determine which individual pieces of nuclear data are the most crucial for r-process calculations. We consider three types of astrophysical scenarios: a traditional hot r-process, a cold r-process in which the temperature and density drop rapidly, and a neutron star merger trajectory.

Surman, R; Cass, J; Bentley, I; Aprahamian, A; McLaughlin, G C

2013-01-01

61

The r-Process in Metal Poor Stars and Black Hole Formation  

SciTech Connect

Nucleosynthesis of heavy nuclei in metal-poor stars is generally ascribed to the r-process, as the abundance pattern in many such stars agrees with the inferred Solar r-process abundances. Nonetheless, a significant number of these stars do not share this r-process template. they suggest that many such stars have begun an r-process, but it was prevented from running to completion in more massive stars by collapse to black holes, creating a 'truncated r-process,' or 'tr-process'. The observed fraction of tr-process stars is found to be consistent with expectations from the initial mass function (IMF), and they suggest that an apparent sharp truncation observed at around mass 160 could result from a combination of collapses to black holes and the difficulty of observing the higher mass rare earths. They test the tr-process hypothesis with calculations that are terminated before all r-process trajectories have been ejected. These produce qualitative agreement with observation when both black hole collapse and observational realities are taken into account.

Boyd, R N; Famiano, M A; Meyer, B S; Motizuki, Y; Kajino, T; Roederer, I U

2011-11-30

62

Prompt Iron Enrichment, Two r-Process Components, and Abundances in Very Metal-Poor Stars  

E-print Network

We present a model to explain the wide range of abundances for heavy r-process elements (mass number A > 130) at low [Fe/H]. This model requires rapid star formation and/or an initial population of supermassive stars in the earliest condensed clots of matter to provide a prompt or initial Fe inventory. Subsequent Fe and r-process enrichment was provided by two types of supernovae: one producing heavy r-elements with no Fe on a rather short timescale and the other producing light r-elements (A < or = 130) with Fe on a much longer timescale.

G. J. Wasserburg; Y. -Z. Qian

1999-11-30

63

Sensitivity of r-Process Nucleosynthesis to Light-Element Nuclear Reactions  

E-print Network

We study the efficiency and sensitivity of r-process nucleosynthesis to 18 light-element nuclear reaction rates. We adopt empirical power-law relations to parameterize the reaction sensitivities. We utilize two different hydrodynamic models for the neutrino-driven winds in order to study the dependence of our result on supernova wind models. We also utilize an exponential model to approximate a wide variety of other plausible conditions for the r-process. We identify several specific nuclear reactions among light neutron-rich nuclei that play a critical role in determining the final r-process nucleosynthesis yields. As an illustration, we examine ``semi-waiting'' points among the carbon isotopes. We show that not only neutron capture and $\\beta$-decay, but also $(\\alpha, \\mathrm{n})$ reactions are important in determining waiting points along the r-process path. Our numerical results from this sensitivity analysis serve foremost to clarify which light nuclear reactions are most influential in determining the final r-process abundances. We also quantify the effects of present nuclear uncertainties on the final r-process abundances. This study thus emphasizes and motivates which future determinations of nuclear reaction rates will most strongly impact our understanding of r-process nucleosynthesis.

T. Sasaqui; T. Kajino; G. J. Mathews; K. Otsuki; K. Nakamura

2005-08-11

64

The fundamental role of fission during r-process nucleosynthesis in neutron star mergers  

NASA Astrophysics Data System (ADS)

The rapid neutron-capture process, or r-process, is known to be of fundamental importance for explaining the origin of approximately half of the A > 60 stable nuclei observed in nature. Despite important efforts, the astrophysical site of the r-process remains unidentified. Here we study r-process nucleosynthesis in a material that is dynamically ejected by tidal and pressure forces during the merging of binary neutron stars. r-process nucleosynthesis during the decompression is known to be largely insensitive to the detailed astrophysical conditions because of efficient fission recycling, producing a composition that closely follows the solar r-abundance distribution for nuclei with mass numbers A > 140. Due to the important role played by fission in such a scenario, the impact of fission is carefully analyzed. We consider different state-of-the-art global models for the determination of the fission paths, nuclear level densities at the fission saddle points and fission fragment distributions. Based on such models, the sensitivity of the calculated r-process abundance distribution is studied. The fission path is found to strongly affect the region of heavy nuclei responsible for the fission recycling, while the fission fragment distribution of nuclei along the A ? 278 isobars defines the abundance pattern of nuclei produced in the 110 ? A ? 170 region. The late capture of prompt fission neutrons is also shown to affect the abundance distribution, and in particular the shape of the third r-process peak around A ? 195.

Goriely, S.

2015-02-01

65

Local and global effects of beta decays on r-process  

E-print Network

Nuclear beta decay rates are an essential ingredient in simulations of the astrophysical r-process. Most of these rates still rely on theoretical modeling. However, modern radioactive ion-beam facilities have allowed to measure beta half lives of some nuclei on or close to the r-process path. These data indicate that r-process half lives are in general shorter than anticipated in the standard theoretical predictions based on the Finite Range Droplet Model (FRDM). The data have also served as important constraints for improved predictions of half lives based on continuum QRPA calculations on top of the energy-density functional theory. Although these calculations are yet limited to spherical nuclei, they include the important r-process waiting point nuclei close to and at the neutron magic numbers $N=50, 82$ and 126. We have studied the impact of these new experimental and theoretical half lives on r-process nucleosynthesis within the two astrophysical sites currently favored for the r process: the neutrino-driven wind from the freshly born neutron star in a supernova explosion and the ejecta of the merger of two neutron stars. We find that the, in general, shorter beta decay rates have several important effects on the dynamics of r-process nucleosynthesis. At first, the matter flow overcomes the waiting point nuclei faster enhancing matter transport to heavier nuclei. Secondly, the shorter half lives result also in a faster consumption of neutrons resulting in important changes of the conditions at freeze-out with consequences for the final r-process abundances. Besides these global effects on the r-process dynamics, the new half lives also lead to some local changes in the abundance distributions.

O. L. Caballero; A. Arcones; I. N. Borzov; K. Langanke; G. Martinez-Pinedo

2014-05-01

66

Efficient Processing of Spatial Joins Using R-Trees  

Microsoft Academic Search

Spatial joins are one of the most important operations for combin- ing spatial objects of several relations. The efficient processing of a spatial join is extremely important since its execution time is super- linear in the number of spatial objects of the participating relations, and this number of objects may be very high. In this paper, we present a first

Thomas Brinkhoff; Hans-Peter Kriegel; Bernhard Seeger

1993-01-01

67

Process Systems Engineering R&D for Advanced Fossil Energy Systems  

SciTech Connect

This presentation will examine process systems engineering R&D needs for application to advanced fossil energy (FE) systems and highlight ongoing research activities at the National Energy Technology Laboratory (NETL) under the auspices of a recently launched Collaboratory for Process & Dynamic Systems Research. The three current technology focus areas include: 1) High-fidelity systems with NETL's award-winning Advanced Process Engineering Co-Simulator (APECS) technology for integrating process simulation with computational fluid dynamics (CFD) and virtual engineering concepts, 2) Dynamic systems with R&D on plant-wide IGCC dynamic simulation, control, and real-time training applications, and 3) Systems optimization including large-scale process optimization, stochastic simulation for risk/uncertainty analysis, and cost estimation. Continued R&D aimed at these and other key process systems engineering models, methods, and tools will accelerate the development of advanced gasification-based FE systems and produce increasingly valuable outcomes for DOE and the Nation.

Zitney, S.E.

2007-09-11

68

The Hamburg/ESO R-process Enhanced Star survey (HERES). X. HE 2252-4225, one more r-process enhanced and actinide-boost halo star  

NASA Astrophysics Data System (ADS)

Context. Studies of the r-process enhanced stars are important for understanding the nature and origin of the r-process better. Aims: We present a detailed abundance analysis of a very metal-poor giant star discovered in the HERES project, HE 2252-4225, which exhibits overabundances of the r-process elements with [r/Fe] = +0.80. Methods: We determined the stellar atmosphere parameters, Teff = 4710 K, log g = 1.65, and [ Fe/H ] = -2.63, and chemical abundances by analysing the high-quality VLT/UVES spectra. The surface gravity was calculated from the non-local thermodynamic equilibrium (NLTE) ionisation balance between Fe i and Fe ii. Results: Accurate abundances for a total of 38 elements, including 22 neutron-capture elements beyond Sr and up to Th, were determined in HE 2252-4225. For every chemical species, the dispersion in the single line measurements around the mean does not exceed 0.12 dex. This object is deficient in carbon, as expected for a giant star with Teff < 4800 K. The stellar Na-Zn abundances are well fitted by the yields of a single supernova of 14.4 M?. For the neutron-capture elements in the Sr-Ru, Ba-Yb, and Os-Ir regions, the abundance pattern of HE 2252-4225 is in excellent agreement with the average abundance pattern of the strongly r-process enhanced stars CS 22892-052, CS 31082-001, HE 1219-0312, and HE 1523-091. This suggests a common origin of the first, second, and third r-process peak elements in HE 2252-4225 in the classical r-process. We tested the solar r-process pattern based on the most recent s-process calculations of Bisterzo, Travaglio, Gallino, Wiescher, and Kppeler and found that elements in the range from Ba to Ir match it very well. No firm conclusion can be drawn about the relationship between the first neutron-capture peak elements, Sr to Ru, in HE 2252-4225 and the solar r-process, owing to the uncertainty in the solar r-process. The investigated star has an anomalously high Th/Eu abundance ratio, so that radioactive dating results in a stellar age of ? = 1.5 1.5 Gyr that is not expected for a very metal-poor halo star. Based on observations collected at the European Southern Observatory, Paranal, Chile (Proposal numbers 170.D-0010, and 280.D-5011).Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A43

Mashonkina, L.; Christlieb, N.; Eriksson, K.

2014-09-01

69

Beta decay rates for nuclei with 115 < A < 140 for r-process nucleosynthesis  

E-print Network

For r-process nucleosynthesis the beta decay rates for a number of neutron-rich intermediate heavy nuclei are calculated. The model for the beta strength function is able to reproduce the observed half~lives quite well.

Kamales Kar; Soumya Chakravarti; V. R. Manfredi

2006-03-19

70

r-process nucleosynthesis in the high-entropy supernova bubble  

NASA Technical Reports Server (NTRS)

We show that the high-temperature, high-entropy evacuated region outside the recent neutron star in a core-collapse supernova may be an ideal r-process site. In this high-entropy environment it is possible that most nucleons are in the form of free neutrons or bound into alpha particles. Thus, there can be many neutrons per seed nucleus even though the material is not particularly neutron rich. The predicted amount of r-process material ejected per event from this environment agrees well with that required by simple galactic evolution arguments. When averaged over regions of different neutron excess in the supernova ejecta, the calculated r-process abundance curve can give a good representation of the solar-system r-process abundances as long as the entropy per baryon is sufficiently high. Neutrino irradiation may aid in smoothing the final abundance distribution.

Meyer, B. S.; Mathews, G. J.; Howard, W. M.; Woosley, S. E.; Hoffman, R. D.

1992-01-01

71

The effects of r-process heating on fallback accretion in compact object mergers  

Microsoft Academic Search

We explore the effects of r-process nucleosynthesis on fallback accretion in neutron star (NS)-NS and black hole-NS mergers, and the resulting implications for short-duration gamma-ray bursts (GRBs). Though dynamically important, the energy released during the r-process is not yet taken into account in merger simulations. We use a nuclear reaction network to calculate the heating (due to beta decays and

B. D. Metzger; A. Arcones; E. Quataert; G. Martnez-Pinedo

2010-01-01

72

Supernovae as the Site of the r-Process: Implications for Gamma-Ray Astronomy  

E-print Network

We discuss how detection of gamma-ray emission from the decay of r-process nuclei can improve our understanding of r-process nucleosynthesis. We find that a gamma-ray detector with a sensitivity of 10**(-7)/cm**2/s at 100-700 keV may detect the emission from the decay of Sb125, Cs137, Ce144, Eu155, and Os194 produced in a future Galactic supernova. In addition, such a detector may detect the emission from the decay of Sn126 in the Vela supernova remnant and the diffuse emission from the decay of Sn126 produced by past supernovae in our Galaxy. The required detector sensitivity is similar to what is projected for the proposed Advanced Telescope for High Energy Nuclear Astrophysics (ATHENA). Both the detection of gamma-ray emission from the decay of several r-process nuclei (e.g., Sb125 and Os194) produced in future Galactic supernovae and the detection of emission from the decay of Sn126 in the Vela supernova remnant would prove that supernovae are a site of the r-process. Furthermore, the former detection would allow us to determine whether or not the r-process nuclei are produced in relative proportions specified by the solar r-process abundance pattern in supernova r-process events. Finally, detection of diffuse emission from the decay of Sn126 in our Galaxy would eliminate neutron star/neutron star mergers as the main source for the r-process nuclei near mass number A=126.

Y. -Z. Qian; P. Vogel; G. J. Wasserburg

1998-03-25

73

NEW ABUNDANCE DETERMINATIONS OF CADMIUM, LUTETIUM, AND OSMIUM IN THE r-PROCESS ENRICHED STAR BD +17 3248  

E-print Network

NEW ABUNDANCE DETERMINATIONS OF CADMIUM, LUTETIUM, AND OSMIUM IN THE r-PROCESS ENRICHED STAR BD +17 ABUNDANCE DETERMINATIONS OF CADMIUM, LUTETIUM, AND OSMIUM IN THE r-PROCESS ENRICHED STAR BD +17 3248, Ian U

Cowan, John

74

Processing of R-Ba-Cu-O superconductors  

SciTech Connect

Precipitation processes were developed to introduce second phases as flux pinning centers in Gd-Ba-Cu-O and Nd-Ba-Cu-O superconductors. In Gd-Ba-Cu-O, precipitation is caused by the decrease of the upper solubility limit of Gd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7} solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd{sub 1.2}Ba{sub 1.8}Cu{sub 3}O{sub 7} in low oxygen partial pressure can produce dispersed second phases. Gd211 is formed as a separate phase while extensive Gd124 type stacking fault is formed instead of a separate CuO phase. As a result of the precipitation reaction, the transition temperature and critical current density are increased. In Nd-Ba-Cu-O, precipitation is caused by the decrease of the lower solubility limit of Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7} solid solution (Nd123ss) in oxygen. DTA results reveal the relative stability of Nd123ss in different oxygen partial pressures. In 1 bar oxygen partial pressure, Nd123ss with x = 0.1 is the most stable phase. In lower oxygen partial pressures, the most stable composition shifts towards the stoichiometric composition. The relative stability changes faster with decreasing oxygen partial pressure. Therefore, processing in oxygen and air tends to produce broad superconducting transitions but sharp transitions can be achieved in 0.01 bar and 0.001 bar oxygen partial pressures. While the lower solubility limits in 0.01 bar and 0.001 bar oxygen partial pressures remain at x = 0.00, the solubility limits in oxygen and air show a narrowing with decreasing temperature. Because of the narrowing of the solubility range in oxygen, oxygen annealing of Nd123 initially processed in low oxygen partial pressures will result in precipitation of second phases. The equilibrium second phase is BaCuO{sub 2} for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba{sub 2}CuO{sub 3.3} and Ba{sub 2}Cu{sub 3}O{sub 5+y}. However, annealing at low temperature may produce a fine metastable transition phase. A coherent intermediate perovskite structure with a composition of BaCuO{sub 2} is observed along with a high density of dislocations during the precipitation process at 500 C in oxygen. It is believed that oxygen annealing at 900 C produces the equilibrium BaCuO{sub 2} phase. These precipitates are responsible for the strong flux pinning in Nd123 melt-textured in low oxygen partial pressure.

Wu, H.

1998-02-23

75

Production of All the r-process Nuclides in the Dynamical Ejecta of Neutron Star Mergers  

NASA Astrophysics Data System (ADS)

Recent studies suggest that binary neutron star (NS-NS) mergers robustly produce heavy r-process nuclei above the atomic mass number A ~ 130 because their ejecta consist of almost pure neutrons (electron fraction of Y e < 0.1). However, the production of a small amount of the lighter r-process nuclei (A ? 90-120) conflicts with the spectroscopic results of r-process-enhanced Galactic halo stars. We present, for the first time, the result of nucleosynthesis calculations based on the fully general relativistic simulation of a NS-NS merger with approximate neutrino transport. It is found that the bulk of the dynamical ejecta are appreciably shock-heated and neutrino processed, resulting in a wide range of Y e (?0.09-0.45). The mass-averaged abundance distribution of calculated nucleosynthesis yields is in reasonable agreement with the full-mass range (A ? 90-240) of the solar r-process curve. This implies, if our model is representative of such events, that the dynamical ejecta of NS-NS mergers could be the origin of the Galactic r-process nuclei. Our result also shows that radioactive heating after ~1 day from the merging, which gives rise to r-process-powered transient emission, is dominated by the ?-decays of several species close to stability with precisely measured half-lives. This implies that the total radioactive heating rate for such an event can be well constrained within about a factor of two if the ejected material has a solar-like r-process pattern.

Wanajo, Shinya; Sekiguchi, Yuichiro; Nishimura, Nobuya; Kiuchi, Kenta; Kyutoku, Koutarou; Shibata, Masaru

2014-07-01

76

The yields of r-process elements and chemical evolution of the Galaxy  

E-print Network

The supernova yields of r-process elements are obtained as a function of the mass of their progenitor stars from the abundance patterns of extremely metal-poor stars on the left-side [Ba/Mg]-[Mg/H] boundary with a procedure proposed by Tsujimoto and Shigeyama. The ejected masses of r-process elements associated with stars of progenitor mass $M_{ms}\\leq18M_{\\odot}$ are infertile sources and the SNe II with 20$M_{\\odot}\\leq M_{ms}\\leq 40M_{\\odot}$are the dominant source of r-process nucleosynthesis in the Galaxy. The ratio of these stars 20$M_{\\odot}\\leq M_{ms}\\leq40M_{\\odot}$ with compared to the all massive stars is about $\\sim$18%. In this paper, we present a simple model that describes a star's [r/Fe] in terms of the nucleosynthesis yields of r-process elements and the number of SN II explosions. Combined the r-process yields obtained by our procedure with the scatter model of the Galactic halo, the observed abundance patterns of the metal-poor stars can be well reproduced

Zhe Chen; Jiang Zhang; YanPing Chen; WenYuan Cui; Bo Zhang

2006-08-26

77

The yields of r-process elements and chemical evolution of the Galaxy  

E-print Network

The supernova yields of r-process elements are obtained as a function of the mass of their progenitor stars from the abundance patterns of extremely metal-poor stars on the left-side [Ba/Mg]-[Mg/H] boundary with a procedure proposed by Tsujimoto and Shigeyama. The ejected masses of r-process elements associated with stars of progenitor mass $M_{ms}\\leq18M_{\\odot}$ are infertile sources and the SNe II with 20$M_{\\odot}\\leq M_{ms}\\leq 40M_{\\odot}$are the dominant source of r-process nucleosynthesis in the Galaxy. The ratio of these stars 20$M_{\\odot}\\leq M_{ms}\\leq40M_{\\odot}$ with compared to the all massive stars is about $\\sim$18%. In this paper, we present a simple model that describes a star's [r/Fe] in terms of the nucleosynthesis yields of r-process elements and the number of SN II explosions. Combined the r-process yields obtained by our procedure with the scatter model of the Galactic halo, the observed abundance patterns of the metal-poor stars can be well reproduced

Chen, Z; Chen, Y P; Cui, W Y; Zhang, B; Chen, Zhe; Zhang, Jiang; Chen, YanPing; Cui, WenYuan; Zhang, Bo

2006-01-01

78

The r-process nucleosynthesis in an expanding hot bubble in supernovae explosion  

NASA Astrophysics Data System (ADS)

The r-process is one of the major nucleosynthesis processes responsible for the production of heavy elements beyond iron. Recent models of r-process nucleosynthesis rely on a neutrino-heated bubble developing at late times, which provides both the necessary conditions and the requisite amount of ejected mass for the r-process (Wooseley et al '94) . In the neutrino-driven explosion, only a small amount of matter is heated to the requisite high specific energy and entropy. Meyer et al (1992) first calculated the r-process under conditions appropriate to a neutrino-heated bubble and found that the solar r-process abundances could be replicated. They showed that the hot bubble that forms outside the protoneutron star during a SN explosion may be a viable site for the r-process as long as the entropy per baryon can be made sufficiently high. But in a very neutron rich environment such as a neutron star , the r-process could occur even at low entropy (Cowan and Thielemann, 2004). The high entropy wind is not the correct r-process site , owing to the inherent deficiencies in the abundance pattern below A=110 as well as the problems in obtaining the high entropies in SN II explosions required for producing the massive r-process nuclei up to A ? 195 and beyond ( Freiburghaus et al., 1999). Modelers of r-process nucleosynthesis find the entropy of the expanding matter and the overall n/p ratio to be more useful parameter than the temp and neutron density. We have tried to associate the explosion entropies with the site-independent classical approach (n[n] and T) and thereby compare the results of the two approaches from the abundances at different entropy conditions. We find that en entropy of ? 300 with Y[e] ? 0.45 can lead to a successful r-process. This is in agreement with the r-process abundance peaks at n[n] ? 10^32 cm^-3 and T[9] ? 1.5 . References : 1. Cowan J.J. and Thielemann F. K., Physics Today, 2004 2. Woosley S.E., Wilson J.R., Mathews G. J., Hoffman R.D. and Meyer B.S., 1994, ApJ, 433, 229 3. Takahashi K., Witti J. and Janka H.-Th., 1994, A & A , 286, 857 4. Meyer B. S., Mathews G. J., Howard W. M., Woosley S. E. and Hoffman R.D.,1992, ApJ, 399, 656 5. Freiburghaus C., Rembges J. F., Rauscher T.,Kolbe E., Thielemann F. K., kratz K. L., Pfeiffer B. and Cowan J. J., 1999, ApJ, 516, 381

Baruah, Rulee; Duorah, H. L.; Duorah, K.

2006-08-01

79

Fast Fully Adaptive Processing: A Multistage STAP O. Saleh, R. S. Adve, and R. J. Riddolls  

E-print Network

optimal space- time adaptive processing (STAP) is well-accepted to be imprac- tical. Previous work has transformation of the space-time data to the angle-Doppler domain. Reducing the adaptive DoF yields corresponding of this algorithm using measured high frequency surface wave radar data. I. INTRODUCTION Space-time adaptive

Adve, Raviraj

80

NanoFermentationTM Process Wins R&D 100 Award  

E-print Network

#12;NanoFermentationTM Process Wins R&D 100 Award New Process Developed for Manufacturing Nanoscale of NanoFermentationTM are the manufacture of highly crystalline nanoscale particles of doped ferrites NanoFermentationTM uses a variety of natural metal-reducing bacterial strains to create tailored

81

3D VISUALIZATION OF CONSTRUCTION PROCESSES AND Vineet R. Kamat1  

E-print Network

. In the construction industry, complex decisions yielding maximum benefit are an essential component of process design construction, such as in the manufacturing and service industries. Construction simulation model developers3D VISUALIZATION OF CONSTRUCTION PROCESSES AND PRODUCTS Vineet R. Kamat1 , Julio C. Martinez2 1

Kamat, Vineet R.

82

R78 Dispatch Language processing: The anatomy of meaning and syntax  

E-print Network

R78 Dispatch Language processing: The anatomy of meaning and syntax Gabriella Vigliocco Recent in processing the structure (syntax) and meaning (semantics) of a sentence, setting the stage- tence (syntax). Recent studies, using imaging techniques to identify regions of the brain whose activity

Vigliocco, Gabriella

83

Scenarios and the design process in medical application R. Rasoulifar*, G. Thomann, F. Villeneuve  

E-print Network

in medical domain have attracted the design researchers. The design process of medial devices has yetScenarios and the design process in medical application R. Rasoulifar*, G. Thomann, F. Villeneuve G of medical application. Keywords: Scenario-Based Design (SBD), Medical Application, User integration 1

Paris-Sud XI, Université de

84

Ris-R-1570(EN) A development process meta-model  

E-print Network

Ris-R-1570(EN) A development process meta-model for Web based expert systems: the Web engineering 2006 #12;Author: Ioannis M. Dokas & Alexandre Alapetite Title: A development process meta-model for Web and experience of Web engineering and expert systems be combined and applied in order to develop effective

85

Electrochromic Polymers for Easily Processed Devices John R. Reynolds,* Avni A. Argun, Irina Schwendeman,  

E-print Network

Electrochromic Polymers for Easily Processed Devices John R. Reynolds,* Avni A. Argun, Irina for electrochromic applications. These polymers exhibit ease of processability and useful mechanical properties (e.g. flexibility). However, the major strength of these organic-based materials is that their electrochromic

Tanner, David B.

86

A Process Calculus for Mobile Ad Hoc Networks$ Anu Singh, C. R. Ramakrishnan, Scott A. Smolka  

E-print Network

A Process Calculus for Mobile Ad Hoc Networks$ Anu Singh, C. R. Ramakrishnan, Scott A. Smolka the -calculus, a process calculus for formally modeling and reason- ing about Mobile Ad Hoc Wireless Networks (MANETs) and their protocols. The -calculus naturally captures essential characteristics of MANETs, includ

Ramakrishnan, C. R.

87

The r-process nucleosynthesis during the decompression of neutron star crust material  

SciTech Connect

About half of the nuclei heavier than iron observed in nature are produced by the so-called rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved, for which essentially no experimental data exist. The present paper emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Both the astrophysics and the nuclear physics difficulties are critically reviewed with special attention paid to the r-process taking place during the decompression of neutron star matter following the merging of two neutron stars.

Goriely, S. [Institut d'Astronomie et d'Astrophysique, CP-226, Universit Libre de Bruxelles, 1050 Brussels (Belgium); Bauswein, A. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece and Max-Planck-Institut fr Astrophysik, Postfach 1317, 85741 Garching (Germany); Janka, H.-T. [Max-Planck-Institut fr Astrophysik, Postfach 1317, 85741 Garching (Germany); Sida, J.-L.; Lematre, J.-F.; Panebianco, S. [C.E.A. Saclay, Irfu/Service de Physique Nuclaire, 91191 Gif-sur-Yvette (France); Dubray, N.; Hilaire, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

2014-05-02

88

Enrichment of the r-process Element Europium in the Galactic Halo  

E-print Network

We investigate the enrichment of europium, as a representative of r-process elements, in the Galactic halo. In present chemical evolution models, stars are assumed to be formed through shock processes by supernovae (SNe). The enrichment of the interstellar medium is calculated by a one-zone approach. The observed large dispersions in [Eu/Fe] for halo stars, converging with increasing metallicity, can be explained with our models. In addition, the mass range of SNe for the {\\it r}-process site is constrained to be either stars of $8-10 M_\\odot$ or $\\gtrsim 30 M_\\odot$.

Yuhri Ishimaru; Shinya Wanajo

1998-12-03

89

The decompression of the outer neutron star crust and r-process nucleosynthesis  

E-print Network

The rapid neutron-capture process, or r-process, is known to be fundamental for explaining the origin of approximately half of the A>60 stable nuclei observed in nature. In recent years nuclear astrophysicists have developed more and more sophisticated r-process models, by adding new astrophysical or nuclear physics ingredients to explain the solar system composition in a satisfactory way. Despite these efforts, the astrophysical site of the r-process remains unidentified. The composition of the neutron star outer crust material is investigated after the decompression that follows its possible ejection. The composition of the outer crust of a neutron star is estimated before and after decompression. Two different possible initial conditions are considered, namely an idealized crust composed of cold catalyzed matter and a crust initially in nuclear statistical equilibrium at temperatures around 10 GK. We show that in this second case before decompression and at temperatures typically corresponding to 8 GK, the...

Goriely, S; Janka, H -T; Pearson, J M

2011-01-01

90

Isotopic compositions of bismuth, lead, thallium, and mercury from mini r-processing  

NASA Technical Reports Server (NTRS)

The yields of stable isotopes of Bi, Pb, Tl and Hg as well as yields of Pb-205 are calculated with a parametrized model for 'mini r-processing' in the Ne, O, C-rich zones of explosive burning in massive stars. The Pb isotopic compositions stand out by their comparatively low Pb-207 yields and by the fact that this r-process variant yields Pb-204 quite abundantly. The average Pb-205/Pb-204 yield ratio of 6.1 is the same order of magnitude as yield ratios deduced for s-processing. The Hg from this mini r-process looks like normal solar-system mercury, but with Hg-196 missing and the light s-isotopes A = 198, 199, 200 and 201 depleted (especially the odd-A species).

Heymann, D.; Liffman, K.

1986-01-01

91

Decay of the $r$-process nuclides $^{137, 138, 139}$Sb, and the A=130 solar $r$-process abundance peak  

E-print Network

Half-life (T(1/2)) and beta-delayed neutron branching (P(n)) values of 492(25) ms and 49(8)\\%, 350(15) ms and 72(8)\\%, and 93(13) ms and 90(10)\\% for the r-process nuclei (137,138,139)Sb, respectively, have been measured at the CERN On-Line Isotope Mass Separator (ISOLDE) facility by counting beta-delayed neutrons. More precise T(1/2) and P(n) values of 300(15) ms and 27(4)\\%, and 273(7) ms and 50(8)\\% for (136,137)Sn, respectively, have also been measured. The sources were prepared by using the selective ionization of Sb or Sn with the Resonance Ionization Laser Ion Source and the high-resolution mass separator. The new data for Sb isotopes are compared with calculated T(1/2) and P(n) values for both spherical and nonspherical shapes. The data have been incorporated into parametrized nucleosynthesis calculations of the r process in high-entropy winds of core-collapse supernovae in order to study the properties of the A = 130 solar-system r-process abundance peak.

Arndt, O; Farouqi, K; Koester, U; Kratz, K-L; Pfeiffer, B; Walters, W B; Hoteling, N; Fedosseev, V; Hennrich, S; Woehr, A; Shergur, J; Hecht, A A

2011-01-01

92

Strength of nuclear shell effects at N=126 in the r-process region  

SciTech Connect

We have investigated nuclear-shell effects across the magic number N=126 in the region of the r-process path. Microscopic calculations have been performed using the relativistic Hartree-Bogoliubov approach within the framework of the relativistic mean-field (RMF) theory for isotopic chains of rare-earth nuclei in the r-process region. The Lagrangian model NL-SV1 with the inclusion of the vector self-coupling of {omega} meson has been employed. The RMF results show that the shell effects at N=126 remain strong and exhibit only a slight reduction in the strength in going from the r-process path to the neutron drip line. This is in striking contrast to a systematic weakening of the shell effects at N=82 in the r-process region predicted earlier in the similar approach. In comparison the shell effects with microscopic-macroscopic mass formulas show a near constancy of shell gaps leading to strong shell effects in the region of r-process path to the drip line. A recent analysis of solar-system r-process abundances in a prompt supernova explosion model using various mass formulas, including the recently introduced mass tables based on Hartree-Fock-Bogoliubov method shows that although mass formulas with weak shell effects at N=126 give rise to a spread and an overproduction of nuclides near the third abundance peak at A{approx}190, mass tables with droplet models showing stronger shell effects are able to reproduce the abundance features near the third peak appropriately. In comparison, several analyses of the second r-process peak at A{approx}130 have required weakened (quenched) shell effects at N=82. Our predictions in the RMF theory with NL-SV1, which exhibit weaker shell effects at N=82 and correspondingly stronger shell effects at N=126 in the r-process region, support the conjecture that a different nature of the shell effects at the magic numbers may be at play in r-process nucleosynthesis of heavy nuclei.

Farhan, A.R.; Sharma, M.M. [Physics Department, Kuwait University, 13060 (Kuwait)

2006-04-15

93

r-PROCESS NUCLEOSYNTHESIS IN DYNAMICALLY EJECTED MATTER OF NEUTRON STAR MERGERS  

SciTech Connect

Although the rapid neutron-capture process, or r-process, is fundamentally important for explaining the origin of approximately half of the stable nuclei with A > 60, the astrophysical site of this process has not been identified yet. Here we study r-process nucleosynthesis in material that is dynamically ejected by tidal and pressure forces during the merging of binary neutron stars (NSs) and within milliseconds afterward. For the first time we make use of relativistic hydrodynamical simulations of such events, defining consistently the conditions that determine the nucleosynthesis, i.e., neutron enrichment, entropy, early density evolution and thus expansion timescale, and ejecta mass. We find that 10{sup -3}-10{sup -2} M{sub sun} are ejected, which is enough for mergers to be the main source of heavy (A {approx}> 140) galactic r-nuclei for merger rates of some 10{sup -5} yr{sup -1}. While asymmetric mergers eject 2-3 times more mass than symmetric ones, the exact amount depends weakly on whether the NSs have radii of {approx}15 km for a 'stiff' nuclear equation of state (EOS) or {approx}12 km for a 'soft' EOS. r-process nucleosynthesis during the decompression becomes largely insensitive to the detailed conditions because of efficient fission recycling, producing a composition that closely follows the solar r-abundance distribution for nuclei with mass numbers A > 140. Estimating the light curve powered by the radioactive decay heating of r-process nuclei with an approximative model, we expect high emission in the B-V-R bands for 1-2 days with potentially observable longer duration in the case of asymmetric mergers because of the larger ejecta mass.

Goriely, Stephane [Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, C.P. 226, B-1050 Brussels (Belgium); Bauswein, Andreas; Janka, Hans-Thomas [Max-Planck-Institut fuer Astrophysik, Postfach 1317, D-85741 Garching (Germany)

2011-09-10

94

The r-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS  

SciTech Connect

We examine r-process nucleosynthesis in the neutrino-driven wind from the thick accretion disk (or 'torus') around a black hole. Such systems are expected as remnants of binary neutron star or neutron star-black hole mergers. We consider a simplified, analytic, time-dependent evolution model of a 3 M{sub Sun} central black hole surrounded by a neutrino emitting accretion torus with 90 km radius, which serves as basis for computing spherically symmetric neutrino-driven wind solutions. We find that ejecta with modest entropies ({approx}30 per nucleon in units of the Boltzmann constant) and moderate expansion timescales ({approx}100 ms) dominate in the mass outflow. The mass-integrated nucleosynthetic abundances are in good agreement with the solar system r-process abundance distribution if a minimal value of the electron fraction at the charged-particle freezeout, Y{sub e,min} {approx} 0.2, is achieved. In the case of Y{sub e,min} {approx} 0.3, the production of r-elements beyond A {approx} 130 does not reach to the third peak but could still be important for an explanation of the abundance signatures in r-process deficient stars in the early Galaxy. The total mass of the ejected r-process nuclei is estimated to be {approx}1 Multiplication-Sign 10{sup -3} M{sub Sun }. If our model was representative, this demands a Galactic event rate of {approx}2 Multiplication-Sign 10{sup -4} yr{sup -1} for black-hole-torus winds from merger remnants to be the dominant source of the r-process elements. Our result thus suggests that black-hole-torus winds from compact binary mergers have the potential to be a major, but probably not the dominant, production site of r-process elements.

Wanajo, Shinya [Technische Universitaet Muenchen, Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching (Germany); Janka, Hans-Thomas, E-mail: shinya.wanajo@universe-cluster.de, E-mail: thj@mpa-garching.mpg.de [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany)

2012-02-20

95

Nucleosynthesis of Light Elements and Heavy r-Process Elements through the nu-Process in Supernova Explosion  

E-print Network

We study the nucleosyntheses of the light elements 7Li and 11B and the r-process elements in Type II supernovae from the point of view of supernova neutrinos and Galactic chemical evolution. We investigate the influence of the luminosity and average energy (temperature) of supernova neutrinos on these two nucleosynthesis processes. Common models of the total energy E_nu and the decay time of the neutrino luminosity tau_nu of supernova neutrinos are adopted to understand both processes. We adopt the model of the supernova explosion of a 16.2 M_odot star, which corresponds to SN 1987A, and calculate the nucleosynthesis of the light elements by the postprocessing. We find that the ejected masses of 7Li and 11B are roughly proportional to the total neutrino energy and weakly dependent on the decay time of the neutrino luminosity. As for the r-process nucleosynthesis, we adopt the same models of the neutrino luminosity in the neutrino-driven wind models of a 1.4 M_odot neutron star. We find that the r-process nucleosynthesis is affected through the peak neutrino luminosity, which depends on E_nu/tau_nu. We also discuss the unresolved problem of the overproduction of 11B in the Galactic chemical evolution of the light elements. We have to assume E_{nu} < 1.2 \\times 10^{53} ergs to avoid the overproduction of 11B, which is too small to accept in comparison to 3.0 \\times 10^{53} ergs deduced from the observation of SN1987A. We propose to reduce the temperature of nu_{mu, tau} and their anti-particles to T_{nu_{mu, tau}} = T_{bar{nu}_{mu,tau}} = 6.0 MeV/k. This modification of the neutrino temperature is shown to resolve the overproduction problem of 11B while still keeping a successful r-process abundance pattern.

T. Yoshida; M. Terasawa; T. Kajino; K. Sumiyoshi

2003-11-21

96

The impact of uncertain nuclear masses near closed shells on the r-process abundance pattern  

NASA Astrophysics Data System (ADS)

Calculations of rapid neutron capture nucleosynthesis involve thousands of pieces of nuclear data for which no experimental information is available. Of the nuclear data sets needed for r-process simulationsmasses, ? -decay rates, ? -delayed neutron emission probabilities, neutron capture rates, fission probabilities and daughter product distributions, neutrino interaction ratesmasses are arguably the most important, because they are a key ingredient in the calculations of all other theoretical quantities. Here, we investigate how uncertainties in nuclear masses translate into uncertainties in the final abundance pattern produced in r-process simulations. We examine the influence of individual mass variations on three types of r-process simulationsa hot wind, cold wind, and neutron star merger r processwith markedly different r-process paths and resulting final abundance patterns. We find the uncertainties in the abundance patterns due to the mass variations exceed the differences due to the astrophysics. This situation can be improved, however, by even modest reductions in mass uncertainties.

Mumpower, M.; Surman, R.; Fang, D. L.; Beard, M.; Aprahamian, A.

2015-03-01

97

PRIMORDIAL r-PROCESS DISPERSION IN METAL-POOR GLOBULAR CLUSTERS  

SciTech Connect

Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). Recent detections of low [Pb/Eu] ratios or upper limits in several metal-poor GCs indicate that the heavy elements in these GCs were produced exclusively by an r-process. Re-examining GC heavy element abundances from the literature, we find unmistakable correlations between the [La/Fe] and [Eu/Fe] ratios in four metal-poor GCs (M5, M15, M92, and NGC 3201), only two of which were known previously. This indicates that the total r-process abundances vary from star to star (by factors of 2-6) relative to Fe within each GC. We also identify potential dispersion in two other GCs (M3 and M13). Several GCs (M12, M80, and NGC 6752) show no evidence of r-process dispersion. The r-process dispersion is not correlated with the well-known light element dispersion, indicating that it was present in the gas throughout the duration of star formation. The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution.

Roederer, Ian U., E-mail: iur@obs.carnegiescience.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2011-05-01

98

On the astrophysical robustness of neutron star merger r-process  

E-print Network

In this study we explore the nucleosynthesis in the dynamic ejecta of compact binary mergers. We are particularly interested in the question how sensitive the resulting abundance patterns are to the parameters of the merging system. Therefore, we systematically investigate combinations of neutron star masses in the range from 1.0 to 2.0 \\Msun and, for completeness, we compare the results with those from two simulations of a neutron star black hole merger. The ejecta masses vary by a factor of five for the studied systems, but all amounts are (within the uncertainties of the merger rates) compatible with being a major source of cosmic r-process. The ejecta undergo a robust r-process nucleosynthesis which produces all the elements from the second to the third peak in close-to-solar ratios. Most strikingly, this r-process is extremely robust, all 23 investigated binary systems yield practically identical abundance patterns. This is mainly the result of the ejecta being extremely neutron rich (\\ye $\\approx0.04$) and the r-process path meandering along the neutron drip line so that the abundances are determined entirely by nuclear rather than by astrophysical properties. This robustness together with the ease with which both the second and third peak are reproduced make compact binary mergers the prime candidate for the source of the observed unique heavy r-process component.

O. Korobkin; S. Rosswog; A. Arcones; C. Winteler

2012-08-04

99

r-Process Abundance Signatures in Metal-Poor Halo Stars  

NASA Astrophysics Data System (ADS)

Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. Recent observations of the r-process-enriched star BD+17 3248 include new abundance determinations for the neutron-capture elements Cd I (Z=48), Lu II (Z = 71) and Os II (Z = 76), the first detections of these elements in metal-poor r-process-enriched halo stars. Combining these and previous observations, we have now detected 32 n-capture elements in BD+17 3248. This is the most of any metal-poor halo star to date. For the most r-process-rich (i.e. [Eu/Fe] ? 1) halo stars, such as CS 22892-052 and BD+17 3248, abundance comparisons show that the heaviest stable n-capture elements (i.e., Ba and above, Z ? 56) are consistent with a scaled solar system r-process abundance distribution. The lighter n-capture element abundances in these stars, however, do not conform to the solar pattern. These comparisons, as well as recent observations of heavy elements in metal-poor globular clusters, suggest the possibility of multiple synthesis mechanisms for the n-capture elements. The heavy element abundance patterns in most metal-poor halo stars do not resemble that of CS 22892-052, but the presence of heavy elements such as Ba in nearly all metal-poor stars without s-process enrichment indicates that r-process enrichment in the early Galaxy is common.

Cowan, John J.; Roederer, Ian U.; Sneden, Christopher; Lawler, James E.

2011-08-01

100

First Results from the CARIBU Facility: Mass Measurements on the r-Process Path  

NASA Astrophysics Data System (ADS)

The Canadian Penning Trap mass spectrometer has made mass measurements of 33 neutron-rich nuclides provided by the new Californium Rare Isotope Breeder Upgrade facility at Argonne National Laboratory. The studied region includes the Sn132 double shell closure and ranges in Z from In to Cs, with Sn isotopes measured out to A=135, and the typical measurement precision is at the 100 ppb level or better. The region encompasses a possible major waiting point of the astrophysical r process, and the impact of the masses on the r process is shown through a series of simulations. These first-ever simulations with direct mass information on this waiting point show significant increases in waiting time at Sn and Sb in comparison with commonly used mass models, demonstrating the inadequacy of existing models for accurate r-process calculations.

Van Schelt, J.; Lascar, D.; Savard, G.; Clark, J. A.; Bertone, P. F.; Caldwell, S.; Chaudhuri, A.; Levand, A. F.; Li, G.; Morgan, G. E.; Orford, R.; Segel, R. E.; Sharma, K. S.; Sternberg, M. G.

2013-08-01

101

Beta-decay spectroscopy relevant to the r-process nucleosynthesis  

SciTech Connect

A scientific program of beta-decay spectroscopy relevant to r-process nucleosynthesis has been started using high intensity U-beam at the RIBF. The first results of {beta}-decay half-lives of very neutron-rich Kr to Tc nuclides, all of which lie close to the r-process path, suggest a systematic enhancement of the the {beta}-decay rates of the Zr and Nb isotopes around A110 with respect to the predictions of the deformed quasiparticle-random-phase-approximation model (FRDM + QRPA). An impact of the results on the astrophysical r-process is discussed together with the future perspective of the {beta}-decay spectroscopy with the EURICA.

Nishimura, Shunji [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Collaboration: RIBF Decay Collaboration

2012-11-12

102

First Results from the CARIBU Facility: Mass Measurements on the r-Process Path  

E-print Network

The Canadian Penning Trap mass spectrometer has made mass measurements of 33 neutron-rich nuclides provided by the new Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The studied region includes the 132Sn double shell closure and ranges in Z from In to Cs, with Sn isotopes measured out to A = 135, and the typical measurement precision is at the 100 ppb level or better. The region encompasses a possible major waiting point of the astrophysical r process, and the impact of the masses on the r process is shown through a series of simulations. These first-ever simulations with direct mass information on this waiting point show significant increases in waiting time at Sn and Sb in comparison with commonly used mass models, demonstrating the inadequacy of existing models for accurate r-process calculations.

J. Van Schelt; D. Lascar; G. Savard; J. A. Clark; P. F. Bertone; S. Caldwell; A. Chaudhuri; 1 A. F. Levand; G. Li; G. E. Morgan; R. Orford; R. E. Segel; K. S. Sharma; M. G. Sternberg

2013-07-01

103

An expanding vortex site for the r-process in rotating stellar collapse  

NASA Technical Reports Server (NTRS)

The astrophysical site of r-process nucleosynthesis is investigated theoretically using two-dimensional expanding-vortex stellar-collapse simulations based on the Eulerian adaptive-mesh MHD code of Symbalisty (1984). The results are presented graphically, and it is found that the classical r-process can be explained as the result of the collapse of the highly rotating iron core of a 15-solar-mass star, in which the angular velocity along the rotation axis reaches a maximum of 1000 rad/s, corresponding to an angular momentum of 3.4 x 10 to the 48th erg/s for the inner 1.5 solar mass. The ejected jets are shown to yield about 0.0004 solar mass per supernova, sufficient to explain the observed abundances of r-process products.

Symbalisty, E. M. D.; Schramm, D. N.; Wilson, J. R.

1985-01-01

104

Evidence for supernova injection into the solar nebula and the decoupling of r-process nucleosynthesis.  

PubMed

The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A < 140 and negative r-process anomalies in isotopes A > 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy. PMID:24101483

Brennecka, Gregory A; Borg, Lars E; Wadhwa, Meenakshi

2013-10-22

105

Evidence for supernova injection into the solar nebula and the decoupling of r-process nucleosynthesis  

PubMed Central

The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calciumaluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A < 140 and negative r-process anomalies in isotopes A > 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy. PMID:24101483

Brennecka, Gregory A.; Borg, Lars E.; Wadhwa, Meenakshi

2013-01-01

106

The effects of r-process heating on fall-back accretion in compact object mergers  

Microsoft Academic Search

We explore the effects of r-process nucleosynthesis on fall-back accretion in\\u000aneutron star(NS)-NS and black hole-NS mergers, and the resulting implications\\u000afor short-duration gamma-ray bursts (GRBs). Though dynamically important, the\\u000aenergy released during the r-process is not yet taken into account in merger\\u000asimulations. We use a nuclear reaction network to calculate the heating (due to\\u000abeta-decays and nuclear fission)

A. Arcones; G. Mart inez-Pinedo; B. D. Metzger; E. Quataert

2009-01-01

107

Neutron capture on 130Sn during r-process freeze-out  

NASA Astrophysics Data System (ADS)

We examine the role of neutron capture on 130Sn during r-process freeze-out in the neutrino-driven wind environment of the core-collapse supernova. We find that the global r-process abundance pattern is sensitive to the magnitude of the neutron capture cross section of 130Sn. The changes to the abundance pattern include not only a relative decrease in the abundance of 130Sn and an increase in the abundance of 131Sn, but also a shift in the distribution of material in the rare earth and third peak regions.

Beun, J.; Blackmon, J. C.; Hix, W. R.; McLaughlin, G. C.; Smith, M. S.; Surman, R.

2009-02-01

108

The isovector imaginary neutron potential: a key ingredient for the r-process nucleosynthesis  

NASA Astrophysics Data System (ADS)

The isovector contribution to the imaginary component of the microscopic optical model potential is adjusted on experimental neutron strength function data. Within the Brckner-Hartree-Fock approximation of Jeukenne-Lejeune-Mahaux, it is shown that experimental data favours a strong isovector component that can have a drastic impact on the radiative neutron capture cross section for neutron-rich nuclei. If confirmed, this result strongly inhibits the resonant capture by exotic nuclei, so that the traditional r-process picture of the fast neutron captures during the nucleosynthesis r-process needs to be revisited in depth.

