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1

R-process Nucleosynthesis in Supernova Explosion  

SciTech Connect

We investigate the possibility of the r-process during the magnetohydrodynamical (MHD) explosion of supernova in a massive star of 13 M{sub {center_dot}} with the effects of neutrinos included. Contrary to the case of the spherical explosion, jet-like explosion due to the combined effects of rotation and magnetic field lowers the electron fraction significantly inside the layers. We find that the ejected material of low electron fraction responsible for the r-process comes out from the inner deep region of the core that is made up of iron-group nuclei. This leads to the production of the second to third peak in the solar r-process elements. We suggest that there are some variations in the r-process nucleosynthesis according to the initial conditions of rotational and magnetic fields.

Saruwatari, M.; Hashimoto, M. [Department of Physics, School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Kotake, K. [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Yamada, S. [Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjyuku, Tokyo, 169-8555 (Japan)

2011-10-28

2

Superheavy elements and r-process  

SciTech Connect

The probability for the production of superheavy elements in the astrophysical r-process is discussed. The dependence of the estimated superheavy-element yields on input data is estimated. Preliminary calculations revealed that the superheavy-element yields at the instant of completion of the r-process may be commensurate with the uranium yield, but the former depend strongly on the models used to forecast the properties of beta-delayed, neutron-induced, and spontaneous fission. This study is dedicated to the 80th anniversary of V.S. Imshennik's birth.

Panov, I. V., E-mail: Igor.Panov@itep.ru; Korneev, I. Yu. [Institute of Theoretical and Experimental Physics (Russian Federation); Thielemann, F.-K. [Institut fuer Physik der Universitaet Basel (Switzerland)

2009-06-15

3

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

4

Neutron captures and the r-process  

NASA Astrophysics Data System (ADS)

In order to study possible neutron-capture effects during an r-process, it is necessary to perform fully dynamical simulations. We have performed such calculations within the model of an adiabatically expanding high-entropy bubble of a SN II, using temperature-dependent reaction rates including the NON-SMOKER neutron-capture rates of Rauscher et al..

Farouqi, K.; Kratz, K.-L.; Pfeiffer, B.; Rauscher, T.; Thielemann, F.-K.

2006-03-01

5

The alpha -Process and the r-Process  

NASA Astrophysics Data System (ADS)

If material initially in nuclear statistical equilibrium (NSE) at high temperature and containing a large fraction of alpha -particles (or nucleons) is expanded and cooled so rapidly that not all the alpha -particles have time to reassemble, its final composition will differ substantially from what is traditionally calculated for particle-deficient freeze-outs. It has long been known that this phenomenon, the ``alpha -rich freeze-out," can lead to the production of elements heavier than the iron group, but only up to about zinc (A ~ 66). Here we explore the alpha -rich freeze-out for values of neutron excess larger than previously treated and discover nuclear systematics that, for neutron excesses greater than about 0.05, allow the creation of heavier elements all the way up to A ~ 100, even when most of the ejecta is in the form of heavy elements. In the limit of a very large fraction of unassembled alpha -particles and a large neutron excess, the alpha -rich freeze-out merges smoothly into the classical r-process. In contrast to previous studies, we find that a large part of the nuclear flow in the r-process may be carried by charged particle reactions up to about A = 100. We speculate that the site of these processes is the high entropy ``wind'' of a young (age 1-10 s) neutron star in which neutrino energy deposition is driving mass loss. The appropriate conditions exist in the delayed supernova explosion mechanism of Mayle & Wilson, but they may occur in other models as well. The mass of r-process ejected per supernova is expected to be ~ 10(-4) M\\sun \\ per Type II or Type Ib supernova, but this will be sensitive to details of the presupernova structure, the explosion mechanism, and the amount of material that falls back onto the neutron star when the reverse shock arrives there.

Woosley, S. E.; Hoffman, R. D.

1992-12-01

6

The alpha-process and the r-process  

NASA Astrophysics Data System (ADS)

The paper explores the alpha-rich freeze-out for values of neutron excesses larger than previously treated, and reports the discovery of nuclear systematics that, for neutron excesses greater than about 0.05, allow the creation of heavier elements all the way up to A of about 100, even when most of the ejecta is in the form of heavy elements. It is found that a large part of the nuclear flow in the r-process may be carried by charged particle reactions up to about A of about 100. It is speculated that the site of these processes is the high-entropy 'wind' of a young neutron star in which neutrino energy deposition is driving mass loss. The pass of r-process ejected per supernova is expected to be about 0.0001 solar mass per Type II or Ib supernova, but this is sensitive to details of the presupernova structure, the explosion mechanism, and the amount of material that falls back onto the neutron star when the reverse shock arrives there.

Woosley, S. E.; Hoffman, Robert D.

1992-08-01

7

The alpha-process and the r-process  

NASA Technical Reports Server (NTRS)

The paper explores the alpha-rich freeze-out for values of neutron excesses larger than previously treated, and reports the discovery of nuclear systematics that, for neutron excesses greater than about 0.05, allow the creation of heavier elements all the way up to A of about 100, even when most of the ejecta is in the form of heavy elements. It is found that a large part of the nuclear flow in the r-process may be carried by charged particle reactions up to about A of about 100. It is speculated that the site of these processes is the high-entropy 'wind' of a young neutron star in which neutrino energy deposition is driving mass loss. The pass of r-process ejected per supernova is expected to be about 0.0001 solar mass per Type II or Ib supernova, but this is sensitive to details of the presupernova structure, the explosion mechanism, and the amount of material that falls back onto the neutron star when the reverse shock arrives there.

Woosley, S. E.; Hoffman, Robert D.

1992-01-01

8

Astrophysical models of r-process nucleosynthesis: An update  

SciTech Connect

An update on astrophysical models for nucleosynthesis via rapid neutron capture, the r process, is given. A neutrino-induced r process in supernova helium shells may have operated up to metallicities of {approx} 10{sup -3} times the solar value. Another r-process source, possibly neutron star mergers, is required for higher metallicities.

Qian Yongzhong [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

2012-11-12

9

THE RARE EARTH PEAK: AN OVERLOOKED r-PROCESS DIAGNOSTIC  

SciTech Connect

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 {approx}> 100k{sub 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.

Mumpower, Matthew R.; McLaughlin, G. C. [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Surman, Rebecca, E-mail: mrmumpow@ncsu.edu, E-mail: gail_mclaughlin@ncsu.edu, E-mail: surmanr@union.edu [Department of Physics and Astronomy, Union College, Schenectady, NY 12308 (United States)

2012-06-20

10

Isotopic r-process abundances produced by supernova explosions  

NASA Astrophysics Data System (ADS)

The rapid neutron capture process (r-process) is one of the major nucleosynthesis processes responsible for the synthesis of heavy nuclei beyond iron. Isotopes beyond Fe are most exclusively formed in neutron capture processes and more heavier ones are produced by the r-process. Approximately half of the heavy elements with mass number A>70 and all of the actinides in the solar system are believed to have been produced in the r-process. We have studied the r-process in supernovae for production of heavy elements beyond A=40 with the newest mass values available. The supernovae envelopes at a temperature >109 K and neutron density of 1024 cm-3 are considered to be one of the most potential sites for the r-process. We investigate the r-process in a site-independent, classical approach which assumes a chemical equilibrium between neutron captures and photodisintegrations followed by a ?-flow equilibrium. We have studied the r-process path corresponding to temperatures ranging from 1.0×109 K to 3.0×109 K and neutron density ranging from 1020 cm-3 to 1030 cm-3. The primary goal of the r-process calculations is to fit the global abundance curve for solar system r-process isotopes by varying time dependent parameters such as temperature and neutron density. This method aims at comparing the calculated abundances of the stable isotopes with observation. The abundances obtained are compared with supernova explosion condition and found in good agreement. The elements obtained along the r-process path are compared with the observed data at all the above temperature and density range.

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

2012-08-01

11

New Observational Perspectives on r-process Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Elements heavier than the iron group can be found in nearly every star whose abundances have been studied in detail. More than 60 percent of the naturally-occurring elements between zinc and uranium have been detected in r-process enriched stars. Models of the r-process rely heavily on matching astronomical observations, so this is good news for studies of r-process nucleosynthesis. I will highlight some of what we've learned from three decades of studying r-process material in other stars, describe current efforts that use the Hubble Space Telescope to expand the chemical inventory in r-process environments beyond the Solar system, and note opportunities for complementary studies by the physics community.

Roederer, Ian U.

2012-10-01

12

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

13

Design of a Wideband UHF RFID Printed Tag Antenna Using the R2R Process  

NASA Astrophysics Data System (ADS)

This paper proposes a printed tag antenna for the universal ultra-high frequency (UHF) radio frequency identification (RFID) band (860-960MHz) using the R2R process. To widen impedance bandwidth, a ?-shaped matching network is suggested. The overall dimension of the proposed tag antenna is 83.4mm × 30.2mm and it has a gain of over 1dBi for the entire UHF RFID band. The performances of the proposed tag antenna, printed with conductivity silver ink using an R2R process, are compared with those of a copper antenna.

Kim, Uisheon; Jung, Gyubong; Choi, Jaehoon

14

The CS\\/R advanced SNG hydrogasification process  

Microsoft Academic Search

Development effort is continuing on the Cities Service\\/Rockwell (CS\\/R) Advanced Hydrogasification System with emphasis shifting from reactor development to process optimization. An 18-ton\\/day integrated process development unit is under construction and will be operational in 1981. Concurrently, an extensive commercial-scale process optimization activity is underway to select the proper reactor operating parameters and subsystem unit processes. Development test data indicate

J. Silverman; J. Friedman; D. R. Kahn; D. Rimmer; R. Matyas

1980-01-01

15

Sensitivity studies for the main r process: nuclear masses  

NASA Astrophysics Data System (ADS)

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.; Bentley, I.; Mumpower, M.; Surman, R.

2014-04-01

16

Nuclear structure studies for the astrophysical r-process  

Microsoft Academic Search

The production of the heaviest elements in nature occurs via the r-process, i.e. a combination of rapid neutron captures, the inverse photodisintegrations, and slower ??-decays, ?-delayed processes as well as fission and possibly interactions with intense neutrino fluxes. A correct understanding and modeling requires the knowledge of nuclear properties far from stability and a detailed prescription of the astrophysical environment.

B. Pfeiffer; K.-L. Kratz; F.-K. Thielemann; W. B. Walters

2001-01-01

17

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

18

The Rare Earth Peak: An Overlooked r-Process Diagnostic  

NASA Astrophysics Data System (ADS)

Where do the heavy elements in the universe come from? While the basic principles of nucleosynthesis have been established, a definite answer to this and many related questions still eludes us. The 'rapid' neutron capture process or r-process is believed to be responsible for generating roughly half the nuclei with atomic mass A ? 100. However, the astrophysical site of this process still remains uncertain. Still further, nucleosynthesis calculations of this process must rely on theoretical extrapolations as the bulk of nuclides participating in this process are short-lived.We examine the formation and final structure of the rare earth peak (A ˜ 160) of the r-process nucleosynthesis. Since rare earth peak formation does not occur during (n, gamma) ? (gamma, n) equilibrium it is sensitive to the strong interplay between late time thermodynamic evolution and nuclear physics input. We show that under high entropy conditions (S > 100 kB), the rare earth peak forms at late times in the r-process after neutron exhaustion (neutron-to-seed ratio unity or R = 1) as matter decays back to stability. Depending on the conditions the peak forms either because of the pattern of the neutron capture rates or because of the pattern of the separation energies. We use features of a successful rare earth region to 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. We study the sensitivity of the r-process abundance pattern to neutron capture rates and beta-decay rates in the region. We identify the range of nuclei which are in uential in rare earth peak formation.

Mumpower, Matthew Ryan

19

β-decay spectroscopy for the r-process nucleosynthesis  

NASA Astrophysics Data System (ADS)

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? 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 238U-beam will be presented together with our future perspectives.

Nishimura, Shunji; the RIBF decay collaborations

2014-05-01

20

The r-Process in Black Hole Winds  

NASA Astrophysics Data System (ADS)

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 neutron-rich wind from a proto-neutron star. In this paper, we discuss nucleosynthesis of the r-process in an alternative astrophysical site, ``black hole wind'', which is the neutrino-driven outflow from the accretion torus around a black hole. This condition is assumed to be realized in double neutron star (or a neutron star a black hole) mergers or hypernovae.

Wanajo, Shinya; Janka, Hans-Thomas

2010-08-01

21

Explosive nucleosynthesis and the astrophysical r-process  

Microsoft Academic Search

We give an overview of chemical equilibria in explosive burning and the role which neutron and\\/or proton separation energies play. We focus then on the rapid neutron-capture process (r-process) which encounters unstable nuclei far from beta-stability with neutron separation energies in the range 1-4 MeV. Its observable features, like the abundances, witness nuclear structure as well as the conditions in

F.-K. Thielemann; C. Freiburghaus; T. Rauscher; E. Kolbe; B. Pfeiffer; K.-L. Kratz; J. J. Cowan

1998-01-01

22

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

23

Nuclear structure studies for the astrophysical r-process  

Microsoft Academic Search

The production of the heaviest elements in nature occurs via the r-process, i.e. a combination of rapid neutron captures, the inverse photodisintegrations, and slower beta--decays, \\/beta-delayed processes as well as fission and possibly interactions with intense neutrino fluxes. A correct understanding and modeling requires the knowledge of nuclear properties far from stability and a detailed prescription of the astrophysical environment.

B. Pfeiffer; K.-L. Kratz; F.-K. Thielemann; W. B. Walters

2001-01-01

24

An ACT-R Representation of Information Processing in Autism  

Microsoft Academic Search

The low-level cognitive processes involved in autism are not well understood and are a target of ongoing research. This paper proposes that autistic behavior can be modeled as an adaptive response to underconnectivity in certain areas of the brain. In the ACT-R architecture, this is represented by a reduction in source activations between the declarative module and other modules, corresponding

Michael Matessa

25

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

26

Some Nucleosynthesis Effects Associated with r-Process Jets  

NASA Astrophysics Data System (ADS)

In a recent work, I have discussed some of the consequences of including rotation and magnetic fields in a model of a core-collapse supernova. Rotation produces equatorial flattening in the resultant neutron star and also produces a surrounding accretion disk. Magnetic fields wrap into a toroid that extrudes material in the equatorial plane. The combination of these effects is an accretion-extrusion disk that feeds material into bipolar jets rooted in the disk where the inward and outward flows meet. The extrusion flow is the site of an r-process in which the seed nuclei embedded in the neutron Fermi sea in the outer neutron star envelope capture the neutrons in which they are embedded. At high latitudes on the neutron star a large neutrino-antineutrino flux drives a neutron wind of the type previously discussed for spherical models, and this is a separate site for a less efficient r-process. In the high-temperature accretion disk, nuclear statistical equilibrium exists, with an abundance peak near mass number 90. The jets are expected to have a velocity of about 0.5c (140 MeV nucleon-1) and to blast holes in the expanding envelope of the supernova, causing large secondary explosions and extensive spallation of both the envelope and jet nuclei. The general purpose of this paper is to discuss nuclear processes and effects associated with this rather complicated scenario and to identify features in the nuclidic abundances in solar system materials that are probably associated with these effects. One discussion tentatively identifies the fission point for r-process fission recycling with the nuclide 297Bh and argues for fission peaks around mass numbers 132 and 165, identifying the latter with an r-process abundance hump in the rare earth region. The equilibrium abundance peak at mass number 90 should be involved in creating the abundance peak in the p-process in that region, previously not understood. Spallation of r-process nuclei near the mass number 132 peak can be identified with an unusual Xe component in interstellar nanodiamonds called Xe-HL. A discussion is given of other isotopic anomalies in meteoritic components that imply mixing and turbulence in the expanding supernova envelope, and it identifies the macroscopic calcium-aluminum inclusions in meteorites as originating in the envelope of a supernova responsible for triggering formation of the primitive solar nebula. Spallation can also be expected to produce DLiBeB fragments in the CO and He layers of the envelope as a primary process, in contrast to cosmic-ray production of such fragments in secondary processes.

Cameron, A. G. W.

2003-04-01

27

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

28

GOES-R AWG product processing system framework  

NASA Astrophysics Data System (ADS)

NOAA/NESDIS/STAR has designed, developed, and implemented the Geostationary Operational Environmental Satellite - R Series (GOES-R) Algorithm Working Group (AWG) Product Processing System Framework. The Framework enabled the development and testing of the Level 2 Advance Baseline Imager (ABI) and the GOES-R Lightning Mapper (GLM) products within a single system. Fifty-six GOES-R ABI algorithms and one GLM algorithm have been integrated and run within the framework with product precedence. The Framework has been modified to be a plug-and-play system with the scientific algorithms. To enable the plug-and-play capabilities, the fifty-seven ABI and GLM algorithms were adjusted such that any data required by the algorithm is brought into the algorithm through function calls. These modifications allowed an algorithm to be developed either within the Framework or within the scientist's offline research system. This approach provided both the algorithm developers and algorithm integrators the ability to work on the same software since the algorithm may be "dropped" into both systems resulting in simple algorithm rollbacks. The design features and the current status of the framework will be discussed.

Sampson, S.; Wolf, Walter; Li, A.; Yu, T.; Garcia, R.; Martin, G.; Liu, X.; Straka, W.; Fan, M.; Schiffer, E.; Goldberg, M.

2012-11-01

29

Explosive nucleosynthesis and the astrophysical r-process  

NASA Astrophysics Data System (ADS)

We give an overview of chemical equilibria in explosive burning and the role which neutron and/or proton separation energies play. We focus then on the rapid neutron-capture process (r-process) which encounters unstable nuclei far from beta-stability with neutron separation energies in the range 1-4 MeV. Its observable features, like the abundances, witness nuclear structure as well as the conditions in the appropriate astrophysical environment. With the remaining lack of a full understanding of its astrophysical origin, parametrized calculations are still necessary. The classical approach is based on (constant) neutron number densities nn and temperatures T over duration timescales ?. Recent investigations, motivated by the neutrino wind scenario from hot neutron stars after a supernova explosion, followed the expansion of matter with initial entropies S and electron fractions Ye over expansion timescales ?. We compare the similarities and differences between the two approaches with respect to resulting abundance features and their relation to solar r-process abundances. Special emphasis is given to the questions (i) whether the same nuclear properties far from stability lead to similar abundance patterns and deficiencies in both approaches and (ii) whether some features can also provide clear constraints on the permitted astrophysical conditions.