Goriely, S.; Delaroche, J.-P.

2008-05-01

109

The isovector imaginary neutron potential: A key ingredient for the r-process nucleosynthesis  

NASA Astrophysics Data System (ADS)

The isovector contribution to the imaginary component of the microscopic optical model potential is adjusted on experimental neutron strength function data. Within the Brckner-Hartree-Fock approximation of Jeukenne-Lejeune-Mahaux, it is shown that experimental data favours a strong isovector component that can have a drastic impact on the radiative neutron capture cross section for neutron-rich nuclei. If confirmed, this result strongly inhibits the resonant capture by exotic nuclei, so that the traditional r-process picture of the fast neutron captures during the nucleosynthesis r-process needs to be revisited in depth.

Goriely, S.; Delaroche, J.-P.

2007-09-01

110

Beta decay studies of r-process nuclei at the National Superconducting Cyclotron Laboratory  

E-print Network

The impact of nuclear physics on astrophysical r-process models is discussed, emphasizing the importance of beta-decay properties of neutron-rich nuclei. Several r-process motivated beta-decay experiments performed at the National Superconducting Cyclotron Laboratory are presented. The experiments include the measurement of beta-decay half-lives and neutron emission probabilities of nuclei in regions around Ni-78; Se-90; Zr-106 and Rh-120, as well as spectroscopic studies of Pd-120. A summary on the different experimental techniques employed, data analysis, results and impact on model calculations is presented.

J. Pereira; A. Aprahamian; O. Arndt; A. Becerril; T. Elliot; A. Estrade; D. Galaviz; S. Hennrich; P. Hosmer; R. Kessler; K. -L. Kratz; G. Lorusso; P. F. Mantica; M. Matos; F. Montes; P. Santi; B. Pfeiffer; M. Quinn; H. Schatz; F. Schertz; L. Schnorrenberger; E. Smith; B. E. Tomlin; W. Walters; A. Wohr

2009-01-13

111

Neutron Capture on 130Sn during r-Process Freeze-Out  

SciTech Connect

We examine the role of neutron capture on {sup 130}Sn during r-process freeze-out in the neutrino-driven wind environment of the core-collapse supernova. We find that the global r-process abundance pattern is sensitive to the magnitude of the neutron capture cross section of {sup 130}Sn. The changes to the abundance pattern include not only a relative decrease in the abundance of {sup 130}Sn and an increase in the abundance of {sup 131}Sn, but also a shift in the distribution of material in the rare earth and third peak regions.

Beun, Joshua [North Carolina State University; Blackmon, Jeffery C [Louisiana State University; Hix, William Raphael [ORNL; Mclaughlin, Gail C [North Carolina State University; Smith, Michael Scott [ORNL; Surman, Rebecca [Union College

2009-01-01

112

Supernovae as the Site of the {ital r}Process: Implications for Gamma-Ray Astronomy  

Microsoft Academic Search

We discuss how detection of gamma-ray emission from the decay of {ital r}-process nuclei can improve our understanding of {ital r}-process nucleosynthesis. We find that a gamma-ray detector with a sensitivity of 10⁻⁷γ cm⁻² s⁻¹ at {ital E}{sub γ} 100700 keV may detect the emission from the decay of ¹²⁵Sb, ¹³⁷Cs, ¹⁴⁴Ce, ¹⁵⁵Eu, and ¹⁹⁴Os produced in a future

Y.-Z. Qian; P. Vogel; G. J. Wasserburg

1998-01-01

113

Compact binary mergers as the origin of r-process elements in the Galactic halo  

SciTech Connect

Compact binary mergers (of double neutron star and black hole-neutron star systems) are suggested to be the major site of the r-process elements in the Galaxy by recent hydrodynamical and nucleosynthesis studies. It has been pointed out, however, that estimated long lifetimes of compact binaries are in conflict with the presence of r-process-enhanced stars at the metallicity [Fe/H] ? ?3. To resolve this problem, we examine the role of compact binary mergers in the early Galactic chemical evolution on the assumption that our Galactic halo was formed from merging sub-halos. The chemical evolutions are modeled for sub-halos with their total stellar masses between 10{sup 4}M{sub ?} and 2 10{sup 8}M{sub ?}. The lifetimes of compact binaries are assumed to be 100 Myr (95%) and 1 Myr (5%) according to recent binary population synthesis studies. We find that the r-process abundances (relative to iron; [r/Fe]) start increasing at [Fe/H] ? ?3 if the star formation rates are smaller for less massive sub-halos. Our models also suggest that the star-to-star scatter of [r/Fe]'s observed in Galactic halo stars can be interpreted as a consequence of greater gas outflow rates for less massive sub-halos. In addition, the sub-solar [r/Fe]'s (observed as [Ba/Fe] ? ?1.5 for [Fe/H] < ?3) are explained by the contribution from the short-lived (? 1 Myr) binaries. Our result indicates, therefore, that compact binary mergers can be potentially the origin of the r-process elements throughout the Galactic history.

Ishimaru, Yuhri [Department of Material Science, International Christian University, 3-10-2 Osawa, Mitaka, Tokyo 181-8585 (Japan); Wanajo, Shinya [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Prantzos, Nikos [Institut d'Astrophysique de Paris, UMR7095 CNRS, Univ. P. and M. Curie, 98bis Bd. Arago, 75104 Paris (France)

2014-05-02

114

Compact binary mergers as the origin of r-process elements in the Galactic halo  

NASA Astrophysics Data System (ADS)

Compact binary mergers (of double neutron star and black hole-neutron star systems) are suggested to be the major site of the r-process elements in the Galaxy by recent hydrodynamical and nucleosynthesis studies. It has been pointed out, however, that estimated long lifetimes of compact binaries are in conflict with the presence of r-process-enhanced stars at the metallicity [Fe/H] -3. To resolve this problem, we examine the role of compact binary mergers in the early Galactic chemical evolution on the assumption that our Galactic halo was formed from merging sub-halos. The chemical evolutions are modeled for sub-halos with their total stellar masses between 104M? and 2 108M?. The lifetimes of compact binaries are assumed to be 100 Myr (95%) and 1 Myr (5%) according to recent binary population synthesis studies. We find that the r-process abundances (relative to iron; [r/Fe]) start increasing at [Fe/H] ? -3 if the star formation rates are smaller for less massive sub-halos. Our models also suggest that the star-to-star scatter of [r/Fe]'s observed in Galactic halo stars can be interpreted as a consequence of greater gas outflow rates for less massive sub-halos. In addition, the sub-solar [r/Fe]'s (observed as [Ba/Fe] -1.5 for [Fe/H] < -3) are explained by the contribution from the short-lived ( 1 Myr) binaries. Our result indicates, therefore, that compact binary mergers can be potentially the origin of the r-process elements throughout the Galactic history.

Ishimaru, Yuhri; Wanajo, Shinya; Prantzos, Nikos

2014-05-01

115

WASTE PROCESSING ANNUAL NUCLEAR SAFETY RELATED R AND D REPORT FOR CY2008  

SciTech Connect

The Engineering and Technology Office of Waste Processing identifies and reduces engineering and technical risks associated with key waste processing project decisions. The risks, and actions taken to mitigate those risks, are determined through technology readiness assessments, program reviews, technology information exchanges, external technical reviews, technical assistance, and targeted technology development and deployment (TDD). The Office of Waste Processing TDD program prioritizes and approves research and development scopes of work that address nuclear safety related to processing of highly radioactive nuclear wastes. Thirteen of the thirty-five R&D approved work scopes in FY2009 relate directly to nuclear safety, and are presented in this report.

Fellinger, A.

2009-10-15

116

Supplementary Material for Structure determinants for accurate processing of miR172a in Arabidopsis thaliana  

E-print Network

Supplementary Material for Structure determinants for accurate processing of miR172a in Arabidopsis structure of A. lyrata pri-miR172a (related to Figure 4). #12;Supplementary Table 1. Key for diagrams

Weigel, Detlef

117

Processing effects in aluminum micro-channel tube for brazed R744 heat exchangers  

Microsoft Academic Search

The effects of processing on the mechanical behavior of aluminum alloy micro-channel tubing used in brazed automotive heat exchangers are evaluated in light of the stringent requirements of CO2 (R744 refrigerant) based systems. An apparatus was developed to simulate system operating conditions of pressure and elevated temperature in tube samples. Commercially extruded and processed AA3102 micro-channel tube samples were given

Gowreesan Vamadevan; Frank F. Kraft

2007-01-01

118

The even-odd systematics in R-process nuclide abundances  

NASA Technical Reports Server (NTRS)

The paper reports and discusses solar system N(R) abundances for nuclides A greater than 70, obtained as differences between measured solar system abundances and calculated S-process contributions. The abundance peak at A of about 163 in the rare earth element region reveals properties which are similar to those of the R-process peaks corresponding to magic neutron numbers N = 82 and N = 126. Systematic differences in the N(R) abundances of even-A and odd-A nuclides are restricted to specific mass regions. It is concluded that these differences are most probably related to the properties of nuclear species during beta(-) decay to the stability valley.

Marti, K.; Suess, H. E.

1988-01-01

119

Diverse Supernova Sources for the r-Process and Abundances in Metal-Poor Stars  

E-print Network

The dispersion and mean trends of r-process abundances in metal-poor stars are discussed based on a model of diverse supernova sources for the r-process. This model is unique in that its key parameters are inferred from solar system data independent of stellar observations at low metallicities. It is shown that this model provides a good explanation for the observed dispersion and mean trend of Eu abundances over -3 < [Fe/H] < -1. It is also shown that this model provides a means to discuss r-abundances in general. For example, the Ag abundance in any metal-poor star with observed Eu and Fe abundances can be calculated from the model. This approach is demonstrated with success for two stars and can be further tested by future Ag data. The dispersion and mean trend of Ag abundances in metal-poor stars are also calculated for comparison with future observations.

Y. -Z. Qian

2001-04-10

120

Development of Highly Efficient Saving Processes of Rare Earth in R-T-B Permanent Magnet  

NASA Astrophysics Data System (ADS)

In this study, cost reduction of manufacturing R (Nd, Pr, and Dy) -T (Fe, Co)-B permanent magnets was investigated. An efficient direct melting recycle of R-T-B magnet scraps and multiple methods for saving Dy were focused. In the former, Decarburization and deoxidation of R-T-B magnet scraps were developed as a pre-treatment technique for conventional induction melting. The decarburized scraps 0.001mass% carbon or less was subsequently deoxidized by calciothermic reduction. The recycled scraps can be used as low cost alloying elements by re-melting. In the latter, the casting conditions for R-T-B alloy with small admixture of Ga and the improved pulverization process of R-T-B magnet alloy were developed. Microstructure of R-T-B magnet alloy with small admixture Ga was optimized by controlling cooling rate during solidification, and its average crystalline size was to be 5 ?m. In order to obtain finer R-T-B magnet alloy powder preferable to the coercive force, conditions of hydrogen decrepitation (HD) prior to pulverization were optimized. Specific surface area of the HD magnet alloy was increased with decreasing temperature and hydrogen pressure, and its grindability was verified by Jet milling.

Saguchi, A.; Uesugi, T.; Takigawa, Y.; Higashi, K.

121

Controls on Nitrogen Loss Processes in Chesapeake Bay Sediments Andrew R. Babbin* and Bess B. Ward  

E-print Network

Controls on Nitrogen Loss Processes in Chesapeake Bay Sediments Andrew R. Babbin* and Bess B. Ward, United States *S Supporting Information ABSTRACT: The flux of fixed nitrogen into the marine environment is increasing as a direct result of anthropogenic nitrogen loading, but the controls on the mechanisms

Ward, Bess

122

OPACITIES AND SPECTRA OF THE r-PROCESS EJECTA FROM NEUTRON STAR MERGERS  

SciTech Connect

Material ejected during (or immediately following) the merger of two neutron stars may assemble into heavy elements through the r-process. The subsequent radioactive decay of the nuclei can power transient electromagnetic emission similar to, but significantly dimmer than, an ordinary supernova. Identifying such events is an important goal of future optical surveys, offering new perspectives on the origin of r-process nuclei and the astrophysical sources of gravitational waves. Predictions of the transient light curves and spectra, however, have suffered from the uncertain optical properties of heavy ions. Here we argue that the opacity of an expanding r-process material is dominated by bound-bound transitions from those ions with the most complex valence electron structure, namely the lanthanides. For a few representative ions, we run atomic structure models to calculate the radiative transition rates for tens of millions of lines. The resulting r-process opacities are orders of magnitude larger than that of ordinary (e.g., iron-rich) supernova ejecta. Radiative transport calculations using these new opacities suggest that the light curves should be longer, dimmer, and redder than previously thought. The spectra appear to be pseudo-blackbody, with broad absorption features, and peak in the infrared ({approx}1 {mu}m). We discuss uncertainties in the opacities and attempt to quantify their impact on the spectral predictions. The results have important implications for observational strategies to find and study the radioactively powered electromagnetic counterparts to neutron star mergers.

Kasen, Daniel; Barnes, Jennifer [Department of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States); Badnell, N. R. [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2013-09-01

123

Inhomogeneous Galactic halo: a possible explanation for the spread observed in s- and r- process elements  

E-print Network

The considerable scatter of the s- and r-process elements observed in low-metallicity stars, compared to the small star to star scatter observed for the alpha elements, is an open question for the chemical evolution studies. We have developed a stochastic chemical evolution model, in which the main assumption is a random formation of new stars, subject to the condition that the cumulative mass distribution follows a given initial mass function. With our model we are able to reproduce the different features of alpha-elements and s-and r-process elements. The reason for this resides in the random birth of stellar masses coupled with the different stellar mass ranges from where alpha-elements and s-and r-process elements originate. In particular, the sites of production of the alpha elements are the whole range of the massive stars, whereas the mass range of production for the s- and r-process elements has an upper limit of 30 solar masses.

G. Cescutti

2007-02-21

124

PostPass Processing of TwoWay Timing Measurements Larry R. D'Addario  

E-print Network

Post­Pass Processing of Two­Way Timing Measurements Larry R. D'Addario 4 February 1993; revised 8 path with predicted uplink time C and downlink time D. This path is shown as a dashed line in Figure 1, not C + D earlier; at the true transmission time, the predicted uplink and downlink times were C 0 and D

Groppi, Christopher

125

Physical processes and hypoxia in the central basin of Lake Erie Yerubandi R. Rao1  

E-print Network

Physical processes and hypoxia in the central basin of Lake Erie Yerubandi R. Rao1 Environment Commonwealth Boulevard, Ann Arbor, Michigan Murray N. Charlton and William M. Schertzer Environment Canada profiles during 2004 and 2005 in the mid-central basin of Lake Erie. The current and temperature spectra

126

Potential Theory of Moderate Markov Dual Processes P.J. Fitzsimmons and R.K. Getoor  

E-print Network

* *xample, Kuznetsov measures, Ray compactifications, h-transforms, and duality theory for* * Borel right processes. Key Words and Phrases: potential theory, excessive measure, Kuznetsov measure, * *duality, h is the Kuznetsov measure Qm governing the Kuznetsov proc* *ess Y = (Yt)t2R associated with X and m. In fact, Xb

Fitzsimmons, Patrick J.

127

Introduction: linked processes of metamorphism and deformation A. R. STALLARD1  

E-print Network

Introduction: linked processes of metamorphism and deformation A. R. STALLARD1 AND G. SOLAR2 1 Avenue, Buffalo, New York, USA (solargs@buffalostate.edu) The interaction of deformation and metamorphism activity as well as the progressive metamorphic and structural development of the crust. Analysis

Solar, Gary S.

128

Long gamma-ray burst as a production site of r-process elements  

SciTech Connect

We simulated the r-process nucleosynthesis in and around a high entropy jet from a long gamma-ray burst (GRB). Our simulation is based on the collapsar scenario for long GRBs and on relativistic magnetohydrodynamic simulations (Harikae et al. 2009, 2010) including ray-tracing neutrino transport, which describe the development of the black hole accretion disk and the heating of the funnel region to produce a relativistic jet. The time evolution of the jet was then extended to later phase via axi-symmetric special relativistic hydrodynamic simulation to follow the temperature, entropy, electron fraction, and density evolution for representative test particles. The evolution of nuclear abundances from nucleons to heavy nuclei for representative test particle trajectories was solved in a large nuclear reaction network including more than 5000 isotopes. We show that a robust r-process successfully occurs within the collapsar jet outflow and that sufficient mass is ejected within the flow to account for the observed r-process abundance distribution along with the large dispersion in r-process elements observed in metal-poor halo stars.

Nakamrua, Ko; Harikae, Seiji; Kajino, Toshitaka; Mathews, Grant J. [National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo, 181-8588 (Japan); Quants Research Department, Financial Engineering Division, Mitsubishi UFJ Morgan Stanley Securities Co., Ltd. (Japan); National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo, 181-8588 and Department of Astronomy, School of Science, University of Tokyo, Tokyo, 113-0033 (Japan); Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556 (United States)

2012-11-12

129

Identification of Defect Processes in Amorphous Materials Dr. Blair R. Tuttle  

E-print Network

Identification of Defect Processes in Amorphous Materials Dr. Blair R. Tuttle Associate Professor-electronics, which require a variety of amorphous oxide materials including low and high K dielectric alloys. In all of these examples, point defects limit the operation of devices, and defects prevent future improvements

Bjørnstad, Ottar Nordal

130

New fission fragment distributions and r-process origin of the rare-earth elements  

E-print Network

Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 140.

Goriely, S; Lemaitre, J -F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H -Thomas

2013-01-01

131

?-decay measurements of A simeq 70 - 110 r-process nuclei at the National Superconducting Cyclotron Laboratory  

NASA Astrophysics Data System (ADS)

The present paper reports on several r-process motivated ?-decay experiments undertaken at the National Superconducting Cyclotron Laboratory. ?-decay half-lives and ?-delayed neutron-emission probabilities were measured for nuclei around the r-process A = 70-80 and A = 90 - 110 mass regions. The data are discussed on the basis of quasi-random phase approximation calculations. The emphasis is made on the impact of these data upon calculations of r-process abundances.

Pereira, J.; Aprahamian, A.; Arndt, O.; Becerril, A.; Elliot, T.; Estrade, A.; Galaviz, D.; Hennrich, S.; Hosmer, P.; Kessler, R.; Kratz, K.-L.; Lorusso, G.; Mantica, P. F.; Matos, M.; Montes, F.; Pfeiffer, B.; Quinn, M.; Santi, P.; Schatz, H.; Schertz, F.; Schnorrenberger, L.; Smith, E.; Stolz, A.; Walters, W. B.; Whr, A.

2011-09-01

132

Stellar Abundances in the Early Galaxy and Two r-Process Components  

E-print Network

We present quantitative predictions for the abundances of r-process elements in stars formed very early in the Galactic history using a phenomenological two-component r-process model based on the I129 and Hf182 inventory in the early solar system. This model assumes that a standard mass of the ISM dilutes the debris from an individual supernova. High frequency supernova H events and low frequency supernova L events are proposed in the model with characteristics determined by the meteoritic data on I129 and Hf182. The yields in an H or L event are obtained from these characteristics and the solar r-process abundances under the assumption that the yield template for the high mass (A > 130) nuclei associated with W182 or the low mass (A < or = 130) nuclei associated with I127 is the same for both the H and L events and follows the corresponding solar r-pattern in each mass region. The abundance of Eu, not Fe, is proposed as a key guide to the age of very metal-poor stars. We predict that stars with log epsilon (Eu) = -2.98 to -2.22 were formed from an ISM contaminated most likely by a single H event within the first 10**7 yr of the Galactic history and should have an Ag/Eu abundance ratio less than the corresponding solar r-process value by a factor of at least 10. Many of the very metal-poor stars observed so far are considered here to have been formed from an ISM contaminated by many (about 10) r-process events. Stars formed from an ISM contaminated only by a pure L event would have an Ag/Eu ratio higher than the corresponding solar r-process value but would be difficult to find due to the low frequency of the L events. However, variations in the relative abundances of the low and high mass regions should be detectable in very metal-poor stars.

Y. -Z. Qian; G. J. Wasserburg

1999-06-15

133

Realistic fission models, new beta-decay half-lives and the r-process in neutron star mergers  

SciTech Connect

Almost half of heavy nuclei beyond iron are considered to be produced by rapid neutron capture process (r-process). This process occurs in the neutron-rich environment such as core-collapse supernovae or neutron star mergers, but the main production site is still unknown. In the r-process of neutron star mergers, nuclear fission reactions play an important role. Also beta-decay half-lives of magic nuclei are crucial for the r-process. We have carried out r-process nucleosynthesis calculations based upon new theoretical estimates of fission fragment distributions and new beta-decay half-lives for N=82 nuclei measured at RIBF-RIKEN. We investigate the effect of nuclear fission on abundance patterns in the matter ejected from neutron star mergers with two different fission fragment mass distributions. We also discuss how the new experimental beta-decay half-lives affect the r-process.

Shibagaki, S.; Kajino, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Chiba, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8850 (Japan); Lorusso, G.; Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556 (United States)

2014-05-02

134

CIS Modules Process R&D: Final Technical Report, October 2005 - June 2006  

SciTech Connect

The primary objectives of this subcontract were to: address key near-term technical R&D issues for continued improvement in thin-film PV products; continue process development for increased production capacity; pursue long-term R&D contributing to progress toward the MYTP goals for 2020 to increase the conversion efficiency to 15% and reduce module manufacturing costs to less than $50/m2, thus enabling PV systems with a 30-year lifetime at an installed cost of under $2.00/W; and advance the understanding of the requirements needed to achieve better thin-film PV cell and module performance, greater reliability and market acceptance, and investigate materials systems and new devices that can improve the cost/performance ratio of future thin-film PV factories. The demonstrated and maintained high production yield is a major accomplishment supporting attractive cost projections for CIS. Process R&D at successive levels of CIS production has led to the continued demonstration of the prerequisites for commitment to large-scale commercialization. Process and packaging R&D during this and previous subcontracts has demonstrated the potential for further cost and performance improvements.

Tarrant, D. E.; Gay, R. R.

2006-07-01

135

New fission fragment distributions and r-process origin of the rare-earth elements  

E-print Network

Neutron star (NS) merger ejecta offer a viable site for the production of heavy r-process elements with nuclear mass numbers A > 140. The crucial role of fission recycling is responsible for the robustness of this site against many astrophysical uncertainties, but calculations sensitively depend on nuclear physics. In particular the fission fragment yields determine the creation of 110 earth peak that is nicely compatible with the abundance patterns in the Sun and metal-poor stars. This new finding further strengthens the case of NS mergers as possible dominant origin of r-nuclei with A > 140.

S. Goriely; J. -L. Sida; J. -F. Lemaitre; S. Panebianco; N. Dubray; S. Hilaire; A. Bauswein; H. -Thomas Janka

2013-11-22

136

The r-process nucleosynthesis during the decompression of neutronised matter  

SciTech Connect

The rapid neutron-capture process, or r-process, is known to be of fundamental importance for explaining the origin of approximately half of the A>60 stable nuclei observed in nature. In recent years nuclear astrophysicists have developed more and more sophisticated r-process models, eagerly trying to add new astrophysical or nuclear physics ingredients to explain the solar system composition in a satisfactory way.We show here that the decompression of the neutron star matter may provide suitable conditions for a robust r-processing. After decompression, the inner crust material gives rise to an abundance distribution for A>130 nuclei similar to the one observed in the solar system. Similarly, the outer crust if heated at a temperature of about 8 10{sup 9} K before decompression is made of exotic neutron-rich nuclei with a mass distribution close to the 80{<=}A{<=}130 solar one. During the decompression, the free neutrons (initially liberated by the high temperatures) are re-captured leading to a final pattern similar to the solar system distribution.

Goriely, S.; Chamel, N. [IAA-ULB, Campus de la Plaine, CP 226, 1050 Brussels (Belgium); Pearson, J. M. [Dept. de Physique, Universite de Montreal, Montreal (Quebec), H3C 3J7 (Canada)

2011-10-28

137

MAGNETOROTATIONALLY DRIVEN SUPERNOVAE AS THE ORIGIN OF EARLY GALAXY r-PROCESS ELEMENTS?  

SciTech Connect

We examine magnetorotationally driven supernovae as sources of r-process elements in the early Galaxy. On the basis of thermodynamic histories of tracer particles from a three-dimensional magnetohydrodynamical core-collapse supernova model with approximated neutrino transport, we perform nucleosynthesis calculations with and without considering the effects of neutrino absorption reactions on the electron fraction (Y{sub e} ) during post-processing. We find that the peak distribution of Y{sub e} in the ejecta is shifted from {approx}0.15 to {approx}0.17 and broadened toward higher Y{sub e} due to neutrino absorption. Nevertheless, in both cases, the second and third peaks of the solar r-process element distribution can be reproduced well. The rare progenitor configuration that was used here, characterized by a high rotation rate and a large magnetic field necessary for the formation of bipolar jets, could naturally provide a site for the strong r-process in agreement with observations of the early Galactic chemical evolution.

Winteler, C.; Perego, A.; Vasset, N.; Nishimura, N.; Liebendoerfer, M.; Thielemann, F.-K. [Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Kaeppeli, R. [Seminar for applied Mathematics, ETH Zuerich, Raemistrasse 101, 8092 Zuerich (Switzerland); Arcones, A., E-mail: christian.winteler@unibas.ch [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 2, D-64289 Darmstadt (Germany)

2012-05-01

138

Massive double compact object mergers: gravitational wave sources and r-process element production sites  

NASA Astrophysics Data System (ADS)

With our galactic evolutionary code that contains a detailed intermediate-mass and massive binary population model, we study the temporal evolution of the galactic population of double neutron star binaries, mixed systems with a neutron star and black hole component, and double black hole binaries. We computed the merger rates of these relativistic binaries and translate them into LIGO II detection rates. We demonstrate that accounting for the uncertainties in the relation "initial mass-final mass" predicted by massive close binary evolution and due to the possible effect of large stellar wind mass loss during the luminous blue variable phase of a star with initial mass higher than 30-40 M? and during the red supergiant phase of a star with initial mass lower than 30-40 M? when such a star is a binary component, the double black hole merger rate may be very low, contrary to predictions made by other groups. Hydrodynamic computations of the r-process chemical yields ejected during the relativistic binary merger process have recently become available. With our galactic code that includes binaries, it is then straightforward to calculate the temporal galactic evolution of the r-process elements ejected by these mergers. We conclude that except for the earliest evolutionary phase of the Galaxy (~the first 100 Myr), double compact star mergers may be the major production sites of r-process elements, and it is probable that the mixed systems dominate this production over double neutron star binary mergers.

Mennekens, N.; Vanbeveren, D.

2014-04-01

139

Balancing SoNaR: IPR versus Processing Issues in a 500-Million-Word Written Dutch Reference Corpus  

E-print Network

Balancing SoNaR: IPR versus Processing Issues in a 500-Million-Word Written Dutch Reference Corpus during the creation of the SoNaR Corpus. Based on recent developments in traditional corpus compiling and new web harvesting approaches, SoNaR is designed to contain 500 million words, balanced over 36 text

Tilburg, Universiteit van

140

INFERENCES FROM OBLIQUE IMPACT CRATERS ABOUT THE ROLE OF THE ATMOSPHERE AND SUBSURFACE VOLATILES IN THE IMPACT CRATERING PROCESS ON MARS R. R. Herrick,  

E-print Network

INFERENCES FROM OBLIQUE IMPACT CRATERS ABOUT THE ROLE OF THE ATMOSPHERE AND SUBSURFACE VOLATILES IN THE IMPACT CRATERING PROCESS ON MARS R. R. Herrick, Geophysical Institute, University of Alaska Fairbanks of the ejecta blankets from Martian low-angle impact craters with those on Venus, the moon, and from small

Herrick, Robert R.

141

Approximating the r-Process on Earth with Thermonuclear Explosions: Lessons Learned and Unanswered Questions  

NASA Astrophysics Data System (ADS)

During the astrophysical r-process, multiple neutron captures occur so rapidly on target nuclei that their daughter nuclei generally do not have time to undergo radioactive decay before another neutron is captured. The r-process can be approximately simulated on Earth in certain types of thermonuclear explosions through an analogous process of rapid neutron captures known as the "prompt capture" process. Between 1952 and 1969, 23 nuclear tests were fielded by the US which were involved (at least partially) with the "prompt capture" process. Of these tests, 15 were at least partially successful. Some of these tests were conducted under the Plowshare Peaceful Nuclear Explosion Program as scientific research experiments. It is now known that the USSR conducted similar nuclear tests during 1966 to 1979. The elements einsteinium and fermium were first discovered by this process. The most successful tests achieved 19 successive neutron captures on the initial target nuclei. A review of the US program, target nuclei used, heavy element yields, scientific achievements of the program, and how some of the results have been used by the astrophysical community is given. Finally, some unanswered questions concerning very neutron-rich nuclei that could potentially have been answered with additional nuclear experiments is presented.

Becker, S. A.

142

Physics and Process Modeling (PPM) and Other Propulsion R and T. Volume 1; Materials Processing, Characterization, and Modeling; Lifting Models  

NASA Technical Reports Server (NTRS)

This CP contains the extended abstracts and presentation figures of 36 papers presented at the PPM and Other Propulsion R&T Conference. The focus of the research described in these presentations is on materials and structures technologies that are parts of the various projects within the NASA Aeronautics Propulsion Systems Research and Technology Base Program. These projects include Physics and Process Modeling; Smart, Green Engine; Fast, Quiet Engine; High Temperature Engine Materials Program; and Hybrid Hyperspeed Propulsion. Also presented were research results from the Rotorcraft Systems Program and work supported by the NASA Lewis Director's Discretionary Fund. Authors from NASA Lewis Research Center, industry, and universities conducted research in the following areas: material processing, material characterization, modeling, life, applied life models, design techniques, vibration control, mechanical components, and tribology. Key issues, research accomplishments, and future directions are summarized in this publication.

1997-01-01

143

The waiting point approximation in R-process calculations. [of astrophysical nucleosynthesis  

NASA Technical Reports Server (NTRS)

The steady flow approximation to the r-process has been used to evaluate the validity of the waiting point assumption (that, for a given charge number Z, neutron captures become balanced by neutron photodisintegrations) under a variety of conditions. The criterion for the accuracy of the approximation for any set of nuclei with the same value of Z is that the ratio of the total rate of neutron photodisintegration in those nuclei to the total rate of neutron captures should be close to unity. No set of conditions involving neutron production by helium thermonuclear reactions (at temperatures up to 10 to the 9th K) could be found for which the waiting point approximation is useful for all values of Z, and it is recommended that all such r-process calculations not use this approximation. At higher temperatures, such as those characteristic of explosive carbon burning (2 x 10 to the 9th K), the waiting point approximation is much better.

Cameron, A. G. W.; Cowan, J. J.; Truran, J. W.

1983-01-01

144

Are collapsars responsible for some r-process elements? How could we tell?  

SciTech Connect

We consider the possibility that supernovae which form hyper-accreting black holes might be responsible for synthesis of r-process elements with mass A {approx}< 130. Calculations are presented which show that these elements are naturally synthesized in neutron-rich magnetically-dominated bubbles born in the inner regions of a black hole accretion disk. Simple considerations suggest that the total mass ejected in the form of these bubbles is about that needed to account for the entire galactic inventory of the 2nd-peak r-process elements. We also argue that if collapsars are responsible for, e.g., Ag synthesis, then Ag abundances should be correlated with Sc and/or Zn abundances in metal-poor stars.

Pruet, J

2004-04-05

145

{beta}-delayed neutron emission measurements around the third r-process abundance peak  

SciTech Connect

This contribution summarizes an experiment performed at GSI (Germany) in the neutron-rich region beyond N=126. The aim of this measurement is to provide the nuclear physics input of relevance for r-process model calculations, aiming at a better understanding of the third r-process abundance peak. Many exotic nuclei were measured around {sup 211}Hg and {sup 215}Tl. Final ion identification diagrams are given in this contribution. For most of them, we expect to derive halflives and and {beta}-delayed neutron emission probabilities. The detectors used in this experiment were the Silicon IMplantation and Beta Absorber (SIMBA) detector, based on an array of highly segmented silicon detectors, and the BEta deLayEd Neutron (BELEN) detector, which consisted of 30 3He counters embedded in a polyethylene matrix.

Caballero-Folch, R.; Cortes, G.; Calvino, F.; Gomez-Hornillos, M. B.; Riego, A. [INTE-DFEN, Universitat Politecnica de Catalunya, Barcelona (Spain); Domingo-Pardo, C.; Tain, J. L.; Agramunt, J.; Rubio, B. [IFIC, CSIC-University of Valencia, Valencia (Spain); Algora, A. [IFIC, CSIC-University of Valencia, Valencia (Spain) and Inst. Nucl. Research, Debrecen (Hungary); Ameil, F.; Farinon, F.; Heil, M.; Knoebel, R.; Kojouharov, I.; Kurcewicz, J.; Kurz, N.; Litvinov, Y.; Mukha, I.; Nociforo, C. [GSI, Darmstadt (Germany); and others

2013-06-10

146

Neutron single particle structure in 131Sn and the r-process  

SciTech Connect

Recent calculations suggest that, at late times in the r-process, the rate of neutron capture by {sup 130}Sn has a significant impact on nucleosynthesis. Direct capture into low-lying bound states is likely the dominant reaction in the r-process near the N=82 closed shell, so reaction rates are strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, we have acquired (d,p) reaction data in the A{approx}132 region in inverse kinematics using {approx}630 MeV beams (4.85 MeV/u for {sup 130}Sn) and CD{sub 2} targets. An array of Si strip detectors, including SIDAR and an early implementation of the new Oak Ridge Rutgers University Barrel Array (ORRUBA), was used to detect reaction products. Preliminary results for the {sup 130}Sn(d,p){sup 131}Sn experiment are reported.

Kozub, R. L. [Tennessee Technological University; Bardayan, Daniel W [ORNL; Adekola, Aderemi S [ORNL; Blackmon, Jeff C [ORNL; Chae, K. Y. [University of Tennessee; Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Erikson, Luke [Colorado School of Mines, Golden; Hatarik, Robert [Rutgers University; Jones, K. L. [University of Tennessee; Krolas, W. [University of Warsaw; Liang, J Felix [ORNL; Ma, Zhanwen [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee; Nesaraja, Caroline D [ORNL; Pain, Steven D [ORNL; Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK

2009-01-01

147

?-delayed neutron emission measurements around the third r-process abundance peak  

NASA Astrophysics Data System (ADS)

This contribution summarizes an experiment performed at GSI (Germany) in the neutron-rich region beyond N=126. The aim of this measurement is to provide the nuclear physics input of relevance for r-process model calculations, aiming at a better understanding of the third r-process abundance peak. Many exotic nuclei were measured around 211Hg and 215Tl. Final ion identification diagrams are given in this contribution. For most of them, we expect to derive halflives and and ?-delayed neutron emission probabilities. The detectors used in this experiment were the Silicon IMplantation and Beta Absorber (SIMBA) detector, based on an array of highly segmented silicon detectors, and the BEta deLayEd Neutron (BELEN) detector, which consisted of 30 3He counters embedded in a polyethylene matrix.

Caballero-Folch, R.; Domingo-Pardo, C.; Tan, J. L.; Corts, G.; Agramunt, J.; Algora, A.; Ameil, F.; Ayyad, Y.; Benlliure, J.; Bowry, M.; Calvio, F.; Cano-Ott, D.; Davinson, T.; Dillmann, I.; Estrade, A.; Evdokimov, A.; Faestermann, T.; Farinon, F.; Galaviz, D.; Garca-Rios, A.; Geissel, H.; Gelletly, W.; Gernhuser, R.; Gmez-Hornillos, M. B.; Guerrero, C.; Heil, M.; Hinke, C.; Knbel, R.; Kojouharov, I.; Kurcewicz, J.; Kurz, N.; Litvinov, Y.; Maier, L.; Marganiec, J.; Marta, M.; Martnez, T.; Montes, F.; Mukha, I.; Napoli, D. R.; Nociforo, C.; Paradela, C.; Pietri, S.; Podolyk, Zs.; Prochazka, A.; Rice, S.; Riego, A.; Rubio, B.; Schaffner, H.; Scheidenberger, C.; Smith, K.; Sokol, E.; Steiger, K.; Sun, B.; Takechi, M.; Testov, D.; Weick, H.; Wilson, E.; Winfield, J. S.; Wood, R.; Woods, P.; Yeremin, A.

2013-06-01

148

Neutrino Fluence after r-Process Freezeout and Abundances of TE Isotopes in Presolar Diamonds  

NASA Astrophysics Data System (ADS)

Using the data of Richter, Ott, & Begemann on Te isotopes in diamond grains from a meteorite, we derive bounds on the neutrino fluence and the decay timescale of the neutrino flux relevant for the supernova r-process. Our new bound on the neutrino fluence \\Fscr after freezeout of the r-process peak at mass number A~130 is more stringent than the previous bound \\Fscr<~0.045 (in units of 1037 ergs cm-2) of Qian et al. and Haxton et al., if the neutrino flux decays on a timescale ??>~0.65 s. In particular, it requires that a fluence of \\Fscr=0.031 be provided by a neutrino flux with ??<~0.84 s. Such a fluence may be responsible for the production of the solar r-process abundances at A=124-126. Our results are based on the assumption of Ott that only the stable nuclei implanted into the diamonds are retained, while the radioactive nuclei are lost from the diamonds upon decay after implantation. We consider that the nanodiamonds are condensed in an environment with C/O>1 in the expanding supernova debris or from the exterior H envelope. This environment need not have the 13C/12C ratio of the bulk diamonds, since the Te- and Xe-containing nanodiamond grains are too rare to affect that ratio. The implantation of nuclei would have occurred ~104-106 s after r-process freezeout. This time interval may be marginally sufficient to permit adequate cooling upon expansion for the formation of diamond grains. The mechanisms of preferential retention/loss of the implanted nuclei are not well understood.

Qian, Y.-Z.; Vogel, P.; Wasserburg, G. J.

1999-03-01

149

Efficient Preparation of (R)-2-chloromandelic Acid Via a Recycle Process of Resolution.  

PubMed

Efficient preparation of (R)-2-chloromandelic acid based on a recycle process of resolution is described. In the process, the desired was obtained by coordination-mediated resolution with D-O,O'-di-(p-toluoyl)-tartaric acid in the presence of Ca(2+) . Meanwhile, the undesired could be racemized in the presence of sodium hydroxide and the product was suitable for further resolution. A carbanion mechanism for the racemization of is proposed. Chirality 27:281-285, 2015. 2015 Wiley Periodicals, Inc. PMID:25640306

Hu, Yu; Wu, Chang; Wu, Xue-Ying; Li, Shao-Lei; Sun, Xiao-Xia; Tang, Ze-Biao

2015-12-01

150

Exploiting pre-rRNA processing in Diamond Blackfan anemia gene discovery and diagnosis.  

PubMed

Diamond Blackfan anemia (DBA), a syndrome primarily characterized by anemia and physical abnormalities, is one among a group of related inherited bone marrow failure syndromes (IBMFS) which share overlapping clinical features. Heterozygous mutations or single-copy deletions have been identified in 12 ribosomal protein genes in approximately 60% of DBA cases, with the genetic etiology unexplained in most remaining patients. Unlike many IBMFS, for which functional screening assays complement clinical and genetic findings, suspected DBA in the absence of typical alterations of the known genes must frequently be diagnosed after exclusion of other IBMFS. We report here a novel deletion in a child that presented such a diagnostic challenge and prompted development of a novel functional assay that can assist in the diagnosis of a significant fraction of patients with DBA. The ribosomal proteins affected in DBA are required for pre-rRNA processing, a process which can be interrogated to monitor steps in the maturation of 40S and 60S ribosomal subunits. In contrast to prior methods used to assess pre-rRNA processing, the assay reported here, based on capillary electrophoresis measurement of the maturation of rRNA in pre-60S ribosomal subunits, would be readily amenable to use in diagnostic laboratories. In addition to utility as a diagnostic tool, we applied this technique to gene discovery in DBA, resulting in the identification of RPL31 as a novel DBA gene. PMID:25042156

Farrar, Jason E; Quarello, Paola; Fisher, Ross; O'Brien, Kelly A; Aspesi, Anna; Parrella, Sara; Henson, Adrianna L; Seidel, Nancy E; Atsidaftos, Eva; Prakash, Supraja; Bari, Shahla; Garelli, Emanuela; Arceci, Robert J; Dianzani, Irma; Ramenghi, Ugo; Vlachos, Adrianna; Lipton, Jeffrey M; Bodine, David M; Ellis, Steven R

2014-10-01

151

Exploiting Pre-rRNA Processing in Diamond Blackfan Anemia Gene Discovery and Diagnosis  

PubMed Central

Diamond Blackfan anemia (DBA), a syndrome primarily characterized by anemia and physical abnormalities, is one among a group of related inherited bone marrow failure syndromes (IBMFS) which share overlapping clinical features. Heterozygous mutations or single-copy deletions have been identified in 12 ribosomal protein genes in approximately 60% of DBA cases, with the genetic etiology unexplained in most remaining patients. Unlike many IBMFS, for which functional screening assays complement clinical and genetic findings, suspected DBA in the absence of typical alterations of the known genes must frequently be diagnosed after exclusion of other IBMFS. We report here a novel deletion in a child that presented such a diagnostic challenge and prompted development of a novel functional assay that can assist in the diagnosis of a significant fraction of patients with DBA. The ribosomal proteins affected in DBA are required for pre-rRNA processing, a process which can be interrogated to monitor steps in the maturation of 40S and 60S ribosomal subunits. In contrast to prior methods used to assess pre-rRNA processing, the assay reported here, based on capillary electrophoresis measurement of the maturation of rRNA in pre-60S ribosomal subunits, would be readily amenable to use in diagnostic laboratories. In addition to utility as a diagnostic tool, we applied this technique to gene discovery in DBA, resulting in the identification of RPL31 as a novel DBA gene. PMID:25042156

Farrar, Jason E.; Quarello, Paola; Fisher, Ross; OBrien, Kelly A.; Aspesi, Anna; Parrella, Sara; Henson, Adrianna L.; Seidel, Nancy E.; Atsidaftos, Eva; Prakash, Supraja; Bari, Shahla; Garelli, Emanuela; Arceci, Robert J.; Dianzani, Irma; Ramenghi, Ugo; Vlachos, Adrianna; Lipton, Jeffrey M.; Bodine, David M.; Ellis, Steven R.

2014-01-01

152

The Final Step in 5.8S rRNA Processing Is Cytoplasmic in Saccharomyces cerevisiae?  

PubMed Central

The 18S rRNA component of yeast (Saccharomyces cerevisiae) 40S ribosomes undergoes cytoplasmic 3? cleavage following nuclear export, whereas exported pre-60S subunits were believed to contain only mature 5.8S and 25S rRNAs. However, in situ hybridization detected 3?-extended forms of 5.8S rRNA in the cytoplasm, which were lost when Crm1-dependent preribosome export was blocked by treatment with leptomycin B (LMB). LMB treatment rapidly blocked processing of 6S pre-rRNA to 5.8S rRNA, leading to TRAMP-dependent pre-rRNA degradation. The 6S pre-rRNA was coprecipitated with the 60S export adapter Nmd3 and cytoplasmic 60S synthesis factor Lsg1. The longer 5.8S+30 pre-rRNA (a form of 5.8S rRNA 3? extended by ?30 nucleotides) is processed to 6S by the nuclear exonuclease Rrp6, and nuclear pre-rRNA accumulated in the absence of Rrp6. In contrast, 6S to 5.8S processing requires the cytoplasmic exonuclease Ngl2, and cytoplasmic pre-rRNA accumulated in strains lacking Ngl2. We conclude that nuclear pre-60S particles containing the 6S pre-rRNA bind Nmd3 and Crm1 and are exported to the cytoplasm prior to final maturation by Ngl2. PMID:20008552

Thomson, Emma; Tollervey, David

2010-01-01

153

The study of s-process nucleosynthesis based on barium stars, CEMP-s and CEMP-r/s stars  

E-print Network

In order to get a broader view of the s-process nucleosynthesis we study the abundance distribution of heavy elements of 35 barium stars and 24 CEMP-stars, including nine CEMP-s stars and 15 CEMP-r/s stars. The similar distribution of [Pb/hs] between CEMP-s and CEMP-r/s stars indicate that the s-process material of both CEMP-s and CEMP-r/s stars should have a uniform origin, i.e. mass transfer from their predominant AGB companions. For the CEMP-r/s stars, we found that the r-process should provide similar proportional contributes to the second s-peak and the third s-peak elements, and also be responsible for the higher overabundance of heavy elements than those in CEMP-s stars. Which hints that the r-process origin of CEMP-r/s stars should be closely linked to the main r-process. The fact that some small $r$ values exist for both barium and CEMP-s stars, implies that the single exposure event of the s-process nucleosynthesis should be general in a wide metallicity range of our Galaxy. Based on the relation be...

Cui, Wenyuan; Geng, Yuanyuan; Zhang, Caixia; Meng, Xiaoying; Shao, Lang; Zhang, Bo; 10.1007/s10509-013-1450-1

2013-01-01

154

r-Process abundances in metal-poor Galactic halo stars  

NASA Astrophysics Data System (ADS)

The site of the r-process is not completely defined, and several models try to explain the origin of the trans-Fe elements. Observed abundances are the best clues to bring some light to this multiplicity of possible mechanisms, and the extremely metal-poor (EMP) Galactic halo stars have a special role in this problem. In this contribution we present the solution of a long-standing problem about the origin of the heavy elements in the metal-poor halo subgiant star HD 140283, and its correlation with the Truran's theory. Next, we describe the results obtained with the EMP r-II star CS 31082-001 in the frame of the ESO Large Program ``First Stars''. Using STIS/HST observations we provide abundances for elements never presented before in this stars, making CS 31082-001 the most complete r-II object studied, with a total of 37 detections of neutron-capture elements. Finally, we present the results obtained from a sample of seven r-I stars, showing how those objects can help us solving the heavy elements problem. Conclusions are also described.

Siqueira-Mello, C.; Barbuy, B.; Spite, M.; Spite, F.; Caffau, E.; Hill, V.; Wanajo, S.; Franois, P.; Bonifacio, P.; Cayrel, R.

155

Handing over the baton: connecting medicinal chemistry with process R&D.  

PubMed

The pharmaceutical industry, as virtually any other industry, is continuously striving to become more effective and efficient. This demand for improving business processes is focused on all parts of the organization-from R&D and manufacturing to marketing and sales. Specifically from an R&D perspective, there are two areas that stand out as having caught more attention than others: attrition and timelines. While the former, so far, has seen relatively small changes for the better, the latter has reached clear targets in reducing the overall time required for the various activities conducted during drug discovery and development phases. For process R&D-the unit accountable for the design and optimization of small-molecule synthetic routes as well as delivery of active substance (API) for clinical and toxicological testing-the key contribution in this respect has been the shortening of lead times for supply of the first batch of material on scale. Thus, applying a work model based on balanced frontloading has shown that this crucial task can be taken off the critical path, and instead of delivering required API amounts several months post candidate drug nomination, the availability can now be guaranteed at or even ahead of reaching this milestone. The paradigm shift that has been necessary in order to reach this goal is the subject of this article. PMID:18560618

Federsel, Hans-Jurgen

2008-05-01

156

3 Continuous-time stochastic processes Definition 3.1. A continuous-time stochastic process is a collection of random variables (Xt, t R+)  

E-print Network

.5. (first version) A standard Brownian motion is a continuous-time stochastic process B = (Bt, t R+) such that - B0 = 0 a.s. - B has independent and stationary increments. - Bt N(0, t), t R+. - B has continuous trajectories. Basic properties. - E(Bt) = 0, E(B2 t ) = t, t R+. - Bt - Bs Bt-s - B0 = Bt-s N(0, t - s), so

Lvque, Olivier

157

R/V Kilo Moana's New Geophysical Instrumentation, Processing Methods, and Online Data Repository  

NASA Astrophysics Data System (ADS)

In 2012 several upgrades were made to the underway geophysical systems on R/V Kilo Moana, which the University of Hawaii School of Ocean and Earth Science and Technology (SOEST) operates as part of the University-National Oceanographic Laboratory System (UNOLS) fleet. New instrumentation includes a Bell BGM-3 forced feedback-type gravimeter, a Kongsberg EM 122 12-kHz receiver array, and a high resolution 70-100 kHz EM 710 multibeam echo sounder. Multibeam acceptance trials carried out in June by the Multibeam Advisory Committee, Gates Acoustic Services and UH-SOEST found that both sonars are performing within expected levels with ~5x water depth (WD) for the EM 710 system in shallow water and ~19 km swath width at 4,700 m depth (~4x WD) for the EM 122 deep water system. UH-SOEST also took steps this year to fulfill its obligation to make Kilo Moana's geophysical data more accessible to the public. After an audit of Kilo Moana data at SOEST, Lamont's Rolling Deck to Repository (R2R) and the National Geophysical Data Center (NGDC), as of July 2012 all National Science Foundation-funded Kilo Moana multibeam, gravity, magnetics, center beam depth and Acoustic Doppler Current Profiler (ADCP) data have been submitted to R2R and any multibeam data over 2 years old is being transferred to NGDC. Because it had previously been difficult to access some of SOEST's geophysical data, updated data processing routines have been developed for converting raw gravity, magnetics, and centerbeam depth data to NGDC's standard marine data exchange format (MGD77) for archival and dissemination by NGDC. MGD77 files are being generated and inspected using rigorous along-track analytical techniques for ~270 surveys dating from 2002 to the present and are being submitted to NGDC. We are also developing an online data portal to further facilitate access to SOEST data.

Miller, J. E.; Chandler, M. T.; Taylor, B.; Shor, A.; Ferguson, J. S.; Wessel, P.

2012-12-01

158

Puzzling Origin of CEMP-r/s Stars: An Interpretation of Abundance and Enrichment of s- and r-Process Elements from Asymptotic Giant Branch Supernovae  

NASA Astrophysics Data System (ADS)

CEMP-r/s stars at low metallicity are known as double-enhanced stars that show enhancements of both r-process and s-process elements. The chemical abundances of these very metal-poor stars provide us a lot of information for putting new restraints on models of neutron-capture processes. In this article, we put forward an accreted scenario in which the double enrichment of r-process and s-process elements is caused by a former intermediate-mass Asymptotic Giant Branch (AGB) companion in a detached binary system. As the AGB superwind is only present at the ultimate phase of AGB stars, there is thus a lot of potential that the degenerate-core mass of an intermediate-mass AGB star reaches the Chandrasekhar limit before the AGB superwind. In these circumstances, both s-process elements produced in the AGB shell and r-process elements synthesized in the subsequent explosion would be sprayed contemporaneously and accreted by its companion. Despite similarity to physical conditions of a core-collapse supernova, a major focus in this scenario is the degenerate C-O core surrounded by an envelope of a former intermediate-mass AGB donor that may collapse and explode. Due to the existence of an outer envelope, r-process nucleosynthesis is expected to occur. Hypothesizing the material-rich europium (Eu) accreted by the secondary via the wind from the supernova to be in proportion to the geometric fraction of the companion with respect to the exploding donor star, we find that the estimated yield of Eu (as representative of r-process elements) per AGB supernova event is about 1 10-9 M ? 5 10-9 M ?. Using the yields of Eu, the overabundance of r-process elements in CEMP-r/s stars can be accounted for. The calculated results show that the value of parameter f , standing for efficiency of wind pollution from the AGB supernova, will reach about 104, which means that the enhanced factor is much larger than unity due to the impact of gravity of the donor and the result of the gravitational focusing effect of the companion.

Zhang, Jiang; Zhao, Fang; Chen, Yanping; Cui, Wenyuan; Zhang, Bo

2013-12-01

159

Salinity inhibits post transcriptional processing of chloroplast 16S rRNA in shoot cultures of jojoba (Simmondsia chinesis).  

PubMed

Chloroplast metabolism is rapidly affected by salt stress. Photosynthesis is one of the first processes known to be affected by salinity. Here, we report that salinity inhibits chloroplast post-transcriptional RNA processing. A differentially expressed 680-bp cDNA, containing the 3' sequence of 16S rRNA, transcribed intergenic spacer, exon 1 and intron of tRNA(Ile), was isolated by differential display reverse transcriptase PCR from salt-grown jojoba (Simmondsia chinesis) shoot cultures. Northern blot analysis indicated that although most rRNA appears to be fully processed, partially processed chloroplast 16S rRNA accumulates in salt-grown cultures. Thus, salinity appears to decrease the processing of the rrn transcript. The possible effect of this decreased processing on physiological processes is, as yet, unknown. PMID:15645309

Mizrahi-Aviv, Ela; Mills, David; Benzioni, Aliza; Bar-Zvi, Dudy

2005-03-01

160

On the Dynamics of Proto-Neutron Star Winds and r-Process Nucleosynthesis  

E-print Network

We study here the formation of heavy r-process nuclei in the high-entropy environment of rapidly expanding neutrino-driven winds from compact objects. In particular, we explore the sensitivity of the element creation in the A>130 region to the low-temperature behavior of the outflows. For this purpose we employ a simplified model of the dynamics and thermodynamical evolution for radiation dominated, adiabatic outflows. It consists of a first stage of fast, exponential cooling, followed by a second phase of slower evolution, either assuming constant density and temperature or a power-law decay of these quantities. These cases are supposed to capture the most relevant effects of a strong deceleration or decreasing acceleration of the transsonic outflows, respectively, e.g. in a wind termination shock caused by the collision with the slower, preceding supernova ejecta. We find that not only the transition temperature between the two expansion phases can make a big difference in the formation of the platinum peak, but also the detailed cooling law during the later phase. Unless the transition temperature and corresponding (free neutron) density become too small (T < 2*10^8 K), a lower temperature or faster temperature decline during this phase allow for a stronger appearance of the third abundance peak. Since the nuclear photodisintegration rates between ~2*10^8 K and ~10^9 K are more sensitive to the temperature than the n-capture rates are to the free neutron density, a faster cooling in this temperature regime shifts the r-process path closer to the n-drip line. With low (gamma,n)- but high beta-decay rates, the r-processing then does not proceed through a (gamma,n)-(n,gamma) equilibrium but through a quasi-equilibrium of (n,gamma)-reactions and beta-decays, as recently also pointed out by Wanajo.

I. V. Panov; H. -Th. Janka

2008-11-24

161

Field testing results for the R-BTEX{sup {trademark}} process for controlling glycol dehydrator emissions  

SciTech Connect

lncreasing regulatory pressure has made emissions of benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX) and total volatile organic compounds (VOC) from glycol dehydration units a major concern for the natural gas industry since there are over 40,000 of these units in operation. The Clean Air Act Amendments (CAAA) of 1990 have been the impetus for air toxics regulations, and the Maximum Achievable Control Technology (MACT) standards for the oil and gas industry will be proposed in June, 1995, and will include glycol dehydrators. In addition, several states are regulating or considering regulation of these units. The most common control systems that have been applied to glycol dehydrators are combustion or condensation systems. Combustion systems suffer from high operating costs since they do not recover the hydrocarbon for sale and require supplemental fuel. Many of the condensation systems may not achieve sufficiently low condenser temperatures to meet regulatory control limits. The R-BTEX{sup TM} process addresses this shortcoming by recovering the steam from the glycol dehydrator and converting it to cooling water; this allows R-BTEX to achieve the lowest condenser temperature possible without refrigeration. The Gas Research Institute (GRI) is conducting a field test program to demonstrate the process under a variety of conditions. Under this program, testing has been completed at one site in south Texas and at another site in western Colorado. Startup of a third unit at a Gulf Coast site in Texas should occur in late 1994. This paper presents the testing results for the first two sites and includes a side-by-side comparison of the R-BTEX process with other available control technologies.

Gamez, J.P.; Rueter, C.O.; Beitler, C.M.

1995-12-01

162

Single Neutron Transfer Experiments Close to the r-Process Path  

SciTech Connect

The first measurements using the (d, p) transfer reaction to study single- particle states in nuclei on the expected r-process path have been made at the Holifield Radioactive Ion Beam Facility. The shell closure at N = 50 has been crossed using the 82Ge(d, p) and 84Se(d, p) reactions. The prop- erties of the lowest-lying states have been determined. Furthermore, the 132Sn(d, p) reaction has been used for the first time to populate single- particle states in 133Sn.

Grzywacz-Jones, Kate L [ORNL; Adekola, Aderemi S [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, Kyung Yuk [ORNL; Chipps, K. [Colorado School of Mines, Golden; Cizewski, Jolie [ORNL; Dean, David Jarvis [ORNL; Erikson, Luke [Colorado School of Mines, Golden; Fitzgerald, R. P. [University of North Carolina, Chapel Hill; Gaddis, A. L. [Furman University; Greife, U. [Colorado School of Mines, Golden; Harlin, Christopher W [ORNL; Hatarik, Robert [Rutgers University; Howard, Joshua A [ORNL; Johnson, Micah [ORNL; Kozub, R. L. [Tennessee Technological University; Liang, J Felix [ORNL; Livesay, Jake [ORNL; Ma, Zhanwen [ORNL; Moazen, Brian [University of Tennessee, Knoxville (UTK); O'Malley, Patrick [Rutgers University; Nesaraja, Caroline D [ORNL; Pain, S. D. [Rutgers University; Patterson, N. P. [University of Surrey, UK; Paulauskas, Stanley V [ORNL; Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Sissom, D. J. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University

2007-01-01

163

Planar Reflective Phaser and Synthesis for Radio Analog Signal Processing (R-ASP)  

E-print Network

A planar reflective phaser based on an open-ended edge-coupled-line structure is proposed. This phaser is the first reported phaser that combines the benefits of high resolution, inherent to cross-coupled resonator reflective phasers, and of compactness, inherent to planar circuits. A 4-ns swing 4.9-5.5 GHz quadratic phase (linear group delay) 4th-order microstrip phaser is synthesized and experimentally demonstrated. Given its advantages, this phaser may find vast applications in Radio Analog Signal Processing (R-ASP) systems.

Zou, Lianfeng; Caloz, Christophe

2014-01-01

164

The neutron long counter NERO for studies of ?-delayed neutron emission in the r-process  

NASA Astrophysics Data System (ADS)

The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring ?-delayed neutron-emission probabilities. The detector was designed to work in conjunction with a ?-delay implantation station, so that ? decays and ?-delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring ?-delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.

Pereira, J.; Hosmer, P.; Lorusso, G.; Santi, P.; Couture, A.; Daly, J.; Del Santo, M.; Elliot, T.; Grres, J.; Herlitzius, C.; Kratz, K.-L.; Lamm, L. O.; Lee, H. Y.; Montes, F.; Ouellette, M.; Pellegrini, E.; Reeder, P.; Schatz, H.; Schertz, F.; Schnorrenberger, L.; Smith, K.; Stech, E.; Strandberg, E.; Ugalde, C.; Wiescher, M.; Whr, A.

2010-06-01

165

Half-lives of N = 126 Isotones and the r-Process  

SciTech Connect

Beta decays of N = 126 isotones are studied by shell model calculations. Both the Gamow-Teller (GT) and first-forbidden (FF) transitions are taken into account to evaluate the half-lives of the isotones (Z = 64-72) with the use of shell model interactions based on G-matrix. The FF transitions are found to be important to reduce the half-lives by twice to several times of those obtained by the GT contributions only. Possible implications of the short half-lives of the waiting point nuclei on the r-process nucleosynthesis during the supernova explosions are discussed.

Suzuki, Toshio [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550, Japan and Center for Nuclear Study, University of Tokyo, Hirosawa, Wako-shi, Saitama, 351-0198 (Japan); Yoshida, Takashi [Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Utsuno, Yutaka [Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Naka-gun, Ibaraki 319-1195 (Japan)

2010-08-12

166

Beta decay rates for r-process for nuclei near neutron number N=82  

E-print Network

For r-process nucleosynthesis the beta decay rates of very neutron-rich nuclei are important ingredients. We consider the region around the neutron number N=82 and calculate the half-lives and rates for a number of nuclei. Forms for beta strength functions based on spectral distribution methods are used. The calculated half-lives are first compared to the observed values and then predictions are made for very neutron-rich nuclei close to drip line for which no experimental values are available.

Kamales Kar; Soumya Chakravarti

2008-12-01

167

Re-187, recycling r-process elements through stars, and the age of the Galaxy.  

NASA Technical Reports Server (NTRS)

The enhanced beta-decay rate of ionized Re-187 in stars has been studied within the context of a detailed numerical model of the production of r-process elements and their recycling through stars during the course of galactic evolution. It is concluded that the enhanced decay rate does not significantly reduce the Re-Os chronometer age for the Galaxy. Consequently, the Re-187 beta-decay half-life and the Os-186/Os-187 neutron cross-section ratio remain as the significant uncertainties in this chronology. Unlike the uncertainties in other chronologies, both are amenable to laboratory measurements.

Talbot, R. J., Jr.

1973-01-01

168

The Origins of Light and Heavy R-process Elements Identified by Chemical Tagging of Metal-poor Stars  

NASA Astrophysics Data System (ADS)

Growing interests in neutron star (NS) mergers as the origin of r-process elements have sprouted since the discovery of evidence for the ejection of these elements from a short-duration ?-ray burst. The hypothesis of a NS merger origin is reinforced by a theoretical update of nucleosynthesis in NS mergers successful in yielding r-process nuclides with A > 130. On the other hand, whether the origin of light r-process elements are associated with nucleosynthesis in NS merger events remains unclear. We find a signature of nucleosynthesis in NS mergers from peculiar chemical abundances of stars belonging to the Galactic globular cluster M15. This finding combined with the recent nucleosynthesis results implies a potential diversity of nucleosynthesis in NS mergers. Based on these considerations, we are successful in the interpretation of an observed correlation between [light r-process/Eu] and [Eu/Fe] among Galactic halo stars and accordingly narrow down the role of supernova nucleosynthesis in the r-process production site. We conclude that the tight correlation by a large fraction of halo stars is attributable to the fact that core-collapse supernovae produce light r-process elements while heavy r-process elements such as Eu and Ba are produced by NS mergers. On the other hand, stars in the outlier, composed of r-enhanced stars ([Eu/Fe] gsim +1) such as CS22892-052, were exclusively enriched by matter ejected by a subclass of NS mergers that is inclined to be massive and consist of both light and heavy r-process nuclides.

Tsujimoto, Takuji; Shigeyama, Toshikazu

2014-11-01

169

An Effective Eigenchannel R-Matrix Method for Calculating Electron-Ion Scattering Processes with Spectroscopic Precision  

NASA Astrophysics Data System (ADS)

The electron-ion scattering processes are very important in various scientific research fields such as astrophysical studies and inertial confinement fusion research. We report our recent development of an efficient method for providing such atomic data with spectroscopic precision. Based on the BreitPauli and the Dirac R-matrix theory, we develop two eigenchannel R-matrix codes, referred to as R-eigen (non-relelativistic eigenchannel R-matrix) and R-R-eigen (relativistic eigenchannel R-matrix), to directly calculate the physical quantities in multichannel quantum defect theory in the whole energy regions. From such physical quantities, we can obtain all energy levels and the related scattering cross sections with accuracies comparable with spectroscopic precision. The e+Kr+ system is used as an illustration example, the degrees of accuracies of scattering matrices are calculated within about 2%, which should be much more accurate than state-of-the-art scattering experiments.

Gao, Xiang; Li, Jia-Ming

2012-03-01

170

rTMS neuromodulation improves electrocortical functional measures of information processing and behavioral responses in autism  

PubMed Central

Objectives: Reports in autism spectrum disorders (ASD) of a minicolumnopathy with consequent deficits of lateral inhibition help explain observed behavioral and executive dysfunctions. We propose that neuromodulation based on low frequency repetitive Transcranial Magnetic Stimulation (rTMS) will enhance lateral inhibition through activation of inhibitory double bouquet interneurons and will be accompanied by improvements in the prefrontal executive functions. In addition we proposed that rTMS will improve cortical excitation/inhibition ratio and result in changes manifested in event-related potential (ERP) recorded during cognitive tests. Materials and Methods: Along with traditional clinical behavioral evaluations the current study used ERPs in a visual oddball task with illusory figures. We compared clinical, behavioral and electrocortical outcomes in two groups of children with autism (TMS, wait-list group). We predicted that 18 session long course in autistic patients will have better behavioral and ERP outcomes as compared to age- and IQ-matched WTL group. We used 18 sessions of 1 Hz rTMS applied over the dorso-lateral prefrontal cortex in 27 individuals with ASD diagnosis. The WTL group was comprised of 27 age-matched subjects with ASD tested twice. Both TMS and WTL groups were assessed at the baseline and after completion of 18 weekly sessions of rTMS (or wait period) using clinical behavioral questionnaires and during performance on visual oddball task with Kanizsa illusory figures. Results: Post-TMS evaluations showed decreased irritability and hyperactivity on the Aberrant Behavior Checklist (ABC), and decreased stereotypic behaviors on the Repetitive Behavior Scale (RBS-R). Following rTMS course we found decreased amplitude and prolonged latency in the frontal and fronto-central N100, N200 and P300 (P3a) ERPs to non-targets in active TMS treatment group. TMS resulted in increase of P2d (P2a to targets minus P2a to non-targets) amplitude. These ERP changes along with increased centro-parietal P100 and P300 (P3b) to targets are indicative of more efficient processing of information post-TMS treatment. Another important finding was decrease of the latency and increase of negativity of error-related negativity (ERN) during commission errors that may reflect improvement in error monitoring and correction function. Enhanced information processing was also manifested in lower error rate. In addition we calculated normative post-error treaction time (RT) slowing response in both groups and found that rTMS treatment was accompanied by post-error RT slowing and higher accuracy of responses, whereas the WTL group kept on showing typical for ASD post-error RT speeding and higher commission and omission error rates. Conclusion: Results from our study indicate that rTMS improves executive functioning in ASD as evidenced by normalization of ERP responses and behavioral reactions (RT, accuracy) during executive function test, and also by improvements in clinical evaluations. PMID:25147508

Sokhadze, Estate M.; El-Baz, Ayman S.; Sears, Lonnie L.; Opris, Ioan; Casanova, Manuel F.

2014-01-01

171

J.R. Simplot: Burner Upgrade Project Improves Performance and Saves Energy at a Large Food Processing Plant  

SciTech Connect

This DOE Industrial Program case study describes how the J.R. Simplot Company saved energy and money by increasing the efficiency of the steam system in its potato processing plant in Caldwell, Idaho.

Not Available

2005-09-01

172

Precision mass measurements of neutron-rich nuclei, and limitations on the r-process environment  

NASA Astrophysics Data System (ADS)

The masses of 65 neutron-rich nuclides and 6 metastable states from Z = 49 to 64 were measured at a typical precision of ?m/m= 10-7 using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements are on fission fragments from 252Cf spontaneous fission sources, including those measurements made at the new Californium Rare Isotope Breeder Upgrade facility (CARIBU) and an earlier source. The measured nuclides lie on or approach the predicted path of the astrophysical r process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in ?-endpoint measurements. Simulations of the r process were undertaken to determine how quickly material can pass through the studied elements for a variety of conditions, placing limits on what temperatures densities allow passage on a desired timescale. The new masses produce manifold differences in effective lifetime compared to simulations performed with some model masses.

Van Schelt, Jonathon A.

173

The r-process nucleosynthesis: a continued challenge for nuclear physics and astrophysics  

E-print Network

The identification of the astrophysical site and the specific conditions in which r-process nucleosynthesis takes place remain unsolved mysteries of astrophysics. The present paper emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the radiative neutron capture rates by exotic nuclei close to the neutron drip line and the fission probabilities of heavy neutron-rich nuclei. These quantities are particularly relevant to determine the composition of the matter resulting from the decompression of initially cold neutron star matter. New detailed r-process calculations are performed and the final composition of ejected inner and outer neutron star crust material is estimated. We discuss the impact of the many uncertainties in the astrophysics and nuclear physics on the final composition of the ejected matter. The similarity between the predicted and the solar abundance pattern for A > 140 nuclei as well as the robustness of the prediction with varied input parameters makes this scenario one of the most promising that deserves further exploration.

S. Goriely; P. Demetriou; H. -Th. Janka; J. M. Pearson; M. Samyn

2004-10-19

174

In situ experimental evidence on R-phase related deformation processes in activated NiTi wires  

Microsoft Academic Search

Although many commercial NiTi wires commonly exhibit sequential B2?R?B19? transformations, their unique stressstraintemperature behaviors are readily comprehended and modeled as being solely due to the B2?B19? martensitic transformation and\\/or reorientation\\/twinning processes B19??B19? in the martensite phase. Omitting the R-phase is commonly advocated by the fact that the B2?R transformation strains are much smaller and not all NiTi alloys exhibit R-phase

P. ittner; P. Sedlk; M. Landa; V. Novk; P. Luk

2006-01-01

175

Enrichment of Very Metal-Poor Stars with Both r-Process and s-Process Elements from 8-10 M_\\odot Stars  

E-print Network

Recent spectroscopic studies have revealed the presence of numerous carbon-enhanced, metal-poor stars with [Fe/H] < -2.0 that exhibit strong enhancements of s-process elements. These stars are believed to be the result of a binary mass-transfer episode from a former asymptotic giant-branch (AGB) companion that underwent s-process nucleosynthesis. However, several such stars exhibit significantly lower Ba/Eu ratios than solar s-process abundances. This might be explained if there were an additional contribution from the r-process, thereby diluting the Ba/Eu ratio by extra production of Eu. We propose a model in which the double enhancements of r-process and s-process elements originate from a former 8-10 M_\\odot companion in a wide binary system, which may undergo s-processing during an AGB phase, followed by r-processing during its subsequent supernova explosion. The mass of Eu (as representative of r-process elements) captured by the secondary through the wind from the supernova is estimated, which is assumed to be proportional to the geometric fraction of the secondary (low-mass, main-sequence) star with respect to the primary (exploding) star. We find that the estimated mass is in good agreement with a constraint on the Eu yield per supernova event obtained from a Galactic chemical evolution study, when the initial orbital separation is taken to be \\sim 1 year. If one assumes an orbital period on the order of five years, the efficiency of wind pollution from the supernova must be enhanced by a factor of \\sim 10. This may, in fact, be realized if the expansion velocity of the supernova's innermost ejecta, in which the r-process has taken place, is significantly slow, resulting in an enhancement of accretion efficiency by gravitational focusing.

S. Wanajo; K. Nomoto; N. Iwamoto; Y. Ishimaru; T. C. Beers

2005-09-27

176

Process R&D under the magnifying glass: organization, business model, challenges, and scientific context.  

PubMed

Initially, the aim is to provide the big picture illustrating the as is situation in the pharmaceutical industry: a lack of productivity resulting in too few products reaching the market; a loss of billions in revenue over the next few years as some of the major megabrands go off patent; a spiraling cost for developing new drugs and taking them through clinical and safety studies. Following on, a look deeper into the organization will offer an insight into the state-of-the-art in a technical function accountable for chemical Process R&D (with a remit to develop scalable, robust, and cost efficient processes for small molecules). The vast majority of compounds already launched in the form of drug products on the market or still being pursued through the phases of discovery and development, fall within the category of small molecules (as opposed to biopharmaceuticals, e.g., proteins, monoclonal antibodies). This typically means molecular weights of <1000Da and puts organic synthesis in the widest sense of the word at the forefront of technologies needed to support R&D programs in the pharma industry. Understandably, the demands on Medicinal Chemistry are quite different to what applies in a Process R&D (PR&D) organization. In the former, making large numbers of potentially interesting molecules, many of which are discarded after testing, is a key driver and for this virtually any synthetic methodology will suffice. For PR&D, however, homing in on selected compounds there is an expectation that the best synthetic routes will be delivered that meet a number of tough criteria, for instance from an environmental and safety point of view, allowing operation on large scale, offering cost competitiveness, avoiding patent infringements, showing sustainability for long-term production, etc. The intention is to focus on issues to be addressed during this transition by providing examples of changes that had to be put in place in order to make the supply of larger amounts of material feasible. At the end some forward looking conclusions will be shared. PMID:20621486

Federsel, Hans-Jrgen

2010-08-15

177

Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy  

NASA Astrophysics Data System (ADS)

We quantify the stellar abundances of neutron-rich r-process nuclei in cosmological zoom-in simulations of a Milky Way-mass galaxy from the Feedback In Realistic Environments project. The galaxy is enriched with r-process elements by binary neutron star (NS) mergers and with iron and other metals by supernovae. These calculations include key hydrodynamic mixing processes not present in standard semi-analytic chemical evolution models, such as galactic winds and hydrodynamic flows associated with structure formation. We explore a range of models for the rate and delay time of NS mergers, intended to roughly bracket the wide range of models consistent with current observational constraints. We show that NS mergers can produce [r-process/Fe] abundance ratios and scatter that appear reasonably consistent with observational constraints. At low metallicity, [Fe/H] ? -2, we predict there is a wide range of stellar r-process abundance ratios, with both supersolar and subsolar abundances. Low-metallicity stars or stars that are outliers in their r-process abundance ratios are, on average, formed at high redshift and located at large galactocentric radius. Because NS mergers are rare, our results are not fully converged with respect to resolution, particularly at low metallicity. However, the uncertain rate and delay time distribution of NS mergers introduce an uncertainty in the r-process abundances comparable to that due to finite numerical resolution. Overall, our results are consistent with NS mergers being the source of most of the r-process nuclei in the Universe.

van de Voort, Freeke; Quataert, Eliot; Hopkins, Philip F.; Kere, Duan; Faucher-Gigure, Claude-Andr

2015-02-01

178

Elevated p53 promotes the processing of miR-18a to decrease estrogen receptor-? in female hepatocellular carcinoma.  

PubMed

The estrogen pathway has long been implicated as a tumor protector in female hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Our previous study identified that estrogen receptor alpha (ER?) protein is downregulated in 60% of female HCC cases, via a miR-18a elevation mediated suppression of ER? translation. This study aims to delineate the mechanism underlying the upregulation of miR-18a in female HCC. The analysis of 77 female HCC specimens revealed that miR-18a levels were associated with pre-miR-18a rather than pri-miR-18a levels, suggesting an enhanced processing of pri- to pre-miR-18a. Among a panel of factors involved in microRNA processing, p53 was identified as a novel regulator for miR-18a maturation process. Knockdown of p53 by si-RNA decreased the level of miR-18a, whereas overexpression of either wild-type or mutant p53 increased its level. The association between the elevation of miR-18a and the accumulation of p53, mainly caused by somatic mutations, was confirmed in the clinical specimens of HBV-related female HCC. By analyzing the association with clinicopathological features, activation of this p53/miR-18a pathway mainly occurs in younger or noncirrhosis female HCC patients and associated with a trend of worse overall survival. Therefore, this study demonstrated a novel function of elevated/mutant p53 in regulating the amount of ER? protein through its promoting the biogenesis of miR-18a, which could lead to decrease the tumor-protective function of the estrogen pathway in female hepatocarcinogenesis. PMID:24975878

Li, Chiao-Ling; Yeh, Kun-Huei; Liu, Wan-Hsin; Chen, Chi-Ling; Chen, Ding-Shinn; Chen, Pei-Jer; Yeh, Shiou-Hwei

2015-02-15

179

Possible discovery of the r-process characteristics in the abundances of metal-rich barium stars  

NASA Astrophysics Data System (ADS)

Aims: We study the abundance distributions of a sample of metal-rich barium stars provided by Pereira et al. (2011, A&A, 533, A51) to investigate the s- and r-process nucleosynthesis in the metal-rich environment. Methods: We compared the theoretical results predicted by a parametric model with the observed abundances of the metal-rich barium stars. Results: We found that six barium stars have a significant r-process characteristic, and we divided the barium stars into two groups: r-rich barium stars (Cr > 5.0, [La/Nd] < 0) and normal barium stars. The behavior of the r-rich barium stars seems more like that of the metal-poor r-rich and CEMP-r/s stars. We suggest that the most possible formation mechanism for these stars is the s-process pollution, although their abundance patterns can be fitted very well when the pre-enrichment hypothesis is included. That we cannot explain them well using the s-process nucleosynthesis alone may be due to our incomplete knowledge on the production of Nd, Eu, and other relevant elements by the s-process in metal-rich and super metal-rich environments (see details in Pereira et al. 2011).

Cui, W. Y.; Zhang, B.; Shi, J. R.; Zhao, G.; Wang, W. J.; Niu, P.

2014-06-01

180

Process R&D for CIS-Based Thin-Film PV: Final Technical Report, April 2002 - April 2005  

SciTech Connect

The primary objectives of this Shell Solar Industries subcontract are to address key near-term technical R&D issues for continued CIS product improvement; continue process development for increased production capacity; develop processes capable of significantly contributing to DOE 2020 PV shipment goals; advance mid- and longer-term R&D needed by industry for future product competitiveness including improving module performance, decreasing production process costs per watt produced, and improving reliability; and perform aggressive module lifetime R&D directed at developing packages that address the DOE goal for modules that will last up to 30 years while retaining 80% of initial power. These production R&D results, production volume, efficiency, high line yield, and advances in understanding are major accomplishments. The demonstrated and maintained high production yield is a major accomplishment supporting attractive cost projections for CIS. Process R&D at successive levels of CIS production has led to the continued demonstration of the prerequisites for commitment to large-scale commercialization. Process and packaging R&D during this and previous subcontracts has demonstrated the potential for further cost and performance improvements.

Tarrant, D. E.; Gay, R. R.

2006-01-01

181

Kek Isotope Separation System for ? Decay Spectroscopy of R-Process Nuclei  

NASA Astrophysics Data System (ADS)

Neutron-rich isotones with neutron shell closure N = 126 on the r-process path are supposed to be progenitors which form a peak around A = 195 in the r-abundance element distribution. Their ? decay properties are considered to play critical roles for better understanding where the heavy elements such as gold and platinum were made in the universe. We are now advancing a project to construct KEK Isotope Separation System to study ? decay properties and nuclear structures of neutron-rich nuclei around N = 126 experimentally. Those isotopes will be obtained via multi-nucleon transfer reactions induced by low-energy beams. For the study of the rare channel reaction products, it is essential to select both the element and mass number of them. We will adopt a gas catcher system combined with the laser resonance ionization and ISOL, which collect all reaction products and select the atomic number and mass of them efficiently. That system allows us to measure their ? decay properties by two-layer plastic scintillators and germanium detectors.

Watanabe, Y. X.; Miyatake, H.; Jeong, S. C.; Ishiyama, H.; Imai, N.; Hirayama, Y.; Oyaizu, M.; Niki, K.; Okada, M.; Wada, M.; Sonoda, T.

2013-09-01

182

?-decay spectroscopy of r-process nuclei with N = 126 at KISS  

NASA Astrophysics Data System (ADS)

The ?-decay properties of nuclei with N = 126, which are believed to act as progenitors in the rapid neutron capture (r-) process path forming the third peak (A 195) in the observed r-abundance element distribution, are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We have constructed the KEK Isotope Separation System (KISS), which consists of a gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 and to study their ?-decay properties, which are also of interest for astrophysics. The isotopes of interest will be produced by multi-nucleon transfer reactions in heavy ion collisions (e.g. 136Xe projectile on 198Pt target). KISS will allow us to study unknown isotopes produced in weak reaction channels under low background conditions. We successfully extracted the stable 56Fe beam from KISS at the last commissioning on-line experiment with the extraction efficiency of 0.25% and beam purity of more than 98%. We can access the nuclei with N = 126 and measure their half-lives using the KISS in the case of the extraction efficiency of 0.1%.

Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Miyatake, H.; Oyaizu, M.; Kim, Y. H.; Mukai, M.; Kimura, S.

2014-05-01

183

?-decay spectroscopy of r-process nuclei with N = 126 at KISS  

SciTech Connect

The ?-decay properties of nuclei with N = 126, which are believed to act as progenitors in the rapid neutron capture (r-) process path forming the third peak (A ? 195) in the observed r-abundance element distribution, are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We have constructed the KEK Isotope Separation System (KISS), which consists of a gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 and to study their ?-decay properties, which are also of interest for astrophysics. The isotopes of interest will be produced by multi-nucleon transfer reactions in heavy ion collisions (e.g. {sup 136}Xe projectile on {sup 198}Pt target). KISS will allow us to study unknown isotopes produced in weak reaction channels under low background conditions. We successfully extracted the stable {sup 56}Fe beam from KISS at the last commissioning on-line experiment with the extraction efficiency of 0.25% and beam purity of more than 98%. We can access the nuclei with N = 126 and measure their half-lives using the KISS in the case of the extraction efficiency of 0.1%.

Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Miyatake, H.; Oyaizu, M. [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Kim, Y. H. [Seoul National University, Seoul 151-742 (Korea, Republic of); Mukai, M.; Kimura, S. [Tsukuba University, Ibaraki 305-0006 (Japan)

2014-05-02

184

Mass measurements near the $r$-process path using the Canadian Penning Trap mass spectrometer  

E-print Network

The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.

J. Van Schelt; D. Lascar; G. Savard; J. A. Clark; S. Caldwell; A. Chaudhuri; J. Fallis; J. P. Greene; A. F. Levand; G. Li; K. S. Sharma; M. G. Sternberg; T. Sun; B. J. Zabransky

2012-04-09

185

Chapter for R. Rama (Ed.), Innovation in the food and drink processing industry, Haworth Press Inc, N.Y.  

E-print Network

, 1990) has waned in the face of consumer resistance to the use of genetically modified organisms in food1 Chapter for R. Rama (Ed.), Innovation in the food and drink processing industry, Haworth Press Inc, N.Y. Biotech Innovation in Europe's Food and Drink Processing Industry: Promise, Barriers

Paris-Sud XI, Université de

186

Stx5 is a novel interactor of VLDL-R to affect its intracellular trafficking and processing.  

PubMed

We identified syntaxin 5 (Stx5), a protein involved in intracellular vesicle trafficking, as a novel interaction partner of the very low density lipoprotein (VLDL)-receptor (VLDL-R), a member of the LDL-receptor family. In addition, we investigated the effect of Stx5 on VLDL-R maturation, trafficking and processing. Here, we demonstrated mutual association of both proteins using several in vitro approaches. Furthermore, we detected a special maturation phenotype of VLDL-R resulting from Stx5 overexpression. We found that Stx5 prevented advanced Golgi-maturation of VLDL-R, but did not cause accumulation of the immature protein in ER, ER to Golgi compartments, or cis-Golgi ribbon, the main expression sites of Stx5. Rather more, abundantly present Stx5 was capable of translocating ER-/N-glycosylated VLDL-R to the plasma membrane, and thus was insensitive to BFA treatment and low temperature. Furthermore, abundant presence of Stx5 significantly interfered with VLDL-R reaching the trans-Golgi network. Based on our findings, we postulate that Stx5 can directly bind to the C-terminal domain of VLDL-R, thereby influencing the receptor's glycosylation, trafficking and processing characteristics. Resulting from that, we further suggest that Stx5 might play a role in modulating VLDL-R physiology by participating in an abrasively described or completely novel Golgi-bypass pathway. PMID:23701949

Wagner, Timo; Dieckmann, Marco; Jaeger, Sebastian; Weggen, Sascha; Pietrzik, Claus U

2013-08-01

187

Julian, B.R. and G.R. Foulger, Monitoring Geothermal Processes with Microearthquake Mechanisms, Thirty-Fourth Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 9-  

E-print Network

Julian, B.R. and G.R. Foulger, Monitoring Geothermal Processes with Microearthquake Mechanisms, Thirty- Fourth Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 9- 11, 2009. Monitoring Geothermal Processes with Microearthquake Mechanisms Bruce R. Julian, U. S

Foulger, G. R.

188

Shelf Edge Exchange Processes--II: SEEP2-10, R/V ENDEAVOR cruise 195  

SciTech Connect

The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. This project consisted of a series of ten cruises, a mooring array, and a series of over-flights by NASA aircraft. Hydrographic data were collected on eight of the cruises, six of which were primarily mooring deployment or recovery cruises. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Two cruises (SEEP2-04 and SEEP2-07) were dedicated to investigating benthic processes and hydrographic data were not collected. The R/V ENDEAVOR cruise 193, SEEP2-09, took place from 2--12 May 1989 and recovered ten mornings along two cross-shelf lines across the outer continental shelf. During this cruise 77 CTD casts were made measuring pressure, temperature, conductivity, dissolved oxygen, fluorescence and light transmission. Discrete samples were taken in rosette-mounted Niskin bottles and analyzed for concentration of nutrients, chlorophyll a, dissolved oxygen, and particulate organic carbon and nitrogen. 14 refs., 9 figs., 3 tabs.

Behrens, W.J.; Wilson, C.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1990-04-01

189

DETECTION OF ELEMENTS AT ALL THREE r-PROCESS PEAKS IN THE METAL-POOR STAR HD 160617  

SciTech Connect

We report the first detection of elements at all three r-process peaks in the metal-poor halo star HD 160617. These elements include arsenic and selenium, which have not been detected previously in halo stars, and the elements tellurium, osmium, iridium, and platinum, which have been detected previously. Absorption lines of these elements are found in archive observations made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We present up-to-date absolute atomic transition probabilities and complete line component patterns for these elements. Additional archival spectra of this star from several ground-based instruments allow us to derive abundances or upper limits of 45 elements in HD 160617, including 27 elements produced by neutron-capture reactions. The average abundances of the elements at the three r-process peaks are similar to the predicted solar system r-process residuals when scaled to the abundances in the rare earth element domain. This result for arsenic and selenium may be surprising in light of predictions that the production of the lightest r-process elements generally should be decoupled from the heavier r-process elements.

Roederer, Ian U. [Carnegie Observatories, Pasadena, CA 91101 (United States); Lawler, James E., E-mail: iur@obs.carnegiescience.edu, E-mail: jelawler@wisc.edu [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

2012-05-01

190

The integration of process R&D in drug discovery--challenges and opportunities.  

PubMed

In today's situation where a lot of attention is put on the whereabouts of the pharmaceutical industry, especially focusing on productivity, pricing policies, time lines, and competition, there is an increased need for a critical revision of work practices in the business. The prevailing prioritization of time-to-market is now more and more shifting over to also put quality, risk management, and effectiveness/efficiency in the limelight. Resources in terms of people and money will continue to be constrained and, therefore, best collaborative principles have to be adopted between different parts of the organization. Only by operating this way will we maximize the output. One of the most important key performance indicators in pharma R&D is the number of newly appointed candidate drugs (CDs). However, it is not only a matter of counting numbers but, more so, to nominate compounds with the best properties and likelihood to survive. In that vein the demands on Process R&D have gone up considerably over recent years and there is now a pronounced need to make forecasts on cost of goods for the API (active pharmaceutical ingredient), scalability issues, IP matters, route design etc. On top of this, there is as always an expectation that the supply of material needed to conduct the various studies is timely, fully reliable, and flexible, even if volumes and delivery dates fluctuate widely. To successfully be able to cope with this challenging and sometimes stressful situation a back-integration into earlier parts of Drug Discovery is a must and, hence, connecting to new projects will have to be initiated already during the LO-stage (lead optimization). The consequences of this and its further implications will constitute the core part of the paper. PMID:16475965

Federsel, Hans-Jrgen

2006-02-01

191

Impact of weak interactions of free nucleons on the r-process in dynamical ejecta from neutron-star mergers  

E-print Network

We investigate beta-interactions of free nucleons and their impact on the electron fraction (Y_e) and r-process nucleosynthesis in ejecta characteristic of binary neutron star mergers (BNSMs). For that we employ trajectories from a relativistic BNSM model to represent the density-temperature evolutions in our parametric study. In the high-density environment, positron captures decrease the neutron richness at the high temperatures predicted by the hydrodynamic simulation. Circumventing the complexities of modelling three-dimensional neutrino transport, (anti)neutrino captures are parameterized in terms of prescribed neutrino luminosities and mean energies, guided by published results and assumed as constant in time. Depending sensitively on the adopted neutrino-antineutrino luminosity ratio, neutrino processes increase Y_e to values between 0.25 and 0.40, still allowing for a successful r-process compatible with the observed solar abundance distribution and a significant fraction of the ejecta consisting of r...

Goriely, Stephane; Just, Oliver; Pllumbi, Else; Janka, Hans-Thomas

2015-01-01

192

AN r-PROCESS KILONOVA ASSOCIATED WITH THE SHORT-HARD GRB 130603B  

SciTech Connect

We present ground-based optical and Hubble Space Telescope (HST) optical and near-IR observations of the short-hard GRB 130603B at z = 0.356, which demonstrate the presence of excess near-IR emission matching the expected brightness and color of an r-process powered transient (a {sup k}ilonova{sup )}. The early afterglow fades rapidly with {alpha} {approx}< -2.6 at t Almost-Equal-To 8-32 hr post-burst and has a spectral index of {beta} Almost-Equal-To -1.5 (F{sub {nu}}{proportional_to}t {sup {alpha}}{nu}{sup {beta}}), leading to an expected near-IR brightness at the time of the first HST observation of m{sub F160W}(t = 9.4 days) {approx}> 29.3 AB mag. Instead, the detected source has m{sub F160W} = 25.8 {+-} 0.2 AB mag, corresponding to a rest-frame absolute magnitude of M{sub J} Almost-Equal-To -15.2 mag. The upper limit in the HST optical observations is m{sub F606W} {approx}> 27.7 AB mag (3{sigma}), indicating an unusually red color of V - H {approx}> 1.9 mag. Comparing the observed near-IR luminosity to theoretical models of kilonovae produced by ejecta from the merger of an NS-NS or NS-BH binary, we infer an ejecta mass of M{sub ej} Almost-Equal-To 0.03-0.08 M{sub Sun} for v{sub ej} Almost-Equal-To 0.1-0.3c. The inferred mass matches the expectations from numerical merger simulations. The presence of a kilonova provides the strongest evidence to date that short GRBs are produced by compact object mergers, and provides initial insight on the ejected mass and the primary role that compact object merger may play in the r-process. Equally important, it demonstrates that gravitational wave sources detected by Advanced LIGO/Virgo will be accompanied by optical/near-IR counterparts with unusually red colors, detectable by existing and upcoming large wide-field facilities (e.g., Pan-STARRS, DECam, Subaru, LSST)

Berger, E.; Fong, W.; Chornock, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-09-10

193

Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars  

E-print Network

Employing high resolution spectra obtained with the near-UV sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2-d coude, we have performed a comprehensive chemical composition analysis of the bright r-process-rich metal-poor red giant star HD221170. Analysis of 57 individual neutral and ionized species yielded abundances for a total of 46 elements and significant upper limits for an additional five. Model stellar atmosphere parameters were derived with the aid of ~200 Fe-peak transitions. From more than 350 transitions of 35 neutron-capture (Z > 30) species, abundances for 30 neutron-capture elements and upper limits for three others were derived. Utilizing 36 transitions of La, 16 of Eu, and seven of Th, we derive ratios of log epsilon(Th/La) = -0.73 (sigma = 0.06) and log epsilon(Th/Eu) = -0.60 (sigma = 0.05), values in excellent agreement with those previously derived for other r-process-rich metal-poor stars such as CS22892-052, BD+17 3248, and HD115444. Based upon the Th/Eu chronometer, the inferred age is 11.7 +/- 2.8 Gyr. The abundance distribution of the heavier neutron-capture elements (Z >= 56) is fit well by the predicted scaled solar system r-process abundances, as also seen in other r-process-rich stars. Unlike other r-process-rich stars, however, we find that the abundances of the lighter neutron-capture elements (37 < Z < 56) in HD221170 are also statistically in better agreement with the abundances predicted for the scaled solar r-process pattern.

Inese I. Ivans; Jennifer Simmerer; Christopher Sneden; James E. Lawler; John J. Cowan; Roberto Gallino; Sara Bisterzo

2006-04-08

194

NEW RARE EARTH ELEMENT ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS  

SciTech Connect

We have derived new abundances of the rare earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low-metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally consistent Ba, rare earth, and Hf (56 {<=} Z {<=} 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

Sneden, Christopher [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Lawler, James E.; Den Hartog, Elizabeth A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Cowan, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Ivans, Inese I. [Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)], E-mail: chris@verdi.as.utexas.edu, E-mail: jelawler@wisc.edu, E-mail: eadenhar@wisc.edu, E-mail: cowan@nhn.ou.edu, E-mail: iii@ociw.edu

2009-05-15

195

New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars  

E-print Network

We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56<= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den

2009-01-01

196

Quark-Novae, cosmic reionization, and early r-process element production  

E-print Network

We examine the case for Quark-Novae (QNe) as possible sources for the reionization and early metal enrichment of the universe. Quark-Novae are predicted to arise from the explosive collapse (and conversion) of sufficiently massive neutron stars into quark stars. A Quark-Nova (QN) can occur over a range of time scales following the supernova event. For QNe that arise days to weeks after the supernovae, we show that dual-shock that arises as the QN ejecta encounter the supernova ejecta can produce enough photons to reionize hydrogen in most of the Inter-Galactic medium (IGM) by z ~ 6. Such events can explain the large optical depth tau_e ~ 0.1 as measured by WMAP, if the clumping factor, C, of the material being ionized is smaller than 10. We suggest a way in which a normal initial mass function (IMF) for the oldest stars can be reconciled with a large optical depth as well as the mean metallicity of the early IGM post reionization. We find that QN also make a contribution to r-process element abundances for atomic numbers A > 130. We predict that the main cosmological signatures of Quark-Novae are the gamma-ray bursts that announce their birth. These will be clustered at redshifts in the range z ~ 7-8 in our model.

R. Ouyed; R. E. Pudritz; P. Jaikumar

2009-06-30

197

s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT  

E-print Network

A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.

C. C. Worley; P. L. Cottrell; E. C. Wylie de Boer

2008-02-04

198

A Study on the Application of Fuzzy Analytic Hierarchy Process to Construct an R and D Management Effectiveness Evaluation Index for Taiwan=s High-Tech Industry  

NASA Astrophysics Data System (ADS)

The high-tech industry is one of the most important links in Taiwan=s economic development. Research and Development (R and D) technology and management is the key to sustainable enterprises. However, the involvement of many difficult quantification factors and the fuzzy character of human subjective judgment on the R and D management content and process makes R and D management effectiveness evaluation more difficult. This study adopted the Fuzzy Analytic Hierarchy Process (FAHP) from the Fuzzy Theory to develop a set of systematized evaluation indices for R and D management effectiveness. This method is designed to assist enterprises in conducting R and D management effectiveness evaluations to achieve the goal increasing enterprise competitiveness. According to the outcome of this study, the researchers found the importance and weight of these major aspects for Taiwan=s high-tech industry=s R and D management effectiveness is shown as follows: R and D and Innovation (0.346), R and D Process (0.269), Customer (0.209) and R and D Personnel (0.184). Moreover, among the effectiveness evaluations on implementing the R and D management in certain industries, R and D and Innovation and R and D Process are determined as the important item that revealed how Taiwan=s high-tech industries are particular about achieving R and D management through the completed R and D and innovation process.