Thielemann, F.-K.; Freiburghaus, C.; Rauscher, T.; Kolbe, E.; Pfeiffer, B.; Kratz, K.-L.; Cowan, J. J.

1998-12-01

30

Direct SNG production by the CS/R hydrogasification process  

SciTech Connect

The CS/R Hydrogasification Process utilizes a short residence-time entrained-flow reactor, derived from aerospace rocket reactor technology, for quickly reacting pulverized coal with hot hydrogen to directly produce substitute natural gas (SNG). Development testing has indicated the feasibility of two primary process options: the production of SNG as the sole major product or the coproduction of SNG and chemical-grade benzene. Recent emphasis has focused on process design, optimization, and economics. Preliminary design studies of commercial-scale (250 x 10/sup 9/ Btu/day) grassroots SNG plants have been completed for two widely different types of feedstock: Kentucky No. 9 hvAb coal and Minnesota peat. This paper summarizes the pertinent experimental data and analytical modeling studies of flash hydropyrolysis used as a basic input to the process design effort. The commercial process flowsheets for each feedstock are described, and the resultant capital and operating costs are discussed. Sensitivity analyses are presented relating the cost of gas to the major process operating variables and economic parameters.

Kahn, D.R.; Combs, L.P.; Garey, M.P.

1983-08-01

31

MDRL lncRNA Regulates the Processing of miR-484 Primary Transcript by Targeting miR-361  

PubMed Central

Long noncoding RNAs (lncRNAs) are emerging as new players in gene regulation, but whether lncRNAs operate in the processing of miRNA primary transcript is unclear. Also, whether lncRNAs are involved in the regulation of the mitochondrial network remains to be elucidated. Here, we report that a long noncoding RNA, named mitochondrial dynamic related lncRNA (MDRL), affects the processing of miR-484 primary transcript in nucleus and regulates the mitochondrial network by targeting miR-361 and miR-484. The results showed that miR-361 that predominantly located in nucleus can directly bind to primary transcript of miR-484 (pri-miR-484) and prevent its processing by Drosha into pre-miR-484. miR-361 is able to regulate mitochondrial fission and apoptosis by regulating miR-484 levels. In exploring the underlying molecular mechanism by which miR-361 is regulated, we identified MDRL and demonstrated that it could directly bind to miR-361 and downregulate its expression levels, which promotes the processing of pri-miR-484. MDRL inhibits mitochondrial fission and apoptosis by downregulating miR-361, which in turn relieves inhibition of miR-484 processing by miR-361. Our present study reveals a novel regulating model of mitochondrial fission program which is composed of MDRL, miR-361 and miR-484. Our work not only expands the function of the lncRNA pathway in gene regulation but also establishes a new mechanism for controlling miRNA expression.

Wang, Jian-Xun; Zhou, Lu-Yu; Long, Bo; Liu, Cui-Yun; Liu, Fang; Li, Pei-Feng

2014-01-01

32

Structure information on the r-process nucleus 135Sn  

NASA Astrophysics Data System (ADS)

The ?- decay of 135Sn was studied for the first time yielding a half-life of 0.6(1) s and a partial level scheme for the ?- decay to 135Sb. The 135Sn activity was produced at the mass separator OSIRIS via the fast neutron-induced fission of a 238U target inside a specially constructed ion source. 135Sn is the heaviest Sn isotope, for which spectroscopic results are presently determined. The new results are in disagreement with some of the theoretical predictions, which are used for modeling of the astrophysical r process.

Korgul, A.; Mach, H.; Fogelberg, B.; Urban, W.; Kurcewicz, W.; Isakov, V. I.

2001-08-01

33

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

34

The r-process and neutrino-heated supernova ejecta  

NASA Technical Reports Server (NTRS)

As a neutron star is formed by the collapse of the iron core of a massive star, its Kelvin-Helmholtz evolution is characterized by the release of gravitational binding energy as neutrinos. The interaction of these neutrinos with heated material above the neutron star generates a hot bubble in an atmosphere that is nearly in hydrostatic equilibrium and heated, after approximately 10 s, to an entropy of S/N(sub AS)k greater than or approximately = 400. The neutron-to-proton ratio for material moving outward through this bubble is set by the balance between neutrino and antineutrino capture on nucleons. Because the electron antineutrino spectrum at this time is hotter than the electron neutrino spectrum, the bubble is neutron-rich (0.38 less than or approximately = Y(sub e) less than or approximately = 0.47). Previous work using a schematic model has shown that these conditions are well suited to the production of heavy elements by the r-process. In this paper we have advanced the numerical modeling of a 20 solar mass 'delayed' supernova explosion to the point that we can follow the detailed evolution of material moving through the bubble at the late times appropiate to r-process nucleosynthesis. The supernova model predicts a final kinetic energy for the ejecta of 1.5 x 10(exp 51) ergs and leaves behind a remnant with a baryon mass of 1.50 solar mass (and a gravitational mass of 1.445 solar mass). We follow the thermodynamic and compositional evolution of 40 trajectories in rho(t), T(t), Y(sub e)(t) for a logarithmic grid of mass elements for the last approximately = 0.03 solar mass to be ejected by the proto-neutron star down to the last less than 10(exp -6) solar mass of material expelled at up to approximately = 18 s after core collapse. We find that an excellent fit to the solar r-process abundance distribution is obtained with no adjustable parameters in the nucleosynthesis calculations. Moreover, the abundances are produced in the quantities required to account for the present Galactic abundances. However, at earlier times, this one-dimensional model ejects too much material with entropies S/N(sub A)k approximately 50 and Y(sub e) approximately 0.46. This leads to an acceptable over production of N = 50 nuclei, particularly Sr-88, Y-89, and Zr-90, relative to their solar abundances. We speculate on various means to avoid the early overproduction and/or ejection of N = 50 isotonic nuclei while still producing and ejecting the correct amount of r-process material.

Woosley, S. E.; Wilson, J. R.; Mathews, G. J.; Hoffman, R. D.; Meyer, B. S.

1994-01-01

35

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

36

Estimating R-Process Yields from Abundances of the Metal-Poor Stars  

NASA Astrophysics Data System (ADS)

The chemical abundances of metal-poor stars provide important clues to explore stellar formation history and set significant constraints on models of the r-process. In this work, we find that the abundance patterns of the light and iron group elements of the main r-process stars are very close to those of the weak r-process stars. Based on a detailed abundance comparison, we find that the weak r-process occurs in supernovae with a progenitor mass range of ˜11-26 M?. Using the SN yields given by Heger & Woosley and the abundances of the weak r-process stars, the weak r-process yields are derived. The SNe with a progenitor mass range of 15 M? < M < 26 M? are the main sites of the weak r-process, and their contributions are larger than 80%. Using the abundance ratios of the weak r-process and the main r-process in the solar system, the average yields of the main r-process are estimated. The observed correlations of [neutron-capture/Eu] versus [Eu/Fe] can be explained by mixing of the two r-process abundances in various fractions.

Li, Hongjie; Ma, Wenjuan; Cui, Wenyuan; Zhang, Bo

2014-06-01

37

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

Microsoft Academic Search

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

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

2006-01-01

38

Enrichment history of r-process elements shaped by a merger of neutron star pairs  

NASA Astrophysics Data System (ADS)

The origin of r-process elements remains unidentified and still puzzles us. The recent discovery of evidence for the ejection of r-process elements from a short-duration ?-ray burst singled out neutron star mergers (NSMs) as their origin. In contrast, core-collapse supernovae are ruled out as the main origin of heavy r-process elements (A > 110) by recent numerical simulations. However, the properties characterizing NSM events - their rarity and high yield of r-process elements per event - have been claimed to be incompatible with the observed stellar records on r-process elements in the Galaxy. We add to this picture with our results, which show that the observed constant [r-process/H] ratio in faint dwarf galaxies and one star unusually rich in r-process in the Sculptor galaxy agree well with this rarity of NSM events. Furthermore, we found that a large scatter in the abundance ratios of r-process elements to iron in the Galactic halo can be reproduced by a scheme that incorporates an assembly of various protogalactic fragments, in each of which r-process elements supplied by NSMs pervade the whole fragment while supernovae distribute heavy elements only inside the regions swept up by the blast waves. Our results demonstrate that NSMs occurring at Galactic rate of 12-23 Myr-1 are the main site of r-process elements, and we predict the detection of gravitational waves from NSMs at a high rate with upcoming advanced detectors.

Tsujimoto, T.; Shigeyama, T.

2014-05-01

39

Helping science to succeed: improving processes in R&D.  

PubMed

Bringing drugs to the market remains a costly and, until now, often unpredictable challenge. Although understanding the underlying science is key to further progress, our imperfect knowledge of disease and complex biological systems leaves excellence in execution as the most tangible lever to sustain our serendipitous approach to drug discovery. The problems encountered in pharmaceutical R&D are not unique, but to learn from other industries it is important to recognise similarity, rather than differences, and to advance industrialisation of R&D beyond technology and automation. Tools like Lean and Six Sigma, already applied to increase business excellence across diverse organisations, can equally be introduced to pharmaceutical R&D and offer the potential to transform operations without large-scale investment. PMID:18342798

Sewing, Andreas; Winchester, Toby; Carnell, Pauline; Hampton, David; Keighley, Wilma

2008-03-01

40

r-Java: an r-process code and graphical user interface for heavy-element nucleosynthesis  

NASA Astrophysics Data System (ADS)

We present r-Java, an r-process code for open use that performs r-process nucleosynthesis calculations. Equipped with a simple graphical user interface, r-Java is capable of carrying out nuclear statistical equilibrium (NSE), as well as static and dynamic r-process calculations, for a wide range of input parameters. In this introductory paper, we present the motivation and details behind r-Java and results from our static and dynamic simulations. Static simulations are explored for a range of neutron irradiation and temperatures. Dynamic simulations are studied with a parameterized expansion formula. Our code generates the resulting abundance pattern based on a general entropy expression that can be applied to both degenerate and non-degenerate matter, allowing us to track the rapid density and temperature evolution of the ejecta during the initial stages of ejecta expansion. At present, our calculations are limited to the waiting-point approximation. We encourage the nuclear astrophysics community to provide feedback on the code and related documentation, which is available for download from the website of the Quark-Nova Project: http://quarknova.ucalgary.ca/.

Charignon, C.; Kostka, M.; Koning, N.; Jaikumar, P.; Ouyed, R.

2011-07-01

41

Heterogeneous evolutionary processes affect R gene diversity in natural populations of Solanum pimpinellifolium  

Microsoft Academic Search

Resistance (R) genes of plants are responsible for pathogen recognition and encode proteins that trigger a cascade of responses when a pathogen invades a plant. R genes are assumed to be under strong selection, but there is limited knowledge of the processes affecting R gene diversity in the wild. In this study, DNA sequence variation of Cf-2 homologs was surveyed

Ana L. Caicedo; Barbara A. Schaal

2004-01-01

42

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

NASA Astrophysics Data System (ADS)

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.; Chiba, S.; Mathews, G. J.

2014-05-01

43

Stretford Process Status and R and D Needs.  

National Technical Information Service (NTIS)

The Stretford process is a liquid-phase oxidation/reduction process which removes H(2)S from gaseous streams and produces either elemental sulfur for sale or a sulfur cake, a waste which is commonly landfilled. Many users have expressed a need for more in...

D. A. Dalrymple F. A. Scheffel T. W. Trofe

1987-01-01

44

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

45

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

46

The Helium r-Process and Neutron-Capture Element Abundances in Low Metallicity Stars  

NASA Astrophysics Data System (ADS)

There is increasingly strong observational evidence that the r-process isotopes identified in solar system matter are in fact the products of two distinct classes of r-process nucleosynthesis events. Spectroscopic observations of extremely metal deficient halo field stars and globular cluster stars provide confirmation of the occurrence of a robust r-process mechanism for the production of the main r-process component, at mass numbers A ? 130-140. This main component is variously argued to have its origin in regions outside the neutronized core, in magnetic jets from the collapsing core, or in neutron star-neutron star mergers. The stellar abundance data available to date suggests, however, that the bulk of the r-process nuclei in the mass region A < ~ 130 are not formed in this environment. Further evidence for such a distinct weak component is provided by the finding that the abundances of the short lived r-process nuclei 129I and 182Hf in the early solar system cannot be explained by a single type of r-process event (Wasserburg, Busso, & Gallino 1996). We report here exploratory calculations of the consequences of r-process synthesis in the shock-processed helium shells of Type II supernovae. The conditions of temperature, density, and composition are those predicted by the models of Woosley and Weaver (1995). Our results establish that these conditions are quite consistent with the production of an r-process pattern of abundances for the A < ~ 130 mass region, although the sensitivity to detailed post shock conditions insures that this process is not as robust as that responsible for the main r-process component A ? 130-140. We discuss the implications of our numerical results for the interpretation both of the abundances in metal poor stars and of the anomalous r-process-like isotopic abundances observed in meteoritic silicon carbide grains (Pellin et al. 2000). This research was funded in part by NSF grant AST-9618332 to JJC and by the ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago under DOE contract B341495 (JWT).

Truran, J. W.; Cowan, J. J.

2000-05-01

47

The Astrophysical r-Process 50 Years after B{sup 2}FH  

SciTech Connect

Since the historical papers by Burbidge et al. and Cameron 50 years ago, it is generally accepted that half of the chemical elements above Fe are formed in explosive stellar scenarios by a rapid neutron-capture process (the classical ''r-process''). Already from their essential ideas, it became clear that a correct modelling of this nucleosynthesis process requires both, the knowledge of various nuclear properties very far from stability and a detailed description of the astrophysical environments. However, it took about three decades, until in 1986 the first experimental nuclear-physics data on the neutron-magic r-isotopes {sup 80}Zn and {sup 130}Cd could be obtained, which act as key ''waiting points'' in the respective A{approx_equal}80 and 130 peaks of the Solar-System (SS) r-abundances (N{sub r,{center_dot}}). Since then, using steadily improved nuclear data, we have optimized our r-process calculations to reproduce the present observables of the isotopic N{sub r,{center_dot}} ''residuals'', as well as the more recent elemental abundances in ultra-metal-poor, r-process-enriched halo stars. Concerning the latter observations, we support the basic idea about two different types of r-processes. Based on our many years' experience with the site-independent ''waiting-point approach'', we recently have extended our studies to fully dynamical network calculations for the most likely astrophysical r-process scenario, i.e. the high-entropy wind (HEW) of core-collapse type II supernovae (SN II). Again, an excellent reproduction of all observables for the ''main'' r-process has been achieved. However, a major difference is the nucleosynthesis origin of the lighter heavy elements in the 29{<=}Z{<=}45 mass region. Here, the HEW model predicts-instead of a ''weak'' neutron-capture r-process component-a primary rapid charged-particle process. This may explain the recent observations of a non-correlation of these elements with the heavier ''main'' r-process elements.

Kratz, K.-L.; Pfeiffer, B. [Max-Planck-Institut fuer Chemie, Otto-Hahn-Institut, D-55128 Mainz (Germany); Farouqi, K. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL60637 (United States); Mashonkina, L. I. [Institute of Astronomy, Russian Academy of Science, RU-119017 Moscow (Russian Federation)

2008-01-24

48

Exploration and exploitation innovation processes: The role of organizational slack in R & D intensive firms  

Microsoft Academic Search

This study considers how organizational slack (available and recoverable) affects the process of innovation by facilitating or hindering the process of exploration and exploitation in the case of technology intensive firms. It is argued that the R & D intensity of the firm moderates the effect of organizational slack on innovation quantity, innovation quality as well as the process of

Scott W. Geiger; Marianna Makri

2006-01-01

49

News from r-Process Nucleosynthesis: Consequences from the ESS to Early Stars  

NASA Astrophysics Data System (ADS)

The exact conditions for the supemova high-entropy wind (HEW) as one of the favored sites for the rapid neutron-capture (r-) process still cannot be reproduced self-consistently in present hydrodynamic astrophysical models. Therefore, we have performed large-scale dynamical network calculations within a parameterized HEW model to constrain the necessary conditions for a full r-process and to compare our results with recent observations. A model-inherently weighted superposition of entropy trajectories results in an excellent reproduction of the overall Solar-System isotopic abundances (Nr,solar) of the ``main'' r-process elements beyond Sn. For the lighter r-elements in the range 26<=Z<=42, our HEW model supports earlier qualitative ideas about a multiplicity of nucleosynthetic processes leading to the total Nr,solar distribution. In the HEW scenario, these suggestions are quantified, and the origin of the missing primary process is confirmed to be a rapid charged-particle process, thus excluding a ``weak'' neutron-capture component. This explains the recent halo-star observations of a Z-dependent non-correlation, respectively partial correlation of the lighter r-elements with metallicity and/or enrichment of ``main'' r-process elements.

Farouqi, K.; Kratz, K.-L.; Mashonkina, L. I.; Pfeiffer, B.; Thielemann, F.-K.

2008-04-01

50

r-process in Type II supernovae and the role of direct capture  

SciTech Connect

We have calculated r-process nucleosynthesis based on acoustic wave driven supernova simulation. The environment includes extremely high entropy cases which has not been studied in previous studies. Plenty of actinide and third peak elements are formed in an averaged abundance, while elements around the first and second peaks are overproduced. We also studied the effect of direct capture in r-process. The direct capture furthers r-process and make freeze out earlier. It will change the final abundance drastically. We recalculated r-process nucleosynthesis of the simulation considering the direct capture reaction. While we could not see a significant difference in averaged abundances, significant differences appeared in several individual yields.

Otsuki, K. [Hokkaido University, N10W8, Kita, Sapporo, Hokkaido, Japan 060-0810 (Japan); Burrows, A. [Princeton University, Princeton, NJ 08544 (United States); Martinez-Pinedo, G.; Typel, S.; Langanke, K. [GSI, Planckstrasse 1, 64291 Darmstadt (Germany); Matos, M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2010-06-01

51

R-process nucleosynthesis in the high-entropy supernova bubble  

NASA Astrophysics Data System (ADS)

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.