Liu, Pang-Lo; Tsai, Chih-Hung

199

Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium  

E-print Network

We present age estimates for the newly discovered very r-process enhanced metal-poor star HE 1523-0901 ([Fe/H]=-2.95) based on the radioactive decay of Th and U. The bright (V=11.1) giant was found amongst a sample of bright metal-poor stars selected from the Hamburg/ESO survey. From an abundance analysis of a high-resolution (R=75,000) VLT/UVES spectrum we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe]=1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 A. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/Eu and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.

Anna Frebel; Norbert Christlieb; John E. Norris; Christopher Thom; Timothy C. Beers; Jaehyon Rhee

2007-03-15

200

Salinity inhibits post transcriptional processing of chloroplast 16S rRNA in shoot cultures of jojoba ( Simmondsia chinesis )  

Microsoft Academic Search

Chloroplast metabolism is rapidly affected by salt stress. Photosynthesis is one of the first processes known to be affected by salinity. Here, we report that salinity inhibits chloroplast post-transcriptional RNA processing. A differentially expressed 680-bp cDNA, containing the 3' sequence of 16S rRNA, transcribed intergenic spacer, exon 1 and intron of tRNAIle, was isolated by differential display reverse transcriptase PCR

Ela Mizrahi-Aviv; David Mills; Aliza Benzioni; Dudy Bar-Zvi

2005-01-01

201

? decay of nuclei around 90Se: Search for signatures of a N=56 subshell closure relevant to the r process  

NASA Astrophysics Data System (ADS)

Background: Nuclear structure plays a significant role on the rapid neutron capture process (r process) since shapes evolve with the emergence of shells and subshells. There was some indication in neighboring nuclei that we might find examples of a new N=56 subshell, which may give rise to a doubly magic 3490Se56 nucleus.Purpose: ?-decay half-lives of nuclei around 90Se have been measured to determine if this nucleus has in fact a doubly magic character.Method: The fragmentation of a 136Xe beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region.Results: We have measured the half-lives of 22 nuclei near the r-process path in the A=90 region. The half-lives of 88As and 90Se have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 subshell, and its possible role in the emergence of a potential doubly magic 90Se. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y, and Zr elements was investigated with a weak r-process network.Conclusions: The new half-lives agree with results obtained from a standard global QRPA model used in r-process calculations, indicating that 90Se has a quadrupole shape incompatible with a closed N=56 subshell in this region. The impact of the measured 90Se half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak r process is shown to be strong.

Quinn, M.; Aprahamian, A.; Pereira, J.; Surman, R.; Arndt, O.; Baumann, T.; Becerril, A.; Elliot, T.; Estrade, A.; Galaviz, D.; Ginter, T.; Hausmann, M.; Hennrich, S.; Kessler, R.; Kratz, K.-L.; Lorusso, G.; Mantica, P. F.; Matos, M.; Montes, F.; Pfeiffer, B.; Portillo, M.; Schatz, H.; Schertz, F.; Schnorrenberger, L.; Smith, E.; Stolz, A.; Walters, W. B.; Whr, A.

2012-03-01

202

24 CFR 235.1220 - Processing section 235(r) mortgages under the direct endorsement program.  

Code of Federal Regulations, 2011 CFR

...Eligibility Requirements: Contract Rights and Obligations; Assistance Payments Contracts; Servicing Responsibilities-Refinancing Mortgages Under Section 235(r) of the National Housing Act Eligibility Requirements; Direct Endorsement ...

2011-04-01

203

24 CFR 235.1220 - Processing section 235(r) mortgages under the direct endorsement program.  

Code of Federal Regulations, 2013 CFR

...Eligibility Requirements: Contract Rights and Obligations; Assistance Payments Contracts; Servicing Responsibilities-Refinancing Mortgages Under Section 235(r) of the National Housing Act Eligibility Requirements; Direct Endorsement ...

2013-04-01

204

24 CFR 235.1220 - Processing section 235(r) mortgages under the direct endorsement program.  

Code of Federal Regulations, 2010 CFR

...Eligibility Requirements: Contract Rights and Obligations; Assistance Payments Contracts; Servicing Responsibilities-Refinancing Mortgages Under Section 235(r) of the National Housing Act Eligibility Requirements; Direct Endorsement ...

2010-04-01

205

24 CFR 235.1220 - Processing section 235(r) mortgages under the direct endorsement program.  

Code of Federal Regulations, 2014 CFR

...Eligibility Requirements: Contract Rights and Obligations; Assistance Payments Contracts; Servicing Responsibilities-Refinancing Mortgages Under Section 235(r) of the National Housing Act Eligibility Requirements; Direct Endorsement ...

2014-04-01

206

24 CFR 235.1220 - Processing section 235(r) mortgages under the direct endorsement program.  

Code of Federal Regulations, 2012 CFR

...Eligibility Requirements: Contract Rights and Obligations; Assistance Payments Contracts; Servicing Responsibilities-Refinancing Mortgages Under Section 235(r) of the National Housing Act Eligibility Requirements; Direct Endorsement ...

2012-04-01

207

30 ENGINEERING & SCIENCE WI NTE R 2012 Whether processing radar signals in Norway or assessing rock properties in Nigeria, Calte  

E-print Network

of genetic engineering in Ireland; he helped establish the Smurfit Institute of Genetics in 1998, where he30 ENGINEERING & SCIENCE WI NTE R 2012 Whether processing radar signals in Norway or assessing rock, England, Sarah Ferguson, BS '08, Engineering & Applied Science (CNS) Sarah Ferguson is a trader at Ronin

208

OPTIMIZATION OF THE DEHYDRATION PROCESS FOR TWO BIOTYPES OF LUCUMA (Pouteria lcuma (R & P) KUNTZE) USING THE RESPONSE SURFACE METHODOLOGY  

Microsoft Academic Search

Lucuma (Pouteria lucuma (R and P) Kuntze) is a native fruit of Peru. Lucuma flavor and color are appreciated in ice cream preparation. The carotene content gives to lucuma pulp a coloration between light yellow and intense orange. Frozen pulp and lucuma meal are two forms for its commercialization. In this research the objective was the optimization of dehydration process

Marianela Inga

209

Analysis and modeling of gas exchange processes in Scaevola aemula Soo-Hyung Kim a,*, Paul R. Fisher b  

E-print Network

Analysis and modeling of gas exchange processes in Scaevola aemula Soo-Hyung Kim a,*, Paul R crop cultivated as a bedding plant or for hanging baskets. We characterized gas exchange properties but significantly reduced at 15 8C. These gas exchange results were used to test the extendibility of a coupled gas

Lieth, J. Heinrich

210

A low initial abundance of 247Cm in the early solar system and implications for r-process nucleosynthesis  

NASA Astrophysics Data System (ADS)

The short-lived nuclide 247Cm is produced by r-process nucleosynthesis. When the presolar nebula formed, 247Cm became isolated from r-process production and its abundance diminished as a result of radioactive decay. Given its short half-life of only 16 million years, 247Cm is presently extinct, but its former presence should be detectable as small variations in 235U/ 238U in primitive meteoritic material, provided Cm was chemically fractionated from U at the time these solid objects formed. The magnitude of U isotopic anomalies in meteorites can thus be used to elucidate the timing and character of the last r-process nucleosynthetic event for input into models describing the formation and evolution of the early solar system. Here we report coupled U isotopic determinations and Nd/U proxy measurements for Cm/U in a series of acid-etched leachates and mineral assemblages extracted from meteorites containing primitive phases expected to show strong Cm-U fractionations. Using multiple-collector ICPMS, we are able to determine 235U/ 238U with 2 ? analytical uncertainties of 1 epsilon (1 epsilon = 1 part in 10,000) on sample sizes consisting of < 3 ng of 238U and < 20 pg of 235U. A double-spiking procedure using a mixed 236U- 233U spike was employed to allow instrumental mass fractionation to be reliably corrected internally and at high precision. Uranium isotopic results for almost 40 different phases show no resolvable deviations in 235U/ 238U from the chondritic value, at the 1-2 epsilon level. These data supplement our previous observations for a suite of bulk meteorite samples [C.H. Stirling, A.N. Halliday, D. Porcelli, In search of live 247Cm in the early solar system, Geochim. Cosmochim. Acta 69 (2005) 1059-1071] and provide evidence for a solar system initial 247Cm/ 235U of < 8 10 - 5 . Such a low value is difficult to explain without a long time-scale of 2.3 10 8 years between the last actinide producing r-process event and the formation of the solar system. As such it is difficult to reconcile with a model of actinide production in the same r-process forming event as 182Hf with a half-life of 8.9 My [G.J. Wasserburg, M. Busso, R. Gallino, Abundances of actinides and short-lived nonactinides in the interstellar medium: Diverse supernova sources for the r-processes, Astrophys. J. 466 (1996) L109-L113]. The alternative models of 182Hf production via a neutron-rich fast s-process, occurring, for example, in the helium burning shell in a 25 solar mass star during explosive nucleosynthesis [G.J. Wasserburg, M. Busso, R. Gallino, Abundances of actinides and short-lived nonactinides in the interstellar medium: Diverse supernova sources for the r-processes, Astrophys. J. 466 (1996) L109-L113], or via a distinct r-process event that is separate from actinide production [G.J. Wasserburg, M. Busso, R. Gallino, K.M. Nollet, Short-lived nuclei in the early solar system: Possible AGB sources, Nucl. Phys. A (in press)], may provide a viable explanation. However, further studies are also required to assess the veracity of Cm-U systematics, which are critically dependent on the suitability of using Nd and the light rare earth elements (LREEs) as a chemical proxy for Cm.

Stirling, Claudine H.; Halliday, Alex N.; Potter, Emma-Kate; Andersen, Morten B.; Zanda, Brigitte

2006-11-01

211

Current status and prospects of radiation processing studies in Taiwan, R. O. C.  

NASA Astrophysics Data System (ADS)

The research on radiation processing in past 5 years in Taiwan covers industrial application of radiation-induced polymerization and curing, medical application of radiosterilization of medical supplies, chemicals, and amniotic membrane for wound dressing as well as agricultural application of food irradiation and genogenesis etc. Radiation-induced polymerization applied on wood and bamboo plastic composite of methyl methacrylate, radiation curing on polyurethane and silicon rubber for biomedical material using to separate oxygen from nitrogen and on crosslinking of pp and ps for artificial skin for wound dressing were all success. Radio-sterilization of disposable medical supplies appears for immediate application after the studies of the dose requirement of several radioresistant microorganisms, dose distribution measured by chemical dosimeters of ceric sulfate and Fricke dosimeter as well as quality control system were completed. The radiosterilization study of tetracycline - HCl and few detoxic agents like atropine sulfate and toxogonin has shown the promising results on radiosterilization of chemicals, the radiosterilization of amniotic membrane for wound dressing are also success. Food irradiation on sprouting inhibition of potatoes, garlic etc, on radiodisinfestation of cereal insects, tobacco bettles, soybean insects, and flour beetles, as well as on frog legs and porks have been also discussed. The legislation on radiosterilization of medical supplies and food irradiation of 14 items has been approved by National Health Administration, R.O.C. in July of 1982 and January of 1985 respectively. Even 24 hrs-operation of 1 Mega curie irradiation plant at INER can not satisfy the requirement of radiosterilization of medical supplies. A private commercial irradiation plant is urgently needed in Taiwan other than at INER now.

Fu, Ying-Kai

212

Spectroscopic Studies of Extremly Metal-Poor Stars with Subaru/HDS:II.The r-process Elements, Including Thorium  

E-print Network

We present the abundance analyses for the neutron-capture elements, and discuss the observed abundance distributions in very metal-poor stars with excesses of r-process elements. As has been found by previous abundance studies, the star-to-star scatter in the abundances of neutron-capture elements are very large. The abundance patterns of the heavy neutron-capture elements (56 $\\leq$ Z $\\leq$ 70) in seven objects with moderate to large excesses of the neutron-capture elements are similar to that of the solar system r-process component. These results strongly suggest that the heavy neutron-capture elements in these objects are primarily synthesized by the r-process. On the other hand, the abundance ratios of the light neutron-capture elements (38 $\\leq$ Z $\\leq$ 46) exhibit a rather large dispersion. Our inspection of the correlation between Sr and Ba abundances in very metal-poor stars reveals that the dispersion of the Sr abundances clearly decreases with increasing Ba abundance. This results support previous suggestions that the light neutron-capture elements are likely to have been produced in different astrophysical sites from those associated with the production of the heavier ones. The Th/Eu abundance ratios (log(Th/Eu)) measured for the seven r-process-enhanced stars range from -0.10 to -0.59. Since these very metal-poor stars are believed to be formed in the early Galaxy, this result means that a small dispersion appears in the abundance ratios between Th and rare-earth elements, such as Eu, in very metal-poor stars. In order to apply the Th/Eu ratios to estimates of stellar ages, further understanding for the Th production by the r-process nucleosynthesis is required.

S. Honda; W. Aoki; T. Kajino; H. Ando; T. C. Beers; H. Izumiura; K. Sadakane; M. Takada-Hidai

2004-02-12

213

Compact Stellar Binary Assembly in the First Nuclear Star Clusters and r-process Synthesis in the Early Universe  

NASA Astrophysics Data System (ADS)

Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that lived and died before them. The presence of r-process elements in a handful of carbon-enhanced metal-poor (CEMP-r) stars, which are assumed to be closely connected to the chemical yield from the first stars, is hard to reconcile with standard neutron star mergers. Here we show that the production rate of dynamically assembled compact binaries in high-z nuclear star clusters can attain a sufficient high value to be a potential viable source of heavy r-process material in CEMP-r stars. The predicted frequency of such events in the early Galaxy, much lower than the frequency of Type II supernovae but with significantly higher mass ejected per event, can naturally lead to a high level of scatter of Eu as observed in CEMP-r stars.

Ramirez-Ruiz, Enrico; Trenti, Michele; MacLeod, Morgan; Roberts, Luke F.; Lee, William H.; Saladino-Rosas, Martha I.

2015-04-01

214

Query processing strategies in the PASCAL\\/R relational database management system  

Microsoft Academic Search

In the database language PASCAL\\/R, the programming language PASCAL and concepts based on the relational data model are integrated. The paper investigates transformation strategies used in the PASCAL\\/R system to evaluate queries with existential and universal quantifiers. Intermediate data structures are described using a high-level language tool called a reference to a selected variable. The predicate calculus approach used in

Matthias Jarke; Joachim W. Schmidt

1982-01-01

215

Near-Ultraviolet Observations of HD 221170: New Insights into the Nature of r-Process-rich Stars  

NASA Astrophysics Data System (ADS)

Employing high-resolution spectra obtained with the near-UV-sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2d-coud, we have performed a comprehensive chemical composition analysis of the bright r-process-rich metal-poor red giant star HD 221170. Analysis of 57 individual neutral and ionized species yielded abundances for a total of 46 elements and significant upper limits for an additional five. Model stellar atmosphere parameters were derived with the aid of ~200 Fe peak transitions. From more than 350 transitions of 35 neutron-capture (Z>30) species, abundances for 30 neutron-capture elements and upper limits for three others were derived. Utilizing 36 transitions of La, 16 of Eu, and seven of Th, we derive ratios of log?(Th/La)=-0.73 (?=0.06) and log?(Th/Eu)=-0.60 (?=0.05), values in excellent agreement with those previously derived for other r-process-rich metal-poor stars such as CS 22892-052, BD +17 3248, and HD 115444. Based on the Th/Eu chronometer, the inferred age is 11.7+/-2.8 Gyr. The abundance distribution of the heavier neutron-capture elements (Z>=56) is fitted well by the predicted scaled solar system r-process abundances, as also seen in other r-process-rich stars. Unlike other r-process-rich stars, however, we find that the abundances of the lighter neutron-capture elements (37r-process pattern. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, University of California, and NASA and was made possible by the financial support of the W. M. Keck Foundation. This paper includes data taken at the McDonald Observatory of the University of Texas at Austin.

Ivans, Inese I.; Simmerer, Jennifer; Sneden, Christopher; Lawler, James E.; Cowan, John J.; Gallino, Roberto; Bisterzo, Sara

2006-07-01

216

Can we monitor the bare soil freeze-thaw process using GNSS-R?: a simulation study  

NASA Astrophysics Data System (ADS)

GNSS-R has recently emerged as a new prosperous remote sensing tool in ocean surface, snow/ice surface and land surface. In this paper, the possible application in sensing the bare soil freeze-thaw process is investigated with GNSS-R. The Fresnel reflectivity from the wave synthesis technique is used to get the circular polarization reflectivity. Large differences are found for the Fresnel reflectivities at V, H, RR polarizations during bare soil freeze-thaw process, but there are almost no differences as for LR polarization. Therefore if a special GNSS-R receiver is designed, the reflected signals of RR polarization should be efficiently used. For GPS multipath reflectometry, the improved Fresnel reflectivity is inserted into the fully polarimetric forward multipath model to get the simulated GPS L1 observables: SNR, carrier phase multipath error and pseudorange code multipath error, which are used to estimate the bare soil freeze-thaw process. Compared to the thawed soil, the amplitudes of GPS observables are smaller for the frozen soil. Therefore, it is possible to monitor bare soil freeze-thaw process with ground geodetic GPS receivers.

Wu, Xuerui; Jin, Shuanggen

2014-11-01

217

Analysis of 26 Barium Stars II. Contributions of s-, r- and p-processes in the production of heavy elements  

E-print Network

Barium stars show enhanced abundances of the slow neutron capture (s-process) heavy elements, and for this reason they are suitable objects for the study of s-process elements. The aim of this work is to quantify the contributions of the s-, r- and p-processes for the total abundance of heavy elements from abundances derived for a sample of 26 barium stars. The abundance ratios between these processes and neutron exposures were studied. The abundances of the sample stars were compared to those of normal stars thus identifying the fraction relative to the s-process main component. The fittings of the sigmaN curves (neutron capture cross section times abundance, plotted against atomic mass number) for the sample stars suggest that the material from the companion asymptotic giant branch star had approximately the solar isotopic composition as concerns fractions of abundances relative to the s-process main component. The abundance ratios of heavy elements, hs, ls and s and the computed neutron exposure are similar to those of post-AGB stars. For some sample stars, an exponential neutron exposure fits well the observed data, whereas for others, a single neutron exposure provides a better fit. The comparison between barium and AGB stars supports the hypothesis of binarity for the barium star formation. Abundances of r-elements that are part of the s-process path in barium stars are usually higher than those in normal stars,and for this reason, barium stars seemed to be also enriched in r-elements, although in a lower degree than s-elements. No dependence on luminosity classes was found in the abundance ratios behaviour among the dwarfs and giants of the sample barium stars.

Dinah M. Allen; Beatriz Barbuy

2006-04-04

218

Thorium-rich halo star HD221170: further evidence against the universality of the r-process  

E-print Network

We report the abundance determination in the atmosphere of the bright halo star HD221170. The spectra were taken with the Terskol Observatory's 2.0-m telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10275 \\AA. The adopted atmospheric parameters correspond to an effective temperature \\Tef=4475 K, a surface gravity \\lgg=1.0, a microturbulent velocity \\vmi=1.7 \\kms, and a macroturbulent velocity \\vma=4 \\kms. The abundances of 43 chemical elements were determined with the method of spectrum synthesis. The large overabundances (by 1 dex relative to iron) of elements with Z$>38$ are shown to follow the same pattern as the solar r-abundances. The present HD221170 analysis confirms the non-universality of the r-process, or more exactly the observation that the astrophysical sites hosting the r-process do not always lead to a unique relative abundance distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the actinides.

Alexander Yushchenko; Vera Gopka; Stephane Goriely; Faig Musaev; Angelina Shavrina; Chulhee Kim; Young Woon Kang; Juliana Kuznietsova; Vladimir Yushchenko

2004-09-22

219

Inhibitory repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex modulates early affective processing.  

PubMed

The dorsolateral prefrontal cortex (dlPFC) has often been suggested as a key modulator of emotional stimulus appraisal and regulation. Therefore, in clinical trials, it is one of the most frequently targeted regions for non-invasive brain stimulation such as repetitive transcranial magnetic stimulation (rTMS). In spite of various encouraging reports that demonstrate beneficial effects of rTMS in anxiety disorders, psychophysiological studies exploring the underlying neural mechanisms are sparse. Here we investigated how inhibitory rTMS influences early affective processing when applied over the right dlPFC. Before and after rTMS or sham stimulation, subjects viewed faces with fearful or neutral expressions while whole-head magnetoencephalography (MEG) was recorded. Due to the disrupted functioning of the right dlPFC, visual processing in bilateral parietal, temporal, and occipital areas was amplified starting at around 90 ms after stimulus onset. Moreover, increased fear-specific activation was found in the right TPJ area in a time-interval between 110 and 170 ms. These neurophysiological effects were reflected in slowed reaction times for fearful, but not for neutral faces in a facial expression identification task while there was no such effect on a gender discrimination control task. Our study confirms the specific and important role of the dlPFC in regulation of early emotional attention and encourages future clinical research to use minimal invasive methods such as transcranial magnetic (TMS) or direct current stimulation (tDCS). PMID:25019678

Zwanzger, Peter; Steinberg, Christian; Rehbein, Maimu Alissa; Brckelmann, Ann-Kathrin; Dobel, Christian; Zavorotnyy, Maxim; Domschke, Katharina; Junghfer, Markus

2014-11-01

220

PRETREATMENT AND FRACTIONATION OF CORN STOVER BY AMMONIA RECYCLE PERCOLATION PROCESS. (R831645)  

EPA Science Inventory

Corn stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed as Ammonia Recycle Percolation (ARP). The aqueous ammonia causes swelling and efficient delignification of biomass at high temperatures. The ARP process solubilizes abou...

221

Point processes, temporal David R. Brillinger, Peter M. Guttorp & Frederic Paik Schoenberg  

E-print Network

, thunder), volcanic eruptions, lightning strikes, tornadoes, power outages, chemical spills (see. A process may be either deterministic or stochastic. In the determin- istic case the values j are fixed. In the latter case (see Stochastic process) the process is determined by a consistent collection

Schoenberg, Frederic Paik (Rick)

222

Decay of the r-process waiting-point nuclide ^130Cd to levels of ^130In  

Microsoft Academic Search

The beta and gamma radiations following the decay of the r-process waiting-point nuclide, ^130Cd to levels of ^130In have been studied at CERN\\/ISOLDE. The 165-ms ^130Cd nuclides were selectively ionized using the Resonance Ionization Laser Ion Source. The 1^+ level populated in Gamow-Teller beta decay was found to lie at 2120 keV, well above the 1400-keV region suggested in several

K.-L. Kratz; I. Dillmann; O. Arndt; M. Hannawald; B. Pfeiffer; A. Ostrowski; A. M. El-Taher; A. Whr; J. Shergur; W. B. Walters; U. Kster; V. Fedoseyev; H. Ravn; D. Seweryniak; P. Hoff; B. A. Brown; T. Isoldecoll

2002-01-01

223

Uranium lines in the spectra of peculiar A stars - A search for recent r-process events  

NASA Technical Reports Server (NTRS)

Uranium wavelengths in the spectra of Ap stars are studied to see if they give any indication of a recent r-process event. It is concluded that there is no credible evidence for an admixture of uranium-235 in these stars, which would imply such an event. The evidence, though negative, is badly confused by blending of lines, and a final judgement must wait for an observational clarification of the situation.

Cowley, C. R.; Adelman, S. J.

1975-01-01

224

Processing of biomorphic porous TiO 2 ceramics by chemical vapor infiltration and reaction (CVI-R) technique  

Microsoft Academic Search

Porous biomorphic TiO2 ceramics were manufactured from paper preforms by chemical vapor infiltration and reaction (CVI-R) in a three-steps process. First, the cellulose fibers of the paper were converted into carbon (Cb) by pyrolysis in an inert atmosphere. Then, Cb-template was infiltrated with a precursor system consisting of TiCl4, CH4 and H2 to produce porous TiC ceramics, which were oxidized

H. Ghanem; M. Kormann; H. Gerhard; N. Popovska

2007-01-01

225

Detection of low Eu abundances in extremely metal-poor stars and the origin of r-process elements  

E-print Network

We report abundance analyses of three extremely metal-poor stars with [Fe/H] $\\lesssim -3$, using the Subaru High Dispersion Spectrograph (HDS). All are found to have sub-solar values of [Eu/Fe]. Comparison with our chemical evolution model of the Galactic halo implies the dominant source of Eu to be the low-mass end of the supernova mass range. Future studies of stars with low Eu abundances will be important to determine the r-process site.

Yuhri Ishimaru; Shinya Wanajo; Wako Aoki; Sean G. Ryan

2003-11-06

226

Rolling Deck to Repository (R2R): Programmatic Quality Assessment and Processing of Marine Gravity and Magnetic Data and Associated Metadata  

NASA Astrophysics Data System (ADS)

With its global capability and diverse array of sensors, the U.S. academic research fleet is an integral component of ocean exploration. The Rolling Deck to Repository (R2R) Program provides a central shore-side gateway for underway data from the U.S. academic research fleet, with the primary goal of preserving and documenting routine underway data. Programmatic tools for Quality Assessment (QA) of multiple underway data types are being developed to provide prompt feedback to shipboard operators and inform down-stream science users. QA tools are being developed in object oriented PHP with modular components that can be distributed for use by the community. Programmatic data processing (DP) tools for select data types are also being developed. We report on recent progress with QA and DP tools developed for underway gravity and magnetics data. For magnetics data, DP includes despiking and removal of bad data, merging with navigation, turn removal, calculation of a layback position, and removal of the IGRF to produce a magnetic anomaly. For gravity data, DP involves merging with navigation, corrections for speed and heading (Etvs) and latitude, some basic filtering, removing bad data, subsampling, and drift corrections. All of these tools follow a programmatic workflow that requires minimal human intervention. Advanced processing which requires human intervention is left to the science user. These tools make use of metadata specific to each device and data type, as well as customizable thresholds and processing parameters. The full suite of metadata that describes each data set, the quality assessment parameters and results, as well as processing steps will accompany the data being submitted to the National Geophysical Data Center. In addition to QA reports for raw data files, day plots are also produced at each step to allow for quick observation and verification of the data quality and processing steps. These plots will also be delivered with the data files. The result of data processing for gravity and magnetics data is a quality assessed multiplexed file (MGD77T). In addition, web tools are being developed to provide science users and operators with a quick and intuitive interface for reviewing QA results.

Morton, J. J.; Ferrini, V.; O'hara, S. H.; Arko, R. A.; Carbotte, S. M.; Coakley, B.

2011-12-01

227

NEW ABUNDANCE DETERMINATIONS OF CADMIUM, LUTETIUM, AND OSMIUM IN THE r-PROCESS ENRICHED STAR BD +17 3248 {sup ,}  

SciTech Connect

We report the detection of Cd I (Z = 48), Lu II (Z = 71), and Os II (Z = 76) in the metal-poor star BD +17 3248. These abundances are derived from an ultraviolet spectrum obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This is the first detection of these neutron-capture species in a metal-poor star enriched by the r process. We supplement these measurements with new abundances of Mo I, Ru I, and Rh I derived from an optical spectrum obtained with the High Resolution Echelle Spectrograph on Keck. Combined with previous abundance derivations, 32 neutron-capture elements have been detected in BD +17 3248, the most complete neutron-capture abundance pattern in any metal-poor star to date. The light neutron-capture elements (38 {<=} Z {<=} 48) show a more pronounced even-odd effect than expected from current solar system r-process abundance predictions. The age for BD +17 3248 derived from the Th II/Os II chronometer is in better agreement with the age derived from other chronometers than the age derived from Th II/Os I. New Hf II abundance derivations from transitions in the ultraviolet are lower than those derived from transitions in the optical, and the lower Hf abundance is in better agreement with the scaled solar system r-process distribution.

Roederer, Ian U.; Sneden, Christopher [Department of Astronomy, University of Texas at Austin, 1 University Station, C1400 Austin, TX 78712-0259 (United States); Lawler, James E. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Cowan, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)], E-mail: iur@astro.as.utexas.edu

2010-05-01

228

Neutrino fluence after r-process freeze-out and abundances of Te isotopes in presolar diamonds  

E-print Network

Using the data of Richter et al. (1998) on Te isotopes in diamond grains from a meteorite, we derive bounds on the neutrino fluence and the decay timescale of the neutrino flux relevant for the supernova r-process. Our new bound on the neutrino fluence F after freeze-out of the r-process peak at mass number A = 130 is more stringent than the previous bound F neutrino flux decays on a timescale tau > 0.65 s. In particular, it requires that a fluence of F = 0.031 be provided by a neutrino flux with tau 1 in the expanding supernova debris or from the exterior H envelope. The implantation of nuclei would have occurred 10**4-10**6 s after r-process freeze-out. This time interval may be marginally sufficient to permit adequate cooling upon expansion for the formation of diamond grains. The mechanisms of preferential retention/loss of the implanted nuclei are not well understood.

Y. -Z. Qian; P. Vogel; G. J. Wasserburg

1998-08-25

229

Ribosomal protein L35 is required for 27SB pre-rRNA processing in Saccharomyces cerevisiae  

PubMed Central

Ribosome synthesis involves the concomitance of pre-rRNA processing and ribosomal protein assembly. In eukaryotes, this is a complex process that requires the participation of specific sequences and structures within the pre-rRNAs, at least 200 trans-acting factors and the ribosomal proteins. There is little information on the function of individual 60S ribosomal proteins in ribosome synthesis. Herein, we have analysed the contribution of ribosomal protein L35 in ribosome biogenesis. In vivo depletion of L35 results in a deficit in 60S ribosomal subunits and the appearance of half-mer polysomes. Pulse-chase, northern hybridization and primer extension analyses show that processing of the 27SB to 7S pre-rRNAs is strongly delayed upon L35 depletion. Most likely as a consequence of this, release of pre-60S ribosomal particles from the nucleolus to the nucleoplasm is also blocked. Deletion of RPL35A leads to similar although less pronounced phenotypes. Moreover, we show that L35 assembles in the nucleolus and binds to early pre-60S ribosomal particles. Finally, flow cytometry analysis indicated that L35-depleted cells mildly delay the G1 phase of the cell cycle. We conclude that L35 assembly is a prerequisite for the efficient cleavage of the internal transcribed spacer 2 at site C2. PMID:20392820

Babiano, Reyes; de la Cruz, Jess

2010-01-01

230

R&D for the Post-EP Processes of Superconducting RF Cavity  

SciTech Connect

The Electro-Polishing (EP) process is the best candidate of final surface treatment for the production of ILC cavities. Nevertheless, the broad distribution of the gradient caused by field emitters in cavities is sitll a serious problem for the EP process. A candidate source of field emitter is the sulfur component which is produced in the EP process and remains the inner-surface of cavities. We studied the effect of Ethanole- and degreaser-rinse processes after the EP process by a unique method. Moreover, we tried to test the sponge cleaning as the post-EP process to remove the field emitter inside the cavcity. This article describe the results of series tests of the post-EP process at KEK.

Saeki, Takayuki [KEK; Funahashi, Y. [KEK; Hayano, H. [KEK; Kato, Seigo [KEK; Nishiwaki, Michiru [KEK; Sawabe, Motoaki [KEK; Ueno, Kenji [KEK; Watanabe, K. [KEK; Antoine, Claire [CEA, Gif-sur-Yvette; Berry, Stefurn [CEA, Gif-sur-Yvette; Eozenou, F. [CEA, Gif-sur-Yvette; Gasser, Y. [CEA, Gif-sur-Yvette; Visentin, B. [CEA, Gif-sur-Yvette; Clemens, William A. [JLAB; Geng, Rongli [JLAB; Manus, Robert [JLAB; Tyagi, Puneet [GUAS/AS, Ibaraki

2009-11-01

231

Nine new metal-poor stars on the subgiant and red horizontal branches with high levels of r-process enhancement  

NASA Astrophysics Data System (ADS)

We report the discovery of nine metal-poor stars with high levels of r-process enhancement (+0.81 ? [Eu/Fe] ? +1.13), including six subgiants and three stars on the red horizontal branch. We also analyse four previously known r-process-enhanced metal-poor red giants. From this sample of 13 stars, we draw the following conclusions. (1) High levels of r-process enhancement are found in a broad range of stellar evolutionary states, reaffirming that this phenomenon is not associated with a chemical peculiarity of red giant atmospheres. (2) Only 1 of 10 stars observed at multiple epochs shows radial-velocity variations, reaffirming that stars with high levels of r-process enhancement are not preferentially found among binaries. (3) Only 2 of the 13 stars are highly enhanced in C and N, indicating that there is no connection between high levels of r-process enhancement and high levels of C and N. (4) The dispersions in [Sr/Ba] and [Sr/Eu] are larger than the dispersions in [Ba/Eu] and [Yb/Eu], suggesting that the elements below the second r-process peak do not always scale with those in the rare Earth domain, even within the class of highly-r-process-enhanced stars. (5) The light-element (12 ? Z ? 30) abundances of highly-r-process-enhanced stars are indistinguishable from those with normal levels of r-process material at the limit of our data, 3.5 per cent (0.015 dex) on average. The nucleosynthetic sites responsible for the large r-process enhancements did not produce any detectable light-element abundance signatures distinct from normal core-collapse supernovae.

Roederer, Ian U.; Cowan, John J.; Preston, George W.; Shectman, Stephen A.; Sneden, Christopher; Thompson, Ian B.

2014-12-01

232

Low-mass supernovae in the early Galactic halo: source of the double r/s-process enriched halo stars?  

E-print Network

Several stars at the low-metallicity extreme of the Galactic halo ([Fe/H]=-2.5) show strong enhancements of both s-process and r-process elements. The presence of s-process elements in main-sequence stars is explained via mass transfer from an AGB companion star in a binary system. r-Process elements originate in type-II supernovae and also require mass transfer. It is however unclear how pollution by both an AGB star and a supernova could have occured. Here I show that the initial--final-mass relation steepens at low metallicity, due to low mass-loss efficiency. This may cause the degenerate cores of low-Z, high-mass AGB stars to reach the Chandresekhar mass, leading to an Iben & Renzini-type-1.5 supernova. Such supernovae can explain both the enhancement patterns and the metallicity dependence of the double-enhanced halo stars. Reduced mass loss efficiency predicts more massive remnants in metal-poor globular clusters. The evidence for a high M/L population in the cores of globular clusters is briefly discussed.

Albert A. Zijlstra

2003-12-18

233

Comparative study of the bioconversion process using R-(+)- and S-(-)-limonene as substrates for Fusarium oxysporum 152B.  

PubMed

This study compared the bioconversion process of S-(-)-limonene into limonene-1,2-diol with the already established biotransformation of R-(+)-limonene into ?-terpineol using the same biocatalyst in both processes, Fusarium oxysporum 152B. The bioconversion of the S-(-)-isomer was tested on cell permeabilisation under anaerobic conditions and using a biphasic system. When submitted to permeabilisation trials, this biocatalyst has shown a relatively high resistance; still, no production of limonene-1,2-diol and a loss of activity of the biocatalyst were observed after intense cell treatment, indicating a complete loss of cell viability. Furthermore, the results showed that this process can be characterised as an aerobic system that was catalysed by limonene-1,2-epoxide hydrolase, had an intracellular nature and was cofactor-dependent because the final product was not detected by an anaerobic process. Finally, this is the first report to characterise the bioconversion of R-(+)- and S-(-)-limonene by cellular detoxification using ultra-structural analysis. PMID:25529726

Molina, Gustavo; Bution, Murillo L; Bicas, Juliano L; Dolder, Mary Anne Heidi; Pastore, Glucia M

2015-05-01

234

EVALUATION OF DIFFERENT SIGNAL PROCESSING OPTIONS IN UNILATERAL AND BILATERAL COCHLEAR FREEDOM IMPLANT RECIPIENTS USING R-SPACE BACKGROUND NOISE  

PubMed Central

Background Difficulty understanding in background noise is a common complaint of cochlear implant (CI) recipients. Programming options are available to improve speech recognition in noise for CI users including Automatic Dynamic Range Optimization (ADRO), Autosensitivity Control (ASC), and BEAM. The processing option, however, which results in the best speech recognition in noise, is unknown. In addition, laboratory measures of these processing options often show greater degrees of improvement than reported by participants in everyday listening situations. To address this issue, Compton-Conley and colleagues developed a test system to replicate a restaurant environment. The R-SPACE consists of eight loudspeakers positioned in a 360 degree arc and utilizes a recording made at a restaurant of background noise. Purpose The present study measured speech recognition in the R-SPACE with four processing options: standard dual-port directional (STD), ADRO, ASC, and BEAM. Research Design A repeated measures, within-subject design was used to evaluate the four different processing options at two noise levels. Study Sample Twenty-seven unilateral and three bilateral adult Nucleus Freedom cochlear implant recipients. Intervention The participants everyday program (with no additional processing) was used as the STD program. ADRO, ASC, and BEAM were added individually to the STD program to create a total of four programs. Data Collection and Analysis Participants repeated HINT sentences presented at a 0 degree azimuth with R-SPACE restaurant noise at two noise levels, 60 and 70 dB SPL. The Reception Threshold for Sentences (RTS) was obtained for each processing condition and noise level. Results In 60 dB SPL noise, BEAM processing resulted in the best RTS, with a significant improvement over STD and ADRO processing. In 70 dB SPL noise, ASC and BEAM processing had significantly better mean RTSs compared to STD and ADRO processing. Comparison of noise levels showed that STD and BEAM processing resulted in significantly poorer RTSs in 70 dB SPL noise compared to the performance with these processing conditions in 60 dB SPL noise. Bilateral participants demonstrated a bilateral improvement compared to the better monaural condition for both noise levels and all processing conditions, except ASC in 60 dB SPL noise. Conclusions The results of this study suggest that the use of processing options that utilize noise reduction, like that available in ASC and BEAM, improve a CI recipients ability to understand speech in noise in listening situations similar to those experienced in the real-world. The choice of the best processing option is dependent on the noise level, with BEAM best at moderate noise levels and ASC best at loud noise levels for unilateral CI recipients. Therefore, multiple noise programs or a combination of processing options may be necessary to provide CI users with the best performance in a variety of listening situations. PMID:21463562

Brockmeyer, Alison M.; Potts, Lisa G.; Brockmeyer, Alison

2013-01-01

235

13,14B(n, ?) via Coulomb Dissociation for Nucleosynthesis towards the r-Process  

NASA Astrophysics Data System (ADS)

Radioactive beams of 14,15B produced by fragmentation of a primary 40Ar beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/R3B setup. Preliminary results for the Coulomb dissociation cross sections as well as for the astrophysically interesting inverse reactions, 13,14B(n,?), are presented.

Altstadt, S. G.; Adachi, T.; Aksyutina, Y.; Alcantara, J.; Alvarez-Pol, H.; Ashwood, N.; Atar, L.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Burgunder, G.; Caamano, M.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkll, J.; Chakraborty, S.; Chartier, M.; Chulkov, L.; Cortina-Gil, D.; Datta Pramanik, U.; Diaz Fernandez, P.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estrade, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Freudenberger, M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Gernhuser, R.; Gbel, K.; Golubev, P.; Gonzalez Diaz, D.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Holt, J. D.; Ickert, G.; Ignatov, A.; Jakobsson, B.; Johansson, H. T.; Jonson, B.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knbel, R.; Krll, T.; Krcken, R.; Kurcewicz, J.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lepyoshkina, O.; Machado, J.; Marganiec, J.; Maroussov, V.; Menndez, J.; Mostazo, M.; Movsesyan, A.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Perea, A.; Pietri, S.; Plag, R.; Prochazka, A.; Rahaman, A.; Rastrepina, G.; Reifarth, R.; Ribeiro, G.; Ricciardi, M. V.; Rigollet, C.; Riisager, K.; Rder, M.; Rossi, D.; Sanchez del Rio, J.; Savran, D.; Scheit, H.; Schwenk, A.; Simon, H.; Simonis, J.; Sonnabend, K.; Sorlin, O.; Stoica, V.; Streicher, B.; Taylor, J.; Tengblad, O.; Terashima, S.; Thies, R.; Togano, Y.; Uberseder, E.; Van de Walle, J.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Wheldon, C.; Wilson, G.; Wimmer, C.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M. V.; Zilges, A.; Zoric, M.; Zuber, K.

2014-06-01

236

Chemistry of the Sagittarius Dwarf Galaxy: A Top-light Initial Mass Function, Outflows, and the R-process  

NASA Astrophysics Data System (ADS)

From chemical abundance analysis of stars in the Sagittarius dwarf spheroidal galaxy (Sgr), we conclude that the ?-element deficiencies cannot be due to the Type Ia supernova (SN Ia) time-delay scenario of Tinsley. Instead, the evidence points to low [?/Fe] ratios resulting from an initial mass function (IMF) deficient in the highest mass stars. The critical evidence is the 0.4 dex deficiency of [O/Fe], [Mg/Fe], and other hydrostatic elements, contrasting with the normal trend of r-process [Eu/Fe] r with [Fe/H]. Supporting evidence comes from the hydrostatic element (O, Mg, Na, Al, Cu) [X/Fe] ratios, which are inconsistent with iron added to the Milky Way (MW) disk trends. Also, the ratio of hydrostatic to explosive (Si, Ca, Ti) element abundances suggests a relatively top-light IMF. Abundance similarities with the LMC, Fornax, and IC 1613 suggest that their ?-element deficiencies also resulted from IMFs lacking the most massive SNe II. The top-light IMF, as well as the normal trend of r-process [Eu/Fe] r with [Fe/H] in Sgr, indicates that massive SNe II (gsim30 M ?) are not major sources of r-process elements. High [La/Y] ratios, consistent with leaky-box chemical evolution, are confirmed but ~0.3 dex larger than theoretical asymptotic giant branch (AGB) predictions. This suggests that a substantial increase in the theoretical 13C pocket in low-mass AGB stars is required. Sgr has the lowest [Rb/Zr] ratios known, consistent with pollution by low-mass (lsim2 M ?) AGB stars near [Fe/H] = -0.6, likely resulting from leaky-box chemical evolution. The [Cu/O] trends in Sgr and the MW suggest that Cu yields increase with both metallicity and stellar mass, as expected from Cu production by the weak s-process in massive stars. Finally, we present an updated hyperfine splitting line list, an abundance analysis of Arcturus, and further develop our error analysis formalism.

McWilliam, Andrew; Wallerstein, George; Mottini, Marta

2013-12-01

237

Processing of double-R-loops in (CAG)(CTG) and C9orf72 (GGGGCC)(GGCCCC) repeats causes instability  

PubMed Central

R-loops, transcriptionally-induced RNA:DNA hybrids, occurring at repeat tracts (CTG)n, (CAG)n, (CGG)n, (CCG)n and (GAA)n, are associated with diseases including myotonic dystrophy, Huntington's disease, fragile X and Friedreich's ataxia. Many of these repeats are bidirectionally transcribed, allowing for single- and double-R-loop configurations, where either or both DNA strands may be RNA-bound. R-loops can trigger repeat instability at (CTG)(CAG) repeats, but the mechanism of this is unclear. We demonstrate R-loop-mediated instability through processing of R-loops by HeLa and human neuron-like cell extracts. Double-R-loops induced greater instability than single-R-loops. Pre-treatment with RNase H only partially suppressed instability, supporting a model in which R-loops directly generate instability by aberrant processing, or via slipped-DNA formation upon RNA removal and its subsequent aberrant processing. Slipped-DNAs were observed to form following removal of the RNA from R-loops. Since transcriptionally-induced R-loops can occur in the absence of DNA replication, R-loop processing may be a source of repeat instability in the brain. Double-R-loop formation and processing to instability was extended to the expanded C9orf72 (GGGGCC)(GGCCCC) repeats, known to cause amyotrophic lateral sclerosis and frontotemporal dementia, providing the first suggestion through which these repeats may become unstable. These findings provide a mechanistic basis for R-loop-mediated instability at disease-associated repeats. PMID:25147206

Reddy, Kaalak; Schmidt, Monika H.M.; Geist, Jaimie M.; Thakkar, Neha P.; Panigrahi, Gagan B.; Wang, Yuh-Hwa; Pearson, Christopher E.

2014-01-01

238

Processing of double-R-loops in (CAG)(CTG) and C9orf72 (GGGGCC)(GGCCCC) repeats causes instability.  

PubMed

R-loops, transcriptionally-induced RNA:DNA hybrids, occurring at repeat tracts (CTG)n, (CAG)n, (CGG)n, (CCG)n and (GAA)n, are associated with diseases including myotonic dystrophy, Huntington's disease, fragile X and Friedreich's ataxia. Many of these repeats are bidirectionally transcribed, allowing for single- and double-R-loop configurations, where either or both DNA strands may be RNA-bound. R-loops can trigger repeat instability at (CTG)(CAG) repeats, but the mechanism of this is unclear. We demonstrate R-loop-mediated instability through processing of R-loops by HeLa and human neuron-like cell extracts. Double-R-loops induced greater instability than single-R-loops. Pre-treatment with RNase H only partially suppressed instability, supporting a model in which R-loops directly generate instability by aberrant processing, or via slipped-DNA formation upon RNA removal and its subsequent aberrant processing. Slipped-DNAs were observed to form following removal of the RNA from R-loops. Since transcriptionally-induced R-loops can occur in the absence of DNA replication, R-loop processing may be a source of repeat instability in the brain. Double-R-loop formation and processing to instability was extended to the expanded C9orf72 (GGGGCC)(GGCCCC) repeats, known to cause amyotrophic lateral sclerosis and frontotemporal dementia, providing the first suggestion through which these repeats may become unstable. These findings provide a mechanistic basis for R-loop-mediated instability at disease-associated repeats. PMID:25147206

Reddy, Kaalak; Schmidt, Monika H M; Geist, Jaimie M; Thakkar, Neha P; Panigrahi, Gagan B; Wang, Yuh-Hwa; Pearson, Christopher E

2014-01-01

239

Molecular Diversity of Eukaryotes in Municipal Wastewater Treatment Processes as Revealed by 18S rRNA Gene Analysis  

PubMed Central

Eukaryotic communities involved in sewage treatment processes have been investigated by morphological identification, but have not yet been well-characterized using molecular approaches. In the present study, eukaryotic communities were characterized by constructing 18S rRNA gene clone libraries. The phylogenetic affiliations of a total of 843 clones were Alveolata, Fungi, Rhizaria, Euglenozoa, Stramenopiles, Amoebozoa, and Viridiplantae as protozoans and Rotifera, Gastrotricha, and Nematoda as metazoans. Sixty percent of the clones had <97% sequence identity to described eukaryotes, indicating the greater diversity of eukaryotes than previously recognized. A core OTU closely related to Epistylis chrysemydis was identified, and several OTUs were shared by 48 libraries. Members of the uncultured lineage LKM11 in Cryptomycota were predominant fungi in sewage treatment processes. This comparative study represents an initial step in furthering understanding of the diversity and role of eukaryotes in sewage treatment processes. PMID:25491751

Matsunaga, Kengo; Kubota, Kengo; Harada, Hideki

2014-01-01

240

FLEXIBLE APPLICATION OF THE JLAB PANSOPHY INFORMATION SYSTEM FOR PROJECT REPORTS, PROCESS MONITORING, AND R&D SAMPLE TRACKING  

SciTech Connect

The use and features of the JLab SRF Institute IT system Pansophy1,2 continue to expand. In support of the cryomodule rework project for CEBAF a full set of web-based travelers has been implemented and an integrated set of live summary reports has been created. A graphical user interface within the reports enables navigation to either higher-level summaries or drill-down to the original source data. In addition to collection of episodic data, Pansophy is now used to capture, coordinate, and display continuously logged process parameter that relate to technical water systems and clean room environmental conditions. In a new expansion, Pansophy is being used to collect and track process and analytical data sets associated with SRF material samples that are part of the surface creation, processing, and characterization R&D program.

Valerie Bookwalter; Bonnie Madre; Charles Reece

2008-02-12

241

EPA'S POLLUTION PREVENTION R&D APPROACHES AND INSIGHTS INTO THECHEMICAL PROCESS INDUSTRY  

EPA Science Inventory

Chemical Engineers face major research challenges associated withthe imperative to protect and improve the environment. hesechallenges include designing optimal, less polluting chemicalplants and processes, improving air quality through research,managing hazardous wastes responsi...

242

Contractor relationships and inter-organizational strategies in NASA's R and D acquisition process  

NASA Technical Reports Server (NTRS)

Interorganizational analysis of NASA's acquisition process for research and development systems is discussed. The importance of understanding the contractor environment, constraints, and motives in selecting an acquisition strategy is demonstrated. By articulating clear project goals, by utilizing information about the contractor and his needs at each stage in the acquisition process, and by thorough analysis of the inter-organizational relationship, improved selection of acquisition strategies and business practices is possible.

Guiltinan, J.

1976-01-01

243

Chromatin Diminution Process Regulates rRNA Gene Copy Number in Freshwater Copepods  

PubMed Central

The results of quantitative PCR (qPCR) presented in the paper clearly demonstrate that the sixteen-fold genome reduction inCyclops kolensisduring chromatin diminution (from 15.3pg to 0.98pg) results in a dramatic decrease in ribosomal RNA gene copy numbers in the genome of a somatic cell line by more than two orders of magnitude. The results presented allow for the consideration of the chromatin diminution as a mechanism of rDNA copy number regulation. PMID:22649664

Zagoskin, M.V.; Marshak, T.L.; Mukha, D.V.; Grishanin, A.K.

2010-01-01

244

R-Process nucleosynthesis in high entropy environment in explosion of supernova type II and neutron star formation  

NASA Astrophysics Data System (ADS)

It is generally acknowledged that Type II supernovae result from the collapse of iron core of a massive star which, at least in some cases, produces a neutron star. At this stage, the neutrinos are produced by neutronization which speeds up as collapse continues. During collapse an outward bound shock wave forms in the matter falling onto the nearly stationary core. The conditions behind the shock at 100 to 200 km are suitable for neutrino heating. This neutrino heating blows a hot bubble above the protoneutron star and is the most important source of energy for Supernova explosion. At this stage, we try to attain the r-process (rapid neutron capture process) path responsible for the production of heavy elements beyond iron, which are otherwise not possible to be formed by fusion reactions. The most interesting evolution occurs as temperature falls from 1010 K to 109 K. At these high temperature conditions, the critical fluids after fusion reactions are forbidden and transform into the respective atoms by r-process path which on beta decaying produce the ultimate elements of the periodic chart.

Baruah, Rulee; Duorah, Kalpana; Duorah, H. L.

2013-03-01

245

GPS-R L1 interference signal processing for soil moisture estimation: an experimental study  

NASA Astrophysics Data System (ADS)

Global positioning system reflectometry (GPS-R) is an emerging area of GPS applications in microwave remote sensing using multipath reflected signals. Soil moisture estimation is one of the many potential applications of the GPS-R technique. The focus of this study is on investigating the feasibility of soil moisture estimation based on GPS L1 band interference signals which can be readily captured using a low-cost off-the-shelf L1-band GPS receiver. The theoretical background is studied, and the field experiments conducted are described. Power spectrum analysis is performed on the received interference signals to determine the interference signal frequency variation, and cosine similarity is applied to identify the initial phase change. Data collected at a number of continuously operating GPS stations are also analyzed. The results demonstrate that both interference signal frequency and phase have changed significantly after rainfalls occurred. That is, it is possible to estimate soil moisture by analyzing the frequency change and phase shift. However, it is also observed that the phase shift is inconsistent in some cases. Ongoing work will focus on figuring out the source of the inconsistency so that reliable estimation of soil moisture can be achieved.

Yan, Songhua; Li, Zhengyong; Yu, Kegen; Zhang, Kefei

2014-12-01

246

Beta-decay studies of nickel-78 and other neutron-rich nuclei in the astrophysical r-process  

NASA Astrophysics Data System (ADS)

The ?-decay properties of several neutron-rich nuclei including the doubly-magic 78Ni were studied. A low-energy neutron detector NERO was designed and calibrated for use in these measurements. ?-decay measurements, especially those that combine both half-life and neutron-emission probability measurements, can offer first tests of nuclear theories of neutron-rich nuclei. In addition, 78Ni is an important waiting-point in the astrophysical r-process. The results of the measurements are compared to several nuclear models, and the astrophysical implications are explored.

Hosmer, Paul Thomas

247

The neutron long counter NERO for studies of beta-delayed neutron emission in the r-process  

E-print Network

The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring beta-delayed neutron-emission probabilities. The detector was designed to work in conjunction with a beta-decay implantation station, so that beta decays and beta-delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring beta-delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.

J. Pereira; P. Hosmer; G. Lorusso; P. Santi; A. Couture; J. Daly; M. Del Santo; T. Elliot; J. Goerres; C. Herlitzius; K. -L. Kratz; L. O. Lamm; H. Y. Lee; F. Montes; M. Ouellette; E. Pellegrini; P. Reeder; H. Schatz; F. Schertz; L. Schnorrenberger; K. Smith; E. Stech; E. Strandberg; C. Ugalde; M. Wiescher; A. Woehr

2010-07-28

248

Sequential Plasma Activated Process for Silicon Direct Bonding M. M. R. Howladera  

E-print Network

. In plasma activation bonding, reactive ion etching (RIE) (3,4), inductively coupled plasma (ICP) (5 and plasma bonded surfaces produce an amorphous interface layer of SiO2 after heating, the hydrophobic bonded by plasma process have been heated at ECS Transactions, 3 (6) 191-202 (2006) 10.1149/1.2357070, copyright

Howlader, Matiar R

249

Seeking Comfort: Women Mental Health Process in I. R. Iran: A Grounded Theory Study  

PubMed Central

Background: Psychosocial factor is considered as intermediate social determinant of health, because it has powerful effects on health especially in women. Hence deeper understanding of the mental-health process needed for its promotion. The aim of this study was to explore women's experience of the mental-health problem and related action-interactions activities to design the appropriate interventions. Methods: In-depth interviews with women 18-65 years were analyzed according to the grounded theory method. The selection of Participants was based on purposeful and theoretical sampling. Results: In this study, a substantive theory was generated; explaining how female with the mental-health problem handled their main concern, which was identified as their effort to achieve comfort (core variable). The other six categories are elements in this process. Daily stress as a trigger, satisfaction is the end point, marriage is the key point and action - interaction activities in this process are strengthening human essence, Developing life skills and help seeking. Conclusions: Better understanding the mental-health process might be useful to design the interventional program among women with mental-health problems. PMID:24627750

Mohammadi, Farahnaz; Eftekhari, Monir Baradaran; Dejman, Masoumeh; Forouzan, Ameneh Setareh; Mirabzadeh, Arash

2014-01-01

250

Categories and Underlying Processes, or Representative Behavior Samples and S-R Analysis: Opposing Strategies.  

ERIC Educational Resources Information Center

Psychological researchers should deal with the concrete stimulus-response principles of learning on which behavior is based, and study behaviors that are representative of real life behaviors. The present research strategy has come from two faulty ideas: first, a concern with underlying, inferred mental processes, rather than with actual tasks or

Staats, Arthur W.

251

F E AT U R E If a biological process could be said to be a  

E-print Network

truly be the `next big thing,' and along the way perhaps even make some money? Emergence of a laboratory companies, has become a mainstream tool."RNAi wasn't used in mam- Unlocking the money-making potential) would be it. The naturally occurring process of RNA suppression of gene activity within a cell (also

Cai, Long

252

Separation and recovery process R&D to enhance automotive materials recycling  

SciTech Connect

Since 1976, the sales-weighted curb-weight of cars and light trucks sold in the United States has decreased by almost 800 pounds. Vehicle weight reduction has, of course, provided for a significant increase in US fleet fuel economy, from 17 to 27 miles per gallon. However, achievement of the weight reduction and concomitant increase in fuel economy was brought about, in part, by the substitution of lighter-weight materials, such as thinner-gauge coated sheet-steels replacing heavy-gauge noncoated sheet-steels and new aluminum alloys replacing steel as well as the increased use of plastics replacing metals. Each of these new materials has created the need for new technology for materials recycling. This paper highlights some of the R&D being conducted at Argonne National Laboratory to develop technology that will enhance and minimize the cost of automotive materials recycling.

Daniels, E.J.

1994-05-01

253

The crystal structure of Mtr4 reveals a novel arch domain required for rRNA processing  

SciTech Connect

The essential RNA helicase, Mtr4, performs a critical role in RNA processing and degradation as an activator of the nuclear exosome. The molecular basis for this vital function is not understood and detailed analysis is significantly limited by the lack of structural data. In this study, we present the crystal structure of Mtr4. The structure reveals a new arch-like domain that is specific to Mtr4 and Ski2 (the cytosolic homologue of Mtr4). In vivo and in vitro analyses demonstrate that the Mtr4 arch domain is required for proper 5.8S rRNA processing, and suggest that the arch functions independently of canonical helicase activity. In addition, extensive conservation along the face of the putative RNA exit site highlights a potential interface with the exosome. These studies provide a molecular framework for understanding fundamental aspects of helicase function in exosome activation, and more broadly define the molecular architecture of Ski2-like helicases.

Jackson, R.N.; Robinson, H.; Klauer, A. A.; Hintze, B. J.; van Hoof, A.; Johnson, S. J.

2010-07-01

254

Half-Life Measurement for the rp -Process Waiting Point Nuclide Z{sup 80}r  

SciTech Connect

X-ray bursts have been suggested as a possible site for the astrophysical rp -process. The time scale for the process is governed by {beta} -decay half-lives of several even-even N=Z waiting point nuclei, in particular, N=Z=40 {sup 80}Zr . A 4.1(+0.8-0.6)- s {beta}{sup +}/EC half-life for {sup 80}Zr was determined by observing delayed 84-keV {gamma} rays depopulating a T{sub 1/2}=4-{mu}s isomer at 312 keV in the daughter {sup 80}Y . As this half-life is lower than many previously predicted values, the calculated excessive production of A=80 nuclides in astrophysical x-ray burst scenarios is reduced, and less extreme conditions are necessary for the production of heavier nuclides. (c) 2000 The American Physical Society.

Ressler, J. J. [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States); Piechaczek, A. [Department of Physics, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)] [Department of Physics, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Walters, W. B. [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States); Aprahamian, A. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Wiescher, M. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Batchelder, J. C. [UNIRIB, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States)] [UNIRIB, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States); Bingham, C. R. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States) [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Brenner, D. S. [Department of Chemistry, Clark University, Worcester, Massachusetts 01610 (United States)] [Department of Chemistry, Clark University, Worcester, Massachusetts 01610 (United States); Ginter, T. N. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)] [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Gross, C. J. [UNIRIB, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States) [UNIRIB, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] (and others)

2000-03-06

255

New Abundance Determinations of Cadmium, Lutetium, and Osmium in the r-process Enriched Star BD+173248  

E-print Network

We report the detection of Cd I (Z = 48), Lu II (Z = 71), and Os II (Z = 76) in the metal-poor star BD+173248. These abundances are derived from an ultraviolet spectrum obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This is the first detection of these neutron-capture species in a metal-poor star enriched by the r-process. We supplement these measurements with new abundances of Mo I, Ru I, and Rh I derived from an optical spectrum obtained with the High Resolution Echelle Spectrograph on Keck. Combined with previous abundance derivations, 32 neutron-capture elements have been detected in BD+173248, the most complete neutron-capture abundance pattern in any metal-poor star to date. The light neutron-capture elements (38 <= Z <= 48) show a more pronounced even-odd effect than expected from current Solar system r-process abundance predictions. The age for BD+173248 derived from the Th II/Os II chronometer is in better agreement with the age derived from other chronome...

Roederer, Ian U; Lawler, James E; Cowan, John J

2010-01-01

256

Electromagnetic Emission and r-process Nucleosynthesis from Late-Time Winds of Neutron Star Merger Remnant Accretion Disks  

NASA Astrophysics Data System (ADS)

Neutron star mergers result in the formation of a remnant accretion disk around a black hole or a hypermassive neutron star. The secular evolution of these disks leads to outflows that can eject a varying fraction of the disk, in amounts comparable to or larger than material ejected promptly due to tidal forces. Here I'll discuss results from two-dimensional, time-dependent hydrodynamic simulations of the long-term (viscous) evolution of these disks, which include the relevant physics needed to characterize the dynamics and composition of the disk. Disk winds generally contribute to a ~week long transient peaking in the near-infrared (kilonova), although a blue precursor can manifest as a signature of delayed black hole formation. The composition of the outflows is expected to include heavy r-process elements when a black hole forms promptly, and lighter elements in the case of a long-lived hypermassive neutron star . Results have implications for the detection of electromagnetic counterparts of LIGO sources and for the galactic r-process element generation.

Fernandez, Rodrigo; Metzger, Brian

2014-08-01

257

Genetic identification of Arabidopsis RID2 as an essential factor involved in pre-rRNA processing.  

PubMed

A temperature-sensitive mutant of Arabidopsis, root initiation defective 2-1 (rid2-1), is characterized by peculiar defects in callus formation. To gain insights into the requirements for the reactivation of cell division, we analyzed this mutant and isolated the gene responsible, RID2. The phenotypes of rid2-1 in tissue culture and in seedlings indicated that the rid2 mutation has various (acute and non-acute) inhibitory effects on different aspects of cell proliferation. This suggests that the RID2 function is not directly involved in every cycle of cell division, but is related to 'vitality', supporting cell proliferation. The rid2-1 mutation was shown to cause nucleolar vacuolation and excessive accumulation of various intermediates of pre-rRNA processing. Positional cloning of the RID2 gene revealed that it encodes an evolutionarily conserved methyltransferase-like protein, which was found to localize in the nucleus, with accumulation being most evident in the nucleolus. It can be inferred from these findings that RID2 contributes to the nucleolar activity for pre-rRNA processing, probably through some methylation reaction. PMID:21401745

Ohbayashi, Iwai; Konishi, Mineko; Ebine, Kazuo; Sugiyama, Munetaka

2011-07-01

258

A divergent Pumilio repeat protein family for pre-rRNA processing and mRNA localization.  

PubMed

Pumilio/feminization of XX and XO animals (fem)-3 mRNA-binding factor (PUF) proteins bind sequence specifically to mRNA targets using a single-stranded RNA-binding domain comprising eight Pumilio (PUM) repeats. PUM repeats have now been identified in proteins that function in pre-rRNA processing, including human Puf-A and yeast Puf6. This is a role not previously ascribed to PUF proteins. Here we present crystal structures of human Puf-A that reveal a class of nucleic acid-binding proteins with 11 PUM repeats arranged in an "L"-like shape. In contrast to classical PUF proteins, Puf-A forms sequence-independent interactions with DNA or RNA, mediated by conserved basic residues. We demonstrate that equivalent basic residues in yeast Puf6 are important for RNA binding, pre-rRNA processing, and mRNA localization. Thus, PUM repeats can be assembled into alternative folds that bind to structured nucleic acids in addition to forming canonical eight-repeat crescent-shaped RNA-binding domains found in classical PUF proteins. PMID:25512524

Qiu, Chen; McCann, Kathleen L; Wine, Robert N; Baserga, Susan J; Hall, Traci M Tanaka

2014-12-30

259

Continuing Development of GOES-R SUVI Automated Solar Image Processing  

NASA Astrophysics Data System (ADS)

NOAA's Space Weather Prediction Center (SWPC) is the Nation's official source of space weather alerts, watches and warnings. In that role, the Center will be ingesting GOES-R Solar Ultraviolet Imager (SUVI) data beginning in the 2015-16 timeframe. Along with other NOAA and non-NOAA sources of solar imagery these observations are used by SWPC forecasters to inform their analysis (nowcast) and forecasts and also as sources of data to run empirical and numerical models. A supervised, multispectral, Bayesian pixel classifier has been developed and produces what are referred to as thematic maps to assist forecasters in their analysis. These maps represent classes of pixels including: space, coronal holes, quiet corona, filaments, active regions, and flares. The thematic maps product underwent initial operational test and evaluation at SWPC in 2012-13. The test used synoptic data from the Atmospheric Imaging Array (AIA) on NASA's SDO mission in near real time as a proxy for SUVI data. The thematic maps product has been upgraded and retrained to incorporate H-alpha imagery to better discriminate between filament channels and coronal holes. We present ongoing results of the operational test and evaluation for thematic maps. Also, we include initial results for automated flare location and coronal hole boundary location that depend on thematic maps as inputs.

Hill, S. M.; Darnel, J.; Vickroy, J.; Steenburgh, R. A.; Rigler, E. J.

2013-12-01

260

A Comprehensive Study on Coastline Process and Sedimentary Dynamics, Sardinera Beach, Mona Island, P.R.  

NASA Astrophysics Data System (ADS)

Sardinera beach in Mona Island, Puerto Rico, has a great recreational and ecological value and is an important research place to gather information on shoreline processes in an area far from the main land and with only scarce man made influences. Beach rock exposures present along the shoreline in Sardinera Beach have increased considerably during the last decade. A new management plan is being developed for Mona Island and the Department of Natural Resources (DNRA) of Puerto Rico wants to better understand the beach sand dynamics on this and other Mona Island beaches. This research includes field and laboratory work that characterize coastal sedimentary processes and helps to better understand the shoreline changes as well as seasonal variations in sand movement and composition. This work also establish the logistics and methodology basis for further studies that will expand to other Mona Island beaches. Benchmarks, GPS coordinates, and landmarks were used to establish ten permanent beach profiles along Sardinera Beach. Beach profiles were (and will be) measured monthly. Sardinera Beach sands are composed mostly of carbonate (CaCO3) components, products of the combination of biological, chemical and diagenetic processes, high grade of micritization, and of lithic limestone fragments. Sand composition differences between Sardinera Beach, the Mona Shelf and adjacent beach, reef crest and reef lagoon systems suggest Sardinera sands are not replenished by the modern marine components produced in these environments. The input of "fresh bioclasts" in this beach seems to be limited by natural (beach rock) and mane made (dock) barriers along the shore and by alteration in the current patterns produced by the man made aperture of the reef. Sardinera's micritized and recrystalized sand deposits seem to have been re-transported between the reefal lagoon and the beach. Sand volume analysis indicates a total sand loss of 1,322 m3 between the months of September to April. Aerial images from the years 1977, 1992 and 2003 show 14 to 27 meters of recession along the coast line.

Rodriguez-Delga, A. M.; Ramirez, W. R.

2008-12-01

261

Shelf edge exchange processes-II SEEP2-06, R/V Endeavor cruise 186  

SciTech Connect

The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984. Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. Hydrographic data were collected on eight of the six cruises.

Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1989-12-01

262

The Binary Frequency of r-Process-element-enhanced Metal-poor Stars and Its Implications: Chemical Tagging in the Primitive Halo of the Milky Way  

NASA Astrophysics Data System (ADS)

A few rare halo giants in the range [Fe/H] ~= -2.9 0.3 exhibit r-process element abundances that vary as a group by factors up to [r/Fe] ~80, relative to those of the iron peak and below. Yet, the astrophysical production site of these r-process elements remains unclear. We report initial results from four years of monitoring the radial velocities of 17 r-process-enhanced metal-poor giants to detect and characterize binaries in this sample. We find three (possibly four) spectroscopic binaries with orbital periods and eccentricities that are indistinguishable from those of Population I binaries with giant primaries, and which exhibit no signs that the secondary components have passed through the asymptotic giant branch stage of evolution or exploded as supernovae. The other 14 stars in our sample appear to be singleincluding the prototypical r-process-element-enhanced star CS 22892-052, which is also enhanced in carbon, but not in s-process elements. We conclude that the r-process (and potentially carbon) enhancement of these stars was not a local event due to mass transfer or winds from a binary companion, but was imprinted on the natal molecular clouds of these (single and binary) stars by an external source. These stars are thus spectacular chemical tracers of the inhomogeneous nature of the early Galactic halo system.

Hansen, Terese; Andersen, Johannes; Nordstrm, Birgitta; Buchhave, Lars A.; Beers, Timothy C.

2011-12-01

263

THE BINARY FREQUENCY OF r-PROCESS-ELEMENT-ENHANCED METAL-POOR STARS AND ITS IMPLICATIONS: CHEMICAL TAGGING IN THE PRIMITIVE HALO OF THE MILKY WAY  

SciTech Connect

A few rare halo giants in the range [Fe/H] {approx_equal} -2.9 {+-} 0.3 exhibit r-process element abundances that vary as a group by factors up to [r/Fe] {approx}80, relative to those of the iron peak and below. Yet, the astrophysical production site of these r-process elements remains unclear. We report initial results from four years of monitoring the radial velocities of 17 r-process-enhanced metal-poor giants to detect and characterize binaries in this sample. We find three (possibly four) spectroscopic binaries with orbital periods and eccentricities that are indistinguishable from those of Population I binaries with giant primaries, and which exhibit no signs that the secondary components have passed through the asymptotic giant branch stage of evolution or exploded as supernovae. The other 14 stars in our sample appear to be single-including the prototypical r-process-element-enhanced star CS 22892-052, which is also enhanced in carbon, but not in s-process elements. We conclude that the r-process (and potentially carbon) enhancement of these stars was not a local event due to mass transfer or winds from a binary companion, but was imprinted on the natal molecular clouds of these (single and binary) stars by an external source. These stars are thus spectacular chemical tracers of the inhomogeneous nature of the early Galactic halo system.

Hansen, Terese; Andersen, Johannes; Nordstroem, Birgitta; Buchhave, Lars A. [Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Beers, Timothy C., E-mail: terese@fys.ku.dk, E-mail: ja@astro.ku.dk, E-mail: birgitta@astro.ku.dk, E-mail: beers@pa.msu.edu, E-mail: buchhave@astro.ku.dk [Department of Physics and Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)

2011-12-10

264

Shelf Edge Exchange Processes, II: SEEP2-08, R/V ENDEAVOR cruise 188  

SciTech Connect

The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984 (Behrens and Flagg, 1986). Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. This project consisted of a series of ten cruises, a mooring array, and a series of over-flights by NASA aircraft. Hydrographic data were collected on eight of the cruises, six of which were primarily mooring deployment or recovery cruises. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Two cruises (SEEP2-04 and SEEP2-07) were dedicated to investigating benthic processes and hydrographic data were not collected.

Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1989-12-01

265

R&D processes for increasing density of cryogenic propellants at FSEC  

NASA Astrophysics Data System (ADS)

At Florida Solar Energy Center (FSEC) of the University of Central Florida, we are probing processes for increasing density of cryogenic propellants for launch vehicle applications. Technologies that provide for the densification of cryogenic propellants, conditioning, transfer, storage and mass gauging are of prime interest to the spaceport of the future and space launch activities. Density increases of 8% for LH 2 and 10% for LO 2 have been shown to have the advantages of reduced gross lift-off weight of a launch vehicle by up to 20% or increased payload capability. In this paper, thermodynamic system analysis will be performed for various liquefaction, densification and recirculation systems. The objectives are to determine the optimum combination of system components including liquefier, cryocooler and heat exchangers for ground support system and launch vehicles. The base analysis results demonstrate various operation conditions and metrics to be used for optimization of densification processes that include higher efficiency, improved reliability and functionality with the state of the art technology.

Baik, Jong H.; T-Raissi, Ali

2004-06-01

266

MOLYBDENUM, RUTHENIUM, AND THE HEAVY r-PROCESS ELEMENTS IN MODERATELY METAL-POOR MAIN-SEQUENCE TURNOFF STARS  

SciTech Connect

The ratios of elemental abundances observed in metal-poor stars of the Galactic halo provide a unique present-day record of the nucleosynthesis products of its earliest stars. While the heaviest elements were synthesized by the r- and s-processes, dominant production mechanisms of light trans-ironic elements were obscure until recently. This work investigates further our 2011 conclusion that the low-entropy regime of a high-entropy wind (HEW) produced molybdenum and ruthenium in two moderately metal-poor turnoff stars that showed extreme overabundances of those elements with respect to iron. Only a few, rare nucleosynthesis events may have been involved. Here we determine abundances for Mo, Ru, and other trans-Fe elements for 28 similar stars by matching spectral calculations to well-exposed near-UV Keck HIRES spectra obtained for beryllium abundances. In each of the 26 turnoff stars with Mo or Ru line detections and no evidence for s-process production (therefore old), we find Mo and Ru to be three to six times overabundant. In contrast, the maximum overabundance is reduced to factors of three and two for the neighboring elements zirconium and palladium. Since the overproduction peaks sharply at Mo and Ru, a low-entropy HEW is confirmed as its origin. The overabundance level of the heavy r-process elements varies significantly, from none to a factor of four, but is uncorrelated with Mo and Ru overabundances. Despite their moderate metallicity, stars in this group trace the products of different nucleosynthetic events: possibly very few events, possibly events whose output depended on environment, metallicity, or time.

Peterson, Ruth C. [Astrophysical Advances, 607 Marion Place, Palo Alto, CA 94301 (United States)

2013-05-01

267

New Half-lives of r-process Zn and Ga Isotopes Measured with Electromagnetic Separation  

SciTech Connect

The {beta} decays of neutron-rich nuclei near the doubly magic {sup 78}Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of {sup 82}Zn (228 {+-} 10 ms), {sup 83}Zn (117 {+-} 20 ms), and {sup 85}Ga (93 {+-} 7 ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the {sup 78}Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A > 140 nuclei.

Madurga, M [University of Tennessee, Knoxville (UTK); Surman, Rebecca [Union College; Borzov, Ivan N [ORNL; Grzywacz, R. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Rykaczewski, Krzysztof Piotr [ORNL; Gross, Carl J [ORNL; Miller, D [University of Tennessee, Knoxville (UTK); Stracener, Daniel W [ORNL; Batchelder, Jon Charles [ORNL; Brewer, N.T. [Vanderbilt University; Cartegni, L. [University of Tennessee, Knoxville (UTK); Hamilton, J. H. [Vanderbilt University; Hwang, J. K. [Vanderbilt University; Liu, S. H. [Vanderbilt University; Ilyushkin, S. [Mississippi State University (MSU); Karny, M. [University of Warsaw; Korgul, A. [Joint Institute for Heavy Ion Research, Oak Ridge; Krolas, W. [Joint Institute for Heavy Ion Research, Oak Ridge; Kuzniak, A. [University of Tennessee, Knoxville (UTK); Mazzocchi, C. [University of Warsaw; Mendez, II, Anthony J [ORNL; Miernik, K. [Oak Ridge National Laboratory (ORNL); Padgett, Stephen [University of Tennessee, Knoxville (UTK); Paulauskas, S. [University of Tennessee, Knoxville (UTK); Ramayya, A. V. [Vanderbilt University; Winger, J. A. [Oak Ridge Associated Universities (ORAU); Wolinska-Cichocka, Marzena [ORNL; Zganjar, E. F. [Louisiana State University

2012-01-01

268

New Half-lives of r-process Zn and Ga Isotopes Measured with Electromagnetic Separation  

NASA Astrophysics Data System (ADS)

The ? decays of neutron-rich nuclei near the doubly magic Ni78 were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of Zn82 (22810ms), Zn83 (11720ms), and Ga85 (937ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the Ni78 region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140 nuclei.

Madurga, M.; Surman, R.; Borzov, I. N.; Grzywacz, R.; Rykaczewski, K. P.; Gross, C. J.; Miller, D.; Stracener, D. W.; Batchelder, J. C.; Brewer, N. T.; Cartegni, L.; Hamilton, J. H.; Hwang, J. K.; Liu, S. H.; Ilyushkin, S. V.; Jost, C.; Karny, M.; Korgul, A.; Krlas, W.; Ku?niak, A.; Mazzocchi, C.; Mendez, A. J., II; Miernik, K.; Padgett, S. W.; Paulauskas, S. V.; Ramayya, A. V.; Winger, J. A.; Woli?ska-Cichocka, M.; Zganjar, E. F.

2012-09-01

269

K. S. Telang, R. W. Pike, F. C. Knopf, J. R. Hopper, J. Saleh, S. Waghchoure, S. C. Hedge and T. A. Hertwig,"An Advanced Process Analysis System for Improving Chemical and Refinery Processes," Computers and Chemical Engineering, Vol. 23, p. S727-730 (1999  

E-print Network

. Hertwig,"An Advanced Process Analysis System for Improving Chemical and Refinery Processes," Computers Chemical and Refinery Processes K. S. Telang, X. Chen, R. W. Pike and F. C. Knopf Louisiana State and refineries for process improvements. The system integrates programs for on-line optimization, chemical

Pike, Ralph W.

270

A high-entropy wind r-process study based on nuclear-structure quantities from the new finite-range droplet model FRDM(2012)  

E-print Network

Theoretical studies of the nucleosynthesis origin of the heavy elements in our Solar System (S.S.) by the rapid neutron-capture process (r-process) still face the entwined uncertainties in the possible astrophysical scenarios and the nuclear-physics properties far from stability. In this paper we present results from the investigation of an r-process in the high-entropy wind (HEW) of core-collapse supernovae (here chosen as one of the possible scenarios for this nucleosynthesis process), using new nuclear-data input calculated in a consistent approach, for masses and $\\beta$-decay properties from the new finite-range droplet model FRDM(2012). The accuracy of the new mass model is 0.56 MeV with respect to {\\sc AME2003}, to which it was adjusted. We compare the new HEW r-process abundance pattern to the latest S.S. r-process residuals and to our earlier calculations with the nuclear-structure quantities based on FRDM(1992). Substantial overall and specific local improvements in the calculated pattern of the r-process between $A\\simeq 110$ and $^{209}$Bi, as well as remaining deficiencies are discussed in terms of the underlying spherical and deformed shell structure far from stability.

Karl-Ludwig Kratz; Khalil Farouqi; Peter Mller

2014-06-10

271

Integrative regulatory mapping indicates that the RNA-binding protein HuR couples pre-mRNA processing and mRNA stability.  

PubMed

RNA-binding proteins coordinate the fates of multiple RNAs, but the principles underlying these global interactions remain poorly understood. We elucidated regulatory mechanisms of the RNA-binding protein HuR, by integrating data from diverse high-throughput targeting technologies, specifically PAR-CLIP, RIP-chip, and whole-transcript expression profiling. The number of binding sites per transcript, degree of HuR association, and degree of HuR-dependent RNA stabilization were positively correlated. Pre-mRNA and mature mRNA containing both intronic and 3' UTR binding sites were more highly stabilized than transcripts with only 3' UTR or only intronic binding sites, suggesting that HuR couples pre-mRNA processing with mature mRNA stability. We also observed HuR-dependent splicing changes and substantial binding of HuR in polypyrimidine tracts of pre-mRNAs. Comparison of the spatial patterns surrounding HuR and miRNA binding sites provided functional evidence for HuR-dependent antagonism of proximal miRNA-mediated repression. We conclude that HuR coordinates gene expression outcomes at multiple interconnected steps of RNA processing. PMID:21723170

Mukherjee, Neelanjan; Corcoran, David L; Nusbaum, Jeffrey D; Reid, David W; Georgiev, Stoyan; Hafner, Markus; Ascano, Manuel; Tuschl, Thomas; Ohler, Uwe; Keene, Jack D

2011-08-01

272

Mass measurements in the vicinity of the r p-process and the {nu} p-process paths with the Penning trap facilities JYFLTRAP and SHIPTRAP  

SciTech Connect

The masses of very neutron-deficient nuclides close to the astrophysical r p- and {nu} p-process paths have been determined with the Penning trap facilities JYFLTRAP at JYFL/Jyvaeskylae and SHIPTRAP at GSI/Darmstadt. Isotopes from yttrium (Z=39) to palladium (Z=46) have been produced in heavy-ion fusion-evaporation reactions. In total, 21 nuclides were studied, and almost half of the mass values were experimentally determined for the first time: {sup 88}Tc, {sup 90-92}Ru, {sup 92-94}Rh, and {sup 94,95}Pd. For the {sup 95}Pd{sup m}, (21/2{sup +}) high-spin state, a first direct mass determination was performed. Relative mass uncertainties of typically {delta}m/m=5x10{sup -8} were obtained. The impact of the new mass values has been studied in {nu} p-process nucleosynthesis calculations. The resulting reaction flow and the final abundances are compared with those obtained with the data of the Atomic Mass Evaluation 2003.

Weber, C.; Elomaa, V.-V.; Aeystoe, J.; Eronen, T.; Hager, U.; Hakala, J.; Jokinen, A.; Kankainen, A.; Moore, I. D.; Penttilae, H.; Rahaman, S.; Rissanen, J.; Saastamoinen, A.; Sonoda, T. [Department of Physics, University of Jyvaeskylae, FI-40014 Jyvaeskylae (Finland); Ferrer, R. [Institut fuer Physik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Froehlich, C. [Enrico Fermi Institute, Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637 (United States); Ackermann, D.; Block, M.; Dworschak, M.; Herfurth, F. [GSI-Darmstadt mbH, D-64291 Darmstadt (Germany)] (and others)

2008-11-15

273

Unit operations used to treat process and/or waste streams at nuclear power plants. [R  

SciTech Connect

Estimates are given of the annual amounts of each generic type of LLW (i.e., Government and commerical (fuel cycle and non-fuel cycle)) that is generated at LWR plants. Many different chemical engineering unit operations used to treat process and/or waste streams at LWR plants include adsorption, evaporation, calcination, centrifugation, compaction, crystallization, drying, filtration, incineration, reverse osmosis, and solidification of waste residues. The treatment of these various streams and the secondary wet solid wastes thus generated is described. The various treatment options for concentrates or solid wet wastes, and for dry wastes are discussed. Among the dry waste treatment methods are compaction, baling, and incineration, as well as chopping, cutting and shredding. Organic materials (liquids (e.g., oils or solvents) and/or solids), could be incinerated in most cases. The filter sludges, spent resins, and concentrated liquids (e.g., evaporator concentrates) are usually solidified in cement, or urea-formaldehyde or unsaturated polyester resins prior to burial. Incinerator ashes can also be incorporated in these binding agents. Asphalt has not yet been used. This paper presents a brief survey of operational experience at LWRs with various unit operations, including a short discussion of problems and some observations on recent trends.

Godbee, H.W.; Kibbey, A.H.

1980-01-01

274

Apollo(R) Thin Film Process Development: Final Technical Report, April 1998 - April 2002  

SciTech Connect

BP Solar first started investigative work on CdTe photovoltaics in 1986. The module product name chosen for the CdTe devices is Apollo. The deposition method chosen was electrochemical deposition due to its simplicity and good control of stoichiometric composition. The window layer used is CdS, produced from a chemical-bath deposition. Initial work focused on increasing photovoltaic cell size from a few mm2 to 900 cm2. At BP Solar's Fairfield plant, work is focused on increasing semiconductor deposition to 1 m2. The primary objective of this subcontract is to establish the conditions required for the efficient plating of CdS/CdTe on large-area, transparent conducting tin-oxide-coated glass superstrate. The initial phase concentrates on superstrate sizes up to 0.55 m2. Later phases will include work on 0.94 m2 superstrates. The tasks in this subcontract have been split into four main categories: (1) CdS and CdTe film studies; (2) Enhanced laser processing; (3) Outdoor testing program for the Apollo module; and (4) Production waste abatement and closed loop study.

Cunningham, D.W.

2002-10-01

275

Formerly Used Sites Remedial Action Program (FUSRAP) W. R. Grace Feasibility Study (FS) Alternative Development Process Challenges And Successes  

SciTech Connect

Monazite sand processing was conducted at the W. R. Grace Curtis Bay Facility (Baltimore, Maryland) in the mid 1950's under contract to the Atomic Energy Commission (AEC), for the extraction of source material in the form of thorium, as well as rare earth elements. The processing was conducted in the southwest quadrant of a five-story building (Building 23) in the active manufacturing portion of the facility. Building components and equipment in the southwest quadrant of Building 23 exhibit residual radiological activity remaining from the monazite sand processing. Waste materials from the processing operations (termed gangue) were disposed in the non-manufacturing portion of the facility, in the area referred to the Radioactive Waste Disposal Area (RWDA). Approximately 19,880 cubic meters (m{sup 3}) of radioactive gangue was buried within the RWDA. Waste was believed to be buried at various depths up to 2.7 meters (m), and possibly as deep as 7.6 m. The RI and a supplemental investigation have been completed for the RWDA and adjacent boundary areas. A Feasibility Study (FS) to address residual radioactivity in soils at the RWDA is in the process of being finalized. The chemical-specific Applicable, Relevant, and Appropriate Requirement (ARAR) was selected for the FUSRAP contaminants, and Remedial Goals (RGs) were calculated for the cleanup. The RGs were developed based upon guidance provided in the selected ARAR, 10 Code of Federal Regulations (CFR) 40, Appendix A, Criterion 6(6). This standard is designed to provide an acceptable level of protection to the average member of a critical group who may be exposed to radium in soil for a given scenario. Scenarios, critical group members, and RGs were established in consultation with stakeholders. Dose assessment calculations were performed in accordance with the ARAR to establish derived concentration guideline levels (DCGLs) for each radionuclide in the 232-Thorium ({sup 232}Th) and 238-Uranium ({sup 238}U) chain for both surface and subsurface soils. A sum of the ratios calculation (also called the unity rule) will be utilized (with the DCGLs) to assure compliance with the benchmark doses associated with the radium standards. Six alternatives (including no action) were considered in the FS and included the following technologies: soil washing, segregation, capping/covering, excavation/disposal, and site restrictions. A bench scale study was conducted by USACE to assess the efficacy of soil washing at the site. Results of the study showed reduction of radiological activity in soil. Segregation can be implemented using traditional sampling/analytical routines or automated (gate) segregation and it is likely to reduce the waste stream by at least 30%, while providing a more complete characterization of the soil with a particularly high level of confidence. Challenges for the FS phase of the project included: managing stakeholder input and expectations, defining separate and distinct alternatives for the FS in accordance with the CERCLA process, and selecting the most appropriate ARARs. The challenges were handled successfully, and USACE is finalizing a robust document acceptable to the stakeholders, which will allow USACE to meet the program milestone. In summary: Conducting the W.R. Grace FUSRAP site FUSRAP process has been challenging from a project management perspective, due in part to the nature and extent of impact at the site (residual radioactivity; active processing building and disposal area) and incorporating site owner involvement in the process. Through the use of mediation and mutual commitment to the project by both parties, USACE and the site owner were able to find agreement on fundamental issues and set a firm foundation for achieving successful remedial action and site closure using a 'forward thinking' approach. Currently, USACE is finalizing the RWDA FS to address contamination in soils at the RWDA. ARARs have been identified and selected as per CERCLA guidance. Although obstacles were encountered, the challenges were handled successfully, and USACE is f

Fatherly, N. [U.S. Army Corps of Engineers - Baltimore District, Baltimore, Maryland (United States); O'Neill, M.; Glemza, A. [EA Engineering, Science, and Technology, Baltimore, Maryland (United States)

2008-07-01

276

Hsa-miR-520d induces hepatoma cells to form normal liver tissues via a stemness-mediated process  

PubMed Central

The human ncRNA gene RGM249 regulates the extent of differentiation of cancer cells and the conversion of 293FT cells to hiPSCs. To identify the factors underlying this process, we investigated the effects of lentivirally inducing miR-520d expression in 293FT and HLF cells in vitro. Subsequently, we evaluated tumor formation in a xenograft model. Transformed HLF cells were Oct4 and Nanog positive within 24?h, showed p53 upregulation and hTERT downregulation, and mostly lost their migration abilities. After lentiviral infection, the cells were intraperitoneally injected into mice, resulting in benign teratomas (6%), the absence of tumors (87%) or differentiation into benign liver tissues (7%) at the injection site after 1 month. We are the first to demonstrate the loss of malignant properties in cancer cells in vivo through the expression of a single microRNA (miRNA). This miRNA successfully converted 293FT and hepatoma cells to hiPSC-like cells. The regulation of malignancy by miR-520d appears to be through the conversion of cancer cells to normal stem cells, maintaining p53 upregulation. PMID:24458129

Tsuno, Satoshi; Wang, Xinhui; Shomori, Kohei; Hasegawa, Junichi; Miura, Norimasa

2014-01-01

277

Shelf Edge Exchange Processes: 2, SEEP2-09, R/V ENDEAVOR cruise 193: Hydrographic data report  

SciTech Connect

The R/V ENDEAVOR cruise 193, SEEP2-09, took place from 17--23 March 1989 and focused primarily on biological processes in the SEEP2 area. Mooring 1 was recovered and re-deployed and a replacement for mooring 4 was deployed. A 24 hour time series was conducted at mooring 1 to study primary and secondary production. The time series involved sampling nutrients, dissolved oxygen, chlorophyll {und a}, zooplankton abundance and distribution and fecal pellet production. Experiments to estimate grazing rates the fecal pellet production of the dominant copepods were also done. MOCNESS tows and box core samples were also taken during the cruise. Sediment and zooplankton data are not reported here. During this cruise 46 CTD casts were made measuring pressure, temperature, conductivity, dissolved oxygen, fluorescence and light transmission. Discrete samples were taken in rosette-mounted Niskin bottles and analyzed for concentration of nutrients, chlorophyll {und a}, dissolved oxygen, and particulate organic carbon and nitrogen.

Behrens, W.J.; Wilson, C.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1990-01-01

278

Pre-processing of Fourier transform infrared spectra by means of multivariate analysis implemented in the R environment.  

PubMed

Pre-processing of Fourier transform infrared (FTIR) spectra is typically the first and crucial step in data analysis. Very often hyperspectral datasets include the regions characterized by the spectra of very low intensity, for example two-dimensional (2D) maps where the areas with only support materials (like mylar foil) are present. In that case segmentation of the complete dataset is required before subsequent evaluation. The method proposed in this contribution is based on a multivariate approach (hierarchical cluster analysis), and shows its superiority when compared to the standard method of cutting-off by using only the mean spectral intensity. Both techniques were implemented and their performance was tested in the R statistical environment - open-source platform - that is a favourable solution if the repeatability and transparency are the key aspects. PMID:25723954

Banas, Krzysztof; Banas, Agnieszka; Gajda, Mariusz; Pawlicki, Bohdan; Kwiatek, Wojciech M; Breese, Mark B H

2015-04-21

279

Modelling the Glass Press-Blow Process S.M.A. Allaart-Bruin, B.J. van der Linden, and R.M.M. Mattheij  

E-print Network

Modelling the Glass Press-Blow Process S.M.A. Allaart-Bruin, B.J. van der Linden, and R.M.M. Mattheij TUE, CASA, Eindhoven, The Netherlands sbruin@win.tue.nl Summary. For the modelling of the glass- ficulties and is applied. Key words: Level Set Method, glass forming process 1 Introduction A typical stage

Eindhoven, Technische Universiteit

280

VizieR Online Data Catalog: Deuteration in massive star formation process (Fontani+, 2015)  

NASA Astrophysics Data System (ADS)

An ever growing number of observational and theoretical evidence suggests that the deuterated fraction (column density ratio between a species containing D and its hydrogenated counterpart, Dfrac) is an evolutionary indicator both in the low- and the high-mass star formation process. However, the role of surface chemistry in these studies has not been quantified from an observational point of view. In order to compare how the deuterated fractions of species formed only in the gas and partially or uniquely on grain surfaces evolve with time, we observed rotational transitions of CH3OH, 13CH3OH, CH2DOH, CH3OD at 3 and 1.3mm, and of NH2D at 3mm with the IRAM-30m telescope, and the inversion transitions (1,1) and (2,2) of NH3 with the GBT, towards most of the cores already observed by Fontani et al. (2011A&A...529L...7F, 2014MNRAS.440..448F) in N2H+, N2D+, HNC, DNC. NH2D is detected in all but two cores, regardless of the evolutionary stage. Dfrac(NH3) is on average above 0.1, and does not change significantly from the earliest to the most evolved phases, although the highest average value is found in the protostellar phase (~0.3). Few lines of CH2DOH and CH3OD are clearly detected, and only towards protostellar cores or externally heated starless cores. This work clearly confirms an expected different evolutionary trend of the species formed exclusively in the gas (N2D+ and N2H+) and those formed partially (NH2D and NH3) or totally (CH2DOH and CH3OH) on grain mantles. The study also reinforces the idea that Dfrac(N2H+) is the best tracer of massive starless cores, while high values of Dfrac(CH3OH) seem rather good tracers of the early protostellar phases, at which the evaporation/sputtering of the grain mantles is most efficient. (7 data files).

Fontani, F.; Busquet, G.; Palau, A.; Caselli, P. Sanchez-Monge A.; Tan, J. C.; Audard, M.

2014-11-01

281

The New Model of Chemical Evolution of r-process Elements Based on the Hierarchical Galaxy Formation. I. Ba and Eu  

NASA Astrophysics Data System (ADS)

We investigate the chemical enrichment of r-process elements in the early evolutionary stages of the Milky Way halo within the framework of hierarchical galaxy formation using a semi-analytic merger tree. In this paper, we focus on heavy r-process elements, Ba and Eu, of extremely metal-poor (EMP) stars and give constraints on their astronomical sites. Our models take into account changes of the surface abundances of EMP stars by the accretion of interstellar medium (ISM). We also consider metal-enrichment of intergalactic medium by galactic winds and the resultant pre-enrichment of proto-galaxies. The trend and scatter of the observed r-process abundances are well reproduced by our hierarchical model with ~10% of core-collapse supernovae in low-mass end (~10 M ?) as a dominant r-process source and the star formation efficiency of ~10-10 yr-1. For neutron star mergers as an r-process source, their coalescence timescale has to be ~107 yr, and the event rates ~100 times larger than currently observed in the Galaxy. We find that the accretion of ISM is a dominant source of r-process elements for stars with [Ba/H] < -3.5. In this model, a majority of stars at [Fe/H] < -3 are formed without r-process elements, but their surfaces are polluted by the ISM accretion. The pre-enrichment affects ~4% of proto-galaxies, and yet, is surpassed by the ISM accretion in the surface of EMP stars.

Komiya, Yutaka; Yamada, Shimako; Suda, Takuma; Fujimoto, Masayuki Y.

2014-03-01

282

atBRX1-1 and atBRX1-2 are involved in an alternative rRNA processing pathway in Arabidopsis thaliana.  