1992-11-01

52

R&D Continues to be an Important Part of the Innovation Process  

NSF Publications Database

... Process innovation appears as prevalent as product innovation. R&D is performed by 84 percent of ... product quality, increase or maintain market share, and extend product range within main product ...

53

The search for the site of the r-process. [rapid neutron capture in stellar nucleosynthesis  

NASA Technical Reports Server (NTRS)

A number of sites have been suggested for the r-process, including neutronized cores of exploding supernovae, jets of neutronized matter ejected from the collapse of rotating magnetized stellar cores, the helium and carbon zones of stars undergoing supernova explosions, and helium core flashes in low-mass stars. Despite much work and many advances in nuclear physics, the site or sites of the r-process is still unknown. Observations of metal-poor stars in the halo of the Galaxy indicate r-process production early in the history of the Galaxy and provide important constraints on galactic nucleosynthesis. Further observations of metal-poor stars, along with advances in understanding the nuclear properties of neutron-rich nuclei and improved astrophysical models of stars in the late stages of evolution, should help to identify the site of the r-process.

Cowan, John J.; Cameron, A. G. W.; Truran, J. W.; Sneden, Christopher

1986-01-01

54

The Sensitivity of r-PROCESS Nucleosynthesis to the Properties of Neutron-Rich Nuclei  

NASA Astrophysics Data System (ADS)

About half of the heavy elements in the Solar System were created by rapid neutron capture, or r-process, nucleosynthesis. In the r-process, heavy elements are built up via a sequence of neutron captures and beta decays in which an intense neutron flux pushes material out towards the neutron drip line. The nuclear network simulations used to test potential astrophysical scenarios for the r-process therefore require nuclear physics data (masses, beta decay lifetimes, neutron capture rates, fission probabilities) for thousands of nuclei far from stability. Only a small fraction of this data has been experimentally measured. Here we discuss recent sensitivity studies that aim to determine the nuclei whose properties are most crucial for r-process calculations.

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

2014-09-01

55

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

56

Processing of Escherichia coli 16S rRNA with bacteriophage lambda leader sequences.  

PubMed Central

To test whether any specific 5' precursor sequences are required for the processing of pre-16S rRNA, constructs were studied in which large parts of the 5' leader sequence were replaced by the coliphage lambda pL promoter and adjacent sequences. Unexpectedly, few full-length transcripts of the rRNA were detected after the pL promoter was induced, implying that either transcription was poor or most of the rRNA chains with lambda leader sequences were unstable. Nevertheless, sufficient transcription occurred to permit the detection of processing by S1 nuclease analysis. RNA transcripts in which 2/3 of the normal rRNA leader was deleted (from the promoter up to the normal RNase III cleavage site) were processed to form the normal 5' terminus. Thus, most of the double-stranded stem that forms from sequences bracketing wild-type 16S pre-rRNA is apparently not required for proper processing; the expression of such modified transcripts, however, must be increased before the efficiency of processing of the 16S rRNA formed can be assessed. Images

Krych, M; Sirdeshmukh, R; Gourse, R; Schlessinger, D

1987-01-01

57

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

58

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

59

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

NASA Astrophysics Data System (ADS)

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.; Bauswein, A.; Janka, H.-T.; Sida, J.-L.; Lemaître, J.-F.; Panebianco, S.; Dubray, N.; Hilaire, S.

2014-05-01

60

Analysis of Business Processes Specified in Z against an E-R Data Model.  

National Technical Information Service (NTIS)

A specification method for business processes is presented, in which not only the processes but also the database integrity constraints are specified in Z based on the structure of an Entity-Relationship data model. The formality of Z facilitates strict r...

J. Ginbayashi

1992-01-01

61

Shell-model calculations of beta-decay rates for s- and r-process nucleosyntheses  

SciTech Connect

Examples of large-basis shell-model calculations of Gamow-Teller ..beta..-decay properties of specific interest in the astrophysical s- and r- processes are presented. Numerical results are given for: (1) the GT-matrix elements for the excited state decays of the unstable s-process nucleus /sup 99/Tc; and (2) the GT-strength function for the neutron-rich nucleus /sup 130/Cd, which lies on the r-process path. The results are discussed in conjunction with the astrophysics problems. 23 refs., 3 figs.

Takahashi, K.; Mathews, G.J.; Bloom, S.D.

1985-10-09

62

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

63

The Hamburg/ESO R-process Enhanced Star survey (HERES). IX. Constraining pure r-process Ba/Eu abundance ratio from observations of r-II stars  

NASA Astrophysics Data System (ADS)

Context. The oldest stars born before the onset of the main s-process are expected to have a pure r-process Ba/Eu abundance ratio. Aims: We revised barium and europium abundances of selected very metal-poor (VMP) and strongly r-process enhanced (r-II) stars to evaluate an empirical r-process Ba/Eu ratio. Methods: Our calculations were based on non-local thermodynamic equilibrium (NLTE) line formation for Ba ii and Eu ii in the classical 1D MARCS model atmospheres. Homogeneous stellar abundances were determined from the Ba ii subordinate and resonance lines by applying a common Ba isotope mixture. We used high-quality VLT/UVES spectra and observational material from the literature. Results: For most investigated stars, NLTE leads to a lower Ba, but a higher Eu abundance. The resulting elemental ratio of the NLTE abundances amounts to, on average, log(Ba/Eu) = 0.78±0.06. This is a new constraint to pure r-process production of Ba and Eu. The obtained Ba/Eu abundance ratio of the r-II stars supports the corresponding solar system r-process ratio as predicted by recent Galactic chemical evolution calculations of Bisterzo, Travaglio, Gallino, Wiescher, and Käppeler. We present the NLTE abundance corrections for the Ba ii and Eu ii lines in the grid of VMP model atmospheres. Based on observations collected at the European Southern Observatory, Paranal, Chile (Proposal numbers 170.D-0010, and 280.D-5011).Tables 7 and 8 are available in electronic form at http://www.aanda.org

Mashonkina, L.; Christlieb, N.

2014-05-01

64

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

65

r-process Nucleosynthesis in Dynamically Ejected Matter of Neutron Star Mergers  

NASA Astrophysics Data System (ADS)

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 10-3-10-2 M sun are ejected, which is enough for mergers to be the main source of heavy (A >~ 140) galactic r-nuclei for merger rates of some 10-5 yr-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 ~15 km for a "stiff" nuclear equation of state (EOS) or ~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; Bauswein, Andreas; Janka, Hans-Thomas

2011-09-01

66

The r-process in the Neutrino-driven Wind from a Black-hole Torus  

NASA Astrophysics Data System (ADS)

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 ? 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 (~30 per nucleon in units of the Boltzmann constant) and moderate expansion timescales (~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 e, min ~ 0.2, is achieved. In the case of Y e, min ~ 0.3, the production of r-elements beyond A ~ 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 ~1 × 10-3 M ?. If our model was representative, this demands a Galactic event rate of ~2 × 10-4 yr-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; Janka, Hans-Thomas

2012-02-01

67

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

68

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

69

Detection of the Second r-process Peak Element Tellurium in Metal-poor Stars  

NASA Astrophysics Data System (ADS)

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 ? 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. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO-8342 and GO-12268. Some of the data presented in this Letter were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These data are associated with programs GO-7348, GO-7402, GO-8197, and GO-9455.

Roederer, Ian U.; Lawler, James E.; Cowan, John J.; Beers, Timothy C.; Frebel, Anna; Ivans, Inese I.; Schatz, Hendrik; Sobeck, Jennifer S.; Sneden, Christopher

2012-03-01

70

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

71

R&D Spillovers: Evidence from U.S. Food Processing, Farm Machinery and Agricultural Sectors  

Microsoft Academic Search

This paper computes private and social rates of return to R&D capital in the three vertically linked sectors, primary agriculture, food processing, and the farm machinery in the United States. Using a cost function approach, the private rates of return to R&D ranged from an average of 21.5% per annum for farm machinery to 87.5% for agriculture. The social rates

Munisamy Gopinath; Terry L. Roe

2000-01-01

72

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

73

R-process Nucleosynthesis in Alfven Wave-Driven Proto-Neutron Star Winds  

NASA Astrophysics Data System (ADS)

We propose magnetic proto-neutron star (PNS) winds driven by Alfvén waves as well as the neu- trino heating as an appropriate site for the r-process nucleosynthesis. Alfvén waves excited by surface motions of a PNS propagate outwardly, and they heat and accelerate the wind by dissipa- tion. In the Alfvén wave-driven wind, larger entropy per baryon and shorter dynamical time scale > are achieved, which favors the r-process. A PNS with surface B0 ˜ 5 × 1014G, gives suitable wind properties for the r-process in a typical case. We also perform nuclear reation calcuations and confirm this result; the 3rd peak elements are sufficiently synthesized in the Alfvén wave- driven wind in such a condition.

Suzuki, Takeru; Nagataki, Shigehiro; Wanajo, Shinya

74

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

75

Beta-delayed fission calculations for the astrophysical r-process  

SciTech Connect

We discuss RPA calculations of the Gamow-Teller properties of neutron-rich nuclei to study the effect of ..beta..-delayed fission and neutron emission on the production of Th, U and Pu chronometric nuclei in the astrophysical r-process. We find significant differences in the amount of ..beta..-delayed fission when compared with the recent calculations of Thielemann et al. (1983). In the simplest case of a constant abundance along the r-process path, however, the inferred production ratios in both calculations are similar.

Meyer, B.S.; Howard, W.M.; Mathews, G.J.; Moeller, P.; Takahashi, K.

1985-10-09

76

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

SciTech Connect

The isovector contribution to the imaginary component of the microscopic optical model potential is adjusted on experimental neutron strength function data. Within the Brueckner-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. [Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, Campus de la Plaine, CP 226, 1050 Brussels (Belgium); Delaroche, J.-P. [DPTA/Service de Physique Nucleaire, CEA/DAM Ile de France, BP 12, 91680 Bruyeres-le-Chatel (France)

2008-05-12

77

Long, cold, early r process? Neutrino-induced nucleosynthesis in He shells revisited.  

PubMed

We revisit a ?-driven r-process mechanism in the He shell of a core-collapse supernova, finding that it could succeed in early stars of metallicity Z ? 10?³ Z(?), at relatively low temperatures and neutron densities, producing A ~ 130 and 195 abundance peaks over ~10-20 s. The mechanism is sensitive to the ? emission model and to ? oscillations. We discuss the implications of an r process that could alter interpretations of abundance data from metal-poor stars, and point out the need for further calculations that include effects of the supernova shock. PMID:21668217

Banerjee, Projjwal; Haxton, W C; Qian, Yong-Zhong

2011-05-20

78

Long, Cold, Early r Process? Neutrino-Induced Nucleosynthesis in He Shells Revisited  

NASA Astrophysics Data System (ADS)

We revisit a ?-driven r-process mechanism in the He shell of a core-collapse supernova, finding that it could succeed in early stars of metallicity Z?10-3Z?, at relatively low temperatures and neutron densities, producing ˜130 and 195 abundance peaks over ˜10-20s. The mechanism is sensitive to the ? emission model and to ? oscillations. We discuss the implications of an r process that could alter interpretations of abundance data from metal-poor stars, and point out the need for further calculations that include effects of the supernova shock.

Banerjee, Projjwal; Haxton, W. C.; Qian, Yong-Zhong

2011-05-01

79

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

80

Processing pathway of Escherichia coli 16S precursor rRNA.  

PubMed Central

Immediate precursors of 16S rRNA are processed by endonucleolytic cleavage at both 5' and 3' mature termini, with the concomitant release of precursor fragments which are further metabolized by both exo- and endonucleases. In wild-type cells rapid cleavages by RNase III in precursor-specific sequences precede the subsequent formation of the mature ends; mature termini can, however, be formed directly from pre-16S rRNA with no intermediate species. The direct maturation is most evident in a strain deficient in RNase III, and the results in whole cells are consistent with results from maturation reactions in vitro. Thus, maturation does not require cleavages within the double-stranded stems that enclose mature rRNA sequences in the pre-16S rRNA. Images

Srivastava, A K; Schlessinger, D

1989-01-01

81

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

82

The neutrino-induced neutron source in helium shell and r-process nucleosynthesis  

NASA Astrophysics Data System (ADS)

The huge neutrino pulse that occurs during the collapse of a massive stellar core, is expected to contribute to the origination of a number of isotopes both of light chemical elements and heavy ones. In particular, evaporation of neutrons from helium nuclei excited by neutrino-nuclear inelastic collisions, may result in the r-process as it was first discussed by Epstein et al. (1988). Here we consider mainly the possibility to obtain the considerable amount of neutrons owing to the neutrino breakup of helium nuclei. It is shown that, in general, the heating of stellar matter due to the neutrino scattering off electrons and the heat released from the neutrino-helium breakup followed by the thermonuclear reactions should be taken into account. On the base of kinetic network, using all the important reactions up to Z=8, the main features and the time-dependent character of the neutrino-driven neutron flux are investigated. The time-dependent densities of free neutrons produced in helium breakup, Y_indis {n}(t), were used to calculate the r-process nucleosynthesis with another full kinetic network for ~ 3200 nuclides. It was found that in the case of metal-deficient stars, Z < 0.01 {Z}_sun, the resulting density of free neutrons seems to be high enough to drive the r-process efficiently under favorable conditions. But it is impossible to obtain a sufficient amount of heavy nuclei in neutrino-induced r-process in a helium shell at radii R > R_indis {cr}~ 10(9) cm. We speculate that to make the neutrino-induced r-process work efficiently in the shell, one has to invoke nonstandard presupernova models in which helium hopefully is closer to the collapsed core owing, for instance, to a large scale mixing or/and rotation and magnetic fields. Apart from this exotic possibility, the neutrino-induced nucleosynthesis in the helium shell is certainly not strong enough to explain the observed solar r-process abundances.

Nadyozhin, D. K.; Panov, I. V.; Blinnikov, S. I.

1998-07-01

83

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

84

Alfvén Wave-driven Proto-Neutron Star Winds and r-Process Nucleosynthesis  

NASA Astrophysics Data System (ADS)

We propose magnetic proto-neutron star (PNS) winds driven by Alfvén waves, as well as the neutrino heating, as an appropriate site for r-process nucleosynthesis. Alfvén waves excited by surface motions of a PNS propagate outwardly, and they heat and accelerate the wind by dissipation. Compared with the wind purely driven by neutrino heating, a larger entropy per baryon and shorter dynamical timescale are achieved, which favors the r-process. We study reasonable cases in which the wave amplitude is 10% of the Alfvén speed at the surface to find that a PNS with surface field strength >~5×1014 G gives suitable wind properties for the r-process, provided that the dissipation length of the wave is at most ~10 times the PNS radius. We also compare properties of transcritical and subcritical winds in light of the r-process. We finally discuss possibilities of detections of ?-rays from radioactive nuclei and absorption lines due to Ba in supernova remnants that possess magnetars.

Suzuki, Takeru K.; Nagataki, Shigehiro

2005-08-01

85

The neutrino-induced neutron source in helium shell and r-process nucleosynthesis  

Microsoft Academic Search

The huge neutrino pulse that occurs during the collapse of a massive stellar core, is expected to contribute to the origination of a number of isotopes both of light chemical elements and heavy ones. In particular, evaporation of neutrons from helium nuclei excited by neutrino-nuclear inelastic collisions, may result in the r-process as it was first discussed by Epstein et

D. K. Nadyozhin; I. V. Panov; S. I. Blinnikov

1998-01-01

86

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

87

Supernova Neutrino Effects on r-Process Nucleosynthesis in Black Hole Formation  

NASA Astrophysics Data System (ADS)

Very massive stars with mass >=8 Msolar culminate their evolution by supernova explosions, which are presumed to be the most viable candidates for the astrophysical sites of r-process nucleosynthesis. If the models for the supernova r-process are correct, then the results of nucleosynthesis could also put a significant constraint on the remnants of supernova explosions, i.e., a neutron star or black hole. In the case of very massive core collapse for a progenitor mass 20-40 Msolar, a remnant stellar black hole is thought to be formed. Intense neutrino flux from the neutronized core and the neutrinosphere might suddenly cease during the Kelvin-Helmholtz cooling phase because of the black hole formation. It is important and interesting to explore the observable consequences of such a neutrino flux truncation. It has recently been argued in the literature that even the neutrino mass can be determined from the time delay of the deformed neutrino energy spectrum after the cessation of neutrino ejection (neutrino cutoff effect). Here we study the expected theoretical response of the r-process nucleosynthesis to the neutrino cutoff effect in order to look for another independent signature of this phenomenon. We found a sensitive response of the r-process yield if the neutrino cutoff occurs after the critical time when the expanding materials in the neutrino-driven wind drop out of nuclear statistical equilibrium (NSE). The r-process nucleosynthesis yields drastically change if the cutoff occurs during the r-process, having maximal effect on the change in abundance of 232Th and 235,238U. There is a large probability of finding this effect in elemental abundances of r-process-enhanced metal-deficient halo stars whose chemical composition is presumed to be affected by Population III supernovae in the early Galaxy. Using this result, connected with future detection of the time variation of the SN neutrino spectrum, we are able to identify when the black hole formation occurs in the course of SN collapse.

Sasaqui, T.; Kajino, T.; Balantekin, A. B.