PubMed

Ribosome biogenesis is an essential process in all organisms. In eukaryotes, multiple ribosome biogenesis factors (RBFs) act in the processing of ribosomal (r)RNAs, assembly of ribosomal subunits and their export to the cytoplasm. We characterized two genes in Arabidopsis thaliana coding for orthologs of yeast BRX1, a protein involved in maturation of the large ribosomal subunit. Both atBRX1 proteins, encoded by AT3G15460 and AT1G52930, respectively, are mainly localized in the nucleolus and are ubiquitously expressed throughout plant development and in various tissues. Mutant plant lines for both factors show a delay in development and pointed leaves can be observed in the brx1-2 mutant, implying a link between ribosome biogenesis and plant development. In addition, the pre-rRNA processing is affected in both mutants. Analysis of the pre-rRNA intermediates revealed that early processing steps can occur either in the 5' external transcribed spacer (ETS) or internal transcribed spacer 1 (ITS1). Interestingly, we also find that in xrn2 mutants, early processing events can be bypassed and removal of the 5' ETS is initiated by cleavage at the P' processing site. While the pathways of pre-rRNA processing are comparable to those of yeast and mammalian cells, the balance between the two processing pathways is different in plants. Furthermore, plant-specific steps such as an additional processing site in the 5' ETS, likely post-transcriptional processing of the early cleavage sites and accumulation of a 5' extended 5.8S rRNA not observed in other eukaryotes can be detected. PMID:25605960

Weis, Benjamin L; Palm, Denise; Missbach, Sandra; Bohnsack, Markus T; Schleiff, Enrico

2015-03-01

283

Parallel processing of real-time dynamic systems simulation on OSCAR (Optimally SCheduled Advanced multiprocessoR)  

NASA Technical Reports Server (NTRS)

Parallel processing of real-time dynamic systems simulation on a multiprocessor system named OSCAR is presented. In the simulation of dynamic systems, generally, the same calculation are repeated every time step. However, we cannot apply to Do-all or the Do-across techniques for parallel processing of the simulation since there exist data dependencies from the end of an iteration to the beginning of the next iteration and furthermore data-input and data-output are required every sampling time period. Therefore, parallelism inside the calculation required for a single time step, or a large basic block which consists of arithmetic assignment statements, must be used. In the proposed method, near fine grain tasks, each of which consists of one or more floating point operations, are generated to extract the parallelism from the calculation and assigned to processors by using optimal static scheduling at compile time in order to reduce large run time overhead caused by the use of near fine grain tasks. The practicality of the scheme is demonstrated on OSCAR (Optimally SCheduled Advanced multiprocessoR) which has been developed to extract advantageous features of static scheduling algorithms to the maximum extent.

Kasahara, Hironori; Honda, Hiroki; Narita, Seinosuke

1989-01-01

284

Molybdenum, Ruthenium, and the Heavy r-process Elements in Moderately Metal-Poor Main-Sequence Turnoff Stars  

E-print Network

The ratios of elemental abundances observed in metal-poor stars of the Galactic halo provide a unique present-day record of the nucleosynthesis products of its earliest stars. While the heaviest elements were synthesized by the r- and s-processes, dominant production mechanisms of light trans-ironic elements were obscure until recently. This work investigates further our 2011 conclusion that the low-entropy regime of a high-entropy wind (HEW) produced molybdenum and ruthenium in two moderately metal-poor turnoff stars that showed extreme overabundances of those elements with respect to iron. Only a few, rare nucleosynthesis events may have been involved. Here we determine abundances for Mo, Ru, and other trans-Fe elements for 28 similar stars by matching spectral calculations to well-exposed near-UV Keck HIRES spectra obtained for beryllium abundances. In each of the 26 turnoff stars with Mo or Ru line detections and no evidence for s-process production (therefore old), we find Mo and Ru to be three to six ti...

Peterson, Ruth C

2013-01-01

285

Surface processes in microgravity for landing and sampling site selection of asteroid missions-Suggestions for MarcoPolo-R  

NASA Astrophysics Data System (ADS)

Surface properties of small asteroids are reviewed in this work focusing on microgravity related processes in order to give constrains for targeting sample acquisition by next missions, especially for MarcoPolo-R proposed by ESA. Based on our current knowledge and the planned capabilities of this mission, good chance exists to get answers for the following basic questions. Formation method of nanophase iron and amorphous ingredients in the regolith could be determined, surface particle size and regolith density estimation would also be gained, and with extrapolation to the rest of the surface, knowledge on transport processes, ages and results of cratering under special gravity-strength regime will be improved. Searching for fresh material on asteroid surface in general requires sophisticated effort, as small craters often do not produce much ejecta in microgravity, but the bright annuli around them could be the result of local surface disturbance, while slopes often exhibit fresh material. To identify these locations high albedo, bluer colour and occasionally the depth of 1 ?m absorption band could be useful as they often change parallel to each other. To identify the best area for sample acquisition addresses a strategic question: while smooth terrains with easy navigation and sample acquisition provide strongly weathered fine grains; steeper terrains give access to less weathered, material more representative for the whole asteroid, but navigation and mechanical sampling rise difficulties there.

Kereszturi, Akos

2014-10-01

286

EXTREME ENHANCEMENTS OF r-PROCESS ELEMENTS IN THE COOL METAL-POOR MAIN-SEQUENCE STAR SDSS J2357-0052  

SciTech Connect

We report the discovery of a cool metal-poor, main-sequence star exhibiting large excesses of r-process elements. This star is one of the two newly discovered cool subdwarfs (effective temperatures of 5000 K) with extremely low metallicity ([Fe/H] < -3) identified from follow-up high-resolution spectroscopy of metal-poor candidates from the Sloan Digital Sky Survey. SDSS J2357-0052 has [Fe/H] = -3.4 and [Eu/Fe] = +1.9, and exhibits a scaled solar r-process abundance pattern of heavy neutron-capture elements. This is the first example of an extremely metal-poor, main-sequence star showing large excesses of r-process elements; all previous examples of the large r-process-enhancement phenomena have been associated with metal-poor giants. The metallicity of this object is the lowest, and the excess of Eu ([Eu/Fe]) is the highest, among the r-process-enhanced stars found so far. We consider possible scenarios to account for the detection of such a star and discuss techniques to enable searches for similar stars in the future.

Aoki, Wako [National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Beers, Timothy C. [Department of Physics and Astronomy and JINA: Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824-1116 (United States); Honda, Satoshi [Kwasan Observatory, Kyoto University, Ohmine-cho Kita Kazan, Yamashina-ku, Kyoto 607-847 (Japan); Carollo, Daniela, E-mail: aoki.wako@nao.ac.j, E-mail: beers@pa.msu.ed, E-mail: honda@kwasan.kyoto-u.ac.j, E-mail: carollo@mso.anu.edu.a [Research School of Astronomy and Astrophysics, Australian National University and Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia)

2010-11-10

287

Reaction temperature optimization procedure for the synthesis of ( R)-mandelonitrile by Prunus amygdalus hydroxynitrile lyase using a process model approach  

Microsoft Academic Search

The reaction temperature was optimized for the enzymatic synthesis of (R)-mandelonitrile in a biphasic system of aqueous buffer and methyl tert-butyl ether by including temperature effects in an existing process model. (R)-Mandelonitrile was synthesized by addition of hydrogen cyanide to benzaldehyde using Prunus amygdalus hydroxynitrile lyase as the catalyst. The reaction was investigated within a temperature range of 5 to

W. F Willeman; A. J. J Straathof; J. J Heijnen

2002-01-01

288

X-ray decay lines from heavy nuclei in supernova remnants as a probe of the r-process origin and the birth periods of magnetars  

NASA Astrophysics Data System (ADS)

The origin of rapid neutron capture (r-process) nuclei remains one of the longest standing mysteries in nuclear astrophysics. Core collapse supernovae (SNe) and neutron star binary mergers are likely r-process sites, but little evidence yet exists for their in situ formation in such environments. Motivated by the advent of sensitive new or planned X-ray telescopes such as the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Large Observatory for X-ray Timing (LOFT), we revisit the prospects for the detection of X-ray decay lines from r-process nuclei in young or nearby supernova remnants. For all remnants planned to be observed by NuSTAR (and several others), we conclude that r-process nuclei are detectable only if the remnant possesses a large overabundance O ? 10^3 relative to the average yield per SN. Prospects are better for the next Galactic SN (assumed age of 3 yr and distance of 10 kpc), for which an average r-process yield is detectable via the 10.7 (9.2) keV line complexes of 194Os by LOFT at 6? (5?) confidence; the 27.3 keV line complex of 125Sb is detectable by NuSTAR at 2? for O ? 2. We also consider X-rays lines from the remnants of Galactic magnetars, motivated by the much higher r-process yields of the magnetorotationally driven SNe predicted to birth magnetars. The 3.6-3.9 keV lines of 126Sn are potentially detectable in the remnants of the magnetars 1E1547.0-5408 and 1E2259+586 by LOFT for an assumed r-process yield predicted by recent simulations. The (non-)detection of these lines can thus probe whether magnetars are indeed born with millisecond periods. Finally, we consider a blind survey of the Galactic plane with LOFT for r-process lines from the most recent binary neutron star merger remnant, concluding that a detection is unlikely without additional information on the merger location.

Ripley, Justin L.; Metzger, Brian D.; Arcones, Almudena; Martnez-Pinedo, Gabriel

2014-03-01

289

Process R&D for CIS-Based Thin-Film PV: Annual Technical Report, January 2003--January 2004  

SciTech Connect

This subcontract report describes Shell Solar Industries' outstanding progress in the initial commercialization of high-performance thin-film CIS technology. Cumulative production for 2002 exceeded 1 MW-about twice the production rate for 2001. SSI 2003 capacity was about 3 MW per year, whereas production for 2003 was just over 1.2 MW per year. Introducing the new product accounts for the main difference between production and capacity. Average laminate efficiency for 2003 was 11.0% with a full width of only 11% of the average. This distribution is nominally the same as the distribution for 2002, but with an about 33% increase in production volume. Line yield increased from about 60% in 2000 to about 85% in 2002. Maintenance of this high line yield was demonstrated during 2003. Process R&D during this and previous subcontract periods, both at SSI and in collaboration with NREL teams, has demonstrated the potential for further cost performance improvements: minimization of transients, increased efficiency, and improved packaging. Long-term outdoor stability has been demonstrated at NREL where {approx}30 x 30 cm and {approx} 30 x 120 cm modules with multiple prototype package designs have undergone testing for over 14 years. Field failure mechanisms related to particular package designs and errors during production have been clearly identified. Additional circuit plate or packaging process variables may have affected durability during particular production timeframes; when losses have been observed, the losses correlated with date of deployment or prototype module configuration. Prototype glass/glass packages for individual 40-W circuit plates have passed accelerated tests, including the damp-heat test. This package incorporates an edge seal developed in collaboration with the National Thin-Film PV Module Reliability Team. Developing and testing of 40-W glass/glass packages is being extended to a new 80-W product made using two nominally 40-W circuit plates laminated to a common front sheet.

Tarrant, D. E.; Gay R. R.

2004-10-01

290

Transcript-based Cloning of RRP46, a Regulator of rRNA Processing and R-Gene-Independent Cell Death in BarleyPowdery Mildew Interactions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Programmed cell death (PCD) plays a pivotal role in plant development and defense. To investigate the degree of interaction between PCD and R-gene mediated defense, we used the 22K Barley1 GeneChip to compare and contrast time-course expression profiles of Blumeria graminis f. sp. hordei (Bgh) chal...

291

Preparation and modification of VO2 thin film on R-sapphire substrate by rapid thermal process  

NASA Astrophysics Data System (ADS)

The VO2 thin film with high performance of metal-insulator transition (MIT) is prepared on R-sapphire substrate for the first time by magnetron sputtering with rapid thermal process (RTP). The electrical characteristic and THz transmittance of MIT in VO2 film are studied by four-point probe method and THz time domain spectrum (THz-TDS). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and search engine marketing (SEM) are employed to analyze the crystalline structure, valence state, surface morphology of the film. Results indicate that the properties of VO2 film which is oxidized from the metal vanadium film in oxygen atmosphere are improved with a follow-up RTP modification in nitrogen atmosphere. The crystallization and components of VO2 film are improved and the film becomes compact and uniform. A better phase transition performance is shown that the resistance changes nearly 3 orders of magnitude with a 2-C hysteresis width and the THz transmittances are reduced by 64% and 60% in thermal and optical excitation respectively.

Zhu, Nai-Wei; Hu, Ming; Xia, Xiao-Xu; Wei, Xiao-Ying; Liang, Ji-Ran

2014-04-01

292

Smoking Gun or Smoldering Embers? A Possible r-process Kilonova Associated with the Short-Hard GRB 130603B  

E-print Network

We present Hubble Space Telescope optical and near-IR observations of the short-hard GRB 130603B (z=0.356) obtained 9.4 days post-burst. At the position of the burst we detect a red point source with m(F160W)=25.8+/-0.2 AB mag and m(F606W)>27.5 AB mag (3-sigma), corresponding to rest-frame absolute magnitudes of M_J -15.2 mag and M_B>-13.5 mag. A comparison to the early optical afterglow emission requires a decline rate of alpha_opt1.7 mag is also potentially consistent with the red optical colors of the afterglow at early time (F_nu nu^-1.6 in gri). Thus, an afterglow interpretation is feasible. Alternatively, the red color and faint absolute magnitude are due to emission from an r-process powered transient ("kilonova") produced by ejecta from the merger of an NS-NS or NS-BH binary, the most likely progenitors of short GRBs. In this scenario, the observed brightness implies an outflow with M_ej 0.01 Msun and v_ej 0.1c, in good agreement with the results of numerical merger simulations for roughly equal mass ...

Berger, E; Chornock, R

2013-01-01

293

Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process  

E-print Network

Nuclear structure plays a significant role on the rapid neutron capture process (r-process) since shapes evolve with the emergence of shells and sub-shells. There was some indication in neighboring nuclei that we might find examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90 nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to determine if this nucleus has in fact a doubly-magic character. The fragmentation of Xe-136 beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region. We have measured the half lives of twenty-two nuclei near the r-process path in the A=90 region. The half lives of As-88 and Se-90 have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 sub-shell, and its possible role in the emergence of a potential doubly-magic Se-90. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y and Zr elements was investigated with a weak r-process network. The new half lives agree with results obtained from a standard global QRPA model used in r-process calculations, indicating that Se-90 has a quadrupole shape incompatible with a closed N=56 sub-shell in this region. The impact of the measured Se-90 half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak-r-process is shown to be strong.

M. Quinn; A. Aprahamian; J. Pereira; R. Surman; O. Arndt; T. Baumann; A. Becerril; T. Elliot; A. Estrade; D. Galaviz; T. Ginter; M. Hausmann; S. Hennrich; R. Kessler; K. -L. Kratz; G. Lorusso; P. F. Mantica; M. Matos; P. Moller; F. Montes; B. Pfeiffer; M. Portillo; S. Hennrich; H. Schatz; F. Schertz; L. Schnorrenberger; E. Smith; A. Stolz; W. B. Walters; A. Wohr

2011-12-21

294

A High-Resolution Transmission-Type (TT) Phaser Based on Reflection-Type (RT) Units for Radio Analog Signal Processing (R-ASP)  

E-print Network

A high Radio Analog Signal Processing (R-ASP) resolution transmission-type (TT) phaser based on reflection-type (RT) phaser units is introduced, theoretically studied and experimentally demonstrated. It is first shown that RT phasers inherently exhibit higher R-ASP resolution than their TT counterparts because their group delay swing is proportional to the reflection coefficient associated with a resonator coupling mechanism (admittance inverter), easy to maximize towards unity, rather than to a coupled-line coupling coefficient, typically restricted to values will inferior to unity, as in the RT case. Moreover, a detailed sensitivity analysis reveals that the proposed phaser is simultaneously features high R-ASP resolution and low sensitivity to fabrication tolerance, which makes it an ideal solution for R-ASP. The proposed phaser exhibits a 5 ns group delay swing over a fractional bandwidth of about 50% around 4 GHz.

Zou, Lianfeng

2014-01-01

295

Performance Evaluation in Multistep ProcessesA Comparison of Evaluation Types With Special Emphasis on R&D  

Microsoft Academic Search

The construction of efficient performance evaluation and incentive systems is an important element of modern R&D management. As R&D activities are characterized by a high degree of sequentiality, there is an ongoing discussion as to whether R&D staff that provides the basis for following projects should be evaluated only on the basis of their individual performance or on the basis

Jennifer Kunz

2010-01-01

296

Properties and Processes for Cryogenic Refrigeration R. Radebaugh, P. Bradley, M. Lewis (838), J. Gary, and A. O'Gallagher (ITL)  

E-print Network

Properties and Processes for Cryogenic Refrigeration R. Radebaugh, P. Bradley, M. Lewis (838), J device company, we completed measurements on the performance of a simple pulse tube refrigerator with pulse tube refrigerators). Using a compressor with a piston-position sensor we were able to characterize

Magee, Joseph W.

297

Ultrasonic waves : a tool for gelation process measurements J.-C. Bacri, J.-M. Courdille, J. Dumas and R. Rajaonarison  

E-print Network

L-369 Ultrasonic waves : a tool for gelation process measurements J.-C. Bacri, J.-M. Courdille, J. Dumas and R. Rajaonarison Laboratoire d'Ultrasons (*), Université Pierre-et-Marie-Curie, Tour 13, 4 of high frequency ultrasonic waves (~ 100 MHz) is very different depending on the phase, sol or gel

Boyer, Edmond

298

In Advances in Neural Information Processing Systems 12 S.A. Solla, T.K. Leen and K.R. M  

E-print Network

. As a consequence, the network shifts from an initially highly nonlinear to a more linear operating regime. SharpIn Advances in Neural Information Processing Systems 12 S.A. Solla, T.K. Leen and K.­R. M ? uller the short term dynamics of the recurrent competition and neural activity in the primary visual cortex

Wichmann, Felix

299

The effect of a combined HeNe and i.r. laser treatment on the regeneration of the lymphatic system during the process of wound healing  

Microsoft Academic Search

To study the effect of a combined HeNe and i.r. laser treatment on the regeneration of the lymphatic system during the process of wound healing, we compared the evolution of a surgical induced incision wound in two groups of mice.

P. C. Lievens

1991-01-01

300

Improved Laboratory Transition Probabilities for Er II and Applications to the Erbium Abundances of the Sun and Five r-Process Rich, Metal-Poor Stars  

E-print Network

Recent radiative lifetime measurements accurate to +/- 5% (Stockett et al. 2007, J. Phys. B 40, 4529) using laser-induced fluorescence (LIF) on 8 even-parity and 62 odd-parity levels of Er II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 418 lines of Er II. This work moves Er II onto the growing list of rare earth spectra with extensive and accurate modern transition probability measurements using LIF plus FTS data. This improved laboratory data set has been used to determine a new solar photospheric Er abundance, log epsilon = 0.96 +/- 0.03 (sigma = 0.06 from 8 lines), a value in excellent agreement with the recommended meteoric abundance, log epsilon = 0.95 +/- 0.03. Revised Er abundances have also been derived for the r-process-rich metal-poor giant stars CS 22892-052, BD+17 3248, HD 221170, HD 115444, and CS 31082-001. For these five stars the average Er/Eu abundance ratio, = 0.42, is in very good agreement with the solar-system r-process ratio. This study has further strengthened the finding that r-process nucleosynthesis in the early Galaxy which enriched these metal-poor stars yielded a very similar pattern to the r-process which enriched later stars including the Sun.

J. E. Lawler; C. Sneden; J. J. Cowan; J. -F. Wyart; I. I. Ivans; J. S. Sobeck; M. H. Stockett; E. A. Den Hartog

2008-04-28

301

Job Title: R&D Software Test and Process Engineer #2051372 As the world's premier measurement company, Agilent works in close collaboration with engineers,  

E-print Network

Job Title: R&D Software Test and Process Engineer #2051372 As the world's premier measurement company, Agilent works in close collaboration with engineers, scientists, and researchers around the globe -- supported by Agilent Research Laboratories, its central research group. Agilent is committed to providing

Ravikumar, B.

302

Determination of effective rAAV-mediated gene transfer conditions to support chondrogenic differentiation processes in human primary bone marrow aspirates.  

PubMed

The genetic modification of freshly aspirated bone marrow may provide convenient tools to enhance the regenerative capacities of cartilage defects compared with the complex manipulation of isolated progenitor cells. In the present study, we examined the ability and safety of recombinant adeno-associated virus (rAAV) serotype 2 vectors to deliver various reporter gene sequences in primary human bone marrow aspirates over time without altering the chondrogenic processes in the samples. The results demonstrate that successful rAAV-mediated gene transfer and expression of the lacZ and red fluorescent protein marker genes were achieved in transduced aspirates at very high efficiencies (90-94%) and over extended periods of time (up to 125 days) upon treatment with hirudin, an alternative anticoagulant that does not prevent the adsorption of the rAAV-2 particles at the surface of their targets compared with heparin. Application of rAAV was safe, displaying neither cytotoxic nor detrimental effects on the cellular and proliferative activities or on the chondrogenic processes in the aspirates especially using an optimal dose of 0.5?mg?ml(-1) hirudin, and application of the potent SOX9 transcription factor even enhanced these processes while counteracting hypertrophic differentiation. The current findings demonstrate the clinical value of this class of vector to durably and safely modify bone marrow aspirates as a means to further develop convenient therapeutic approaches to improve the healing of cartilage defects. PMID:25338919

Rey-Rico, A; Frisch, J; Venkatesan, J K; Schmitt, G; Madry, H; Cucchiarini, M

2015-01-01

303

miR-124-regulated RhoG reduces neuronal process complexity via ELMO/Dock180/Rac1 and Cdc42 signalling  

PubMed Central

The small GTPase RhoG plays a central role in actin remodelling during diverse biological processes such as neurite outgrowth, cell migration, phagocytosis of apoptotic cells, and the invasion of pathogenic bacteria. Although it is known that RhoG stimulates neurite outgrowth in the rat pheochromocytoma PC12 cell line, neither the physiological function nor the regulation of this GTPase in neuronal differentiation is clear. Here, we identify RhoG as an inhibitor of neuronal process complexity, which is regulated by the microRNA miR-124. We find that RhoG inhibits dendritic branching in hippocampal neurons in vitro and in vivo. RhoG also inhibits axonal branching, acting via an ELMO/Dock180/Rac1 signalling pathway. However, RhoG inhibits dendritic branching dependent on the small GTPase Cdc42. Finally, we show that the expression of RhoG in neurons is suppressed by the CNS-specific microRNA miR-124 and connect the regulation of RhoG expression by miR-124 to the stimulation of neuronal process complexity. Thus, RhoG emerges as a cellular conductor of Rac1 and Cdc42 activity, in turn regulated by miR-124 to control axonal and dendritic branching. PMID:22588079

Franke, Kristin; Otto, Wolfgang; Johannes, Sascha; Baumgart, Jan; Nitsch, Robert; Schumacher, Stefan

2012-01-01

304

Oligomers, protofibrils and amyloid fibrils from recombinant human lysozyme (rHL): Fibrillation process and cytotoxicity evaluation for ARPE-19 cell line.  

PubMed

Amyloid-associated diseases, such Alzheimer's, Huntington's, Parkinson's, and type II diabetes, are related to protein misfolding and aggregation. Herein, the time evolution of scattered light intensity, hydrophobic properties, and conformational changes during fibrillation processes of rHL solutions at 55C and pH 2.0 were used to monitor the aggregation process of recombinant human lysozyme (rHL). Dynamic light scattering (DLS), thioflavin T (ThT) fluorescence, and surface tension (ST) at the air-water interface were used to analyze the hydrophobic properties of pre-amyloid aggregates involved in the fibrillation process of rHL to find a correlation between the hydrophobic character of oligomers, protofibrils and amyloid aggregates with the gain in cross-?-sheet structure, depending on the increase in the incubation periods. The ability of the different aggregates of rHL isolated during the fibrillation process to be adsorbed at the air-water interface can provide important information about the hydrophobic properties of the protein, which can be related to changes in the secondary structure of rHL, resulting in cytotoxic or non-cytotoxic species. Thus, we evaluated the cytotoxic effect of oligomers, protofibrils and amyloid fibrils on the cell line ARPE-19 using the MTT reduction test. The more cytotoxic protein species arose after a 600-min incubation time, suggesting that the hydrophobic character of pre-amyloid fibrils, in addition to the high prevalence of the cross-?-sheet conformation, can become toxic for the cell line ARPE-19. PMID:25618793

Ruiz, Eva D; Almada, Mario; Burboa, Mara G; Taboada, Pablo; Mosquera, Vctor; Valdez, Miguel A; Jurez, Josu

2015-02-01

305

Half-lives and branchings for ?-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process  

NASA Astrophysics Data System (ADS)

The ? decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL ?-counting station in conjunction with the neutron detector NERO. We measured the branchings for ?-delayed neutron emission (Pn values) for Co74 (1815%) and Ni75-77 (102.8%, 143.6%, and 3024%, respectively) for the first time, and remeasured the Pn values of Cu77-79, Zn79,81, and Ga82. For Cu77-79 and for Zn81 we obtain significantly larger Pn values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of Co75 (3011 ms) and Cu80 (170-50+110 ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is better able to reproduce the A=78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

Hosmer, P.; Schatz, H.; Aprahamian, A.; Arndt, O.; Clement, R. R. C.; Estrade, A.; Farouqi, K.; Kratz, K.-L.; Liddick, S. N.; Lisetskiy, A. F.; Mantica, P. F.; Mller, P.; Mueller, W. F.; Montes, F.; Morton, A. C.; Ouellette, M.; Pellegrini, E.; Pereira, J.; Pfeiffer, B.; Reeder, P.; Santi, P.; Steiner, M.; Stolz, A.; Tomlin, B. E.; Walters, W. B.; Whr, A.

2010-08-01

306

Liouville-space R-matrix-Floquet description of atomic radiative processes involving autoionizing states in the presence of intense electromagnetic fields  

NASA Astrophysics Data System (ADS)

A reduced-density-operator description is developed for coherent optical phenomena in many-electron atomic systems, utilizing a Liouville-space, multiple-mode Floquet-Fourier representation. The Liouville-space formulation provides a natural generalization of the ordinary Hilbert-space (Hamiltonian) R-matrix-Floquet method, which has been developed for multi-photon transitions and laser-assisted electron-atom collision processes. In these applications, the R-matrix-Floquet method has been demonstrated to be capable of providing an accurate representation of the complex, multi-level structure of many-electron atomic systems in bound, continuum, and autoionizing states. The ordinary Hilbert-space (Hamiltonian) formulation of the R-matrix-Floquet method has been implemented in highly developed computer programs, which can provide a non-perturbative treatment of the interaction of a classical, multiple-mode electromagnetic field with a quantum system. This quantum system may correspond to a many-electron, bound atomic system and a single continuum electron. However, including pseudo-states in the expansion of the many-electron atomic wave function can provide a representation of multiple continuum electrons. The dressed many-electron atomic states thereby obtained can be used in a realistic non-perturbative evaluation of the transition probabilities for an extensive class of atomic collision and radiation processes in the presence of intense electromagnetic fields. In order to incorporate environmental relaxation and decoherence phenomena, we propose to utilize the ordinary Hilbert-space (Hamiltonian) R-matrix-Floquet method as a starting-point for a Liouville-space (reduced-density-operator) formulation. To illustrate how the Liouville-space R-matrix-Floquet formulation can be implemented for coherent atomic radiative processes, we discuss applications to electromagnetically induced transparency, as well as to related pump-probe optical phenomena, and also to the unified description of radiative and dielectronic recombination in electron-ion beam interactions and high-temperature plasmas.

Jacobs, V. L.; Burke, P. G.; Potvliege, R. M.

2014-01-01

307

Presentation Processing Support for Adaptive Multimedia Applications Edward J. Posnak, Harrick M. Vin, and R. Greg Lavender  

E-print Network

heterogeneity in networks, end-systems and compression formats. Development of PPEs is facilitated, filters, transcoders etc. to facilitate the implementation of emerging compression standards processing modules, the framework facilitates the development of extensible presentation processing engines

Lavender, Greg

308

Frequency and clinical implication of the R450H mutation in the thyrotropin receptor gene in the Japanese population detected by Smart Amplification Process 2.  

PubMed

In Japanese pediatric patients with thyrotropin (TSH) resistance, the R450H mutation in TSH receptor gene (TSHR) is occasionally observed. We studied the frequency and clinical implication of the R450H mutation in TSHR in the general population of Japanese adults using smart amplification process 2 (SmartAmp2). We designed SmartAmp2 primer sets to detect this mutation using a drop of whole blood. We analyzed thyroid function, antithyroid antibodies, and this mutation in 429 Japanese participants who had not been found to have thyroid disease. Two cases without antithyroid antibodies were heterozygous for the R450H mutation in TSHR. Thus, the prevalence of this mutation was 0.47% in the general population and 0.63% among those without antithyroid antibodies. Their serum TSH concentrations were higher than the average TSH concentration not only in subjects without antithyroid antibodies but also in those with antithyroid antibodies. The R450H mutation in TSHR is relatively common in the Japanese population and potentially affects thyroid function. The present study demonstrates that the SmartAmp2 method is useful to detect the R450H mutation in TSHR, which is one of the common causes of TSH resistance in the Japanese population. PMID:24895636

Tsunekawa, Katsuhiko; Yanagawa, Yoshimaro; Aoki, Tomoyuki; Morimura, Tadashi; Araki, Osamu; Kimura, Takao; Ogiwara, Takayuki; Kotajima, Nobuo; Yanagawa, Masumi; Murakami, Masami

2014-01-01

309

miR-181b as a key regulator of the oncogenic process and its clinical implications in cancer (Review)  

PubMed Central

MicroRNAs (miRNAs or miRs) are small, non-coding, single-stranded RNA molecules that regulate gene expression at the post-transcriptional level to repress protein expression of target genes. Among these, miR-181b has been found to be a critical regulatory miRNA linking inflammation and cancer. The functional significance of miR-181b in various tumors and translational research suggests that it exhibits great potential as a predictive and prognostic biomarker. Extensive efforts are underway to identify mRNA targets and the affected regulatory networks, which may be the key to providing a better understanding of miR-181b-mediated signaling pathways. PMID:24649060

LIU, JUAN; SHI, WEIFENG; WU, CHANGPING; JU, JINGFANG; JIANG, JINGTING

2014-01-01

310

The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F): Exploratory and confirmatory factor analyses at item level  

Microsoft Academic Search

The underlying structure of the Revised Two factor version of the Study Process Questionnaire (R-SPQ-2F), a 20-item instrument\\u000a for the evaluation of students approaches to learning (SAL), was examined at item level using two independent groups of undergraduate\\u000a students enrolled in the first (n=314) and last (n=522) years of their studies. The methods used were (a) Exploratory factor\\u000a analysis (EFA)

Fernando Justicia; M. Carmen Pichardo; Francisco Cano; A. B. G. Berbn; Jess De la Fuente

2008-01-01

311

Mpp10p, a U3 Small Nucleolar Ribonucleoprotein Component Required for Pre18S rRNA Processing in Yeast  

Microsoft Academic Search

We have isolated and characterized Mpp10p, a novel protein component of the U3 small nucleolar ribonu- cleoprotein (snoRNP) from the yeast Saccharomyces cerevisiae. The MPP10 protein was first identified in human cells by its reactivity with an antibody that recognizes specific sites of mitotic phosphorylation. To study the functional role of MPP10 in pre-rRNA processing, we identified the yeast protein

D. A. DUNBAR; S. WORMSLEY; T. M. AGENTIS; S. J. BASERGA

1997-01-01

312

Measurement of the Europium Isotope Ratio for the Extremely Metal-Poor, r-Process-Enhanced Star CS31082-001  

E-print Network

We report the first measurement of the isotope fraction of europium (151Eu and 153Eu) for the extremely metal-poor, r-process-enhanced star CS31082-001, based on high-resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph. We have also obtained new measurements of this ratio for two similar stars with previous europium isotope measurements, CS22892-052 and HD115444. The measurements were made using observations of the Eu lines in these spectra that are most significantly affected by isotope shifts and hyperfine splitting. The fractions of 151Eu derived for CS31082-001, CS22892-052, and HD115444 are 0.44, 0.51, and 0.46, respectively, with uncertainties of about +/-0.1. CS31082-001, the first star with a meaningful measurement of U outside of the solar system, is known to exhibit peculiar abundance ratios between the actinide and rare-earth elements (e.g., Th/Eu), ratios that are significantly different from those for other stars with large excesses of r-process elements, such as our two comparison objects. Nevertheless, our analysis indicates that the Eu isotope ratio of CS31082-001 agrees, within the errors, with those of other r-process-enhanced objects, and with that of solar-system material.

W. Aoki; S. Honda; T. C. Beers; C. Sneden

2002-11-28

313

Exploring the Interrelationship of Structure and Process in Family Child Care: The FCCERS-R and "Combined" CLASS  

ERIC Educational Resources Information Center

This study examined the correlations between two prominent family child care environmental rating scales, the Family Child Care Environment Rating Scale - Revised (FCCERS-R) and the "Combined" Classroom Assessment Scoring System ("Combined" CLASS), both of which were used during the pilot study of Washington State's

Enns, Lionel

2012-01-01

314

ACToR Chemical Structure processing using Open Source ChemInformatics Libraries (FutureToxII)  

EPA Science Inventory

ACToR (Aggregated Computational Toxicology Resource) is a centralized database repository developed by the National Center for Computational Toxicology (NCCT) at the U.S. Environmental Protection Agency (EPA). Free and open source tools were used to compile toxicity data from ove...

315

Laser Remote Measurements of atmospheric pollutants (Las-R-Map): UV-Visible Laser system description and data processing  

NASA Astrophysics Data System (ADS)

Laser radar more popularly known as LIDAR LIght Detection And Ranging is becoming one of the most powerful techniques for active remote sensing of the earth s atmosphere Around the globe several new lidar systems have been developed based on the scientific interest Particularly the DIfferential Absorption Lidar DIAL technique is only one which can provide the better accuracy of measuring atmospheric pollutants Using modern advanced techniques and instrumentation a mobile DIAL system called laser remote measurements of atmospheric pollutants hear after referred as Las-R-Map is designed at National Laser Centre NLC --Pretoria 25 r 45 prime S 28 r 17 prime E Las-R-Map is basically used for measuring atmospheric pollutants applying the principle of absorption by constituents The system designed primarily to focus on the following pollutant measurements such as SO 2 CH 4 CO 2 NO 2 and O 3 In future the system could be used to measure few particulate matter between 2 5 mu m and 10 mu m Benzene Hg 1 3-butadiene H 2 S HF and Volatile Organic Compounds VOC Las-R-map comprises of two different laser sources Alexandrite and CO 2 optical receiver data acquisition and signal processor It uses alexandrite laser in the UV-Visible region from 200 nm to 800 nm and CO 2 laser in the Far-IR region from 9 2 mu m to 10 8 mu m Such two different laser sources make feasibility for studying the wide range of atmospheric pollutants The present paper is focused on technical details

Sivakumar, V.; Wyk, H. V.

316

Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process  

NASA Astrophysics Data System (ADS)

Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. In particular, large samples of stars with metallicities -5 < [Fe/H] <-1 and measured abundances of Sr, Ba, Y, and Eu are now available. These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims: We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods: We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture (EC) supernovae and the magnetorotationally driven (MRD) supernovae scenarios. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results: The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] <-2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenarios that match the observations. Conclusions: With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenarios in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic ratios in a [Ba/Fe] or [Sr/Ba] vs. [Fe/H] diagram. Appendix A is available in electronic form at http://www.aanda.org

Cescutti, G.; Chiappini, C.

2014-05-01

317

Microbial community of salt crystals processed from Mediterranean seawater based on 16S rRNA analysis.  

PubMed

Phylogenetic analysis of 16S rRNA was used to investigate for the first time the structure of the microbial community that inhabits salt crystals retrieved from the bottom of a solar saltern, located in the coastal area of the Mediterranean Sea (Sfax, Tunisia). This community lives in an extremely salty environment of 250-310 g/L total dissolved salt. A total of 78 bacterial 16S rRNA clone sequences making up to 21 operational taxonomic units (OTUs), determined by the DOTUR program to 97% sequence similarity, was analyzed. These OTUs were affiliated to Bacteroidetes (71.4% of OTUs), and gamma-Proteobacteria and alpha-Proteobacteria (equally represented by 14.2% of the OTUs observed). The archaeal community composition appeared more diverse with 68 clones, resulting in 44 OTUs, all affiliated with the Euryarchaeota phylum. Of the bacterial and archaeal clones showing <97% 16S rRNA sequence identity with sequences in public databases, 47.6% and 84.1% respectively were novel clones. Both rarefaction curves and diversity measurements (Simpson, Shannon-Weaver, Chao) showed a more diverse archaeal than bacterial community at the Tunisian solar saltern pond. The analysis of an increasing clone's number may reveal additional local diversity. PMID:20130693

Baati, Houda; Guermazi, Sonda; Gharsallah, Neji; Sghir, Abdelghani; Ammar, Emna

2010-01-01

318

Half-lives and branchings for {beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process  

SciTech Connect

The {beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {beta}-delayed neutron emission (P{sub n} values) for {sup 74}Co (18{+-}15%) and {sup 75-77}Ni (10{+-}2.8%, 14{+-}3.6%, and 30{+-}24%, respectively) for the first time, and remeasured the P{sub n} values of {sup 77-79}Cu, {sup 79,81}Zn, and {sup 82}Ga. For {sup 77-79}Cu and for {sup 81}Zn we obtain significantly larger P{sub n} values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of {sup 75}Co (30{+-}11 ms) and {sup 80}Cu (170{sub -50}{sup +110} ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is better able to reproduce the A=78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

Hosmer, P.; Estrade, A.; Montes, F.; Ouellette, M.; Pellegrini, E. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Schatz, H. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824 (United States); Aprahamian, A. [Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Arndt, O.; Pfeiffer, B. [Institut fuer Kernchemie, Universitaet Mainz, Fritz-Strassmann Weg 2, D-55128 Mainz (Germany); HGF Virtuelles Institut fuer Kernstruktur und Nukleare Astrophysik (Germany); Clement, R. R. C.; Mueller, W. F.; Morton, A. C.; Pereira, J.; Santi, P.; Steiner, M.; Stolz, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Farouqi, K. [Department of Astronomy and Astrophysics and Joint Institute for Nuclear Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Kratz, K.-L. [HGF Virtuelles Institut fuer Kernstruktur und Nukleare Astrophysik (Germany); Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut), J.-J.-Becherweg 27, D-55128 Mainz (Germany); Liddick, S. N.; Mantica, P. F. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States)

2010-08-15

319

A KINETIC MODEL FOR H2O2/UV PROCESS IN A COMPLETELY MIXED BATCH REACTOR. (R825370C076)  

EPA Science Inventory

A dynamic kinetic model for the advanced oxidation process (AOP) using hydrogen peroxide and ultraviolet irradiation (H2O2/UV) in a completely mixed batch reactor (CMBR) is developed. The model includes the known elementary chemical and photochemical reac...

320

MEMBRANE-MODERATED STRIPPING PROCESS FOR REMOVING VOCS FROM WATER IN A COMPOSITE HOLLOW FIBER MODULE. (R825511C027)  

EPA Science Inventory

The "stripmeation" process for removing volatile organic compounds (VOCs) from water has been introduced and studied. An aqueous solution of the VOC is passed through the bores of hydrophobic microporous polypropylene hollow fibers having a plasma polymerized silicone ...

321

Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process  

E-print Network

Nuclear structure plays a significant role on the rapid neutron capture process (r-process) since shapes evolve with the emergence of shells and sub-shells. There was some indication in neighboring nuclei that we might find examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90 nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to determine if this nucleus has in fact a doubly-magic character. The fragmentation of Xe-136 beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region. We have measured the half lives of twenty-two nuclei near the r-process path in the A=90 region. The half lives of As-88 and Se-90 have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 sub-shell, and its possible role in the emergence of a potential doubly-magic Se-90. The impact of such hypothesis on the sy...

Quinn, M; Pereira, J; Surman, R; Arndt, O; Baumann, T; Becerril, A; Elliot, T; Estrade, A; Galaviz, D; Ginter, T; Hausmann, M; Hennrich, S; Kessler, R; Kratz, K -L; Lorusso, G; Mantica, P F; Matos, M; Moller, P; Montes, F; Pfeiffer, B; Portillo, M; Hennrich, S; Schatz, H; Schertz, F; Schnorrenberger, L; Smith, E; Stolz, A; Walters, W B; Wohr, A

2011-01-01

322

Novel Magnetically Fluidized Bed Reactor Development for the Looping Process: Coal to Hydrogen Production R&D  

SciTech Connect

The coal to hydrogen project utilizes the iron/iron oxide looping process to produce high purity hydrogen. The input energy for the process is provided by syngas coming from gasification process of coal. The reaction pathways for this process have been studied and favorable conditions for energy efficient operation have been identified. The Magnetically Stabilized Porous Structure (MSPS) is invented. It is fabricated from iron and silica particles and its repeatable high performance has been demonstrated through many experiments under various conditions in thermogravimetric analyzer, a lab-scale reactor, and a large scale reactor. The chemical reaction kinetics for both oxidation and reduction steps has been investigated thoroughly inside MSPS as well as on the surface of very smooth iron rod. Hydrogen, CO, and syngas have been tested individually as the reducing agent in reduction step and their performance is compared. Syngas is found to be the most pragmatic reducing agent for the two-step water splitting process. The transport properties of MSPS including porosity, permeability, and effective thermal conductivity are determined based on high resolution 3D CT x-ray images obtained at Argonne National Laboratory and pore-level simulations using a lattice Boltzmann Equation (LBE)-based mesoscopic model developed during this investigation. The results of those measurements and simulations provide necessary inputs to the development of a reliable volume-averaging-based continuum model that is used to simulate the dynamics of the redox process in MSPS. Extensive efforts have been devoted to simulate the redox process in MSPS by developing a continuum model consist of various modules for conductive and radiative heat transfer, fluid flow, species transport, and reaction kinetics. Both the Lagrangian and Eulerian approaches for species transport of chemically reacting flow in porous media have been investigated and verified numerically. Both approaches lead to correct prediction of hydrogen production rates over a large range of experimental conditions in the laboratory scale reactor and the bench-scale reactor. In the economic analysis, a comparison of the hydrogen production plants using iron/iron oxide looping cycle and the conventional process has been presented. Plant configurations are developed for the iron/iron oxide looping cycle. The study suggests a higher electric power generation but a lower hydrogen production efficiency comparing with the conventional process. Additionally, it was shown that the price of H{sub 2} obtained from our reactor can be as low as $1.7/kg, which is 22% lower than the current price of the H{sub 2} obtained from reforming plants.

Mei, Renwei; Hahn, David; Klausner, James; Petrasch, Jorg; Mehdizadeh, Ayyoub; Allen, Kyle; Rahmatian, Nima; Stehle, Richard; Bobek, Mike; Al-Raqom, Fotouh; Greek, Ben; Li, Like; Chen, Chen; Singh, Abhishek; Takagi, Midori; Barde, Amey; Nili, Saman

2013-09-30

323

Ferromanganese nodules from MANOP Sites H, S, and R - Control of mineralogical and chemical composition by multiple accretionary processes  

NASA Astrophysics Data System (ADS)

The chemical composition of ferromanganese nodules from the three nodule-bearing MANOP sites in the Pacific can be accounted for in a qualitative way by variable contributions of distinct accretionary processes. These accretionary modes are: (1) hydrogenous, i.e., direct precipitation or accumulation of colloidal metal oxides in seawater, (2) oxic diagenesis which refers to a variety of ferromanganese accretion processes occurring in oxic sediments; and (3) suboxic diagenesis which results from reduction of Mn +4 by oxidation of organic matter in the sediments. Geochemical evidence suggests processes (1) and (2) occur at all three MANOP nodule-bearing sites, and process (3) occurs only at the hemipelagic site, H, which underlies the relatively productive waters of the eastern tropical Pacific. A normative model quantitatively accounts for the variability observed in nearly all elements. Zn and Na, however, are not well explained by the three end-member model, and we suggest that an additional accretionary process results in greater variability in the abundances of these elements. Variable contributions from the three accretionary processes result in distinct top-bottom compositional differences at the three sites. Nodule tops from H are enriched in Ni, Cu, and Zn, instead of the more typical enrichments of these elements in nodule bottoms. In addition, elemental correlations typical of most pelagic nodules are reversed at site H. The three accretionary processes result in distinct mineralogies. Hydrogenous precipitation produces ?MnO 2. Oxic diagenesis, however, produces Cu-Ni-rich todorokite, and suboxic diagenesis results in an unstable todorokite which transforms to a 7 phase ("birnessite") upon dehydration. The presence of Cu and Ni as charge-balancing cations influence the stability of the todorokite structure. In the bottoms of H nodules, which accrete dominantly by suboxic diagenesis, Na + and possibly Mn +2 provide much of the charge balance for the todorokite structure. Limited growth rate data for H nodules suggest suboxic accretion is the fastest of the three processes, with rates at least 200 mm/10 6 yr. Oxic accretion is probably 10 times slower and hydrogenous 100 times slower. Since these rates predict more suboxic component in bulk nodules than is calculated by the normative analysis, we propose that suboxic accretion is a non-steady-state process. Variations in surface water productivity cause pulses of particulate flux to the sea floor which result in transient Mn reduction in the surface sediments and reprecipitation on nodule surfaces.

Dymond, Jack; Lyle, Mitchell; Finney, Bruce; Piper, David Z.; Murphy, Kim; Conard, Roberta; Pisias, Nicklas

1984-05-01

324

Beta-decay half-lives and beta-delayed neutron emisison probabilities of nuclei in the region A. 110, relevant for the r-process  

SciTech Connect

Measurements of the {beta}-decay properties of A {approx}< 110 r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. {beta}-decay half-lives for {sup 105}Y, {sup 106,107}Zr and {sup 108,111}Mo, along with ,B-delayed neutron emission probabilities of 104Y, 109,11OMo and upper limits for 105Y, 103-107Zr and 108,111 Mo have been measured for the first time. Studies on the basis of the quasi-random phase approximation are used to analyze the ground-state deformation of these nuclei.

Moller, Peter [Los Alamos National Laboratory; Pereira, J [MSU; Hennrich, S [MSU; Aprahamian, A [UNIV OF NOTRE DAME; Arndt, O [GERMANY; Becerril, A [MSU; Elliot, T [MSU; Estrade, A [MSU; Galaviz, D [MSU; Kessler, R [UNIV MAINZ; Kratz, K - L [GERMANY; Lorusso, G [MSU; Mantica, P F [MSU; Matos, M [MSU; Montes, F [MSU; Pfeiffer, B [UNIV MAINZ; Schatz, F [MSU; Schnorrenberger, L [GERMANY; Smith, E [MSU; Stolz, A [MSU; Quinn, M [UNIV OF NOTRE DAME; Walters, W B [UNIV OF MARYLAND; Wohr, A [UNIV OF NOTRE DAME

2009-01-01

325

Beta-decay half-lives and beta-delayed neutron emission probabilities of nuclei in the region below A=110, relevant for the r-process  

E-print Network

Measurements of the beta-decay properties of r-process nuclei below A=110 have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. Beta-decay half-lives for Y-105, Zr-106,107 and Mo-111, along with beta-delayed neutron emission probabilities of Y-104, Mo-109,110 and upper limits for Y-105, Zr-103,104,105,106,107 and Mo-108,111 have been measured for the first time. Studies on the basis of the quasi-random phase approximation are used to analyze the ground-state deformation of these nuclei.

J. Pereira; S. Hennrich; A. Aprahamian; O. Arndt; A. Becerril; T. Elliot; A. Estrade; D. Galaviz; R. Kessler; K. -L. Kratz; G. Lorusso; P. F. Mantica; M. Matos; P. Moller; F. Montes; B. Pfeiffer; H. Schatz; F. Schertz; L. Schnorrenberger; E. Smith; A. Stolz; M. Quinn; W. B. Walters; A. Wohr

2009-02-10

326

6.8 Cylinder Liner Boring Case Study Demonstrating the Process of SPC The following case study demonstrates the application of X and R control charts to the study of  

E-print Network

liner production process (Figure 6.24). Figure 6.24 Flow Chart of Cylinder Liner Manufacturing Process6.8 Cylinder Liner Boring Case Study ­ Demonstrating the Process of SPC The following case study demonstrates the application of X and R control charts to the study of a manufacturing operation

Di Bucchianico, Alessandro

327

NATO/CCMS PILOT STUDY CLEAN PRODUCTS AND PROCESSES (PHASE 1) 1998 ANNUAL REPORT (EPA/600/R-98/065)  

EPA Science Inventory

This annual report presents the proceedings of the first annual NATO/CCMS pilot study meeting in Cincinnati in March 1998. Guest speakers focused on efforts in the research arena of clean products, clean processes, life cycle analysis, ecolabeling, and pollution prevention tools....

328

A MECHANISTIC MODEL FOR ESTIMATING VOC EMISSIONS FROM INDUSTRIAL PROCESS DRAINS PART I: THE UNDERLYING CHANNEL. (R823335)  

EPA Science Inventory

Recent research has indicated the potential for emissions of volatile organic compound (VOCs) from industrial process drains, and a need for better understanding of the mass transfer kinetics associated with such emissions. rn this study, a two-zone model was developed in a...

329

Neutron-Capture Elements in the Double-Enhanced Star HE 1305-0007: a New s- and r-Process Paradigm  

E-print Network

The star HE 1305-0007 is a metal-poor double-enhanced star with metallicity [Fe/H] $=-2.0$, which is just at the upper limit of the metallicity for the observed double-enhanced stars. Using a parametric model, we find that almost all s-elements were made in a single neutron exposure. This star should be a member of a post-common-envelope binary. After the s-process material has experienced only one neutron exposure in the nucleosynthesis region and is dredged-up to its envelope, the AGB evolution is terminated by the onset of common-envelope evolution. Based on the high radial-velocity of HE 1305-0007, we speculate that the star could be a runaway star from a binary system, in which the AIC event has occurred and produced the r-process elements.

Wen-Yuan Cui; D. N. Cui; Y. S. Du; B. Zhang

2007-04-04

330

Spectroscopic Studies of Extremely Metal-Poor Stars with the Subaru High Dispersion Spectrograph. II. The r-Process Elements, Including Thorium  

NASA Astrophysics Data System (ADS)

We have obtained high-resolution, high signal-to-noise near-UV-blue spectra of 22 very metal-poor stars ([Fe/H]<-2.5) with the Subaru High Dispersion Spectrograph and measured the abundances of elements from C to Th. The metallicity range of the observed stars is -3.2<[Fe/H]<-2.4. As found by previous studies, the star-to-star scatter in the measured abundances of neutron-capture elements in these stars is very large, much greater than could be assigned to observational errors, in comparison with the relatively small scatter in the ?- and iron-peak elements. In spite of the large scatter in the ratios of the neutron-capture elements relative to iron, the abundance patterns of heavy neutron-capture elements (56<=Z<~72) are quite similar within our sample stars. The Ba/Eu ratios in the 11 very metal-poor stars in our sample in which both elements have been detected are nearly equal to that of the solar system r-process component. Moreover, the abundance patterns of the heavy neutron-capture elements (56<=Z<=70) in seven objects with clear enhancements of the neutron-capture elements are similar to that of the solar system r-process component. These results prove that heavy neutron-capture elements in these objects are primarily synthesized by the r-process. In contrast, the abundance ratios of the light neutron-capture elements (38<=Z<=46) relative to the heavier ones (56<=Z<=70) exhibit a large dispersion. Our inspection of the correlation between Sr and Ba abundances in very metal-poor stars reveals that the dispersion of the Sr abundances clearly decreases with increasing Ba abundance. This trend is naturally explained by hypothesizing the existence of two processes, one that produces Sr without Ba and another that produces Sr and Ba in similar proportions. This result should provide a strong constraint on the origin of the light neutron-capture elements at low metallicity. We have identified a new highly r-process element enhanced, metal-poor star, CS 22183-031, a giant with [Fe/H]=-2.93 and [Eu/Fe]=+1.2. We also identified a new, moderately r-process-enhanced, metal-poor star, CS 30306-132, a giant with [Fe/H]=-2.42 and [Eu/Fe]=+0.85. The abundance ratio of the radioactive element Th (Z=90) relative to the stable rare-earth elements (e.g., Eu) in very metal-poor stars has been used as a cosmochronometer by a number of previous authors. Thorium is detected in seven stars in our sample, including four objects for which the detection of Th has already been reported. New detections of thorium have been made for the stars HD 6268, HD 110184, and CS 30306-132. The Th/Eu abundance ratios [log(Th/Eu)], are distributed over the range -0.10 to -0.59, with typical errors of 0.10 to 0.15 dex. In particular, the ratios in two stars, CS 31082-001 and CS 30306-132, are significantly higher than the ratio in the well-studied object CS 22892-052 and those of other moderately r-process-enhanced metal-poor stars previously reported. Since these very metal-poor stars are believed to be formed in the early Galaxy, this result suggests that the abundance ratios between Th and stable rare-earth elements such as Eu, both of which are presumably produced by r-process nucleosynthesis, may exhibit real star-to-star scatter, with implications for (1) the astrophysical sites of the r-process, and (2) the use of Th/Eu as a cosmochronometer. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Honda, Satoshi; Aoki, Wako; Kajino, Toshitaka; Ando, Hiroyasu; Beers, Timothy C.; Izumiura, Hideyuki; Sadakane, Kozo; Takada-Hidai, Masahide

2004-05-01

331

Process innovation in high-performance systems: From polymeric composites R&D to design and build of airplane showers  

NASA Astrophysics Data System (ADS)

In the aerospace industry reducing aircraft weight is key because it increases flight performance and drives down operating costs. With fierce competition in the commercial aircraft industry, companies that focused primarily on exterior aircraft performance design issues are turning more attention to the design of aircraft interior. Simultaneously, there has been an increase in the number of new amenities offered to passengers especially in first class travel and executive jets. These new amenities present novel and challenging design parameters that include integration into existing aircraft systems without sacrificing flight performance. The objective of this study was to design a re-circulating shower system for an aircraft that weighs significantly less than pre-existing shower designs. This was accomplished by integrating processes from polymeric composite materials, water filtration, and project management. Carbon/epoxy laminates exposed to hygrothermal cycling conditions were evaluated and compared to model calculations. Novel materials and a variety of fabrication processes were developed to create new types of paper for honeycomb applications. Experiments were then performed on the properties and honeycomb processability of these new papers. Standard water quality tests were performed on samples taken from the re-circulating system to see if current regulatory standards were being met. These studies were executed and integrated with tools from project management to design a better shower system for commercial aircraft applications.

Wu, Yi-Jui

332

EVALUATING REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL, REGIONAL-MERCURY CYCLING MODEL (R-MCM), APPLIED TO 91 VERMONT AND NEW HAMPSHIRE LAKES AND PONDS, USA  

EPA Science Inventory

Regulatory agencies must develop fish consumption advisories for many lakes and rivers with limited resources. Process-based mathematical models are potentially valuable tools for developing regional fish advisories. The Regional Mercury Cycling model (R-MCM) was specifically d...

333

Assessing the reliability and validity of the Revised Two Factor Study Process Questionnaire (R-SPQ2F) in Ghanaian medical students  

PubMed Central

Purpose: We investigated the validity and reliability of the Revised Two Factor Study Process Questionnaire (R-SPQ2F) in preclinical students in Ghana. Methods: The R-SPQ2F was administered to 189 preclinical students of the University for Development Studies, School of Medicine and Health Sciences. Both descriptive and inferential statistics with Cronbachs alpha test and factor analysis were done. Results: The mean age of the students was 22.69 0.18years, 60.8% (n=115) were males and 42.3% (n=80) were in their second year of medical training. The students had higher mean deep approach scores (31.237.19) than that of surface approach scores (22.626.48). Findings of the R-SPQ2F gave credence to a solution of two-factors indicating deep and surface approaches accounting for 49.80% and 33.57%, respectively, of the variance. The scales of deep approach (Cronbachs alpha, 0.80) and surface approach (Cronbachs alpha, 0.76) and their subscales demonstrated an internal consistency that was good. The factorial validity was comparable to other studies. Conclusion: Our study confirms the construct validity and internal consistency of the R-SPQ2F for measuring approaches to learning in Ghanaian preclinical students. Deep approach was the most dominant learning approach among the students. The questionnaire can be used to measure students approaches to learning in Ghana and in other African countries. PMID:25112447

2014-01-01

334

Shelf edge exchange processes-II SEEP2-06, R/V Endeavor cruise 186. Hydrographic data report  

SciTech Connect

The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984. Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. Hydrographic data were collected on eight of the six cruises.

Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1989-12-01

335

Shelf Edge Exchange Processes, II: SEEP2-08, R/V ENDEAVOR cruise 188. Hydrographic data report  

SciTech Connect

The Shelf Edge Exchange Processes (SEEP) program sponsored by the United States Department of Energy is a multi-institutional effort designed to investigate the flux of suspended material from the continental shelf to the waters of the upper slope, and then possibly into the slope sediments. Phase I of SEEP consisted of a series of nine cruises and a mooring array across the outer continental shelf of New England during 1983--1984 (Behrens and Flagg, 1986). Phase II focused specifically on the shelf/slope frontal region of the mid-Atlantic bight off the Delmarva Peninsula. This project consisted of a series of ten cruises, a mooring array, and a series of over-flights by NASA aircraft. Hydrographic data were collected on eight of the cruises, six of which were primarily mooring deployment or recovery cruises. The cruises were consecutively designated SEEP2-01 to SEEP2-10. Two cruises (SEEP2-04 and SEEP2-07) were dedicated to investigating benthic processes and hydrographic data were not collected.

Wilson, C.; Behrens, W.J.; Flagg, C.N.; Wallace, D.W.R.; Wilke, R.J.; Wyman, K.D.

1989-12-01

336

Fungal diversity in composting process of pig manure and mushroom cultural waste based on partial sequence of large subunit rRNA.  

PubMed

Fungal diversity during composting was investigated by culture-independent rDNA sequence analysis. Composting was carried out with pig manure and mushroom cultural waste using a field-scale composter (Hazaka system), and samples were collected at various stages. Based on partial sequence analysis of large subunit (LSU) ribosomal RNA (rRNA) and sequence identity values, a total of 12 different fungal species were found at six sampling sites; Geotrichum sp., Debaryomyces hansenii, Monographella nivalis, Acremonium strictum, Acremonium alternatum, Cladosporium sphaerospermum, Myriangium durosai, Pleurotus eryngii, Malassezia globosa, Malassezia restricta, Rhodotorula glutinis, and Fusarium sporotrichioides. Geotrichum sp. of the class Saccharomycetes was the most predominant fungal species throughout the composting process (185 out of a total of 236 identified clones, or 78.4%), followed by Acremonium strictum (7.6%), Monographella nivalis (5.1%), and Pleurotus eryngii (3.8%). The prevalence of Geotrichum sp. was the lowest (61.1%) at the beginning of composting, and then gradually increased to 92.5% after 10 days of composting. PMID:19734710

Cho, Kye Man; Kwon, Eun Ju; Kim, Sung Kyum; Kambiranda, Devaiah M; Math, Reukaradhya K; Lee, Young Han; Kim, Jungho; Yun, Han Dae; Kim, Hoon

2009-08-01

337

Evidence that PC2 is the endogenous pro-neurotensin convertase in rMTC 6-23 cells and that PC1- and PC2-transfected PC12 cells differentially process pro-neurotensin.  

PubMed

The neuropeptide precursor proneurotensin/neuromedin N (pro-NT/NN) is mainly expressed and differentially processed in the brain and in the small intestine. We showed previously that rMTC 6-23 cells process pro-NT/NN with a pattern similar to brain tissue and increase pro-NT/NN expression in response to dexamethasone, and that PC12 cells also produce pro-NT/NN but are virtually unable to process it. In addition, PC12 cells were reported to be devoid of the prohormone convertases PC1 and PC2. The present study was designed to identify the proprotein convertase(s) (PC) involved in pro-NT/NN processing in rMTC 6-23 cells and to compare PC1- and PC2-transfected PC12 cells for their ability to process pro-NT/NN. rMTC 6-23 cells were devoid of PC1, PC4, and PC5 but expressed furin and PC2. Stable expression of antisense PC2 RNA in rMTC 6-23 cells led to a 90% decrease in PC2 protein levels that correlated with a > 80% reduction of pro-NT/NN processing. PC2 expression was stimulated by dexamethasone in a time- and concentration-dependent manner. Stable PC12/PC2 transfectants processed pro-NT/NN with a pattern similar to that observed in the brain and in rMTC 6-23 cells. In contrast, stable PC12/PC1 transfectants reproduced the pro-NT/NN processing pattern seen in the gut. We conclude that (i) PC2 is the major pro-NT/NN convertase in rMTC 6-23 cells; (ii) its expression is coregulated with that of pro-NT/NN in this cell line; and (iii) PC2 and PC1 differentially process pro-NT/NN with brain and intestinal phenotype, respectively. PMID:8626691

Rovre, C; Barbero, P; Kitabgi, P

1996-05-10

338

Diverse nucleosynthetic components in barium isotopes of carbonaceous chondrites: Incomplete mixing of s- and r-process isotopes and extinct 135Cs in the early solar system  

NASA Astrophysics Data System (ADS)

Barium isotopic compositions of chemical leachates from six carbonaceous chondrites, Orgueil (CI), Mighei (CM2), Murray (CM2), Efremovka (CV3), Kainsaz (CO3), and Karoonda (CK4), were determined using thermal ionization mass spectrometry in order to assess the chemical evolution in the early solar system. The Ba isotopic data from most of the leachates show variable 135Ba excesses correlated with 137Ba excesses, suggesting the presence and heterogeneity of additional nucleosynthetic components for s- and r-processes in the solar system. The isotopic deviations observed in this study were generally small (-1 < ? < +1) except in the case of the acid residues of CI and CM meteorites. Large deviations of 135Ba (? = -13.5 to -5.0) and 137Ba (? = -6.2-1.2) observed in the acid residues from one CI and two CM meteorites show significant evidence for the enrichment of s-process isotopes derived from presolar grains. Two models were proposed to estimate the 135Cs isotopic abundances by subtraction of the s- and r-isotopic components from the total Ba isotopic abundances in the three CM meteorites, Mighei, Murchison (measured in a previous study), and Murray. The data points show individual linear trends between 135Cs/ 136Ba ratios and 135Ba isotopic deviations for the three samples. Considering the different trends observed in the three CM meteorites, the Ba isotopic composition of the CM meteorite parent body was heterogeneous at its formation. Chronological information is unclear in the data for Murchison and Murray because of large analytical uncertainties imposed by error propagation. Only the Mighei meteorite data indicate the possible existence of presently extinct 135Cs ( 135Cs/ 133Cs = (2.7 1.6) 10 -4) in the early solar system. Another explanation of the data for the three CM meteorite is mixing of at least three components with different Ba isotopic compositions, although this is model-dependent.

Hidaka, Hiroshi; Yoneda, Shigekazu

2011-07-01

339

Yeast polypeptide exit tunnel ribosomal proteins L17, L35 and L37 are necessary to recruit late-assembling factors required for 27SB pre-rRNA processing  

PubMed Central

Ribosome synthesis involves the coordinated folding and processing of pre-rRNAs with assembly of ribosomal proteins. In eukaryotes, these events are facilitated by trans-acting factors that propel ribosome maturation from the nucleolus to the cytoplasm. However, there is a gap in understanding how ribosomal proteins configure pre-ribosomes in vivo to enable processing to occur. Here, we have examined the role of adjacent yeast r-proteins L17, L35 and L37 in folding and processing of pre-rRNAs, and binding of other proteins within assembling ribosomes. These three essential ribosomal proteins, which surround the polypeptide exit tunnel, are required for 60S subunit formation as a consequence of their role in removal of the ITS2 spacer from 27SB pre-rRNA. L17-, L35- and L37-depleted cells exhibit turnover of aberrant pre-60S assembly intermediates. Although the structure of ITS2 does not appear to be grossly affected in their absence, these three ribosomal proteins are necessary for efficient recruitment of factors required for 27SB pre-rRNA processing, namely, Nsa2 and Nog2, which associate with pre-60S ribosomal particles containing 27SB pre-rRNAs. Altogether, these data support that L17, L35 and L37 are specifically required for a recruiting step immediately preceding removal of ITS2. PMID:23268442

Gamalinda, Michael; Jakovljevic, Jelena; Babiano, Reyes; Talkish, Jason; de la Cruz, Jess; Woolford, John L.

2013-01-01

340

Introducing the Fission-Fusion Reaction Process: Using a Laser-Accelerated Th Beam to produce Neutron-Rich Nuclei towards the N=126 Waiting Point of the r Process  

E-print Network

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process around the waiting point N=126 by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a CH2 layer), where the light fission fragments of the beam fuse with the light fission fragments of the target. Via the 'hole-boring' mode of laser Radiation Pressure Acceleration using a high-intensity, short pulse laser, very efficiently bunches of 232Th with solid-state density can be generated from a Th layer, placed beneath a deuterated polyethylene foil, both forming the production target. Th ions laser-accelerated to about 7 MeV/u will pass through a thin CH2 layer placed in front of a thicker second Th foil closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD2 production target will be accelerated as well to about 7 MeV/u, inducing the fission process of 232Th also in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10^14 times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again. In contrast to classical radioactive beam facilities, where intense but low-density radioactive beams are merged with stable targets, the novel fission-fusion process draws on the fusion between neutron-rich, short-lived, light fission fragments both from beam and target. The high ion beam density may lead to a strong collective modification of the stopping power in the target, leading to significant range enhancement. Using a high-intensity laser as envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP), estimates promise a fusion yield of about 10^3 ions per laser pulse in the mass range of A=180-190, thus enabling to approach the r-process waiting point at N=126.

D. Habs; P. G. Thirolf; M. Gross; K. Allinger; J. Bin; A. Henig; D. Kiefer; W. Ma; J. Schreiber

2010-09-10

341

PV Manufacturing R&D Project Status and Accomplishments under 'In-Line Diagnostics and Intelligent Processing' and 'Yield, Durability and Reliability': Preprint  

SciTech Connect

The PV Manufacturing R&D (PVMR&D) Project conducts cost-shared research and development programs with U.S. PV industry partners. There are currently two active industry partnership activities. ''In-line Diagnostics and Intelligent Processing'', launched in 2002, supports development of new in-line diagnostics and monitoring with real-time feedback for optimal process control and increased yield in the fabrication of PV modules, systems, and other system components. ''Yield, Durability and Reliability'', launched in late 2004, supports enhancement of PV module, system component, and complete system reliability in high-volume manufacturing. A second key undertaking of the PVMR&D Project is the collection and analysis of module production cost-capacity metrics for the U.S. PV industry. In the period from 1992 through 2005, the average module manufacturing cost in 2005 dollars fell 54% (5.7% annualized) to $2.74/Wp, and the capacity increased 18.6-fold (25% annualized) to 253 MW/yr. An experience curve analysis gives progress ratios of 87% and 81%, respectively, for U.S. silicon and thin-film module production.

Friedman, D. J.; Mitchell, R. L.; Keyes, B. M.; Bower, W. I.; King, R.; Mazer, J.

2006-05-01

342

The nucleotide sequence of the intergenic region between the 5.8S and 26S rRNA genes of the yeast ribosomal RNA operon. Possible implications for the interaction between 5.8S and 26S rRNA and the processing of the primary transcript.  

PubMed Central

We have determined the nucleotide sequence of part of a cloned yeast ribosomal RNA operon extending from the 5.8S RNA gene downstream into the 5' -terminal region of the 26S RNA gene. We mapped the pertinent processing sites, viz. the 5' end of 26S rRNA and the 3'ends of 5.8S rRNA and its immediate precursor, 7S RNA. At the 3' end of 7S RNA we find the sequence UCGUUU which is very similar to the type I consensus sequence UCAUUA/U present at the 3' ends of 17S, 5.8S and 26S rRNA as well as 18S precursor rRNA in yeast. At the 5' end of the 26S RNA gene we find a sequence of thirteen nucleotides which is homologous to the type II sequence present at the 5' termini of both the 17S and the 5.8S RNA gene. These findings further support the suggestion put forward earlier (G.M. Veldman et al. (1980) Nucl. Acids Res. 8, 2907-2920) that both consensus sequences are involved in the recognition of precursor rRNA by the processing nuclease(s). We discuss a model for the processing of yeast rRNA in which a processing enzyme sequentially recognizes several combinations of a type I and a type II consensus sequence. We also describe the existence of a significant base complementarity between sequences in the 5' -terminal region of 26S rRNA and the 3' -terminal region of 5.8S rRNA. We suggest that base pairing between these sequences contributes to the binding between 5.8S and 26S rRNA. Images PMID:7312619

Veldman, G M; Klootwijk, J; van Heerikhuizen, H; Planta, R J

1981-01-01

343

A Leu to Ile but not Leu to Val change at HIV-1 reverse transcriptase codon 74 in the background of K65R mutation leads to an increased processivity of K65R+L74I enzyme and a replication competent virus  

PubMed Central

Background The major hurdle in the treatment of Human Immunodeficiency virus type 1 (HIV-1) includes the development of drug resistance-associated mutations in the target regions of the virus. Since reverse transcriptase (RT) is essential for HIV-1 replication, several nucleoside analogues have been developed to target RT of the virus. Clinical studies have shown that mutations at RT codon 65 and 74 which are located in ?3-?4 linkage group of finger sub-domain of RT are selected during treatment with several RT inhibitors, including didanosine, deoxycytidine, abacavir and tenofovir. Interestingly, the co-selection of K65R and L74V is rare in clinical settings. We have previously shown that K65R and L74V are incompatible and a R?K reversion occurs at codon 65 during replication of the virus. Analysis of the HIV resistance database has revealed that similar to K65R+L74V, the double mutant K65R+L74I is also rare. We sought to compare the impact of L?V versus L?I change at codon 74 in the background of K65R mutation, on the replication of doubly mutant viruses. Methods Proviral clones containing K65R, L74V, L74I, K65R+L74V and K65R+L74I RT mutations were created in pNL4-3 backbone and viruses were produced in 293T cells. Replication efficiencies of all the viruses were compared in peripheral blood mononuclear (PBM) cells in the absence of selection pressure. Replication capacity (RC) of mutant viruses in relation to wild type was calculated on the basis of antigen p24 production and RT activity, and paired analysis by student t-test was performed among RCs of doubly mutant viruses. Reversion at RT codons 65 and 74 was monitored during replication in PBM cells. In vitro processivity of mutant RTs was measured to analyze the impact of amino acid changes at RT codon 74. Results Replication kinetics plot showed that all of the mutant viruses were attenuated as compared to wild type (WT) virus. Although attenuated in comparison to WT virus and single point mutants K65R, L74V and L74I; the double mutant K65R+L74I replicated efficiently in comparison to K65R+L74V mutant. The increased replication capacity of K65R+L74I viruses in comparison to K65R+L74V viruses was significant at multiplicity of infection 0.01 (p = 0.0004). Direct sequencing and sequencing after population cloning showed a more pronounced reversion at codon 65 in viruses containing K65R+L74V mutations in comparison to viruses with K65R+L74I mutations. In vitro processivity assays showed increased processivity of RT containing K65R+L74I in comparison to K65R+L74V RT. Conclusions The improved replication kinetics of K65R+L74I virus in comparison to K65R+L74V viruses was due to an increase in the processivity of RT containing K65R+L74I mutations. These observations support the rationale behind structural functional analysis to understand the interactions among unique RT mutations that may emerge during the treatment with specific drug regimens. PMID:21255423

2011-01-01

344

Introducing the fission-fusion reaction process: using a laser-accelerated Th beam to produce neutron-rich nuclei towards the N=126 waiting point of the r-process  

NASA Astrophysics Data System (ADS)

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process (the rapid neutron-capture process) around the waiting point N=126 (Kratz et al. in Prog. Part. Nucl. Phys. 59:147, 2007; Arnould et al. in Phys. Rep. 450:97, 2007; Panov and Janka in Astron. Astrophys. 494:829, 2009) by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a polyethylene layer, CH2), where the light fission fragments of the beam fuse with the light fission fragments of the target. Using the `hole-boring' (HB) mode of laser radiation pressure acceleration (RPA) (Robinson et al. in Plasma Phys. Control. Fusion 51:024004, 2009; Henig et al. in Phys. Rev. Lett. 103:245003, 2009; Tajima et al. in Rev. Accel. Sci. Technol. 2:221, 2009) using a high-intensity, short pulse laser, bunches of 232Th with solid-state density can be generated very efficiently from a Th layer (ca. 560 nm thick), placed beneath a deuterated polyethylene foil (CD2 with ca. 520 nm), both forming the production target. Th ions laser-accelerated to about 7 MeV/u will pass through a thin CH2 layer placed in front of a thicker second Th foil (both forming the reaction target) closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD2 production target will be accelerated as well to about 7 MeV/u, also inducing the fission process of 232Th in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 1014 times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again when the fragments from the thorium beam strike the Th layer of the reaction target. In contrast to classical radioactive beam facilities, where intense but low-density radioactive beams of one ion species are merged with stable targets, the novel fission-fusion process draws on the fusion between neutron-rich, short-lived, light fission fragments from both beam and target. Moreover, the high ion beam density may lead to a strong collective modification of the stopping power in the target by `snowplough-like' removal of target electrons, leading to significant range enhancement, thus allowing us to use rather thick targets. Using a high-intensity laser with two beams with a total energy of 300 J, 32 fs pulse length and 3 ?m focal diameter, as, e.g. envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP) ( http://www.eli-np.ro , 2010), order-of-magnitude estimates promise a fusion yield of about 103 ions per laser pulse in the mass range of A=180-190, thus enabling us to approach the r-process waiting point at N=126. First studies on ion acceleration, collective modifications of the stopping behaviour and the production of neutron-rich nuclei can also be performed at the upcoming new laser facility CALA (Center for Advanced Laser Applications) in Garching.

Habs, D.; Thirolf, P. G.; Gross, M.; Allinger, K.; Bin, J.; Henig, A.; Kiefer, D.; Ma, W.; Schreiber, J.

2011-05-01

345

A precision measurement of the Z{sup 0} lineshape parameters for the process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}}  

SciTech Connect

In this dissertation, a measurement of the partial decay width of the process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}} using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z{sup 0} resonance were determined, and from a fit to those cross sections, the mass of the Z{sup 0}, its total decay width and its partial decay width into {tau}{sup +}{tau}{sup {minus}} final states were determined as M{sub Z} = 91.183 {+-} 0.020 GeV, {Lambda}{sub tot} = 2.514 {+-} 0.018 GeV and {Lambda}{sub {tau}{tau}} = 84.54 {+-} 0.59 MeV. Using published results for M{sub Z}, and {Lambda}{sub tot} with higher accuracy, a value for the partial decay width of {Lambda}{sub {tau}{tau}} = 84.02 {+-} 0.20 MeV was obtained. Further using published results for the decay width of the Z{sup 0} into quark pair final states, the invisible decay width of the Z{sup 0} was determined as {Lambda}{sub inv} = 496.9 {+-} 4.1 MeV, and the number of neutrino generations was determined as N{sub {nu}} = 2.974 {+-} 0.025(exp) {+-} 0.007 (m{sub top}, M{sub Higgs}). All results were found to be in good agreement with the Standard Model predictions and were consistent with the assumption of lepton universality within the Standard Model framework.

Lahmann, R.

1996-12-31

346

Interpretation of Fracture Toughness and R-Curve Behavior by Direct Observation of Microfracture Process in Ti-Based Dendrite-Containing Amorphous Alloys  

NASA Astrophysics Data System (ADS)

Fracture properties of Ti-based amorphous alloys containing ductile ? dendrites were explained by directly observing microfracture processes. Three Ti-based amorphous alloys were fabricated by adding Ti, Zr, V, Ni, Al, and Be into a Ti-6Al-4V alloy by a vacuum arc melting method. The effective sizes of dendrites varied from 63 to 104 ?m, while their volume fractions were almost constant within the range from 74 to 76 pct. The observation of the microfracture of the alloy containing coarse dendrites revealed that a microcrack initiated at the amorphous matrix of the notch tip and propagated along the amorphous matrix. In the alloy containing fine dendrites, the crack propagation was frequently blocked by dendrites, and many deformation bands were formed near or in front of the propagating crack, thereby resulting in a zig-zag fracture path. Crack initiation toughness was almost the same at 35 to 36 MPa?m within error ranges in the three alloys because it was heavily affected by the stress applied to the specimen at the time of crack initiation at the crack tip as well as strength levels of the alloys. According to the R-curve behavior, however, the best overall fracture properties in the alloy containing fine dendrites were explained by mechanisms of blocking of the crack growth and crack blunting and deformation band formation at dendrites.

Jeon, Changwoo; Kim, Choongnyun Paul; Kim, Hyoung Seop; Lee, Sunghak

2015-01-01

347

Interpretation of Fracture Toughness and R-Curve Behavior by Direct Observation of Microfracture Process in Ti-Based Dendrite-Containing Amorphous Alloys  

NASA Astrophysics Data System (ADS)

Fracture properties of Ti-based amorphous alloys containing ductile ? dendrites were explained by directly observing microfracture processes. Three Ti-based amorphous alloys were fabricated by adding Ti, Zr, V, Ni, Al, and Be into a Ti-6Al-4V alloy by a vacuum arc melting method. The effective sizes of dendrites varied from 63 to 104 ?m, while their volume fractions were almost constant within the range from 74 to 76 pct. The observation of the microfracture of the alloy containing coarse dendrites revealed that a microcrack initiated at the amorphous matrix of the notch tip and propagated along the amorphous matrix. In the alloy containing fine dendrites, the crack propagation was frequently blocked by dendrites, and many deformation bands were formed near or in front of the propagating crack, thereby resulting in a zig-zag fracture path. Crack initiation toughness was almost the same at 35 to 36 MPa?m within error ranges in the three alloys because it was heavily affected by the stress applied to the specimen at the time of crack initiation at the crack tip as well as strength levels of the alloys. According to the R-curve behavior, however, the best overall fracture properties in the alloy containing fine dendrites were explained by mechanisms of blocking of the crack growth and crack blunting and deformation band formation at dendrites.

Jeon, Changwoo; Kim, Choongnyun Paul; Kim, Hyoung Seop; Lee, Sunghak

2015-04-01

348

P h y s i c a l O c e a n o g r a p h y D i v i s i o n Intra-American Study of Climate Processes  

E-print Network

.S., Mexico, Caribbean and Central/South American countries over the 2009-2014 time period, IASCLIP aims toP h y s i c a l O c e a n o g r a p h y D i v i s i o n Intra-American Study of Climate Processes David Enfield The Intra-American Study of Climate Processes (IASCLIP) is scheduled to run from 2009

349

P h y s i c a l O c e a n o g r a p h y D i v i s i o n Intra-American Study of Climate Processes  

E-print Network

in the U.S., Mexico, Caribbean and Central/South American countries over the 2009-2014 time period, IASCLIPP h y s i c a l O c e a n o g r a p h y D i v i s i o n Intra-American Study of Climate Processes Chunzai Wang and Sang-Ki Lee The Intra-American Study of Climate Processes (IASCLIP) is scheduled to run

350

Trypanosoma brucei 5'ETS A'-cleavage is directed by 3'-adjacent sequences, but not two U3 snoRNA-binding elements, which are all required for subsequent pre-small subunit rRNA processing events.  

PubMed

Trypanosoma brucei pre-rRNA processing commences by cleavage near the 5' end of 5.8 S sequences. The 5' external transcribed spacer (5'ETS) is removed from pre-small subunit (SSU) rRNAs by sequential cleavages at internal A' and A0 sites, and A1 at the 5' end of SSU rRNA. The A' and A0 sites positionally resemble the U3 small nucleolar RNA-dependent, primary pre-rRNA cleavages of vertebrates and yeast, respectively. Uniquely in T. brucei, two U3-crosslinkable 5'ETS sites are essential for SSU rRNA production: site1b is novel in its 3' location to the A' site, and site3 lies upstream of A0 in a position analogous to the yeast U3-binding site. Here, in vivo analysis of mutated 5'ETS sequences shows that sequences 5' to the A' site are not needed for A' cleavage or SSU rRNA production. A' cleavage is linked to, but is not sufficient to trigger, downstream pre-SSU rRNA processing events. These events require an intact 11 nt sequence, 3'-adjacent to A', which directs efficient and accurate A' cleavage. Neither the A' nearby site1b nor the site3 U3-binding elements affect A' processing, yet each is required for A0 and A1 cleavage, and SSU rRNA production. The same U3 3' hinge bases evidently bind a core element, UGUu/gGGU, within site1a and site3; the U3-site1b interaction is less reliant on base-pairing than the U3-site3 interaction. As yeast U3 5' hinge bases pair to 5'ETS sequences, it is clear that distinct U3 hinge regions can interact at both novel and related 5'ETS sites to promote 3'-proximal 5'ETS processing events in diverse organisms. The T. brucei data fit a model wherein processing factors assemble at the 5'ETS site1a to affect A' cleavage and stabilize a U3-site1b complex, which may work in concert with the downstream U3-site3 complex to assist processing events leading to ribosomal SSU production. PMID:11697900

Hartshorne, T; Toyofuku, W; Hollenbaugh, J

2001-11-01

351

WBSCR22/Merm1 is required for late nuclear pre-ribosomal RNA processing and mediates N7-methylation of G1639 in human 18S rRNA.  

PubMed

Ribosomal (r)RNAs are extensively modified during ribosome synthesis and their modification is required for the fidelity and efficiency of translation. Besides numerous small nucleolar RNA-guided 2'-O methylations and pseudouridinylations, a number of individual RNA methyltransferases are involved in rRNA modification. WBSCR22/Merm1, which is affected in Williams-Beuren syndrome and has been implicated in tumorigenesis and metastasis formation, was recently shown to be involved in ribosome synthesis, but its molecular functions have remained elusive. Here we show that depletion of WBSCR22 leads to nuclear accumulation of 3'-extended 18SE pre-rRNA intermediates resulting in impaired 18S rRNA maturation. We map the 3' ends of the 18SE pre-rRNA intermediates accumulating after depletion of WBSCR22 and in control cells using 3'-RACE and deep sequencing. Furthermore, we demonstrate that WBSCR22 is required for N(7)-methylation of G1639 in human 18S rRNA in vivo. Interestingly, the catalytic activity of WBSCR22 is not required for 18S pre-rRNA processing, suggesting that the key role of WBSCR22 in 40S subunit biogenesis is independent of its function as an RNA methyltransferase. PMID:25525153

Haag, Sara; Kretschmer, Jens; Bohnsack, Markus T

2015-02-01

352

WBSCR22/Merm1 is required for late nuclear pre-ribosomal RNA processing and mediates N7-methylation of G1639 in human 18S rRNA  

PubMed Central

Ribosomal (r)RNAs are extensively modified during ribosome synthesis and their modification is required for the fidelity and efficiency of translation. Besides numerous small nucleolar RNA-guided 2?-O methylations and pseudouridinylations, a number of individual RNA methyltransferases are involved in rRNA modification. WBSCR22/Merm1, which is affected in WilliamsBeuren syndrome and has been implicated in tumorigenesis and metastasis formation, was recently shown to be involved in ribosome synthesis, but its molecular functions have remained elusive. Here we show that depletion of WBSCR22 leads to nuclear accumulation of 3?-extended 18SE pre-rRNA intermediates resulting in impaired 18S rRNA maturation. We map the 3? ends of the 18SE pre-rRNA intermediates accumulating after depletion of WBSCR22 and in control cells using 3?-RACE and deep sequencing. Furthermore, we demonstrate that WBSCR22 is required for N7-methylation of G1639 in human 18S rRNA in vivo. Interestingly, the catalytic activity of WBSCR22 is not required for 18S pre-rRNA processing, suggesting that the key role of WBSCR22 in 40S subunit biogenesis is independent of its function as an RNA methyltransferase. PMID:25525153

Haag, Sara; Kretschmer, Jens

2015-01-01

353

Thomas, A.K., & Millar, P.R. (2011). Reducing the framing effect in older and younger adults by encouraging analytic processing. The Journals of Gerontology, Series B: Psychological Sciences and Social Sciences, 10.1093/geronb/gbr076  

E-print Network

. For example, prospect theory proposes that the framing effect is a result of reference dependence. PeopleThomas, A.K., & Millar, P.R. (2011). Reducing the framing effect in older and younger adults by encouraging analytic processing. The Journals of Gerontology, Series B: Psychological Sciences and Social

Patel, Aniruddh D.

354

R fluids  

E-print Network

A theory of collisionless fluids is developed in a unified picture, where nonrotating figures with anisotropic random velocity component distributions and rotating figures with isotropic random velocity component distributions, make adjoints configurations to the same system. R fluids are defined and mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The definition of figure rotation is extended to R fluids. The generalized tensor virial equations are formulated for R fluids and further attention is devoted to axisymmetric configurations where, for selected coordinate axes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and vice versa. A microscopical analysis of systematic and random motions is performed under a few general hypotheses, by reversing the sign of tangential or axial velocity components of an assigned fraction of particles, leaving the distribution function and other parameters unchanged (Meza 2002). The application of the reversion process to tangential velocity components, implies the conversion of random motion rotation kinetic energy into systematic motion rotation kinetic energy. The application of the reversion process to axial velocity components, implies the conversion of random motion translation kinetic energy into systematic motion translation kinetic energy, and the loss related to a change of reference frame is expressed in terms of systematic (imaginary) motion rotation kinetic energy. A procedure is sketched for deriving the spin parameter distribution (including imaginary rotation) from a sample of observed or simulated large-scale collisionless fluids i.e. galaxies and galaxy clusters.

R. Caimmi

2007-10-20

355

VOLUME 85, NUMBER 23 P H Y S I C A L R E V I E W L E T T E R S 4 DECEMBER 2000 Discretized Diffusion Processes  

E-print Network

in fractal growth processes such as diffusion limited ag- gregation (DLA) [4] and the dielectric breakdown to determine the value of the exponents characterizing the process. We believe that this prototype model systems, such as the Bak-Tang-Wiesenfeld [1] or the Zhang model [2], threshold and discretization play

Caldarelli, Guido

356

A COMPOSITE HOLLOW FIBER MEMBRANE-BASED PERVAPORATION PROCESS FOR SEPARATION OF VOCS FROM AQUEOUS SURFACTANT SOLUTIONS. (R825511C027)  

EPA Science Inventory

The separation and recovery of VOCs from surfactant-containing aqueous solutions by a composite hollow fiber membrane-based pervaporation process has been studied. The process employed hydrophobic microporous polypropylene hollow fibers having a thin plasma polymerized silicon...

357

Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data  

E-print Network

Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log epsilon = 1.61 +/- 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17 3248, CS 22892-052, CS 31082-001, HD 115444 and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of 0.01 dex similar to the Solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process ...

Lawler, J E; Cowan, J J; Ivans, I I; Hartog, E A Den

2009-01-01

358

Parallel Processing Letters, Vol. 18, No. 4 (2008) 453-469 %%&* World Scientific Publishing Company Y I P ^ 0 r l d  

E-print Network

Company Y I P ^ 0 r l d , ^ C i e ^ t i f i c www.worldscientific.com A PERFORMANCE EVALUATION Communicated by Guest Editors ABSTRACT In this work we present an initial performance evaluation of Intel the performance of some applications by up to 50%. Keywords: Performance Analysis, Multi-core, Scientific

2008-01-01

359

Processes Affecting Tropospheric Ozone Inferred from Ozonesonde and Other Tracer Data from the R/V R H Brown Atlantic Cruise (37N-34S) in January-February 1999  

NASA Technical Reports Server (NTRS)

During the Aerosols-99 trans-Atlantic cruise from Norfolk, VA, to Cape Town, South Africa, 22 ozonesondes were launched from the NOAA R/V R H Brown between 17 Jan and 6 Feb 1999, with all sondes but one reaching 30 km. A composite of ozone profiles along the transect shows high free tropospheric ozone (up to 100 ppbv at 9 km) between 5N and 20S, a coherent feature straddling either side of the ITCZ. Latitudinal variations of tropospheric ozone are interpreted using correlative measurements of surface ozone, CO, water vapor, and aerosol optical thickness (column absorbance) measured from the ship. Elevated ozone in the lower troposphere results from photochemical reactions of precursors emitted by biomass burning north of the ITCZ. However, the greatest ozone mixing ratios are in the mid-troposphere south of the ITCZ, which gives evidence of interhemispheric transport. Column-integrated tropospheric ozone, 35 DU from 0-16 km, agrees with that derived from the TOMS satellite by the modified-residual method [Thompson and Hudson, 1999]. NCEP wind fields, ship-launched radiosondes and back trajectories are consistent with a picture of recirculating air parcels centered in the tropical Atlantic region which is identified with the maximum wave-one amplitude in total ozone seen in sondes and by satellite.

Thompson, Anne M.; Doddridge, B. G.; Luke, W. T.; Johnson, J. E.; Witte, J. C.; Reynolds, R. M.; Johnson, B.; Oltmans, S. J.

1999-01-01

360

544 C. R. O'Farrell, A. M. Heimsath and J. M. Kaste Copyright 2006 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms 32, 544560 (2007)  

E-print Network

. Both continuous, low-magnitude processes as well as infrequent, high-magnitude events drive erosion independent, field-based methods to a well-studied catchment in the Marin Headlands of northern California. We-specific erosion rates and use these rates to infer dominant erosion processes across the landscape. When examined

Heimsath, Arjun M.

361

Tracking the interactions of rRNA processing proteins during nucleolar assembly in living Nicole Angelier,* Marc Tramier, Emilie Louvet,* Mat Coppey-Moisan, Tula M. Savino,*  

E-print Network

Reorganization of the nuclear machinery after mitosis is a fundamental but poorly understood process. Here we condense at the beginning of mitosis and re-assembled at the end of mitosis. During mitosis functions after mitosis, we chose to investigate the assembly of the nucleolar processing machinery in real

Paris-Sud XI, Université de

362

S2P3-R (v1.0): a framework for efficient regional modelling of physical and biological structures and processes in shelf seas  

NASA Astrophysics Data System (ADS)

An established 1-dimensional model of Shelf Sea Physics and Primary Production (S2P3) is adapted for regional use in realistic geographical domains over selected years, for selected regions. The S2P3-R framework (v1.0) can be used to efficiently map 3-D physical and biological structures in shelf seas, in particular the tidal mixing fronts that seasonally develop at boundaries between mixed and stratified water. The model has primarily been developed for undergraduate oceanography modules and research projects, providing a practical tool for linking theory and field observations, but it is also useful as an investigative research tool alongside more complex and computationally expensive models. Four different configurations of S2P3-R are described and evaluated, illustrating a range of diagnostics, evaluated where practical with available observations. The model can be forced with daily meteorological variables for any selected year in the reanalysis era (1948 onwards). Example simulations illustrate the considerable extent of synoptic-to-interannual variability in the physics and biology of shelf seas. In discussion, the present limitations of S2P3-R are emphasized, and future model developments are outlined.

Marsh, R.; Hickman, A. E.; Sharples, J.

2015-01-01

363

Mycobacterial RNA isolation optimized for non-coding RNA: high fidelity isolation of 5S rRNA from Mycobacterium bovis BCG reveals novel post-transcriptional processing and a complete spectrum of modified ribonucleosides.  

PubMed

A major challenge in the study of mycobacterial RNA biology is the lack of a comprehensive RNA isolation method that overcomes the unusual cell wall to faithfully yield the full spectrum of non-coding RNA (ncRNA) species. Here, we describe a simple and robust procedure optimized for the isolation of total ncRNA, including 5S, 16S and 23S ribosomal RNA (rRNA) and tRNA, from mycobacteria, using Mycobacterium bovis BCG to illustrate the method. Based on a combination of mechanical disruption and liquid and solid-phase technologies, the method produces all major species of ncRNA in high yield and with high integrity, enabling direct chemical and sequence analysis of the ncRNA species. The reproducibility of the method with BCG was evident in bioanalyzer electrophoretic analysis of isolated RNA, which revealed quantitatively significant differences in the ncRNA profiles of exponentially growing and non-replicating hypoxic bacilli. The method also overcame an historical inconsistency in 5S rRNA isolation, with direct sequencing revealing a novel post-transcriptional processing of 5S rRNA to its functional form and with chemical analysis revealing seven post-transcriptional ribonucleoside modifications in the 5S rRNA. This optimized RNA isolation procedure thus provides a means to more rigorously explore the biology of ncRNA species in mycobacteria. PMID:25539917

Hia, Fabian; Chionh, Yok Hian; Pang, Yan Ling Joy; DeMott, Michael S; McBee, Megan E; Dedon, Peter C

2015-03-11

364

Mycobacterial RNA isolation optimized for non-coding RNA: high fidelity isolation of 5S rRNA from Mycobacterium bovis BCG reveals novel post-transcriptional processing and a complete spectrum of modified ribonucleosides  

PubMed Central

A major challenge in the study of mycobacterial RNA biology is the lack of a comprehensive RNA isolation method that overcomes the unusual cell wall to faithfully yield the full spectrum of non-coding RNA (ncRNA) species. Here, we describe a simple and robust procedure optimized for the isolation of total ncRNA, including 5S, 16S and 23S ribosomal RNA (rRNA) and tRNA, from mycobacteria, using Mycobacterium bovis BCG to illustrate the method. Based on a combination of mechanical disruption and liquid and solid-phase technologies, the method produces all major species of ncRNA in high yield and with high integrity, enabling direct chemical and sequence analysis of the ncRNA species. The reproducibility of the method with BCG was evident in bioanalyzer electrophoretic analysis of isolated RNA, which revealed quantitatively significant differences in the ncRNA profiles of exponentially growing and non-replicating hypoxic bacilli. The method also overcame an historical inconsistency in 5S rRNA isolation, with direct sequencing revealing a novel post-transcriptional processing of 5S rRNA to its functional form and with chemical analysis revealing seven post-transcriptional ribonucleoside modifications in the 5S rRNA. This optimized RNA isolation procedure thus provides a means to more rigorously explore the biology of ncRNA species in mycobacteria. PMID:25539917

Hia, Fabian; Chionh, Yok Hian; Pang, YanLingJoy; DeMott, Michael S.; McBee, Megan E.; Dedon, Peter C.

2015-01-01

365

EVALUATING THE REGIONAL PREDICTIVE CAPACITY OF A PROCESS-BASED MERCURY EXPOSURE MODEL (R-MCM) FOR LAKES ACROSS VERMONT AND NEW HAMPSHIRE, USA  

EPA Science Inventory

Regulatory agencies are confronted with a daunting task of developing fish consumption advisories for a large number of lakes and rivers with little resources. A feasible mechanism to develop region-wide fish advisories is by using a process-based mathematical model. One model of...

366

AN EXPERIMENTAL INVESTIGATION INTO THE EFFECT OF PROCESS CONDITIONS ON THE MASS CONCENTRATION OF CUTTING FLUID MIST IN TURNING. (R825370C057)  

EPA Science Inventory

Cutting fluid mists that are generated during machining processes represent a significant waste stream as well as a health hazard to humans. Epidemiological studies have shown a link between worker exposure to cutting fluid mist and an increase in respiratory ailments and seve...