2005-11-01

88

Silver and palladium help unveil the nature of a second r-process  

NASA Astrophysics Data System (ADS)

Context. The rapid neutron-capture process, which created about half of the heaviest elements in the solar system, is believed to have been unique. Many recent studies have shown that this uniqueness is not true for the formation of lighter elements, in particular those in the atomic number range 38 < Z < 48. Among these, palladium (Pd) and especially silver (Ag) are expected to be key indicators of a possible second r-process, but until recently they have been studied only in a few stars. We therefore target Pd and Ag in a large sample of stars and compare these abundances to those of Sr, Y, Zr, Ba, and Eu produced by the slow (s-) and rapid (r-) neutron-capture processes. Hereby we investigate the nature of the formation process of Ag and Pd. Aims: We study the abundances of seven elements (Sr, Y, Zr, Pd, Ag, Ba, and Eu) to gain insight into the formation process of the elements and explore in depth the nature of the second r-process. Methods: By adopting a homogeneous one-dimensional local thermodynamic equilibrium (1D LTE) analysis of 71 stars, we derive stellar abundances using the spectral synthesis code MOOG, and the MARCS model atmospheres. We calculate abundance ratio trends and compare the derived abundances to site-dependent yield predictions (low-mass O-Ne-Mg core-collapse supernovae and parametrised high-entropy winds), to extract characteristics of the second r-process. Results: The seven elements are tracers of different (neutron-capture) processes, which in turn allows us to constrain the formation process(es) of Pd and Ag. The abundance ratios of the heavy elements are found to be correlated and anti-correlated. These trends lead to clear indications that a second/weak r-process, is responsible for the formation of Pd and Ag. On the basis of the comparison to the model predictions, we find that the conditions under which this process takes place differ from those for the main r-process in needing lower neutron number densities, lower neutron-to-seed ratios, and lower entropies, and/or higher electron abundances. Conclusions: Our analysis confirms that Pd and Ag form via a rapid neutron-capture process that differs from the main r-process, the main and weak s-processes, and charged particle freeze-outs. We find that this process is efficiently working down to the lowest metallicity sampled by our analysis ([Fe/H] = - 3.3). Our results may indicate that a combination of these explosive sites is needed to explain the variety in the observationally derived abundance patterns. Based on observations made with the ESO Very Large Telescope at Paranal Observatory, Chile (ID 65.L-0507(A), 67.D-0439(A), 68.B-0475(A), 68.D-0094(A), 71.B-0529(A); P.I. F. Primas).Appendices are available in electronic form at http://www.aanda.org

Hansen, C. J.; Primas, F.; Hartman, H.; Kratz, K.-L.; Wanajo, S.; Leibundgut, B.; Farouqi, K.; Hallmann, O.; Christlieb, N.; Nilsson, H.

2012-09-01

89

Rrp5 Binding at Multiple Sites Coordinates Pre-rRNA Processing and Assembly  

PubMed Central

Summary In vivo UV crosslinking identified numerous preribosomal RNA (pre-rRNA) binding sites for the large, highly conserved ribosome synthesis factor Rrp5. Intramolecular complementation has shown that the C-terminal domain (CTD) of Rrp5 is required for pre-rRNA cleavage at sites A0–A2 on the pathway of 18S rRNA synthesis, whereas the N-terminal domain (NTD) is required for A3 cleavage on the pathway of 5.8S/25S rRNA synthesis. The CTD was crosslinked to sequences flanking A2 and to the snoRNAs U3, U14, snR30, and snR10, which are required for cleavage at A0–A2. The NTD was crosslinked to sequences flanking A3 and to the RNA component of ribonuclease MRP, which cleaves site A3. Rrp5 could also be directly crosslinked to several large structural proteins and nucleoside triphosphatases. A key role in coordinating preribosomal assembly and processing was confirmed by chromatin spreads. Following depletion of Rrp5, cotranscriptional cleavage was lost and preribosome compaction greatly reduced.

Lebaron, Simon; Segerstolpe, Asa; French, Sarah L.; Dudnakova, Tatiana; de lima Alves, Flavia; Granneman, Sander; Rappsilber, Juri; Beyer, Ann L.; Wieslander, Lars; Tollervey, David

2013-01-01

90

Rrp5 binding at multiple sites coordinates pre-rRNA processing and assembly.  

PubMed

In vivo UV crosslinking identified numerous preribosomal RNA (pre-rRNA) binding sites for the large, highly conserved ribosome synthesis factor Rrp5. Intramolecular complementation has shown that the C-terminal domain (CTD) of Rrp5 is required for pre-rRNA cleavage at sites A0-A2 on the pathway of 18S rRNA synthesis, whereas the N-terminal domain (NTD) is required for A3 cleavage on the pathway of 5.8S/25S rRNA synthesis. The CTD was crosslinked to sequences flanking A2 and to the snoRNAs U3, U14, snR30, and snR10, which are required for cleavage at A0-A2. The NTD was crosslinked to sequences flanking A3 and to the RNA component of ribonuclease MRP, which cleaves site A3. Rrp5 could also be directly crosslinked to several large structural proteins and nucleoside triphosphatases. A key role in coordinating preribosomal assembly and processing was confirmed by chromatin spreads. Following depletion of Rrp5, cotranscriptional cleavage was lost and preribosome compaction greatly reduced. PMID:24239293

Lebaron, Simon; Segerstolpe, Asa; French, Sarah L; Dudnakova, Tatiana; de Lima Alves, Flavia; Granneman, Sander; Rappsilber, Juri; Beyer, Ann L; Wieslander, Lars; Tollervey, David

2013-12-12

91

r-Process nucleosynthesis: Present status and future experiments at the FRS and ESR  

NASA Astrophysics Data System (ADS)

No astrophysical process other than the rapid neutron capture process (r process) is used more often to motivate the necessity of the new-generation radioactive beam facilities with higher beam intensities. In the dawn of these facilities (RIBF at RIKEN, FRIB at Michigan State University, and FAIR in Darmstadt) experiments carried out at the presently existing facilities mark a transition between the past and the future. Two such facilities are the Fragment Separator (FRS) and Experimental Storage Ring (ESR) at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. Up to now one could only “scratch” the regions where the r process takes place-with the exception of the N=126 region, which remains an experimental “terra incognita”. Owing to the upgrade of the GSI accelerator and to the development of new highly sensitive and efficient detection techniques in view of the future FAIR facility, planned experiments at the FRS and ESR aim at filling this gap, approaching the r-process path also at N=126.

Dillmann, Iris; Litvinov, Yuri A.

2011-04-01

92

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

93

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

94

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

95

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

NASA Astrophysics Data System (ADS)

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.; Chiba, S.; Lorusso, G.; Nishimura, S.; Mathews, G. J.

2014-05-01

96

IL-4R?-Associated Antigen Processing by B Cells Promotes Immunity in Nippostrongylus brasiliensis Infection  

PubMed Central

In this study, B cell function in protective TH2 immunity against N. brasiliensis infection was investigated. Protection against secondary infection depended on IL-4R? and IL-13; but not IL-4. Protection did not associate with parasite specific antibody responses. Re-infection of B cell-specific IL-4R??/? mice resulted in increased worm burdens compared to control mice, despite their equivalent capacity to control primary infection. Impaired protection correlated with reduced lymphocyte IL-13 production and B cell MHC class II and CD86 surface expression. Adoptive transfer of in vivo N. brasiliensis primed IL-4R? expressing B cells into naïve BALB/c mice, but not IL-4R? or IL-13 deficient B cells, conferred protection against primary N. brasiliensis infection. This protection required MHC class II compatibility on B cells suggesting cognate interactions by B cells with CD4+ T cells were important to co-ordinate immunity. Furthermore, the rapid nature of these protective effects by B cells suggested non-BCR mediated mechanisms, such as via Toll Like Receptors, was involved, and this was supported by transfer experiments using antigen pulsed Myd88?/? B cells. These data suggest TLR dependent antigen processing by IL-4R?-responsive B cells producing IL-13 contribute significantly to CD4+ T cell-mediated protective immunity against N. brasiliensis infection.

Hoving, Jennifer C.; Nieuwenhuizen, Natalie; McSorley, Henry J.; Ndlovu, Hlumani; Bobat, Saeeda; Kimberg, Matti; Kirstein, Frank; Cutler, Anthony J.; DeWals, Benjamin; Cunningham, Adam F.; Brombacher, Frank

2013-01-01

97

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

98

New Precision Mass Measurements of Heavy ^252Cf Fission Fragments Near the r-Process Path  

NASA Astrophysics Data System (ADS)

Precision mass measurements of nuclides near the astrophysical r-process path are vital to reduce the uncertainties in the relevant neutron separation energies given by mass models, and the consequent abundance predictions. As part of an ongoing program, the Canadian Penning Trap mass spectrometer at Argonne National Laboratory has measured the masses of fission products from a ^252Cf source in a large-volume gas catcher. This has produced 38 new mass measurements of neutron-rich nuclides ranging from Z=51 to 64, many closer to the r-process path than had previously been measured for these elements. Systematic deviations from the AME 2003 are seen over a wide range of elements. The program of mass measurements will continue at the CARIBU upgrade to the ATLAS accelerator at ANL this fall.

van Schelt, J.; Savard, G.; Caldwell, S.; Sternberg, M.; Clark, J. A.; Greene, J. P.; Levand, A. F.; Sun, T.; Zabransky, B. J.; Fallis, J.; Sharma, K. S.; Lascar, D.; Segel, R. E.; Li, G.

2009-10-01

99

{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

100

Analysis of launch site processing effectiveness for the Space Shuttle 26R payload  

Microsoft Academic Search

A trend analysis study has been performed on problem reports recorded during the Space Shuttle 26R payload's processing cycle at NASA-Kennedy, using the defect-flow analysis (DFA) methodology; DFA gives attention to the characteristics of the problem-report 'population' as a whole. It is established that the problem reports contain data which distract from pressing problems, and that fully 60 percent of

Carlos A. Flores; Robert E. Heuser; Richard E. Pepper Jr.; Anthony M. Smith

1991-01-01

101

THE r-PROCESS IN PROTO-NEUTRON-STAR WIND REVISITED  

SciTech Connect

We examine the r-process in the neutrino-driven proto-neutron-star (PNS) wind of core-collapse supernovae in light of the recent findings of massive neutron stars in binaries as well as of an indication of neutron-richness in the PNS ejecta because of the nucleon potential corrections on neutrino opacities. To this end, a spherically symmetric, general relativistic, steady-state wind model is applied for a wide range of PNS masses between 1.2 M{sub Sun} and 2.4 M{sub Sun} with the latter reaching the causality limit. Nucleosynthesis calculations with these PNS models are performed by assuming a time evolution of electron fraction with its minimal value of Y{sub e} = 0.4, which mimics recent hydrodynamical results. The fundamental nucleosynthetic aspect of the PNS wind is found to be the production of Sr, Y, and Zr in quasi-equilibrium and of the elements with A Almost-Equal-To 90-110 by a weak r-process, which can be an explanation for the abundance signatures in r-process-poor Galactic halo stars. PNSs more massive than 2.0 M{sub Sun} can eject heavy r-process elements, however, with substantially smaller amount than what is needed to account for the solar content. PNS winds can be thus the major origin of light trans-iron elements but no more than 10% of those heavier than A {approx} 110, although they may be the sources of the low-level abundances of Sr and Ba found in numerous metal-poor stars if the maximum mass of PNSs exceeds 2.0 M{sub Sun }.

Wanajo, Shinya, E-mail: shinya.wanajo@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2013-06-20

102

The r-process in Proto-neutron-star Wind Revisited  

NASA Astrophysics Data System (ADS)

We examine the r-process in the neutrino-driven proto-neutron-star (PNS) wind of core-collapse supernovae in light of the recent findings of massive neutron stars in binaries as well as of an indication of neutron-richness in the PNS ejecta because of the nucleon potential corrections on neutrino opacities. To this end, a spherically symmetric, general relativistic, steady-state wind model is applied for a wide range of PNS masses between 1.2 M ? and 2.4 M ? with the latter reaching the causality limit. Nucleosynthesis calculations with these PNS models are performed by assuming a time evolution of electron fraction with its minimal value of Y e = 0.4, which mimics recent hydrodynamical results. The fundamental nucleosynthetic aspect of the PNS wind is found to be the production of Sr, Y, and Zr in quasi-equilibrium and of the elements with A ? 90-110 by a weak r-process, which can be an explanation for the abundance signatures in r-process-poor Galactic halo stars. PNSs more massive than 2.0 M ? can eject heavy r-process elements, however, with substantially smaller amount than what is needed to account for the solar content. PNS winds can be thus the major origin of light trans-iron elements but no more than 10% of those heavier than A ~ 110, although they may be the sources of the low-level abundances of Sr and Ba found in numerous metal-poor stars if the maximum mass of PNSs exceeds 2.0 M ?.

Wanajo, Shinya

2013-06-01

103

Controlled Perturbation of sets of line segments in R 2 with smart processing order  

Microsoft Academic Search

Controlled Perturbation is a framework for perturbing geometric sets to make the processes that use them more robust for fixed-precision manipulation. We present a Controlled Perturbation scheme for sets of line segments in R2 (CPLS, for short). CPLS iteratively perturbs the endpoints of the line segments to eliminate potential degeneracies that may cause round-off errors when using fixed-precision arithmetic. We

Eli Packer

2011-01-01

104

On the dynamics of proto-neutron star winds and r-process nucleosynthesis  

Microsoft Academic Search

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 of the thermodynamical evolution

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

2009-01-01

105

R-process nucleosynthesis in the high-entropy supernova bubble  

Microsoft Academic Search

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

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

1992-01-01

106

Analysis of rRNA processing and translation in mammalian cells using a synthetic 18S rRNA expression system.  

PubMed

Analysis of processing, assembly, and function of higher eukaryotic ribosomal RNA (rRNA) has been hindered by the lack of an expression system that enables rRNA to be modified and then examined functionally. Given the potential usefulness of such a system, we have developed one for mammalian 18S rRNA. We inserted a sequence tag into expansion segment 3 of mouse 18S rRNA to monitor expression and cleavage by hybridization. Mutations were identified that confer resistance to pactamycin, allowing functional analysis of 40S ribosomal subunits containing synthetic 18S rRNAs by selectively blocking translation from endogenous (pactamycin-sensitive) subunits. rRNA constructs were suitably expressed in transfected cells, shown to process correctly, incorporate into ? 15% of 40S subunits, and function normally based on various criteria. After rigorous analysis, the system was used to investigate the importance of sequences that flank 18S rRNA in precursor transcripts. Although deletion analysis supported the requirement of binding sites for the U3 snoRNA, it showed that a large segment of the 5' external transcribed spacer and the entire first internal transcribed spacer, both of which flank 18S rRNA, are not required. The success of this approach opens the possibility of functional analyses of ribosomes, with applications in basic research and synthetic biology. PMID:22718970

Burman, Luke G; Mauro, Vincent P

2012-09-01

107

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

108

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

109

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

110

In Search of r-Process 247Cm in the Early Solar System  

NASA Astrophysics Data System (ADS)

The r-process only nuclide 247Cm decays to 235U with a characteristic half-life of ˜16 million years. 247Cm is presently extinct, but offers considerable potential as a short-lived r-process chronometer, providing constraints on the time interval between the last r-process nucleosynthetic event and the formation of the solar system. The existence of "live" 247Cm in the early solar system should be manifested today as variations in 235U/238U, provided Cm was chemically fractionated from U when solids formed in the early solar system. The Cm-U system also has a direct bearing on the fundamental U-Pb cosmochronometer, which currently assumes no Cm effects in early solar system material. Using a Nu Instruments NuPlasma and new techniques in multiple-collector ICPMS, we are able to resolve variations in 235U/238U at the two epsilon level (2? ; 1 ? = 1 part in 10,000) on sample sizes consisting of <20 pg of 235U. The high precision of our measurements offers the potential to resolve 235U anomalies, including samples where Cm-U effects had previously been unobserved. Our first uranium isotopic measurements were acquired on bulk samples of a suite of carbonaceous chondrite, ordinary chondrite and eucrite meteorites, for which conflicting results had previously been obtained. These data show no well-resolved excursions in 235U/238U from the terrestrial value at the ˜2 epsilon level, and constrain the amount of 247Cm-produced excess 235U atoms to less than ˜1 x 108 atoms per gram of chondritic meteorite, with respect to terrestrial 235U/238U (Stirling et al., in press, Geochim. Cosmochim. Acta). We have extended the search for "live" 247Cm in the early solar system to small samples from mineral phases in primitive objects that are likely to display strong Cm-U fractionations. In particular, uranium isotopic measurements have been acquired on acid-etched leachates for a suite of chondritic meteorites, and for a suite of minerals separated from chondrites and angrites. Some of these data show resolvable excursions away from the composition of our terrestrial standard, and as such, have important implications for the 247Cm-235U cosmochronometer and the timing of r-process nucleosynthesis relative to the formation of the first solar system materials.

Stirling, C. H.; Halliday, A. N.; Potter, E.; Andersen, M. B.

2004-12-01

111

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

112

Nop2p is required for pre-rRNA processing and 60S ribosome subunit synthesis in yeast.  

PubMed Central

To investigate the function of the nucleolar protein Nop2p in Saccharomyces cerevisiae, we constructed a strain in which NOP2 is under the control of a repressible promoter. Repression of NOP2 expression lengthens the doubling time of this strain about fivefold and reduces steady-state levels of 60S ribosomal subunits, 80S ribosomes, and polysomes. Levels of 40S subunits increase as the free pool of 60S subunits is reduced. Nop2p depletion impairs processing of the 35S pre-rRNA and inhibits processing of 27S pre-rRNA, which results in lower steady-state levels of 25S rRNA and 5.8S rRNA. Processing of 20S pre-rRNA to 18S rRNA is not significantly affected. Processing at sites A2, A3, B1L, and B1S and the generation of 5' termini of different pre-rRNA intermediates appear to be normal after Nop2p depletion. Sequence comparisons suggest that Nop2p may function as a methyltransferase. 2'-O-ribose methylation of the conserved site UmGm psi UC2922 is known to take place during processing of 27S pre-rRNA. Although Nop2p depletion lengthens the half-life of 27S pre-RNA, methylation of UmGm psi UC2922 in 27S pre-rRNA is low during Nop2p depletion. However, methylation of UmGm psi UC2922 in mature 25S rRNA appears normal. These findings provide evidence for a close interconnection between methylation at this conserved site and the processing step that yields the 25S rRNA.

Hong, B; Brockenbrough, J S; Wu, P; Aris, J P

1997-01-01

113

Mass measurements beyond the major r-process waiting point 80Zn.  

PubMed

High-precision mass measurements on neutron-rich zinc isotopes (71m,72-81)Zn have been performed with the Penning trap mass spectrometer ISOLTRAP. For the first time, the mass of 81Zn has been experimentally determined. This makes 80Zn the first of the few major waiting points along the path of the astrophysical rapid neutron-capture process where neutron-separation energy and neutron-capture Q-value are determined experimentally. The astrophysical conditions required for this waiting point and its associated abundance signatures to occur in r-process models can now be mapped precisely. The measurements also confirm the robustness of the N=50 shell closure for Z=30. PMID:19437636

Baruah, S; Audi, G; Blaum, K; Dworschak, M; George, S; Guénaut, C; Hager, U; Herfurth, F; Herlert, A; Kellerbauer, A; Kluge, H J; Lunney, D; Schatz, H; Schweikhard, L; Yazidjian, C

2008-12-31

114

?-decay and neutron emission studies of r-process nuclei near ^137Sb  

NASA Astrophysics Data System (ADS)

The ?-decays of very neutron rich nuclides in the A=130 region, including the astrophysically relevant nuclei ^137Sb, were studied experimentally at the Helmholtzzentrum für Schwerionenforchung (GSI) using a stack of four 500 ?m thick double-sided silicon strip detectors in conjunction with the Mainz 4? neutron long counter detector. The system allows the time correlation of ion implant and decay events and the detection of neutrons emitted during the decay. We measured half-lives and branchings for ?-delayed neutron emission (Pn values) for a number of nuclei in the region. The impact of our results on various types of models for the astrophysical rapid neutron capture process (r-process) is explored.

Smith, Karl; Attallah, F.; Faestermann, T.; Giesen, U.; Geissel, H.; Hannawald, M.; Hausmann, M.; Hellstroem, M.; Kessler, R.; Kratz, K.-L.; Litvinov, Y.; Mahmud, H.; Mineva, M. N.; Montes, F.; Muenzenberg, G.; Pfeiffer, B.; Pereira Conca, J.; Santi, P.; Schatz, H.; Scheidenberger, C.; Schmidt, K.; Schneider, R.; Stolz, A.; Suemmerer, K.; Stadlmann, J.

2011-10-01

115

Precision Mass Measurements of Heavy ^252Cf Fission Fragments Near the r-Process Path  

NASA Astrophysics Data System (ADS)

Precision mass measurements of species near the astrophysical r-process path are vital to reduce the uncertainties in the relevant neutron separation energies given by mass models, and the consequent abundance predictions. As part of an ongoing program, the Canadian Penning Trap mass spectrometer at Argonne National Laboratory is measuring the masses of fission products from a 150 ?Ci ^252Cf source placed inside a new large-volume He gas catcher. New precision mass measurements have been made closer to the r-process path than have previously been published, with precisions near 15 keV/c^2. Presented measurements include Pr, Nd, Pm, Sm, Eu, and Gd to N = 96, 97, 98, 99, and 99 respectively, and our results differ from the AME 2003 by up to 515 keV/c^2. Work will continue with the current fission source until 2009, when measurements of many more neutron-rich isotopes will be made at the CARIBU upgrade to the ATLAS accelerator at ANL.

van Schelt, J.; Savard, G.; Caldwell, S.; Sternberg, M.; Clark, J. A.; Greene, J. P.; Levand, A. F.; Sun, T.; Zabransky, B. J.; Fallis, J.; Sharma, K. S.; Lascar, D.; Segel, R. E.; Li, G.

2008-10-01

116

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

117

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

118

The inferior frontal cortex in artificial syntax processing: an rTMS study.  

PubMed

The human capacity to implicitly acquire knowledge of structured sequences has recently been investigated in artificial grammar learning using functional magnetic resonance imaging. It was found that the left inferior frontal cortex (IFC; Brodmann's area (BA) 44/45) was related to classification performance. The objective of this study was to investigate whether the IFC (BA 44/45) is causally related to classification of artificial syntactic structures by means of an off-line repetitive transcranial magnetic stimulation (rTMS) paradigm. We manipulated the stimulus material in a 2 x 2 factorial design with grammaticality status and local substring familiarity as factors. The participants showed a reliable effect of grammaticality on classification of novel items after 5 days of exposure to grammatical exemplars without performance feedback in an implicit acquisition task. The results show that rTMS of BA 44/45 improves syntactic classification performance by increasing the rejection rate of non-grammatical items and by shortening reaction times of correct rejections specifically after left-sided stimulation. A similar pattern of results is observed in FMRI experiments on artificial syntactic classification. These results suggest that activity in the inferior frontal region is causally related to artificial syntax processing. PMID:18617159

Uddén, Julia; Folia, Vasiliki; Forkstam, Christian; Ingvar, Martin; Fernandez, Guillen; Overeem, Sebastiaan; van Elswijk, Gijs; Hagoort, Peter; Petersson, Karl Magnus

2008-08-11

119

?-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

120

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

PubMed

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?A?170 nuclei. Here, we apply a new scission-point model, called SPY, to derive the fission fragment distribution (FFD) of all relevant neutron-rich, fissioning nuclei. The model predicts a doubly asymmetric FFD in the abundant A?278 mass region that is responsible for the final recycling of the fissioning material. Using ejecta conditions based on relativistic NS merger calculations, we show that this specific FFD leads to a production of the A?165 rare-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. PMID:24483647

Goriely, S; Sida, J-L; Lemaître, J-F; Panebianco, S; Dubray, N; Hilaire, S; Bauswein, A; Janka, H-T

2013-12-13

121

Precision Mass Measurements of Heavy ^252Cf Fission Fragments Near the Astrophysical r-Process Path  

NASA Astrophysics Data System (ADS)

Precision mass measurements of species near the path of the astrophysical r-process---expected to occur in core-collapse supernovae or neutron star mergers---are vital to reduce the uncertainties in the relevant neutron separation energies given by mass models and the consequent predictions of nucleosynthesis yields. As part of an ongoing program, the Canadian Penning Trap mass spectrometer at Argonne National Laboratory is measuring the masses of fission products from a 150 ?Ci ^252Cf source placed inside a large-volume He gas catcher. Presented measurements include Pr, Nd, Pm, Sm, Eu, and Gd to N = 96, 97, 98, 99, 98, and 99 respectively with precisions near 15 keV/c^2, and our results differ from the AME 2003 by up to 390 keV/c^2. Measurements of many more neutron-rich isotopes will be made in 2009 at the CARIBU upgrade to the ATLAS accelerator at ANL, which is approaching operation.

van Schelt, J.; Savard, G.; Caldwell, S.; Sternberg, M.; Clark, J. A.; Greene, J. P.; Levand, A. F.; Sun, T.; Zabransky, B. J.; Fallis, J.; Sharma, K. S.; Lascar, D.; Segel, R. E.; Li, G.

2009-05-01

122

Structures of exotic 131,133Sn isotopes and effect on r-process nucleosynthesis  

SciTech Connect

Background: Four strong single-particle bound levels with strikingly similar level spacings have recently been measured in 131Sn and 133Sn. This similarity has not yet been addressed with a theoretical nuclear structure model. Information on these single particle bound levels, as well as on resonant levels above the neutron capture threshold, are also needed to determine neutron capture cross sections -- and corresponding capture reaction rates -- on 130,132Sn. The 130Sn(n,gamma) rate was shown in a recent sensitivity study to significantly impact the synthesis of heavy elements in the r-process in supernovae. Purpose: Understand the structure of bound and resonant levels in 131,133Sn, and determine if the densities of unbound resonant levels are sufficiently high to warrant statistical model treatments of neutron capture on 130,132Sn. Method: Single-particle bound and resonant levels for 131,133Sn are self-consistently calculated by the analytical continuation of the coupling constant (ACCC) based on a relativistic mean field (RMF) theory with BCS approximation. Results: We obtain four strong single-particle bound levels in both 131,133Sn with an ordering that agrees with experiments and spacings that, while differing from experiment, are consistent between the Sn isotopes. We also find at most one single-particle level in the effective energy range for neutron captures in the r-process. Conclusions: Our RMF+ACCC+BCS model successfully reproduces observed single-particle bound levels in 131,133Sn and self-consistently predicts single-particle resonant levels with densities too low for widely used traditional statistical model treatments of neutron capture cross sections on 130,132Sn employing Fermi gas level density formulations.

Zhang, Shisheng [ORNL; Smith, Michael Scott [ORNL; Arbanas, Goran [ORNL; Kozub, R. L. [Tennessee Technological University

2012-01-01

123

An r-process Kilonova Associated with the Short-hard GRB 130603B  

NASA Astrophysics Data System (ADS)

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 "kilonova"). The early afterglow fades rapidly with ? <~ -2.6 at t ? 8-32 hr post-burst and has a spectral index of ? ? -1.5 (F ?vpropt ???), leading to an expected near-IR brightness at the time of the first HST observation of m F160W(t = 9.4 days) >~ 29.3 AB mag. Instead, the detected source has m F160W = 25.8 ± 0.2 AB mag, corresponding to a rest-frame absolute magnitude of MJ ? -15.2 mag. The upper limit in the HST optical observations is m F606W >~ 27.7 AB mag (3?), indicating an unusually red color of V - H >~ 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 ej ? 0.03-0.08 M ? for v ej ? 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.

2013-09-01

124

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

125

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

126

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

127

Process R and D plan: Post-Baseline Research and Technology Subcontract Programs (Task 203)  

SciTech Connect

This Process R and D Plan defines Task 203 - Research and Technology Subcontract Programs - to be carried out as part of the ICRC Post Baseline Activities set forth in Letter No. ICRC/DOE-1777. Budgets and schedules for the programs in this task as well as a procedure for cost accounting, were also presented in this reference letter. The budgeted cost of each program is the contract price less any cost accruals before July 1, 1982 - the beginning of the Post Baseline Activity period. For the two programs without contracts i, place on July 1, 1981 (16.2, 22.4), the budgeted cost reflects the initial response to the request for proposal. The Task 203 programs fall into three categories: (1) Two Stage Liquefaction Process Support, (2) Product Characterization, and (3) Thermophysical Property Measurement. Each program description includes the classification, performing organization, background, justification, and task description of the work to be performed. A final report will be issued upon the completion of each program. Table I summarizes the programs and budgeted costs for Task 203 - Post Baseline Research and Technology Subcontract Programs.

Not Available

1983-01-01

128

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

Microsoft Academic Search

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

N. Fatherly; M. ONeill; A. Glemza

2008-01-01

129

HRIBF studies of r-process nuclei and first results with the new SuperORRUBA detector  

NASA Astrophysics Data System (ADS)

The astrophysical rapid neutron-capture process (r-process) is believed to have produced approximately half of the nuclear species more massive than Fe. Unfortunately, almost nothing is known about the structure of the majority of the extremely neutron-rich nuclei involved in the reaction flow. At exotic beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF), measurements with accelerated beams of fission fragments have provided some of the first spectroscopic information on many r-process nuclei. The new SuperORRUBA (Oak Ridge Rutgers University Barrel Array) detector has been constructed at the HRIBF to study such nuclei, and first results are presented.

Bardayan, D. W.; Ahn, S.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hardy, S.; Howard, M. E.; Jones, K. L.; Kozub, R. L.; O'Malley, P. D.; Manning, B.; Matoš, M.; Nesaraja, C. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Ratkiewicz, A.; Schmitt, K. T.; Smith, M. S.; Spassova, I.; Strauss, S.

2013-10-01

130

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

131

Right prefrontal HF-rTMS attenuates right amygdala processing of negatively valenced emotional stimuli in healthy females  

Microsoft Academic Search

Repetitive transcranial magnetic stimulation (rTMS) studies investigating brain imaging correlates of emotion modulation in healthy volunteers can improve our understanding of the ‘affective’ impact of this application. In this fMRI study, we focused on lateralized amygdala functioning when processing salient emotional visual stimuli after one high-frequency (HF)-rTMS session. In a ‘uniform sample’ of 20 right-handed, non-depressed, healthy female subjects we

C. Baeken; R. De Raedt; P. Van Schuerbeek; M. A. Vanderhasselt; J. De Mey; A. Bossuyt; R. Luypaert

2010-01-01

132

Vascular remodeling process in pulmonary arterial hypertension, with focus on miR-204 and miR-126 (2013 Grover Conference series)  

PubMed Central

Abstract Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized primarily by increased proliferation and resistance to apoptosis in distal pulmonary arteries. Previous literature has demonstrated that the transcription factors NFAT (nuclear factor of activated T cells) and HIF-1? (hypoxia inducible factor 1?) are extensively involved in the pathogenesis of this disease and, more recently, has implicated STAT3 (signal transducer and activator of transcription 3) in their activation. Novel research shows that miR-204, a microRNA recently found to be notably downregulated through induction of PARP-1 (poly [ADP-ribose] polymerase 1) by excessive DNA damage in PAH, inhibits activation of STAT3. Contemporary research also indicates systemic impairment of skeletal muscle microcirculation in PAH and attributes this to a debilitated vascular endothelial growth factor pathway resulting from reduced miR-126 expression in endothelial cells. In this review, we focus on recent research implicating miR-204 and miR-126 in vascular remodeling processes, data that allow a better understanding of PAH molecular pathways and constitute a new hope for future therapy.

2014-01-01

133

Structure And Decay Of Neutron-Rich Nuclides In The 115 <= A <= 138 Mass Range And r-Process Nucleosynthesis  

NASA Astrophysics Data System (ADS)

The structure and decay of neutron-rich r-process nuclides has been studied by a variety of means that take advantage of enhanced selectivity to permit identification of exotic nuclides. New level structures are presented for 134,135Sb along with data for Ag isomers and Cd yrast structures. Some of the properties measured play an important role in calculations of the yields of elements and isotopes produced in r-process nucleosynthesis that takes place at high temperature in the presence of large densities of neutrons.

Walters, W. B.; Stoyer, M. A.; Shergur, J.; Hoteling, N.; Ressler, J. J.; Rikovska, J.; Kratz, K.-L.; Wöhr, A.; Pfeiffer, B.; Arndt, O.; Mantica, P. F.; Tomlin, B.; Schatz, H.; Montes, F.; Brown, B. A.; Seweryniak, D.; Ravn, H.; Fedoseyev, V.; Köster, U.; Wu, C. Y.; Cline, D.; Hua, H.; Hayes, A. B.; ISOLDE Collaboration

2005-04-01

134

The RmaX Network: R-Matrix Calculations for X-Ray Atomic Processes  

Microsoft Academic Search

The RmaX network ('R-matrix for X-rays') has been formed to calculate using abinitio R-matrix techniques electron and photon collisional properties to higher precision than hitherto for transitions in the soft X-ray region, to improve understanding of the dynamics of X-ray transitions in astrophysical plasmas.

Keith A. Berrington

2000-01-01

135

RNA polymerase I transcription and pre-rRNA processing are linked by specific SSU processome components  

PubMed Central

Sequential events in macromolecular biosynthesis are often elegantly coordinated. The small ribosomal subunit (SSU) processome is a large ribonucleoprotein (RNP) required for processing of precursors to the small subunit RNA, the 18S, of the ribosome. We have found that a subcomplex of SSU processome proteins, the t-Utps, is also required for optimal rRNA transcription in vivo in the yeast Saccharomyces cerevisiae. The t-Utps are ribosomal chromatin (r-chromatin)-associated, and they exist in a complex in the absence of the U3 snoRNA. Transcription is required neither for the formation of the subcomplex nor for its r-chromatin association. The t-Utps are associated with the pre-18S rRNAs independent of the presence of the U3 snoRNA. This association may thus represent an early step in the formation of the SSU processome. Our results indicate that rRNA transcription and pre-rRNA processing are coordinated via specific components of the SSU processome.

Gallagher, Jennifer E.G.; Dunbar, David A.; Granneman, Sander; Mitchell, Brianna M.; Osheim, Yvonne; Beyer, Ann L.; Baserga, Susan J.

2004-01-01

136

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

137

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

138

Investigation of very neutron-rich Fe, Co and Ni isotopes encountered along the r-process path.  

National Technical Information Service (NTIS)

Very neutron-rich nuclei beyond Fe must be investigated in order to understand the r-process. New Ni, Co and Fe isotopes, with ten to twelve neutrons more than the heaviest stable isotopes, were discovered in the thermal fission of (sup 235)U and (sup 239...

S. Czajkowski M. Bernas J. L. Sida P. Armbruster H. Faust

1992-01-01

139

R-chondrite bulk-chemical compositions and diverse oxides: Implications for parent-body processes  

NASA Astrophysics Data System (ADS)

R chondrites are among the most oxidized chondrite groups; they also have the highest ?17O values known in whole-rock meteorites. We analyzed R chondrites (six Antarctic, four hot-desert) by instrumental neutron activation analysis. Data for one of the former and three of the latter show large weathering effects, but the remainder show only moderate scatter and permit us to determine trends and mean compositions for the group. Bulk R-chondrite compositions are similar to those in H and L chondrites, but the concentrations of several volatiles, especially Se and Zn, are higher; the more volatile the element, the higher the enrichment in R chondrites relative to H and L.

Isa, Junko; Rubin, Alan E.; Wasson, John T.

2014-01-01

140

Comparing the after-effects of continuous theta burst stimulation and conventional 1 Hz rTMS on semantic processing.  

PubMed

Our aim was to evaluate continuous theta burst stimulation (cTBS) as a tool to induce temporary impairment (virtual lesion) in semantic processing. Four groups with 20 subjects each were stimulated. In the three experimental groups the stimulation site was the left superior temporal cortex. Stimulation was either 1Hz repetitive transcranial magnetic stimulation (rTMS) at 100% resting motor threshold (RMT) or cTBS, with intensities of 80% or 90% active motor threshold (AMT). The TMS-control group was stimulated at the right medial prefrontal cortex with 1 Hz rTMS. After stimulation subjects accomplished a lexical decision task with a duration of about 20 min. In an additional fifth group the lexical decision task was performed without TMS. Reaction times were not influenced by cTBS applied with 80% AMT, but prolonged for about 80 ms with 90% AMT compared to the no stimulation condition. An increase of 140 ms was found after 1 Hz rTMS. The effect lasted for the whole task, but declined from the first to the second half of the experiment. The direct comparison of cTBS and 1 Hz rTMS suggests that both stimulation patterns can induce virtual lesions in the left superior temporal cortex and impair semantic processing. We suppose that cTBS could replace 1 Hz rTMS in this field since the application is faster and it is more comfortable to the subjects. PMID:23276670

Brückner, S; Kiefer, M; Kammer, T

2013-03-13

141

Mutation of R555 in CFTR-delta F508 enhances function and partially corrects defective processing.  