367

I N V I T E D N E L R E V E I W The neurobiology of pleasure, reward processes, addiction and their health implications  

Microsoft Academic Search

Modern science begins to understand pleasure as a potential component of salu- togenesis. Thereby, pleasure is described as a state or feeling of happiness and satisfaction resulting from an experience that one enjoys. We examine the neuro- biological factors underlying reward processes and pleasure phenomena. Further, health implications related to pleasurable activities are analyzed. With regard to possible negative effects

Tobias Esch; George B. Stefano

368

Effects of Low Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Gamma Frequency Oscillations and Event-Related Potentials during Processing of Illusory Figures in Autism  

ERIC Educational Resources Information Center

Previous studies by our group suggest that the neuropathology of autism is characterized by a disturbance of cortical modularity. In this model a decrease in the peripheral neuropil space of affected minicolumns provides for an inhibitory deficit and a readjustment in their signal to noise bias during information processing. In this study we

Sokhadze, Estate M.; El-Baz, Ayman; Baruth, Joshua; Mathai, Grace; Sears, Lonnie; Casanova, Manuel F.

2009-01-01

369

Process for functionalizing alkanes  

DOEpatents

Process for functionalizing saturated hydrocarbons comprises: (a) reacting said saturated hydrocarbons of the formula: R[sub 1]H wherein H represents a hydrogen atom; and R[sub 1] represents a saturated hydrocarbon radical, with a metal complex of the formula: CpRh[P(R[sub 2])[sub 3

Bergman, R.G.; Janowicz, A.H.; Periana, R.A.

1988-05-24

370

Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Affects Event-Related Potential Measures of Novelty Processing in Autism  

Microsoft Academic Search

In our previous study on individuals with autism spectrum disorder (ASD) (Sokhadze et al., Appl Psychophysiol Biofeedback\\u000a 34:3751, 2009a) we reported abnormalities in the attention-orienting frontal event-related potentials (ERP) and the sustained-attention\\u000a centro-parietal ERPs in a visual oddball experiment. These results suggest that individuals with autism over-process information\\u000a needed for the successful differentiation of target and novel stimuli. In the

Estate Sokhadze; Joshua Baruth; Allan Tasman; Mehreen Mansoor; Rajesh Ramaswamy; Lonnie Sears; Grace Mathai; Ayman El-Baz; Manuel F. Casanova

2010-01-01

371

Product Innovation, Process Innovation, and Size  

Microsoft Academic Search

We test the hypothesis that large firms devote a higher proportion of their research and development (R & D) expenditure on process innovation thansmaller firms. According to the estimates, process- and product R & D expenditure rise less than in proportion to size. The size effect is somewhat stronger for process R & D but the difference to product R

Michael Fritsch; Monika Meschede

2001-01-01

372

Simulation of self-organization processes in crystal-forming systems: Supramolecular cyclic R6 cluster precursors and self-assembly of TeO2- TEL ( Tellurite) and TeO2- PAR ( Paratellurite) structures  

NASA Astrophysics Data System (ADS)

The supramolecular chemistry of oxides of sp elements (SO2, SeO2, and TeO2) is considered. The self-assembly of TeO2- TEL ( Tellurite) and TeO2- PAR ( Paratellurite) crystal structures is simulated. Methods of combinatorial and topological analysis (TOPOS program package) are applied which are based on constructing a basis 3D network of the structure in the form of a graph, the sites of which correspond to the positions of centroids of TeO2 molecules and the edges characterize bonds between them. The topological type of the basis 2D network in the TeO2- TEL structure corresponds to graphite (C- GRA), while in the TeO2- PAR structure the basis network corresponds to the 3D diamond network (C- DIA). A nanocluster precursor of cyclic type ( R6) composed of six covalently bound TeO2 molecules (chair conformation) is established for both structures. The desymmetrization of the cyclic structure of the R6 cluster in TeO2- PAR is related to the formation of Te-Te bonds with lengths of 3.824 and 4.062 . The symmetry and topology code of the processes of self-assembly of 3D structures from nanocluster precursors is completely reconstructed into the form "primary chain ? microlayer ? microframework." In both structures R6 clusters form 2D packings with a coordination number of 6. The cluster self-assembly model explains the specific features of the morphogenesis of TeO2- TEL and TeO2- PAR (phases with low and high crystallization temperatures, respectively): platelike shape, perfect cleavage in the (110) plane, and preferred growth in the primar-chain direction [100] in the former case and growth in the direction of the primary [001] axis with the preferred formation of tetragonal prism faces (110) in the latter case.

Ilyushin, G. D.

2014-11-01

373

Cardiac R-wave detector  

NASA Technical Reports Server (NTRS)

Cardiac R wave detector obtains the systolic contraction signal of the human heart and uses it as a reference signal for the heart-assist pump cycle. It processes the electrocardiac signal /QRS wave complex/ of the natural heart in a sequence of operations which essentially elimates all components from the input signal except the R wave.

Gebben, V. D.

1968-01-01

374

Curriculum Vitae Howard R. Turtle  

E-print Network

Curriculum Vitae Howard R. Turtle Center for Natural Language Processing Syracuse University · Xiaozhong Liu and Howard Turtle. Real-time User Interest for Real-time Ranking. Journal of the American, and Howard R. Turtle. PIC Matices: a Compu- tationally Tractable Class of Probabilistic Query Operators, ACM

Crowston, Kevin

375

Control technology assessment for coal gasification and liquefaction processes, Rockwell International 3/4 tpd cs/r Hydrogasification Integrated Process Development Unit, Santa Susana, California. Report for the site visit of September 1981. Final report  

SciTech Connect

A control technology survey was conducted at Rockwell International (SIC-1211), Canoga Park, California in September, 1981 to study control technologies currently in use for preventing occupational exposures to hazardous agents in coal conversion facilities. The Integrated Process Development Unit (IPDU), which was under construction, was surveyed. The site was built into the side of a canyon. Blowout barriers extended on two sides to channel plumes or explosions away from the site to a controlled area. Work practice guidelines were planned to supplement engineering controls. Health and safety guidelines were also planned as part of the operations manual, along with employee training sessions prior to test runs. Management review, certification programs, and controlled access were part of the projected administrative controls. Participation in a medical surveillance program was required for all workers, including complete work and medical histories, and complete annual physicals. Personal protective clothing and equipment were provided as needed, depending on the system and type of hazard involved. The author concludes that the company's industrial hygiene staff is working to develop provisions for a health and safety program for the IPDU and is evaluating hazards based on prior program experience and literature review.

Telesca, D.R.

1982-04-01

376

Effect of Processing on Synthesis and Dielectric Properties of Lead free (Bi0.98R0.02)0.5Na0.5TiO3 Ceramics  

NASA Astrophysics Data System (ADS)

In the present work, an effort has been made to synthesize (Bi1-xRx)0.5Na0.5TiO3 (BRNT) system with compositions x = 0 & 0.02, where R = La, Nd and Gd by Semi-Wet Technique. Processing of the composition with x = 0 has been optimized by two precursor solution one by citric acid and other by ethylene glycol. The XRD patterns of these samples, prepared by ethylene glycol precursor solution, have shown pure phase of perovskite structure with a rhombohedral symmetry. The studies on structure, phase transitions and dielectric properties for all the samples have been carried out over the temperature range from RT to 450 C at 100 kHz frequency. It has been observed that two phase transitions (i) ferroelectric to anti-ferroelectric and (ii) anti ferroelectric to paraelectric occur in all the samples. All samples exhibit a modified Curie-Weiss law above Tc. A linear fitting of the modified Curie- Weiss law to the experimental data shows diffuse type transition. The dielectric properties of BNT ceramics have been found to be improved with the substitution of rare earth elements.

Pal, Vijayeta; Dwivedi, R. K.

2015-02-01

377

Intrusive [r] and Optimal Epenthetic Consonants  

ERIC Educational Resources Information Center

This paper argues against the view of intrusive [r] as a synchronically arbitrary insertion process. Instead, it is seen as a phonologically natural process, which can be modelled within the framework of Optimality Theory (OT). Insertion of [r] in phonologically restricted environments is a consequence of a more general theory of consonant

Uffmann, Christian

2007-01-01

378

e n g e n i o u s w i n t e r 2 0 0 3 1 A transistor in a given process technology is usually characterized by its unity-gain frequency shown as fT . This is the frequency at which the cur-  

E-print Network

e n g e n i o u s w i n t e r 2 0 0 3 1 A transistor in a given process technology is usually ratio of the output current to input current) of a transistor drops to unity. While the unity-gain frequency of a transistor provides an approximate measure to compare transistors in different technologies

379

FINAL REPORT DETERMINATION OF THE PROCESSING RATE OF RPP WTP HLW SIMULANTS USING A DURAMELTER J 1000 VITRIFICATION SYSTEM VSL-00R2590-2 REV 0 8/21/00  

SciTech Connect

This report provides data, analysis, and conclusions from a series of tests that were conducted at the Vitreous State Laboratory of The Catholic University of America (VSL) to determine the melter processing rates that are achievable with RPP-WTP HLW simulants. The principal findings were presented earlier in a summary report (VSL-00R2S90-l) but the present report provides additional details. One of the most critical pieces of information in determining the required size of the RPP-WTP HLW melter is the specific glass production rate in terms of the mass of glass that can be produced per unit area of melt surface per unit time. The specific glass production rate together with the waste loading (essentially, the ratio of waste-in to glass-out, which is determined from glass formulation activities) determines the melt area that is needed to achieve a given waste processing rate with due allowance for system availability. As a consequence of the limited amount of relevant information, there exists, for good reasons, a significant disparity between design-base specific glass production rates for the RPP-WTP LAW and HLW conceptual designs (1.0 MT/m{sup 2}/d and 0.4 MT/m{sup 2}/d, respectively); furthermore, small-scale melter tests with HLW simulants that were conducted during Part A indicated typical processing rates with bubbling of around 2.0 MT/m{sup 2}/d. This range translates into more than a factor of five variation in the resultant surface area of the HLW melter, which is clearly not without significant consequence. It is clear that an undersized melter is undesirable in that it will not be able to support the required waste processing rates. It is less obvious that there are potential disadvantages associated with an oversized melter, over and above the increased capital costs. A melt surface that is consistently underutilized will have poor cold cap coverage, which will result in increased volatilization from the melt (which is generally undesirable) and increased plenum temperatures due to increased thermal radiation from the melt surface (which mayor may not be desirable but the flexibility to choose may be lost). Increased volatilization is an issue both in terms of the increased challenge to the off-gas system as well as for the ability to effectively close the recycle loops for volatile species that must be immobilized in the glass product, most notably technetium and cesium. For these reasons, improved information is needed on the specific glass production rates of RPP-WTP HLW streams in DuraMelterJ systems over a range of operating conditions. Unlike the RPP-WTP LAW program, for which a pilot melter system to provide large-scale throughout information is already in operation, there is no comparable HLW activity; the results of the present study are therefore especially important. This information will reduce project risk by reducing the uncertainty associated with the amount of conservatism that mayor may not be associated with the baseline RPP-WTP HLW melter sizing decision. After the submission of the first Test Plan for this work, the RPP-WTP requested revisions to include tests to determine the processing rates that are achievable without bubbling, which was driven by the potential advantages of omitting bubblers from the HLW melter design in terms of reduced maintenance. A further objective of this effort became the determination of whether the basis of design processing rate could be achieved without bubbling. Ideally, processing rate tests would be conducted on a full-scale RPP-WTP melter system with actual HLW materials, but that is clearly unrealistic during Part B1. As a practical compromise the processing rate determinations were made with HL W simulants on a DuraMelter J system at as close to full scale as possible and the DM 1000 system at VSL was selected for that purpose. That system has a melt surface area of 1.2 m{sup 2}, which corresponds to about one-third scale based on the specific glass processing rate of 0.4 MT/m{sup 2}/d assumed in the RPP-WTP HLW conceptual design, but would correspon

KRUGER AA; MATLACK KS; KOT WK; PEREZ-CARDENAS F; PEGG IL

2011-12-29

380

R u t c o r R e p o r t  

E-print Network

; 21. A known result is that 9 #20; f(1; 2) #20; 2F (F (9)) + 1, where F (r) = r!(r) r is the Erd!(r) r is the Erdos- Rado function (Erdos and Rado [1]). We note that 2F (F (9))+1 #21; 2(10 14 )!(10

381

Parallel Processing here at the School of Statistics  

E-print Network

the unix fork command and runs it independently of the main R process. Call the main R process the "parent" process and the forked copies the "child" processes (unix terminology). The parent process keeps going when a child process is forked, eventually spawning nsplit child processes running in parallel. When

Jiang, Tiefeng

382

L E T T E R S miR-34 miRNAs provide a barrier for somatic cell  

E-print Network

L E T T E R S miR-34 miRNAs provide a barrier for somatic cell reprogramming Yong Jin Choi1 regulate this process. Here, we demonstrate that miR-34 microRNAs (miRNAs), particularly miR-34a, exhibit p53-dependent induction during reprogramming. Mir34a deficiency in mice significantly increased

He, Lin

383

Oceanography Vol. 19, No. 1, Mar. 200692 BY PI E R R E F. J . L E R MU S I AU X ,  

E-print Network

Oceanography Vol. 19, No. 1, Mar. 200692 BY PI E R R E F. J . L E R MU S I AU X , C H I N G S A N G U M DA R , A L E X PA N G , A N D F R A N CO I S L E K I E N Oceanography Vol. 19, No. 1, Mar Uncertainties #12;Oceanography Vol. 19, No. 1, Mar. 2006 93 A multitude of physical and biological processes

Leonard, John J.

384

1,2-dichlorohexafluoro-cyclobutane (1,2-c-C4F6Cl2, R-316c) a Potent Ozone Depleting Substance and Greenhouse Gas: Atmospheric Loss Processes, Lifetimes, and Ozone Depletion and Global Warming Potentials for the (E)- and (Z)- Stereoisomers  

NASA Astrophysics Data System (ADS)

1,2-dichlorohexafluoro-cyclobutane (1,2-c-C4F6Cl2, R-316c) is currently used in medical applications, as inhaled non-immobilizer amnesiac, in limited quantities and has recently been considered as a potential chlorofluoro/hydrofluoro-carbon replacement compound. R-316c usage is not restricted under the Montreal Protocol, although, R-316c represents a potent ozone depleting substance and greenhouse gas. In this work, a combination of laboratory studies of infrared absorption spectra, kinetic, and photolysis processes were performed for the (E)- and (Z)- stereoisomers of R-316c to enable an evaluation of their atmospheric lifetimes, ozone depletion (ODPs) and global warming potentials (GWPs). More specifically, O(1D), OH, and O3 reaction rate coefficients, as well as UV absorption spectra, including temperature dependence, and photolysis quantum yields and stable photolysis end-products were determined. The results from these studies will be presented. R-316c lifetimes and ODPs were evaluated using a 2-D atmospheric chemical model. Both isomers of R-316c were shown to be long-lived substances, primarily removed in the stratosphere by UV photolysis, with large ODPs, >0.3. A line-by-line radiative transfer model was used to calculate radiative efficiencies and, thus, GWPs. The GWPs for both isomers are substantial, ~5000 on the 100-year time horizon. In this presentation, we highlight the need for a thorough evaluation of the atmospheric processing of proposed replacement substances prior to usage and their inevitable emission into the atmosphere. The results of such studies enable policy makers to make informed decisions.

Papadimitriou, V. C.; McGillen, M. R.; Smith, S. C.; Jubb, A. M.; Portmann, R. W.; Hall, B. D.; Fleming, E. L.; Jackman, C. H.; Burkholder, J. B.

2013-12-01

385

Topics in genomic image processing  

E-print Network

: Electrical Engineering TOPICS IN GENOMIC IMAGE PROCESSING A Dissertation by JIANPING HUA Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved as to style and content by: Zixiang Xiong... Image Processing. (December 2004) Jianping Hua, B.E., Tsinghua University, P.R. China; M.S., Tsinghua University, P.R. China Chair of Advisory Committee: Dr. Zixiang Xiong The image processing methodologies that have been actively studied and developed...

Hua, Jianping

2006-04-12

386

1,2-Dichlorohexafluoro-cyclobutane (1,2-c-C4F6Cl2, R-316c) a potent ozone depleting substance and greenhouse gas: atmospheric loss processes, lifetimes, and ozone depletion and global warming potentials for the (E) and (Z) stereoisomers.  

PubMed

The atmospheric processing of (E)- and (Z)-1,2-dichlorohexafluoro-cyclobutane (1,2-c-C4F6Cl2, R-316c) was examined in this work as the ozone depleting (ODP) and global warming (GWP) potentials of this proposed replacement compound are presently unknown. The predominant atmospheric loss processes and infrared absorption spectra of the R-316c isomers were measured to provide a basis to evaluate their atmospheric lifetimes and, thus, ODPs and GWPs. UV absorption spectra were measured between 184.95 to 230 nm at temperatures between 214 and 296 K and a parametrization for use in atmospheric modeling is presented. The Cl atom quantum yield in the 193 nm photolysis of R-316c was measured to be 1.90 0.27. Hexafluorocyclobutene (c-C4F6) was determined to be a photolysis co-product with molar yields of 0.7 and 1.0 (10%) for (E)- and (Z)-R-316c, respectively. The 296 K total rate coefficient for the O((1)D) + R-316c reaction, i.e., O((1)D) loss, was measured to be (1.56 0.11) 10(-10) cm(3) molecule(-1) s(-1) and the reactive rate coefficient, i.e., R-316c loss, was measured to be (1.36 0.20) 10(-10) cm(3) molecule(-1) s(-1) corresponding to a ~88% reactive yield. Rate coefficient upper-limits for the OH and O3 reaction with R-316c were determined to be <2.3 10(-17) and <2.0 10(-22) cm(3) molecule(-1) s(-1), respectively, at 296 K. The quoted uncertainty limits are 2? and include estimated systematic errors. Local and global annually averaged lifetimes for the (E)- and (Z)-R-316c isomers were calculated using a 2-D atmospheric model to be 74.6 3 and 114.1 10 years, respectively, where the estimated uncertainties are due solely to the uncertainty in the UV absorption spectra. Stratospheric photolysis is the predominant atmospheric loss process for both isomers with the O((1)D) reaction making a minor, ~2% for the (E) isomer and 7% for the (Z) isomer, contribution to the total atmospheric loss. Ozone depletion potentials for (E)- and (Z)-R-316c were calculated using the 2-D model to be 0.46 and 0.54, respectively. Infrared absorption spectra for (E)- and (Z)-R-316c were measured at 296 K and used to estimate their radiative efficiencies (REs) and GWPs; 100-year time-horizon GWPs of 4160 and 5400 were obtained for (E)- and (Z)-R-316c, respectively. Both isomers of R-316c are shown in this work to be long-lived ozone depleting substances and potent greenhouse gases. PMID:24079521

Papadimitriou, Vassileios C; McGillen, Max R; Smith, Shona C; Jubb, Aaron M; Portmann, Robert W; Hall, Bradley D; Fleming, Eric L; Jackman, Charles H; Burkholder, James B

2013-10-31

387

1,2-Dichlorohexafluoro-Cyclobutane (1,2-c-C4F6Cl2, R-316c) a Potent Ozone Depleting Substance and Greenhouse Gas: Atmospheric Loss Processes, Lifetimes, and Ozone Depletion and Global Warming Potentials for the (E) and (Z) stereoisomers  

NASA Technical Reports Server (NTRS)

The atmospheric processing of (E)- and (Z)-1,2-dichlorohexafluorocyclobutane (1,2-c-C4F6Cl2, R-316c) was examined in this work as the ozone depleting (ODP) and global warming (GWP) potentials of this proposed replacement compound are presently unknown. The predominant atmospheric loss processes and infrared absorption spectra of the R-316c isomers were measured to provide a basis to evaluate their atmospheric lifetimes and, thus, ODPs and GWPs. UV absorption spectra were measured between 184.95 to 230 nm at temperatures between 214 and 296 K and a parametrization for use in atmospheric modeling is presented. The Cl atom quantum yield in the 193 nm photolysis of R- 316c was measured to be 1.90 +/- 0.27. Hexafluorocyclobutene (c-C4F6) was determined to be a photolysis co-product with molar yields of 0.7 and 1.0 (+/-10%) for (E)- and (Z)-R-316c, respectively. The 296 K total rate coefficient for the O(1D) + R-316c reaction, i.e., O(1D) loss, was measured to be (1.56 +/- 0.11) 10(exp -10)cu cm/ molecule/s and the reactive rate coefficient, i.e., R-316c loss, was measured to be (1.36 +/- 0.20) 10(exp -10)cu cm/molecule/s corresponding to a approx. 88% reactive yield. Rate coefficient upper-limits for the OH and O3 reaction with R-316c were determined to be <2.3 10(exp -17) and <2.0 10(exp -22)cu cm/molecule/s, respectively, at 296 K. The quoted uncertainty limits are 2(sigma) and include estimated systematic errors. Local and global annually averaged lifetimes for the (E)- and (Z)-R-316c isomers were calculated using a 2-D atmospheric model to be 74.6 +/- 3 and 114.1 +/-10 years, respectively, where the estimated uncertainties are due solely to the uncertainty in the UV absorption spectra. Stratospheric photolysis is the predominant atmospheric loss process for both isomers with the O(1D) reaction making a minor, approx. 2% for the (E) isomer and 7% for the (Z) isomer, contribution to the total atmospheric loss. Ozone depletion potentials for (E)- and (Z)-R-316c were calculated using the 2-D model to be 0.46 and 0.54, respectively. Infrared absorption spectra for (E)- and (Z)-R-316c were measured at 296 K and used to estimate their radiative efficiencies (REs) and GWPs; 100-year time-horizon GWPs of 4160 and 5400 were obtained for (E)- and (Z)-R-316c, respectively. Both isomers of R-316c are shown in this work to be long-lived ozone depleting substances and potent greenhouse gases.

Papadimitriou, Vassileios C.; McGillen, Max R.; Smith, Shona C.; Jubb, Aaron M.; Portmann, Robert W.; Hall, Bradley D.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

2013-01-01

388

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar The Ballot Theorem and the Reflection Principle Rating receives b votes, where a kb for some positive integer k. The number of ways the ballots can be ordered so

Dunbar, Steve

389

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar Local Limit Theorems Rating Mathematicians Only=1 Xi is a binomial random variable indicating the number of successes in a com- posite experiment. 3

Dunbar, Steve

390

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar Smoothed Analysis of Linear Optimization Rating, the number of bits of precision required to achieve a given output accuracy, the number of cache misses

Dunbar, Steve

391

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar Binomial Distribution Rating Mathematically Mature: may Sn counts the number of successes in a sequence of n trials of an experiment. 2. A binomial random

Dunbar, Steve

392

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar Worst Case and Average Case Behavior of the Simplex that take an exponential number of pivots with the maximum improvement entering criterion as well. According

Dunbar, Steve

393

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar The Moderate Deviations Result Rating Mathematicians with probability p or 1 - p respectively. Then Sn = n k=1 Xi is a binomial random variable indicating the number

Dunbar, Steve

394

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar Positive Walks Rating Mathematicians Only: prolonged (0, a) and endpoint (n, b) crossing the x-axis (call these paths of the first type) equals the number

Dunbar, Steve

395

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln Theory and Stochastic Processes Steven R. Dunbar The Hitting Time Theorem Rating Mathematicians Only. By dividing by the total number of ballot permutations in the counting of the specialized ballot theorem

Dunbar, Steve

396

Steven R. Dunbar Department of Mathematics  

E-print Network

Steven R. Dunbar Department of Mathematics 203 Avery Hall University of Nebraska-Lincoln Lincoln number of visits to an intermediate level in the random process. 4. Using the expected number of visits

Dunbar, Steve

397

Arsenite evokes IL-6 secretion, autocrine regulation of STAT3 signaling, and miR-21 expression, processes involved in the EMT and malignant transformation of human bronchial epithelial cells  

SciTech Connect

Arsenite is an established human carcinogen, and arsenite-induced inflammation contributes to malignant transformation of cells, but the molecular mechanisms by which cancers are produced remain to be established. The present results showed that, evoked by arsenite, secretion of interleukin-6 (IL-6), a pro-inflammatory cytokine, led to the activation of STAT3, a transcription activator, and to increased levels of a microRNA, miR-21. Blocking IL-6 with anti-IL-6 antibody and inhibiting STAT3 activation reduced miR-21 expression. For human bronchial epithelial cells, cultured in the presence of anti-IL-6 antibody for 3 days, the arsenite-induced EMT and malignant transformation were reversed. Thus, IL-6, acting on STAT3 signaling, which up-regulates miR-21in an autocrine manner, contributes to the EMT induced by arsenite. These data define a link from inflammation to EMT in the arsenite-induced malignant transformation of HBE cells. This link, mediated through miRNAs, establishes a mechanism for arsenite-induced lung carcinogenesis. - Highlights: Arsenite evokes IL-6 secretion. IL-6 autocrine mediates STAT3 signaling and up-regulates miR-21expression. Inflammation is involved in arsenite-induced EMT.

Luo, Fei; Xu, Yuan [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Ling, Min [Jiangsu Center for Disease Control and Prevention, Nanjing 211166, Jiangsu (China); Zhao, Yue; Xu, Wenchao [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Liang, Xiao [Mental Health Center of Xuhui-CDC, Shanghai 200232 (China); Jiang, Rongrong; Wang, Bairu [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); Bian, Qian [Jiangsu Center for Disease Control and Prevention, Nanjing 211166, Jiangsu (China); Liu, Qizhan, E-mail: drqzliu@hotmail.com [Institute of Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China); The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University (China)

2013-11-15

398

B.G. Thomas, R. O'Malley, et.al., MCWASP IX, Shaker Verlag, GmbH, Aachen, Germany, 2000, pp. 769-776. Modeling of Casting, Welding and Advanced Solidification Processes IX  

E-print Network

B.G. Thomas, R. O'Malley, et.al., MCWASP IX, Shaker Verlag, GmbH, Aachen, Germany, 2000, pp. 769. Hansen and James G. Conley (Proceedings of Conference held August 20-25, 2000, Aachen) Shaker Verlag GmbH, Aachen, Germany, 2000, pp. 769-776. Validation of Fluid Flow and Solidification Simulation

Thomas, Brian G.

399

D. R. Morrell and Y. Xue, "Bayesian Analysis of Target Localization using a Dual-Mode Sensor," Proceedings of the 2002 International Conference on Acoustics, Speech, and Signal Processing, May 2002, pp. 15931596.  

E-print Network

D. R. Morrell and Y. Xue, "Bayesian Analysis of Target Localization using a Dual-Mode Sensor. In this problem, a target (if present) is located in one of M cells. A dual-mode sensor repeat- edly interrogates for a dual-mode sensor in a simple target detection and localization problem. We attempt to find

Morrell, Darryl

400

R E S E A R C H A R T I C L E Links between methane uxand transcriptional activities of  

E-print Network

and microbial functional activity was investigated by analysis of the transcriptional dynamics of the keyR E S E A R C H A R T I C L E Links between methane £uxand transcriptional activities oxidation; gene : transcript ratio. Abstract The relationship between biogeochemical process rates

Saleska, Scott

401

R E S E A R C H A R T I C L E Ecosystem Changes Following Restoration of a  

E-print Network

ecosystem processes in ways that either increase C storage (e.g. high productivity, recalcitrant litterR E S E A R C H A R T I C L E Ecosystem Changes Following Restoration of a Buckthorn in plant-community composition following habitat degradation and species invasions can alter ecosystem

Fant, Jeremie

402

Evaluation of Z-(R,R)-IQNP for the potential imaging of m2 mAChR rich regions of the brain and heart.  

PubMed

Alterations in the function or density of the m2 muscarinic (mAChR) subtype have been postulated to play an important role in various dementias such as Alzheimer's disease. The ability to image and quantify the m2 mAChR subtype is of importance for a better understanding of the m2 subtype function in various dementias. Z-(R)-1-Azabicyclo[2.2.2]oct-3-y (R)-alpha-hydroxy-alpha-(1-iodo-1-propen-3-yl)-alpha-phenylacetate (Z-(R,R)-IQNP) has demonstrated significant uptake in cerebral regions that contain a high concentration of m2 mAChR subtype in addition to heart tissue. The present study was undertaken to determine if the uptake of Z-(R,R)-IQNP in these regions is a receptor mediated process and to identify the radiospecies responsible for binding at the receptor site. A blocking study demonstrated cerebral and cardiac levels of activity were significantly reduced by pretreatment (2-3 mg/kg) of (R)-3-quinuclidinyl benzilate, dexetimide and scopolamine, established muscarinic antagonists. A direct comparison of the cerebral and cardiac uptake of [I-125]-Z-(R,R)-IQNP and [I-131]-E-(R,R)-IQNP (high uptake in ml, m4 rich mAChR cerebral regions) demonstrated Z-(R,R)-IQNP localized to a higher degree in cerebral and cardiac regions containing a high concentration of the m2 mAChR subtype as directly compared to E-(R,R)-IQNP. In addition, a study utilizing [I-123]-Z-(R,R)-IQNP, [I-131]-iododexetimide and [I-125]-R-3-quinuclidinyl S-4-iodobenzilate, Z-(R,R)-IQNP demonstrated significantly higher uptake and longer residence time in those regions which contain a high concentration of the m2 receptor subtype. Folch extraction of global brain and heart tissue at various times post injection of [I-125]-Z-(R,R)-IQNP demonstrated that approximately 80% of the activity was extracted in the lipid soluble fraction and identified as the parent ligand by TLC and HPLC analysis. These results demonstrate Z-(R,R)-IQNP has significant uptake, long residence time and high stability in cerebral and cardiac tissues containing high levels of the m2 mAChR subtype. These combined results strongly suggest that Z-(R,R)-IQNP is an attractive ligand for the in vivo imaging and evaluation of m2 rich cerebral and cardiac regions by SPECT. PMID:10714889

McPherson, D W; Greenbaum, M; Luo, H; Beets, A L; Knapp, F F

2000-01-01

403

R u t c o r R e p o r t  

E-print Network

R u t c o r Research R e p o r t RUTCOR Rutgers Center for Operations Research Rutgers University for Operations Research, Rutgers Univer- sity, 640 Bartholomew Rd, Piscataway, NJ 08854-8003, U.S.A.; e-mail: igor@rutcor.rutgers.edu b ASA Institute of Technology, 151 Lawrence Street, Brooklyn, NY 11201 U

404

2007 R&D 100 Award Entry Form 2007 R&D 100 Award Entry Form  

E-print Network

.W.Stromberg@lmco.com Self-Assembling Process for Fabricating Tailored Thin Films This simple,economical nanotechnology unattainable by any other processing method. Product Name Brief Product Description Joint Entry #12;2007 R@sandia.gov Co-Developers D.Bruce Burckel Sandia National Laboratories Ceramic Processing and Inorganic Materials

405

Processing of preribosomal RNA in Saccharomyces cerevisiae.  

PubMed

Most, if not all RNAs, are transcribed as precursors that require processing to gain functionality. Ribosomal RNAs (rRNA) from all organisms undergo both exo- and endonucleolytic processing. Also, in all organisms, rRNA processing occurs inside large preribosomal particles and is coupled to nucleotide modification, folding of the precursor rRNA (pre-rRNA), and assembly of the ribosomal proteins (r-proteins). In this review, we focus on the processing pathway of pre-rRNAs of cytoplasmic ribosomes in the yeast Saccharomyces cerevisiae, without doubt, the organism where this pathway is best characterized. We summarize the current understanding of the rRNA maturation process, particularly focusing on the pre-rRNA processing sites, the enzymes responsible for the cleavage or trimming reactions and the different mechanisms that monitor and regulate the pathway. Strikingly, the overall order of the various processing steps is reasonably well conserved in eukaryotes, perhaps reflecting common principles for orchestrating the concomitant events of pre-rRNA processing and ribosome assembly. PMID:25327757

Fernndez-Pevida, Antonio; Kressler, Dieter; de la Cruz, Jess

2015-01-01

406

Learning and Memory Eric R. Kandel  

E-print Network

/psychological approaches. In the next chapter we shall examine learning and memory processes at the cellular and molecularBack 62 Learning and Memory Eric R. Kandel Irving Kupfermann Susan Iversen BEHAVIOR IS THE RESULT the environment alters behavior are learning and memory. Learning is the process by which we acquire knowledge

Ulanovsky, Nachum

407

An R Package Conculsions/Future  

E-print Network

Processes #12;Motivation Methods An R Package Examples Conculsions/Future Primary Biliary Cirrhosis in Newcastle-Upon-Tyne Primary Biliary Cirrhosis in Newcastle-Upon-Tyne (Aggregated) Gastrointestinal Disease Surveillance Bovine Tuberculosis in Cornwall Spatial Point Process Data · Primary biliary cirrhosis

Diggle, Peter J.

408

UneCLIPsing HuR nuclear function.  

PubMed

The RNA-binding protein HuR, while known to stabilize cytoplasmic mRNAs, is largely nuclear. In this issue of Molecular Cell, Mukherjee et al. (2011) and Lebedeva et al. (2011) identify transcriptome-wide HuR-RNA interactions using PAR-CLIP, unveiling HuR's nuclear role in pre-mRNA processing. PMID:21816340

Srikantan, Subramanya; Gorospe, Myriam

2011-08-01

409

Unconscious Priming According to Multiple S-R Rules  

ERIC Educational Resources Information Center

The present study investigated if unconscious primes can be processed according to different stimulus-response (S-R) rules simultaneously. Participants performed two different S-R rules, such as judging a digit as smaller or larger than five and judging a letter as vowel or consonant. These S-R rules were administered in random order and announced

Kiesel, Andrea; Kunde, Wilfried; Hoffmann, Joachim

2007-01-01

410

Hydrocarbon Processing`s gas processes `96  

SciTech Connect

This review summarizes 71 processes, describing the process, its application, products, operating conditions, economics, installations, and licensor. Processes include desulfurization, CO{sub 2} removal, sulfur recovery, NGL recovery, deoxygenation, hydrogen production and separation, cryogenic separation of hydrocarbon fractions, dehydration, liquefaction of natural gas, LPG recovery, denitrogenation, and synthesis gas production. While most processes apply to natural gas, some are also useful for refinery gas, synthesis gas, coal mine gas, and tail gas from other processes.

NONE

1996-04-01

411

Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD  

E-print Network

1 1 Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting Jun downregulates miR-155 through miR-663 Key words: Inflammation; miR-155; monocytes; resveratrol; THP-1 cells hal related to an obvious inflammatory process. Several microRNAs, and especially miR-155, play an essential

Paris-Sud XI, Université de

412

R u t c o r R e p o r t  

E-print Network

R u t c o r Research R e p o r t RUTCOR Rutgers Center for Operations Research Rutgers University a maximum stable set. We extend this class. #12; RRR 332001 Page 1 For a graph G = (V; E) and a vertex u 2 V , we denote by N(u) the neighborhood of u (i.e., the set of all vertices in G that adjacent to u

413

R u t c o r R e p o r t  

E-print Network

sets in R d . Let us recall that a set of points S #18; R d is called convex if for any two points y; z of two convex sets is convex. It is customary to denote the C d -hull of a set X #18; R d by conv under intersection. Let us denote the B d -hull of a subset X #18; R d by box(X) and call it the box

414

Process for functionalizing alkanes  

DOEpatents

Process for functionalizing saturated hydrocarbons comprising: (a) reacting said saturated hydrocarbons of the formula: R.sub.1 H wherein H represents a hydrogen atom; and R.sub.1 represents a saturated hydrocarbon radical, with a metal complex of the formula: CpRh[P(R.sub.2).sub.3 ]H.sub.2 wherein Cp represents a cyclopentadienyl or alkylcyclopentadienyl radical; Rh represents a rhodium atom; P represents a phosphorus atom; R.sub.2 represents a hydrocarbon radical; H represents a hydrogen atom, in the presence of ultraviolet radiation to form a hydridoalkyl complex of the formula: CpRh[P(R.sub.2).sub.3 ](R.sub.1)H (b) reacting said hydridoalkyl complex with an organic halogenating agent such as a tetrahalomethane or a haloform of the formulas: CX'X''X'''X'''' or CHX'X''X''' wherein X', X'', X'", X"" represent halogens selected from bromine, iodine or chlorine atom, at a temperature in the range of about -60.degree. to -17.degree. C. to form the corresponding haloalkyl complex of step (a) having the formula: CpRhPMe.sub.3 RX; and, (c) reacting said haloalkyl complex formed in (b) with halogen (X.sub.2) at a temperature in the range of about -60.degree. to 25.degree. C. (i.e., ambient) to form a functional haloalkyl compound.

Bergman, Robert G. (Kensington, CA); Janowicz, Andrew H. (Wilmington, DE); Periana, Roy A. (Berkeley, CA)

1988-01-01

415

A holistic abundance analysis of r-rich stars  

NASA Astrophysics Data System (ADS)

The chemical abundances of metal-poor stars are an excellent test bed by which to set new constraints on models of neutron-capture processes at low metallicity. Some r-process-rich (hereafter r-rich) metal-poor stars, such as HD 221170, show an overabundance of the heavier neutron-capture elements and excesses of lighter neutron-capture elements. The study of these r-rich stars could give us a better understanding of weak and main r-process nucleosynthesis at low metallicity. Based on conclusions from the observation of metal-poor stars and neutron-capture element nucleosynthesis theory, we set up a model to determine the relative contributions from weak and main r-processes to the heavy-element abundances in metal-poor stars. Using this model, we find that the abundance patterns of light elements for most sample stars are close to the pattern of weak r-process stars, and those of heavier neutron-capture elements very similar to the pattern of main r-process stars, while the lighter neutron-capture elements can be fitted by the mixing of weak and main r-process material. The production of weak r-process elements appears to be associated with the light elements, while the production of main r-process elements is almost decoupled from that of the light elements. We compare our results with the observed data at low metallicities, showing that the predicted trends are in good agreement with the observed trends, at least for the metallicity range [Fe/H] < -2.1. For most sample stars, the abundance patterns of both neutron-capture elements and light elements could be best explained by a star formed in a molecular cloud that has been polluted by both weak and main r-process material.

Zhang, Jiang; Cui, Wenyuan; Zhang, Bo

2010-12-01

416

CARL R. JOHNSON PUBLICATIONS  

E-print Network

, Worth Publishers, 1976. D. J. Pasto and C. R. Johnson, Organic Chemistry--A Source Book for the Laboratory, Prentice-Hall, 1979 D. J. Pasto, C. R. Johnson and M. J. Miller, Experiments and Techniques. Paquette, Ed., John Wiley & Sons Limited, 1995. T. D. Whitaker, K. S. Whitaker and C. R. Johnson, p

Baskaran, Mark

417

This is an unofficial update/changes to NIST Special Publication 800-81r1. The Special Publication was released while the Internet community is still in the process  

E-print Network

of signature of the public key of a child by its parent. The public key of the trusted name servers is called in the source is called data origin authentication. Hence, the security objectives--and consequently the trust anchor. After authenticating the source, the next process DNSSEC calls for is to authenticate

418

Quantum information processing using frequency control of impurity spins in diamond A. M. Zagoskin,1,2 J. R. Johansson,2 S. Ashhab,2 and Franco Nori2,3  

E-print Network

a universal two-qubit gate CPHASE . rf and optical control together promise a scalable quantum computing Impurity spins in diamond are among the most promising candidates for solid-state quantum hardware. The soQuantum information processing using frequency control of impurity spins in diamond A. M. Zagoskin

Nori, Franco

419

Fundamental Plasma Processes in Saturn's Magnetosphere B.H. Mauk, D.C. Hamilton, T.W. Hill, G.B. Hospodarsky, R.E. Johnson, C. Paranicas, E. Roussos,  

E-print Network

Chapter 11 Fundamental Plasma Processes in Saturn's Magnetosphere B.H. Mauk, D.C. Hamilton, T that control the extensive space environ- ment, or magnetosphere, of Saturn (see Chapter 9, for the global under- standing of the operations of Saturn's magnetosphere and its relationship to those of Earth

Johnson, Robert E.

420

Hydrocarbon Processing`s gas processes `98  

SciTech Connect

The paper summarizes 82 processes for natural gas desulfurization, separation, liquefaction, and materials recovery, especially of hydrogen. Each entry describes the application, end products, the process, operating conditions, economics, installations, licensor, and gives references, if appropriate.

NONE

1998-04-01

421

Hydrocarbon Processing`s environmental processes `96  

SciTech Connect

Summaries of 54 processes are presented, containing descriptions of their application, the process, economics, installations, and licensor. Processes are for air, water, and land pollution abatement and control and remedial action of contaminated sites. Processes include: biodegradation, vapor and solvent recovery, membrane transport, pressure swing adsorption, oxidation, selective catalytic reduction, scrubbing, incineration, steam stripping, activated carbon adsorption, extraction, aerobic digestion, anaerobic digestion, desulfurization, and recycling.

NONE

1996-08-01

422

Released on r e c e i p t b u t intended f o r use  

E-print Network

these c r e a t u r e s at a distance. The mariners who sighLe4 a spout would shout, stamp on the deck on ignorance a i d s u p e r s t i t i o n . No 'Ja'berspout was ever d i s p e l l e d by t h i s process, or by any other a r t i f i c i a l process. It.i s j u s t us f u t i l e as the process of bombarding

423

Kinetics of ( R, S)- and ( R)-mandelic acid in an unseeded cooling batch crystallizer  

NASA Astrophysics Data System (ADS)

The objective of this work is to determine the nucleation and growth kinetics of ( R, S)-mandelic acid (( R,S)-MA) and ( R)-mandelic acid (( R)-MA) in aqueous solutions using an unseeded cooling crystallization process. To obtain the nucleation and growth kinetics, the solubility, metastable zone limits, and supersaturation were measured by in-situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and focused beam reflectance measurement (FBRM). The nucleation rate and growth rate parameters were determined by a nonlinear optimization algorithm. The effects of initial concentration and cooling rate on supersaturation and the nucleation rate are also discussed.

Mao, Shimin; Zhang, Yan; Rohani, Sohrab; Ray, Ajay K.

2010-11-01

424

PapR peptide maturation: role of the NprB protease in Bacillus cereus 569 PlcR/PapR global gene regulation.  

PubMed

The global transcriptional regulator PlcR controls gene expression in Bacillus cereus and Bacillus thuringiensis. Activity of PlcR is regulated by PapR, the product of an ORF located immediately downstream of plcR. To be active in B. cereus, PapR must be secreted and then processed to the mature peptide by an unknown protease. This peptide is transported by an oligopeptide permease into the cell, where it activates PlcR. In this study, we show that the neutral protease B (NprB) secreted by B. cereus 569 is required for extracellular PapR maturation. Purified recombinant NprB processed the synthetic PapR propeptide to produce a set of peptides derived from the C-terminal domain of PapR. Supplementation of growth media with synthetic PapR-derived C-terminal 5-, 7-, 8- and 27-amino acid (aa) peptides caused activation of intracellular PlcR in a PapR-deficient strain of B. cereus 569 while only the 5- and 7-aa peptides activated PlcR in a nprB mutant. The maximum activity was found for the 7-mer peptide. However, even the 7-mer peptide could not activate PlcR with a C-terminal truncation of as few as 6 aa. This indicates that interactions of the C-terminal regions of both PlcR and PapR are important in transcriptional activation of the B. cereus 569 PlcR regulon. PMID:19159431

Pomerantsev, Andrei P; Pomerantseva, Olga M; Camp, Andrew S; Mukkamala, Radhika; Goldman, Stanley; Leppla, Stephen H

2009-04-01

425

Image Inpainting with Gaussian Processes Alfredo Kalaitzis  

E-print Network

Image Inpainting with Gaussian Processes Alfredo Kalaitzis TH E U N I V E R S ITY OF E D I N B U R for image inpainting, a process which reconstructs lost or deteriorated parts of an image based Background 5 2.1 Image Inpainting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2

Rattray, Magnus

426

77 FR 36907 - Establishment of Restricted Areas R-5402, R-5403A, R-5403B, R-5403C, R-5403D, R-5403E, and R...  

Federal Register 2010, 2011, 2012, 2013, 2014

...R-5403D, R-5403E, and R-5403F; Devils Lake, ND AGENCY: Federal Aviation Administration...restricted area airspace within the Devils Lake Military Operations Area (MOA), overlying...Grafton Range, in the vicinity of Devils Lake, ND. The new restricted areas...

2012-06-20

427

miR172 regulates soybean nodulation.  

PubMed

Micro-RNAs (miRNAs) play a pivotal role in the control of gene expression and regulate plant developmental processes. miRNA 172 (miR172) is a conserved miRNA in plants reported to control the expression of genes involved in developmental phase transition, floral organ identity, and flowering time. However, the specific role of miR172 in legume nodulation is undefined. Ectopic expression of soybean miR172 resulted in an increase in nodule numbers in transgenic roots and an increase in the expression of both symbiotic leghemoglobin and nonsymbiotic hemoglobin. These nodules showed higher levels of nitrogenase activity. Further analysis revealed a complex regulatory circuit in which miR156 regulates miR172 expression and controls the level of an AP2 transcription factor. The latter, either directly or indirectly, controls the expression of nonsymbiotic hemoglobin, which is essential for regulating the levels of nodulation. PMID:23980625

Yan, Zhe; Hossain, Md Shakhawat; Wang, Jun; Valds-Lpez, Oswaldo; Liang, Yan; Libault, Marc; Qiu, Lijuan; Stacey, Gary

2013-12-01

428

Dielectric Constants of Refrigerants R113, R114, R114B2, R115, R116, and R124  

NASA Astrophysics Data System (ADS)

The dielectric constants of six refrigerants have been measured in both gaseous and liquid phases. The fluids used and the experimental ranges of temperature and pressure are as follows : R113 (1, 2, 2- Trichlorotrifluoroethane CClF2CCl2F) : 298.15-423.15K, 0.1-17.3MPa, R1l4 (1, 2- Dichlorotetrafluoroethane CClF2CClF2) : 298.15-423.15K, 0.2-17.2MPa, R114B2 (1, 2- Dibromotetrafluoroethane CBrF2CBrF2) : 298.15-423.15K, 0.2-17.3MPa, R1l5 (Chloropentafluoroethane CClF2CF3) : 298.15 373.15K. O.1-17.1MPa, R1l6 (Hexafluoroethane CF3CF3) : 283.15-373.15 K, 0.2-16.9MPa, R124 (1-Chloro-2, 2, 2, -tetrafluoroethane CHClFCF3) : 273.15 373.15K, 0.1-10.5MPa The measurements were performed using a frequency-counting method on a relative basis with an uncertainty less than 0.1%.The experimental results are given by polynomial equations. The smoothed value tables are also given for practical convenience. The pressure dependence of dielectric constants in liquid phase is represented by a similar expression to the Tait equation. The effects of pressure, temperature, and density on the dielectric constant and the molar polarization defined by the Clausius-Mossotti relation are discussed in term of polarity of molecules of each refrigerant.

Kashiwagi, Hiroshi; Harada, Noboru; Tanaka, Yoshiyuki; Kubota, Hironobu; Makita, Tadashi

429

XagR, a LuxR homolog, contributes to the virulence of Xanthomonas axonopodis pv. glycines to soybean.  

PubMed

A novel luxR homolog, termed XagR, in Xanthomonas axonopodis pv. glycines, the cause of soybean pustule, controls expression of pip, yapH, and at least 77 other genes. Although XagR and Pip are required for full virulence of X. axonopodis pv. glycines to soybean, constitutive overproduction of XagR suppresses infection. The xagR-dependent induction of pip occurs in planta only 2 days or more after inoculation. Although the transcription of xagR appears constitutive, XagR accumulates only in cells that have colonized soybean plants for more than 2 days suggesting that some components produced during the infection process mediate post-transcriptional control, likely by protecting XagR