PubMed

The most common cystic fibrosis mutation deletes phenylalanine 508 in CFTR (CFTR-F508). This mutation causes the loss of CFTR Cl- channel activity by disrupting biosynthetic processing so that mutant protein does not reach the plasma membrane. It also decreases the rate at which mutant channels open. To identify second-site mutations that could reverse the effects of delta F508, we used a chimeric yeast STE6/CFTR system bearing the delta F508 mutation. This chimera manifests defective mating. After mutagenesis of the first nucleotide-binding domain, we found that mutation R555K partially restored mating. However, it also increased mating in the chimera lacking the delta F508 mutation. When we introduced the R555K mutation into human CFTR-delta F508, we found that the loss of apical Cl- current caused by delta F508 was partially restored, predominantly due to a partial correction of the delta F508 processing defect. Analysis of single CFTR Cl- channels showed that the R555K mutation did not correct the prolonged closed time associated with delta F508, rather it increased activity of both wild-type and delta F508 channels by prolonging the duration of bursts of activity. These data suggest that the region around residue R555 in the first nucleotide-binding domain is important both in determining the ability of the delta F508 protein to be properly processed and in determining channel function. PMID:8723647

Teem, J L; Carson, M R; Welsh, M J

1996-01-01

142

NMDA-R inhibition affects cellular process formation in Tilapia Melanocytes; a model for pigmented adrenergic neurons in process formation and retraction.  

PubMed

Parkinson's disease has long been described to be a product of dopamine and (or) melanin loss in the substanstia nigra (SN). Although most studies have focused on dopaminergic neurons, it is important to consider the role of pigment cells in the etiology of the disease and to create an in vitro live cell model for studies involving pigmented adrenergic cells of the SN in Parkinsonism. The Melanocytes share specific features with the pigmented adrenergic neurons as both cells are pigmented, contain adrenergic receptors and have cellular processes. Although the melanocyte cellular processes are relatively short and observable only when stimulated appropriately by epinephrine and other factors or molecules. This study employs the manipulation of N-Methyl-D-Aspartate Receptor (NMDA-R), a major receptor in neuronal development, in the process formation pattern of the melanocyte in order to create a suitable model to depict cellular process elongation and shortening in pigmented adrenergic cells. NMDA-R is an important glutamate receptor implicated in neurogenesis, neuronal migration, maturation and cell death, thus we investigated the role of NMDA-R potentiation by glutamate/KCN and its inhibition by ketamine in the behavior of fish scale melanocytes in vitro. This is aimed at establishing the regulatory role of NMDA-R in this cell type (melanocytes isolated form Tilapia) in a similar manner to what is observable in the mammalian neurons. In vitro live cell culture was prepared in modified Ringer's solution following which the cells were treated as follows; Control, Glutamate, Ketamine, Glutamate + Ketamine, KCN + Ketamine and KCN. The culture was maintained for 10 min and the changes were captured in 3D-Time frame at 0, 5 and 10 min for the control and 5, 7 and 10 min for each of the treatment category. Glutamate treatment caused formation of short cellular processes localized directly on the cell body while ketamine treatment (inhibition of NMDA-R) facilitated elongation of secondary cellular processes (highly branched) from primary major processes (Less branched); co-incubation of glutamate and ketamine induced short and highly branched process formation. Cyanide toxicity induced degeneration and reduction of cell size while co-treatment of cyanide and ketamine gave changes similar to that observed in glutamate-ketamine co-incubation. NMDA-R is present in the melanocytes. Activation of the receptor reduced elongation process, while inhibition of the receptor facilitated cell process elongation and branching. This confirms that like pigmented adrenergic cells of the nervous system, this cell contains NMDA-R and this receptor also regulates cell process elongation. The study also showed that inhibition of NMDA-R in melanocytes gave opposite outcomes to the role of the receptor in developing neurons; a function that is protective in adult neurons. PMID:24242214

Ogundele, Olalekan Michael; Okunnuga, Adetokunbo Adedotun; Fabiyi, Temitope Deborah; Olajide, Olayemi Joseph; Akinrinade, Ibukun Dorcas; Adeniyi, Philip Adeyemi; Ojo, Abiodun Ayodele

2014-06-01

143

Quasiclassical R -matrix theory of inelastic processes in collisions of electrons with HCl molecules  

SciTech Connect

The {ital R}-matrix theory for the vibrational excitation and dissociative attachment in {ital e}-HCl collisions is developed. Only one pole in the {ital R}-matrix expansion is included. This allows for making a connection between the {ital R}-matrix and the nonlocal-complex-potential theories, and for obtaining the expression for the dissociative-attachment cross section without using the {ital R}-matrix radius in the internuclear coordinate. All matrix elements in the equation for the vibrational-excitation and dissociative-attachment amplitudes are calculated using the quasiclassical approach. We study how the results depend on the number of vibrational levels of the neutral molecule included in the theory and show how to exclude the vibrational continuum by a modification of the nonlocal-complex potential. The results for the vibrational-excitation cross sections are extremely sensitive to the behavior of the {ital R}-matrix potential curve near the point of crossing this curve with the potential curve of the neutral molecule. Particularly in some cases the cross section at the threshold peak exhibits the boomerang oscillations earlier found for HCl by Domcke (in {ital Aspects} {ital of} {ital Electron}{minus}{ital Molecule} {ital Scattering} {ital and} {ital Photoionization}, edited by A. Herzenberg (AIP, New Haven, 1989), p. 169). The dissociative-attachment cross sections are in reasonable agreement with experiment and with other theories.

Fabrikant, I.I. (Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588-0111 (US))

1991-04-01

144

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 (Eötvös) 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

145

R&D activities in airborne SAR image processing/analysis at Lockheed Martin Canada  

NASA Astrophysics Data System (ADS)

We give an overview of some R&D projects in SAR imagery at Lockheed Martin Canada. These projects are motivated by airborne surveillance applications such as the landmass and coastal surveillance missions of the Canadian CP-140 (Aurora) aircraft. The activities reviewed here are: (1) R&D supports to CP-140 Spotlight SAR upgrade, (2) fast multiresolution prescreening filter for CFAR detection, (3) comparison of traditional and wavelet-based speckle filters and (4) high-level ship classification in high-resolution SAR imagery.

Gagnon, Langis; Oppenheim, H.; Valin, Pierre

1998-12-01

146

Explosive Nucleosynthesis in Magnetohydrodynamical Jets from Collapsars. II --- Heavy-Element Nucleosynthesis of s, p, r-Processes  

NASA Astrophysics Data System (ADS)

We investigate the nucleosynthesis in a massive star of 70 M_{?} with solar metallicity in the main sequence stage. The helium core mass after hydrogen burning corresponds to 32 M_{?}. Nucleosynthesis calculations have been performed during the stellar evolution and the jetlike supernova explosion of a collapsar model. We focus on the production of elements heavier than iron group nuclei. Nucleosynthesis calculations have been accomplished consistently from hydrostatic to dynamic stages by using large nuclear reaction networks, where the weak s-, p-, and r-processes are taken into account. We confirm that s-elements of 60 < A < 90 are highly overproduced relative to the solar abundances in the hydrostatic nucleosynthesis. During oxygen burning, p-elements of A > 90 are produced via photodisintegrations of seed s-elements. However, the produced p-elements are disintegrated in later stages except for ^{180}Ta. In the explosive nucleosynthesis, elements of 90 < A < 160 are significantly overproduced relative to the solar values owing to the r-process, which is very different from the results of spherical explosion models. Only heavy p-elements (N > 50) are overproduced via the p-process because of the low peak temperatures in the oxygen- and neon-rich layers. Compared with the previous study of r-process nucleosynthesis calculations in the collapsar model of 40 M_{?} by Fujimoto et al. [S. Fujimoto, M. Hashimoto, K. Kotake and S. Yamada, Astrophys. J. 656 (2007), 382; S. Fujimoto, N. Nishimura and M. Hashimoto, Astrophys. J. 680 (2008), 1350], our jet model cannot contribute to the third peak of the solar r-elements and intermediate p-elements, which have been much produced because of the distribution of the lowest part of electron fraction in the ejecta. Averaging the overproduction factors over the progenitor masses with the use of Salpeter's IMF, we suggest that the 70 M_{?} star could contribute to the solar weak s}-elements of 60 < A < 90 and neutron-rich elements of 90 < A < 160. We confirm the primary synthesis of light p-elements in the ejected matter of high peak temperature. The ejected matter has [Sr/Eu] ˜ -0.4, which is different from that of a typical r-process-enriched star CS22892-052 ([Sr/Eu] ˜ -1). We find that Sr-Y-Zr isotopes are primarily synthesized in the explosive nucleosynthesis in a similar process of the primary production of light p-elements, which has been considered as one of the sites of a lighter element primary process (LEPP).

Ono, M.; Hashimoto, M.; Fujimoto, S.; Kotake, K.; Yamada, S.

2012-10-01

147

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

148

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

149

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

150

Improving R&D processes by an ISO 9001-based Quality Management System  

Microsoft Academic Search

This paper presents practical experience in planning, implementing, and adopting a Quality Management System (QMS) for embedded systems development at VTT Electronics. The main objective for the development of the QMS was to make it practical for real-life embedded systems research and development (R&D) projects. We have applied the ISO 9001 standard and ISO 9000–3 guidelines in building the quality

Antti Auer; Jukka Karjalainen; Veikko Seppänen

1996-01-01

151

Heavy elements in globular clusters and dwarf galaxies as probes of the origin of r-process elements  

NASA Astrophysics Data System (ADS)

Chemical abundances of very metal-poor stars record the nucleosynthesis products in the early Galaxy. Previous observational studies have revealed that the r-process is the dominant source of neutron-capture elements in extremely metal-poor stars, but the total amount of neutron-capture elements relative to lighter elements (e.g. Fe) shows large star-to-star scatter. These features are key to understanding the astrophysical sites of the r-process as well as the formation of stellar systems including extremely metal-poor stars. Such abundance studies for neutron-capture elements have been extended to metal-poor stars in globular clusters and dwarf galaxies around the Milky Way, in addition to field halo stars. We investigated the abundance ratios of neutron-capture elements for an extremely metal-poor star in the Sextans dwarf galaxy for which a significant excess of Ba was detected by a previous study, and found that the origin of heavy elements in this object is the sprocess. Although the sample size is still small, no r-process enhanced star has been found in dwarf galaxies at such low metallicity, in contrast to the Galactic halo. From ourmeasurements of neutroncapture elements in three very metal-poor globular clusters, we confirmed star-to-star scatter of Eu abundance ratios in M15, but found that these clusters are almost homogeneously enriched in lighter neutron-capture elements.

Honda, Satoshi; Aoki, Wako; Arimoto, Nobuo; Sadakane, Kozo; Otsuki, Kaori; Kajino, Toshitaka; Mathews, Grant J.

2012-11-01

152

Astrophysical conditions for an r-process in the high-entropy wind scenario of type II supernovae  

NASA Astrophysics Data System (ADS)

Within a full dynamical parameter study including freezeout effects, we have determined the astrophysical conditions for an r-process in the so-called "neutrino-wind" scenario of core-collapse type II supernovae (SNII). We have started our calculations after the total photodisintegration of the matter above the nascent neutron star at 9?10 Kelvin with protons and neutrons. We have used the charged-particle network of Thielemann and the r-process code of Freiburghaus, combined with the NON-SMOKER neutron-capture rates of Rauscher, nuclear masses from the ETFSI-Q mass model and recent experimental and theoretical gross ?-decay properties. Using the three parameters V (expansion speed of the shock wave), S (entropy of the bubble) and the neutron-to-proton ratio Y, we show that the above quantities have to fulfill specific conditions in order to make a successful r-process. According to observations and hydrodynamical simulations, respectively, a realistic value for V is 7500 km/s, and Y<0.5.

Farouqi, K.; Freiburghaus, C.; Kratz, K.-L.; Pfeiffer, B.; Rauscher, T.; Thielemann, F.-K.

2005-07-01

153

The r-Process in the Neutrino Winds of Core-Collapse Supernovae and U-Th Cosmochronology  

NASA Astrophysics Data System (ADS)

The discovery of the second highly r-process-enhanced, extremely metal poor star, CS 31082-001 ([Fe/H]=-2.9) has provided a powerful new tool for age determination by virtue of the detection and measurement of the radioactive species uranium and thorium. Because the half-life of 238U is one-third that of 232Th, the U-Th pair can, in principle, provide a far more precise cosmochronometer than the Th-Eu pair that has been used in previous investigations. In the application of this chronometer, the age of (the progenitor of) CS 31082-001 can be regarded as the minimum age of the Galaxy, and hence of the universe. One of the serious limitations of this approach, however, is that predictions of the production ratio of U and Th have not been made in the context of a realistic astrophysical model of the r-process. We have endeavored to produce such a model, based on the ``neutrino winds'' that are expected to arise from the nascent neutron star of a core-collapse supernova. In this model, the proto-neutron star mass and the (asymptotic) neutrino sphere radius are assumed to be 2.0 Msolar and 10 km, respectively. Recent hydrodynamic studies indicate that there may exist difficulties in obtaining such a compact (massive and/or small in radius) remnant. Nevertheless, we utilize this set of parameter choices since previous work suggests that the third r-process peak (and thus U and Th) is hardly reached when one adopts a less compact proto-neutron star in the framework of the neutrino-wind scenario. The temperature and density histories of the material involved in the neutron-capture processes are obtained with the assumption of a steady flow of the neutrino-powered winds, with general relativistic effects taken into account. The electron fraction is taken to be a free parameter, constant with time. The r-process nucleosynthesis in these trajectories is calculated with a nuclear reaction network code including actinides up to Z=100. The mass-integrated r-process yields, obtained by assuming a simple time evolution of the neutrino luminosity, are compared to the available spectroscopic elemental abundance data of CS 31082-001. As a result, the ``age'' of this star is determined to be 14.1+/-2.5 Gyr, in excellent agreement with lower limits on the age of the universe estimated by other dating techniques, as well as with other stellar radioactive age estimates. Future measurements of Pt and Pb in this star, as well as expansion of searches for additional r-process-enhanced, metal-poor stars (especially those in which both U and Th are measurable), are of special importance to constrain the current astrophysical models for the r-process.

Wanajo, Shinya; Itoh, Naoki; Ishimaru, Yuhri; Nozawa, Satoshi; Beers, Timothy C.

2002-10-01

154

DD3R zeolite membranes in separation and catalytic processes: Modelling and application  

Microsoft Academic Search

Around 2004 the annual energy consumption of the Dutch (petro-)chemical industry was estimated to be 460 PJ of which 200 PJ could be allocated to separation processes [1]. In 2009, 15% of the global energy consumption was required for separation and purification processes to produce commodities. Moreover, it is expected that in 2040 the global commodity demand is three times

J. Van den Bergh

2010-01-01

155

s-process studies in the light of new experimental cross sections - Distribution of neutron fluences and r-process residuals  

NASA Technical Reports Server (NTRS)

A best set of neutron-capture cross sections has been evaluated for the most important s-process isotopes. With this data base, s-process studies have been carried out using the traditional model which assumes a steady neutron flux and an exponential distribution of neutron irradiations. The calculated sigma-N curve is in excellent agreement with the empirical sigma-N-values of pure s-process nuclei. Simultaneously, good agreement is found between the difference of solar and s-process abundances and the abundances of pure r-process nuclei. The abundance pattern of the iron group elements where s-process results complement the abundances obtained from explosive nuclear burning is discussed. The results obtained from the traditional s-process model such as seed abundances, mean neutron irradiations, or neutron densities are compared to recent stellar model calculations which assume the He-burning shells of red giant stars as the site for the s-process.

Kaeppeler, F.; Beer, H.; Wisshak, K.; Clayton, D. D.; Macklin, R. L.; Ward, R. A.

1982-01-01

156

S-process studies in the light of new experimental cross sections - Distribution of neutron fluences and r-process residuals  

NASA Astrophysics Data System (ADS)

A best set of neutron-capture cross sections has been evaluated for the most important s-process isotopes. With this data base, s-process studies have been carried out using the traditional model which assumes a steady neutron flux and an exponential distribution of neutron irradiations. The calculated sigma-N curve is in excellent agreement with the empirical sigma-N-values of pure s-process nuclei. Simultaneously, good agreement is found between the difference of solar and s-process abundances and the abundances of pure r-process nuclei. The abundance pattern of the iron group elements where s-process results complement the abundances obtained from explosive nuclear burning is discussed. The results obtained from the traditional s-process model such as seed abundances, mean neutron irradiations, or neutron densities are compared to recent stellar model calculations which assume the He-burning shells of red giant stars as the site for the s-process.

Kaeppeler, F.; Beer, H.; Wisshak, K.; Clayton, D. D.; Macklin, R. L.; Ward, R. A.

1982-06-01

157

An effective eigenchannel R-matrix calculation of electron-ion scattering processes with spectroscopic precision  

NASA Astrophysics Data System (ADS)

Using our eigenchannel R-matrix method, the scattering matrices in the whole energy regions can be directly calculated with spectroscopic precision. From the short range scattering matrices, various scattering cross sections, such as total excitation cross sections, differential cross sections and so on, can be obtained. The e+Kr+ system is used as an illustration example, the degree of accuracies of scattering matrices is calculated within about 6%, which should be much more accurate than state-of-the-art scattering experiments.

Gao, Xiang; Li, Jia-Ming

2014-04-01

158

A new tool for studying GNSS-R signals for applications in surface hydrology processes  

NASA Astrophysics Data System (ADS)

Receiving Global Navigation Satellite System (GNSS) signals that are reflected off the surface, together with directly received GNSS signals makes possible the monitoring of the water level variations over land and ocean. In the context of the development of a new GNSS-R research activity at GRGS in Toulouse, we have built a simulator for modeling the trajectories of GNSS electromagnetic waves that are reflected on the surface of the Earth (i.e., water and soil), as realistic as possible, once the satellite constellation is known by orbit ephemeris, and the position of the receiver is fixed for a peculiar time session. It includes the possible masking of the terrestrial topography that may cancel the reception of GNSS satellites. Atmospheric delay effects derived from mapping functions are also taken into account for both direct and reflected signals. Our simulator helps us for determining the availability and geographical locations at an accuracy lesser than 10 cm of the specular reflection points, and thus selecting an optimal site for getting meaningful GNSS-R observations. In the future, analysis of the reflected waveforms proposed by our simulator would allow us to estimate other parameters such as significant ocean wave height, surface wind speed and soil moisture content.

Roussel, Nicolas; Frappart, Frédéric; Ramillien, Guillaume; Desjardins, Camille; Gegout, Pascal; Biancale, Richard; Perosanz, Félix

2013-04-01

159

Hydrogen Technology Validation as a "Learning Demonstration" that Feeds the R&D Process (Presentation)  

SciTech Connect

This presentation, which provides information about how hydrogen technology validation is used as a learning demonstration that feeds the research and development process, was given at a National Hydrogen Association meeting in April 2004.

Wipke, K.; Gronich, S.; Hooker, D.

2004-04-01

160

Classification of Counseling and Therapy Theorists, Methods, Processes, and Goals: The E-R-A Model.  

ERIC Educational Resources Information Center

Presents an Emotionality-Rationality-Activity model that integrates recent classifications of counseling and psychotherapy. The model also serves as a theoretical basis from which methods, goals, and processes during counseling, psychotherapy, and training can be derived and integrated. (Author)

L'Abate, Luciano

1981-01-01

161

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

162

CircE: an R implementation of Browne's circular stochastic process model.  

PubMed

In confirmatory analysis of whether data have a circumplex structure, Browne's (1992) model has played a major role. However, implementation of this model requires a dedicated program, CIRCUM, because the analysis routine is not integrated in any of the most widely used statistical software packages. Hence, data entry and graphical representation of the results require the use of one or more additional programs. We propose a package for the R statistical environment, termed CircE, that can be used to enter or import data, implement Browne's confirmatory analysis, and graphically represent the results. Using this new software, we put forward a new approach to assess the sustainability of theoretical models when the analysis is carried out at the level of questionnaire items. The CircE package (for either Mac OS X or Windows) and additional files may be downloaded from http://brm.psychonomic-journals.org/content/supplemental. PMID:20160286

Grassi, Michele; Luccio, Riccardo; Di Blas, Lisa

2010-02-01

163

Streamlining digital signal processing: A tricks of the trade guidebook (R. Lyons, Ed.) [book review  

Microsoft Academic Search

This book is a collection of 28 digital signal processing (DSP) tricks (chapters) that the book's editor managed to glean, finagle, or coerce from a very talented group of practicing engineers. The book is organized into five sections covering efficient digital filters, signal and spectrum analysis tricks, fast function approximation algorithms, signal generation techniques and assorted high-performance DSP techniques. Almost

Al Clark

2008-01-01

164

E Td i rP Entrepreneurial .___ _ .Research: Contextual and Process Issues  

Microsoft Academic Search

Low and MacMillan (1988) suggested that research into entrepreneurial behavior should consider contextual issues and identify the processes that explain rather than merely de- scribe the entrepreneurial phenomenon. Recent studies focusing upon entrepreneurial be- havior, especially heuristics, and differences between 'types' of entrepreneurs are dis- cussed in this review. The literature focusing upon opportunity recognition and information search is examined.

Deniz Ucbasaran; Paul Westhead; Mike Wright

165

Pri-miR-17-92a transcript folds into a tertiary structure and autoregulates its processing  

PubMed Central

MicroRNAs control gene expression either by RNA transcript degradation or translational repression. Expressions of miRNAs are highly regulated in tissues, disruption of which leads to disease. How this regulation is achieved and maintained is still largely unknown. MiRNAs that reside on clustered or polycistronic transcripts represent a more complex case where individual miRNAs from a cluster are processed with different efficiencies despite being cotranscribed. To shed light on the regulatory mechanisms that might be operating in these cases, we considered the long polycistronic primary miRNA transcript pri-miR-17-92a that contains six miRNAs with diverse functions. The six miRNA domains on this cluster are differentially processed to produce varying amounts of resultant mature miRNAs in different tissues. How this is achieved is not known. We show, using various biochemical and biophysical methods coupled with mutational studies, that pri-miR-17-92a adopts a specific three-dimensional architecture that poses a kinetic barrier to its own processing. This tertiary structure could create suboptimal protein recognition sites on the pri-miRNA cluster due to higher-order structure formation.

Chakraborty, Saikat; Mehtab, Shabana; Patwardhan, Anand; Krishnan, Yamuna

2012-01-01

166

Human RNase H1 Is Associated with Protein P32 and Is Involved in Mitochondrial Pre-rRNA Processing  

PubMed Central

Mammalian RNase H1 has been implicated in mitochondrial DNA replication and RNA processing and is required for embryonic development. We identified the mitochondrial protein P32 that binds specifically to human RNase H1, but not human RNase H2. P32 binds human RNase H1 via the hybrid-binding domain of the enzyme at an approximately 1?1 ratio. P32 enhanced the cleavage activity of RNase H1 by reducing the affinity of the enzyme for the heteroduplex substrate and enhancing turnover, but had no effect on the cleavage pattern. RNase H1 and P32 were partially co-localized in mitochondria and reduction of P32 or RNase H1 levels resulted in accumulation of mitochondrial pre ribosomal RNA [12S/16S] in HeLa cells. P32 also co-immunoprecipitated with MRPP1, a mitochondrial RNase P protein required for mitochondrial pre-rRNA processing. The P32-RNase H1 complex was shown to physically interact with mitochondrial DNA and pre-rRNA. These results expand the potential roles for RNase H1 to include assuring proper transcription and processing of guanosine-cytosine rich pre-ribosomal RNA in mitochondria. Further, the results identify P32 as a member of the ‘RNase H1 degradosome’ and the key P32 enhances the enzymatic efficiency of human RNase H1.

Wu, Hongjiang; Sun, Hong; Liang, Xuehai; Lima, Walt F.; Crooke, Stanley T.

2013-01-01

167

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

168

511. An Enzyme Linked Immunosorbent Assay for the Detection of Herpes Simplex Virus Type 1 Proteins in a Novel rAAV Production and Purification Process  

Microsoft Academic Search

AGTC has developed a recombinant herpes simplex virus (rHSV-1)-based adeno-associated virus (AAV) production process. This method requires two rHSV-1 viruses; rHSV-1-rep\\/cap which expresses the AAV2 rep and cap proteins, and a second rHSV-1 that contains the therapeutic gene of interest flanked by AAV2 inverted terminal repeats (ITRs) necessary for rAAV production. Following co-infection of these two helper viruses onto HEK-293

Guo-jie Ye; Tammy Mandell

2006-01-01

169

Proto-Neutron Star Winds With Magnetic Fields and Rotation: Implications for Magnetar Birth, GRBs, and r-process Nucleosynthesis  

NASA Astrophysics Data System (ADS)

We solve the 1D neutrino-heated non-relativistic MHD wind problem for conditions that range from slowly rotating (spin period P > 10 ms) protoneutron stars (PNSs) with surface field strengths typical of radio pulsars (B < 10^13 G), to "proto-magnetars" with B 10^14-10^15 G in their hypothesized rapidly rotating initial states (P 1 ms). We use the simulations of Bucciantini et al. (2006) to map our monopole results onto a more physical dipole geometry and to estimate the spindown of PNSs when their winds are relativistic. We then quantify the effects of rotation and magnetic fields on the mass loss, energy loss, and r-process nucleosynthesis in PNS winds. We describe the evolution of PNS winds through the Kelvin-Helmholtz cooling epoch, emphasizing the transition between (1) thermal neutrino-driven, (2) non-relativistic magnetically-dominated, and (3) relativistic magnetically-dominated outflows. We find that proto-magnetars with P 1 ms and B > 10^15 G drive relativistic winds with luminosities, energies, and Lorentz factors (magnetization sigma 1-1000) consistent with those required to produce long duration gamma-ray bursts and hyper-energetic supernovae (SNe). A significant fraction of the rotational energy may be extracted in only a few seconds, sufficiently rapidly to alter the asymptotic energy of the SN remnant, its morphology, and, potentially, its nucleosynthetic yield. Winds from PNSs with more modest rotation periods (2 10 ms) and with magnetar-strength fields produce conditions significantly more favorable for the r-process than winds from slowly rotating PNSs. Lastly, we show that energy and momentum deposition by convectively-excited waves further increase the likelihood of successful r-process in PNS winds.

Metzger, Brian D.; Thompson, T. A.; Quataert, E.

2006-12-01

170

Evaluation of bleached kraft mill process water using Microtox(R), Ceriodaphnia dubia, and Menidia beryllina toxicity tests.  

PubMed

To determine whether a 7- to 10-d embryo toxicity/teratogenicity test with the inland silverside fish, Menidia beryllina, is a sensitive indicator for evaluation of bleached kraft mill effluents, we compared this test with the Microtox(R) 15-min acute toxicity test and the Ceriodaphnia dubia 7-d chronic toxicity test. Water samples used in each test were collected from three areas in a bleached kraft pulp and paper mill using a 100% chlorine dioxide bleaching process: 1) river water prior to use in the mill; 2) the combined acid/base waste stream from the pulping process prior to biological treatment in the aerated stabilization basin (ASB); and 3) the effluent from the ASB with a retention time of approximately 11 d. Relative toxicity determined by the three tests for each water sampling location was compared. All three toxicity tests were predictive indicators of toxicity; however, the C. dubia and M. beryllina tests were the more similar and sensitive indicators of toxicity. Process water (ASB influent) prior to biological treatment in the ASB was toxic at all concentrations using the Microtox(R) and C. dubia tests. The fish embryo test showed no toxicity at 1% concentrations, slight toxicity at 10%, and acute toxicity at the 100% ASB influent concentration. Tests with biologically-treated ASB effluent indicated a substantial reduction in observed toxicity to Microtox(R) bacteria, C. dubia, and M. beryllina. No toxic responses were observed in any test at a 1% ASB effluent concentration which was the approximate effluent concentration in the receiving river following mixing. No relationship was found among any toxicological response and effluent levels of adsorbable organic halides, polychlorinated phenolic compounds, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, total suspended solids, color, chemical oxygen demand, or total organic carbon. PMID:9175501

Middaugh, D P; Beckham, N; Fournie, J W; Deardorff, T L

1997-05-01

171

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

172

Chemical Process Research Department substitute-natural-gas supply R and D status report. December 1987  

SciTech Connect

This document discusses the status of ongoing and planned substitute natural gas supply-related research activities in GRI's Chemical Process Research Program as described in the 1988 GRI plan. The program is part of a broad research program to develop the technologies for providing new gas supplies from natural and synthetic sources while also addressing economic, environmental, and safety issues. An exploratory RandD activity is also in progress to examine new chemistry and catalysts for converting natural gas to higher-valued products. Areas covered are coal gasification, in-situ coal gasification, methane from wastes, coal sciences, and gas separation and chemical processes. Presented are objectives and goals, accomplishments, strategy and basis for each project area, and 1987 status review sheets for projects within the project area.

Not Available

1987-12-01

173

A SIMULINK c ? AND TEXAS INSTRUMENTS C6713r BASED DIGITAL SIGNAL PROCESSING LABORATORY  

Microsoft Academic Search

In this contribution1 a digital signal processing educational lab, es- tablished at the School of Electrical and Computers Engineering at Bar-Ilan University, Israel is presented. A unique educational approach is adopted. In this approach so- phisticated algorithms can be implemented in an intuitive top-level design using Simulink c ?. Simultaneously, our approach gives the students the opportunity to conduct hands-on

Sharon Gannot; Vadim Avrin

174

Functional cooperation of the mitochondrial processing peptidase subunits 1 1 Edited by R. Huber  

Microsoft Academic Search

Domains important for the activity of the heterodimeric mitochondrial processing peptidase (MPP) were investigated, by inserting one alanine residue at ten positions along the polypeptide chain of the ?-subunit (?-MPP). An alanine residue inserted after Glu70, Ser114, Lys215 and Ser314 respectively, abolished the cleavage activity of MPP. When the ?-subunit (?-MPP) was co-expressed with N-terminal hexa-histidine tagged ?-MPP, ?-MPP was

Pierre Luciano; Séverine Geoffroy; Anders Brandt; Jean-François Hernandez; Vincent Géli

1997-01-01

175

Proenzymic C1s associated with catalytic amounts of C1r. Study of the activation process.  

PubMed

1. Proenzymic C1s isolated from human plasma by euglobulin precipitation and DEAE-cellulose chromatography is associated with trace amounts of C1r (0.5--1% on a molar basis). Incubation for 2 h at 37 degrees C leads to the proteolytic activation of C1s. The proteolysis is characterized by the sigmoidal appearance of C1s esterase activity and of the typical heavy (57 000-dalton) and light (28 000-dalton) fragments of C1s on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. 2. The C1s activation process observed is markedly temperature and concentration dependent, and the rate of activation is decreased by calcium and high ionic strength (I = 0.9). Diisopropyl phosphorofluoridate, benzamidine, polyanethol sulfonate and pentosane polysulphate inhibit the activation, which is also sensitive to C1-inactivator and anti-C1r IgC. From the kinetic experiments and from the inhibition characteristics, the activation of C1s can be attributed to the presence of C1r, which appears to undergo activation and then to activate secondarily C1s. PMID:303116

Arlaud, G J; Reboul, A; Colomb, M G

1977-11-23

176

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

177

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

178

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

179

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

180

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

181

New half-lives of r-process Zn and Ga isotopes measured with electromagnetic separation.  

PubMed

The ? decays of neutron-rich nuclei near the doubly magic (78)Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of (82)Zn (228±10??ms), (83)Zn (117±20??ms), and (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 (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. PMID:23005622

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; Królas, W; Ku?niak, A; Mazzocchi, C; Mendez, A J; Miernik, K; Padgett, S W; Paulauskas, S V; Ramayya, A V; Winger, J A; Woli?ska-Cichocka, M; Zganjar, E F

2012-09-14

182

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

183

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

NASA Astrophysics Data System (ADS)

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.

2013-05-01

184

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

185

An Exploratory Study of the Coordinating Mechanisms Between R and D and Marketing as an Influence on the Innovation Process. Final Report.  

National Technical Information Service (NTIS)

Marketing and R&D are reciprocally dependent for information flows, key decisions, and resource commitments that are fundamental to the firm's innovation process. Thus, it is essential that the two parties achieve organizational integration: a state of hi...

W. E. Souder

1977-01-01

186

The r Process in the region of transuranium elements and the contribution of fission products to the nucleosynthesis of nuclei with A ? 130  

Microsoft Academic Search

We discuss the influence of nuclear masses and mass distributions of fission products on the formation of heavy elements at\\u000a the final stages of the r-process recycled through fission on long duration timescales. The fission recycling is of great importance in an environment\\u000a with a high density of free neutrons (e.g., in neutron star merger scenarios), when the r-process duration

I. V. Panov; I. Yu. Korneev; F.-K. Thielemann

2008-01-01

187

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

PubMed

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

188

The Fuel Processing Research Facility - A Platform for the Conduct of Synthesis Gas Technology R&D  

SciTech Connect

Vision 21 is the U. S. Department of Energy's initiative to deploy high efficiency, ultraclean co-production coal conversion power plants in the twenty-first century. These plants will consist of power and co-production modules, which are integrated to meet specific power and chemical markets. A variety of fuel gas processing technology issues involving gas separations, cleanup, gas-to-liquid fuels production and chemical synthesis, to mention a few, will be addressed by the program. The overall goal is to effectively eliminate, at competitive costs, environmental concerns associated with the use of fossil fuels for producing electricity and transportation fuels. The Fuel Processing Research Facility (FPRF) was developed as a fuel-flexible platform to address many of these technology needs. The facility utilizes a simplified syngas generator that is capable of producing 2,000 standard cubic feet per hour of 900 degree Celsius and 30 atmosphere synthesis gas that can be tailored to the gas composition of interest. It was built on a ''mid-scale'' level in an attempt to successfully branch the traditionally difficult scale-up from laboratory to pilot scale. When completed, the facility will provide a multi-faceted R&D area for the testing of fuel cells, gas separation technologies, and other gas processing unit operations.

Monahan, Michael J.; Berry, David A.; Gardner, Todd H.; Lyons, K. David

2001-11-06

189

R-phycoerythrin as a time-temperature integrator to verify the thermal processing adequacy of beef patties.  

PubMed

The objective of this study was to relate R-phycoerythrin (PE) fluorescence decay to the inactivation of Salmonella in beef patties cooked using adequate and inadequate thermal processes as defined by the U.S. Department of Agriculture (USDA) safe harbor requirements and lethality standards. Ground beef containing 4.8 or 19.1% fat was inoculated with an eight-strain cocktail of Salmonella and formed into 113-g patties. Capillary tubes containing PE in borate buffer at pH 9.0 were attached to a thermocouple and inserted horizontally into the patties. Patties (n = 43) were cooked on a grill maintained at 177 degrees C for 6 to 13 min and reached internal temperatures ranging from 57 to 77 degrees C. Patties were analyzed for Salmonella survivors and for fluorescence decay of PE. The thermal lethality of each process was calculated at a reference temperature of 65 degrees C. Twenty-four of the 43 high-fat patties met the USDA safe harbor regulations, with thermal lethalities of >66 s, whereas only 20 of these patties met the proposed 5-log10 lethality standard. Three of the 20 low-fat patties that met USDA regulations did not meet the proposed lethality standard. A normalized PE fluorescence value of about 0.3 (confidence interval = 99%) indicated that patties had been processed sufficiently to reduce Salmonella by 5 log10 cycles. PE has the potential for use as a marker to verify processing adequacy in food-processing plants and in other settings in which the use of the target pathogen is inappropriate. PMID:12030293

Smith, S E; Orta-Ramirez, A; Ofoli, R Y; Ryser, E T; Smith, D M

2002-05-01

190

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

191

The essential WD-repeat protein Rsa4p is required for rRNA processing and intra-nuclear transport of 60S ribosomal subunits  

PubMed Central

We report the characterization of a novel factor, Rsa4p (Ycr072cp), which is essential for the synthesis of 60S ribosomal subunits. Rsa4p is a conserved WD-repeat protein that seems to localize in the nucleolus. In vivo depletion of Rsa4p results in a deficit of 60S ribosomal subunits and the appearance of half-mer polysomes. Northern hybridization and primer extension analyses of pre-rRNA and mature rRNAs show that depletion of Rsa4p leads to the accumulation of the 27S, 25.5S and 7S pre-rRNAs, resulting in a reduction of the mature 25S and 5.8S rRNAs. Pulse–chase analyses of pre-rRNA processing reveal that, at least, this is due to a strong delay in the maturation of 27S pre-rRNA intermediates to mature 25S rRNA. Furthermore, depletion of Rsa4p inhibited the release of the pre-60S ribosomal particles from the nucleolus to the nucleoplasm, as judged by the predominantly nucleolar accumulation of the large subunit Rpl25-eGFP reporter construct. We propose that Rsa4p associates early with pre-60S ribosomal particles and provides a platform of interaction for correct processing of rRNA precursors and nucleolar release of 60S ribosomal subunits.

de la Cruz, Jesus; Sanz-Martinez, Eloisa; Remacha, Miguel

2005-01-01

192

MiR-138 downregulates miRNA processing in HeLa cells by targeting RMND5A and decreasing Exportin-5 stability  

PubMed Central

MicroRNAs (miRNAs) are a class of non-coding small RNAs that consist of ?22 nt and are involved in several biological processes by regulating target gene expression. MiR-138 has many biological functions and is often downregulated in cancers. Our results showed that overexpression of miR-138 downregulated target RMND5A (required for meiotic nuclear division 5 homolog A) and reduced Exportin-5 stability, which results in decreased levels of pre-miRNA nuclear export in HeLa cells. We also found that miR-138 could significantly inhibit HeLa cell migration by targeting RMND5A. Our study therefore identifies miR-138–RMND5A–Exportin-5 as a previously unknown miRNA processing regulatory pathway in HeLa cells.

Li, Jie; Chen, Ying; Qin, Xingliang; Wen, Junzhi; Ding, Hongmei; Xia, Wei; Li, Shaohua; Su, Xueting; Wang, Wei; Li, Hui; Zhao, Qiang; Fang, Tao; Qu, Lianghu; Shao, Ningsheng

2014-01-01

193

Suppression of yeast RNA polymerase III mutations by FHL1, a gene coding for a fork head protein involved in rRNA processing.  

PubMed Central

The FHL1 gene was isolated by screening for high-copy-number suppressors of conditional RNA polymerase III mutations. This gene is unique on the yeast genome and was located close to RPC40 and PRE2 on the right arm of chromosome XVI. It codes for a 936-amino-acid protein containing a domain similar to the fork head DNA-binding domain, initially found in the developmental fork head protein of Drosophila melanogaster and in the HNF-3 family of hepatocyte mammalian transcription factors. Null mutations caused a severe reduction in growth rate and a lower rRNA content that resulted from defective rRNA processing. There was no detectable effect on mRNA splicing. Thus, the Fhl1p protein plays a key role in the control of rRNA processing, presumably by acting as a transcriptional regulator of genes specifically involved in that process. Moreover, mutants carrying the RNA polymerase III mutations were slightly defective in rRNA processing. This accounts for the isolation of FHL1 as a dosage-dependent suppressor and suggests that rRNA processing depends on a still-unidentified RNA polymerase III transcript. Images

Hermann-Le Denmat, S; Werner, M; Sentenac, A; Thuriaux, P

1994-01-01

194

GGRESRC: A Monte Carlo generator for the two-photon process e+e-?e+e-R(J=0) in the single-tag mode  

NASA Astrophysics Data System (ADS)

The Monte Carlo event generator GGRESRC is described. The generator is developed for the simulation of events of the two-photon process e+e-?e+e-R, where R is a pseudoscalar resonance, ?0, ?, ??, ?c, or ?b. The program is optimized for the generation of two-photon events in the single-tag mode. For single-tag events, radiative correction simulation is implemented in the generator including photon emission from the initial and final states.

Druzhinin, V. P.; Kardapoltsev, L. V.; Tayursky, V. A.

2014-01-01

195

Enp1, a yeast protein associated with U3 and U14 snoRNAs, is required for pre-rRNA processing and 40S subunit synthesis  

PubMed Central

ENP1 is an essential Saccharomyces cerevisiae gene encoding a 483 amino acid polypeptide. Enp1 protein is localized in the nucleus and concentrated in the nucleolus. An enp1-1 temperature-sensitive mutant inhibited 35S pre-rRNA early processing at sites A0, A1 and A2 as shown by northern analysis of steady state levels of rRNA precursors. Pulse-chase analysis further revealed that the enp1-1 strain was defective in the synthesis of 20S pre-rRNA and hence 18S rRNA, which led to reduced formation of 40S ribosomal subunits. Co-precipitation analysis revealed that Enp1 was associated with Nop1 protein, as well as with U3 and U14 RNAs, two snoRNAs implicated in early pre-rRNA processing steps. These results suggest a direct role for Enp1 in the early steps of rRNA processing.

Chen, Weidong; Bucaria, Jean; Band, David A.; Sutton, Ann; Sternglanz, Rolf

2003-01-01

196

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

197

Cost and revenue impact of advanced process control (APC) with an emphasis on run-to-run control (R2R)  

NASA Astrophysics Data System (ADS)

This paper takes published improvements in fabricator metrics that result from Advanced Process Control,and, applying an International SEMATECH cost model to the results, quantifies the expected economic impact. By converting the improvements in factory metrics to dollars, they can be compared. The benefits are given by equipment type, and by factory benefit mechanism. The majority of these calculations are based on Run-to-Run control.

Stanley, Timothy D.; Markle, Richard J.; Van Eck, Brad; Cusson, Brian K.; Purdy, Matthew A.; Stanley, K. J.

2003-06-01

198

Age-related alterations of relaxation processes and non-Markov effects in stochastic dynamics of R R intervals variability from human ECGs  

Microsoft Academic Search

In this paper, we consider the age-related alterations of heart rate variability on the basis of the study of non-Markovian effects. The age dynamics of relaxation processes is quantitatively described by means of local relaxation parameters, calculated by the specific localization procedure. We offer a quantitative informational measure of non-Markovity to evaluate the change of statistical effects of memory. Local

Renat M. Yulmetyev; Sergey A. Demin; Oleg Yu. Panischev; Peter Hänggi

2005-01-01

199

Age-related alterations of relaxation processes and non-Markov effects in stochastic dynamics of R–R intervals variability from human ECGs  

Microsoft Academic Search

In this paper, we consider the age-related alterations of heart rate variability on the basis of the study of non-Markovian effects. The age dynamics of relaxation processes is quantitatively described by means of local relaxation parameters, calculated by the specific localization procedure. We offer a quantitative informational measure of non-Markovity to evaluate the change of statistical effects of memory. Local

Renat M. Yulmetyev; Sergey A. Demin; Oleg Yu. Panischev; Peter Hänggi

2005-01-01

200

Process modeling of the lipase-catalyzed dynamic kinetic resolution of (R, S)-suprofen 2,2,2-trifluoroethyl thioester in a hollow-fiber membrane.  

PubMed

A Candida rugosa lipase immobilized on polypropylene powder was employed as the biocatalyst for the enantioselective hydrolysis of (R, S)-suprofen 2,2,2-trifluorothioester in cyclohexane, in which trioctylamine was added as the catalyst to perform in situ racemization of the remaining (R)-thioester. A hollow-fiber membrane was also integrated with the dynamic kinetic resolution process in order to continuously extract the desired (S)-suprofen into an aqueous solution containing NaOH. A kinetic model for the whole process (operating in batch and feed-batch modes) was developed, in which enzymatic hydrolysis and deactivation, lipase activation, racemization and non-enantioselective hydrolysis of the substrate by trioctylamine, and reactive extraction of (R)- and (S)-suprofen into the aqueous phase in the membrane were considered. Theoretical predictions from the model for the time-course variations of substrate and product concentrations in each phase were compared with experimental data. PMID:15645310

Wang, L W; Cheng, Y C; Tsai, S W

2004-12-01

201

The s-process in low-metallicity stars - III. Individual analysis of CEMP-s and CEMP-s/r with asymptotic giant branch models  

NASA Astrophysics Data System (ADS)

We provide an individual analysis of 94 carbon-enhanced metal-poor stars showing an s-process enrichment (CEMP-s) collected from the literature. The s-process enhancement observed in these stars is ascribed to mass transfer by stellar winds in a binary system from a more massive companion evolving faster towards the asymptotic giant branch (AGB) phase. The theoretical AGB nucleosynthesis models have been presented in Bisterzo et al. (Paper I of this series). Several CEMP-s show an enhancement in both s- and r-process elements (CEMP-s/r). In order to explain the peculiar abundances observed in CEMP-s/r, we assume that the molecular cloud from which CEMP-s formed was previously enriched in r-elements by supernova pollution. A general discussion and the method adopted in order to interpret the observations have been provided in Bisterzo et al. (Paper II of this series). We present in this paper a detailed study of spectroscopic observations of individual stars. We consider all elements from carbon to bismuth, with particular attention to the three s-process peaks, ls (Y, Zr), hs (La, Nd, Sm) and Pb, and their ratios [hs/ls] and [Pb/hs]. The presence of an initial r-process contribution may be typically evaluated by [La/Eu]. We found possible agreements between theoretical predictions and spectroscopic data. In general, the observed [Na/Fe] (and [Mg/Fe]) provides information on the AGB initial mass, while [hs/ls] and [Pb/hs] are mainly indicators of the s-process efficiency. A range of 13C-pocket strengths are required to interpret the observations. However, major discrepancies between models and observations exist. We highlight star by star the agreements and the main problems encountered and, when possible, we suggest potential indications for further studies. These discrepancies provide starting points of debate for unsolved problems in which spectroscopic and theoretical studies may intervene.

Bisterzo, S.; Gallino, R.; Straniero, O.; Cristallo, S.; Käppeler, F.

2012-05-01

202

The Astrophysical r-Process: A Comparison of Calculations following Adiabatic Expansion with Classical Calculations Based on Neutron Densities and Temperatures  

Microsoft Academic Search

The rapid neutron-capture process (r-process) encounters unstable nuclei far from beta-stability. Therefore its observable features, like the abundances, witness (still uncertain) nuclear structure as well as the conditions in the appropriate astrophysical environment. With the remaining lack of a full understanding of its astrophysical origin, parameterized calculations are still needed. We consider two approaches: (1) the classical approach is based

C. Freiburghaus; J.-F. Rembges; T. Rauscher; E. Kolbe; F.-K. Thielemann; K.-L. Kratz; B. Pfeiffer; J. J. Cowan

1999-01-01

203

The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F): Exploratory and Confirmatory Factor Analyses at Item Level  

ERIC Educational Resources Information Center

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

Justicia, Fernando; Pichardo, M. Carmen; Cano, Francisco; Berben, A. B. G.; De la Fuente, Jesus

2008-01-01

204

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

205

Prototype Plant for Nuclear Process Heat (PNP), Reference Phase. R+D-Work on Hydrogasification of Coal (HKV).  

National Technical Information Service (NTIS)

Processes for coal gasification are well known and proved for a long time past. The coal gasification processes using nuclear process heat, however, being developed within the framework of the PNP project, have the advantages of saving feed coal, improvin...

H. P. Gerigk H. Langer L. Schrader H. J. Schumacher

1983-01-01

206

Over-Expression of miR-106b Promotes Cell Migration and Metastasis in Hepatocellular Carcinoma by Activating Epithelial-Mesenchymal Transition Process  

PubMed Central

Hepatocellular carcinoma (HCC) is one the the most fatal cancers worldwide. The poor prognosis of HCC is mainly due to the developement of distance metastasis. To investigate the mechanism of metastasis in HCC, an orthotopic HCC metastasis animal model was established. Two sets of primary liver tumor cell lines and corresponding lung metastasis cell lines were generated. In vitro functional analysis demonstrated that the metastatic cell line had higher invasion and migration ability when compared with the primary liver tumor cell line. These cell lines were subjected to microRNA (miRNAs) microarray analysis to identify differentially expressed miRNAs which were associated with the developement of metastasis in vivo. Fifteen human miRNAs, including miR-106b, were differentially expressed in 2 metastatic cell lines compared with the primary tumor cell lines. The clinical significance of miR-106b in 99 HCC clinical samples was studied. The results demonstrated that miR-106b was over-expressed in HCC tumor tissue compared with adjacent non-tumor tissue (p?=?0.0005), and overexpression of miR-106b was signficantly correlated with higher tumor grade (p?=?0.018). Further functional studies demonstrated that miR-106b could promote cell migration and stress fiber formation by over-expressing RhoGTPases, RhoA and RhoC. In vivo functional studies also showed that over-expression of miR-106b promoted HCC metastasis. These effects were related to the activation of the epithelial-mesenchymal transition (EMT) process. Our results suggested that miR-106b expression contributed to HCC metastasis by activating the EMT process promoting cell migration in vitro and metastasis in vivo.

Yau, Wing Lung; Lam, Colin Siu Chi; Ng, Lui; Chow, Ariel Ka Man; Chan, Sylvia Tsz Ching; Chan, Jacky Yu Ki; Wo, Jana Yim Hung; Ng, Kevin Tak Pan; Man, Kwan; Poon, Ronnie Tung Ping; Pang, Roberta Wen Chi

2013-01-01

207

A novel "oxygen-induced" greening process in a cyanobacterial mutant lacking the transcriptional activator ChlR involved in low-oxygen adaptation of tetrapyrrole biosynthesis.  

PubMed

ChlR activates the transcription of the chlAII-ho2-hemN operon in response to low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803. Three genes in the operon encode low-oxygen-type enzymes to bypass three oxygen-dependent reactions in tetrapyrrole biosynthesis. A chlR-lacking mutant, ?chlR, shows poor photoautotrophic growth due to low chlorophyll (Chl) content under low-oxygen conditions, which is caused by no induction of the operon. Here, we characterized the processes of etiolation of ?chlR cells in low-oxygen conditions and the subsequent regreening of the etiolated cells upon exposure to oxygen, by HPLC, Western blotting, and low-temperature fluorescence spectra. The Chl content of the etiolated ?chlR cells incubated under low-oxygen conditions for 7 days was only 10% of that of the wild-type with accumulation of almost all intermediates of the magnesium branch of Chl biosynthesis. Both photosystem I (PSI) and photosystem II (PSII) were significantly decreased, accompanied by a preferential decrease of antenna Chl in PSI. Upon exposure to oxygen, the etiolated ?chlR cells resumed to produce Chl after a short lag (?2 h), and the level at 72 h was 80% of that of the wild-type. During this novel "oxygen-induced" greening process, the PSI and PSII contents were largely increased in parallel with the increase in Chl contents. After 72 h, the PSI content reached ?50% of the wild-type level in contrast to the full recovery of PSII. ?chlR provides a promising alternative system to investigate the biogenesis of PSI and PSII. PMID:24297184

Aoki, Rina; Hiraide, Yuto; Yamakawa, Hisanori; Fujita, Yuichi

2014-01-17

208

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

PubMed

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

2012-06-29

209

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.

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

2012-01-01

210

Dbp3p, a putative RNA helicase in Saccharomyces cerevisiae, is required for efficient pre-rRNA processing predominantly at site A3.  

PubMed Central

In Saccharomyces cerevisiae, ribosomal biogenesis takes place primarily in the nucleolus, in which a single 35S precursor rRNA (pre-rRNA) is first transcribed and sequentially processed into 25S, 5.8S, and 18S mature rRNAs, leading to the formation of the 40S and 60S ribosomal subunits. Although many components involved in this process have been identified, our understanding of this important cellular process remains limited. Here we report that one of the evolutionarily conserved DEAD-box protein genes in yeast, DBP3, is required for optimal ribosomal biogenesis. DBP3 encodes a putative RNA helicase, Dbp3p, of 523 amino acids in length, which bears a highly charged amino terminus consisting of 10 tandem lysine-lysine-X repeats ([KKX] repeats). Disruption of DBP3 is not lethal but yields a slow-growth phenotype. This genetic depletion of Dbp3p results in a deficiency of 60S ribosomal subunits and a delayed synthesis of the mature 25S rRNA, which is caused by a prominent kinetic delay in pre-rRNA processing at site A3 and to a lesser extent at sites A2 and A0. These data suggest that Dbp3p may directly or indirectly facilitate RNase MRP cleavage at site A3. The direct involvement of Dbp3p in ribosomal biogenesis is supported by the finding that Dbp3p is localized predominantly in the nucleolus. In addition, we show that the [KKX] repeats are dispensable for Dbp3p's function in ribosomal biogenesis but are required for its proper localization. The [KKX] repeats thus represent a novel signaling motif for nuclear localization and/or retention.

Weaver, P L; Sun, C; Chang, T H

1997-01-01

211

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.

212

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

213

Frequency and Clinical Implication of the R450H Mutation in the Thyrotropin Receptor Gene in the Japanese Population Detected by Smart Amplification Process 2  

PubMed Central

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.

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

2014-01-01

214

An end-to-end system in support of a broad scope of GOES-R sensor and data processing study  

NASA Astrophysics Data System (ADS)

The mission of NOAA's Geostationary Operational Environmental Satellite System (GOES) R series satellites, in the 2012 time frame, is to provide continuous, near real-time meteorological, oceanographic, solar, and space environment data that supports NOAA's strategic mission goals. It presents an exciting opportunity to explore new instruments, satellite designs, and system architectures utilizing new communication and instrument technologies in order to meet the ever-increasing demands made of Earth observation systems by national agencies and end users alike. The GOES-R sensor suite includes a 16 spectral band Advanced Baseline Imager (ABI), an approximately 1500 high spectral resolution band Hyperspectral Environmental Suite (HES), plus other sensors designed to detect lightning and to explore the ocean, solar and space environment. The Cooperative Institute for Meteorological Satellite Studies (CIMSS) as part of the Space Science and Engineering Center (SSEC) of the University of Wisconsin-Madison, the long time partner of NOAA, has developed the first operational end-to-end processing system for GOES. Based on this heritage, and with recent support from the NASA/NOAA Geosynchrous Imaging FTS (GIFTS) project, the Navy's Multiple University Research Initiative (MURI), and NOAA's GOES-R Risk Reduction program, SSEC has built a near-complete end-to-end system that is capable of simulating sensor measurements from top of atmosphere radiances, raw sensor data (level 0) through calibrated and navigated sensor physical measurements (level 1) to the processed products (level 2). In this paper, the SSEC Hyperspectral Imaging and Sounding Simulator and Processor (HISSP) will be presented in detail. HISSP is capable of demonstrating most of the processing functions such as data compression/decompression, sensor calibration, data processing, algorithm development, and product generation. In summary, HISSP is an end-to-end system designed to support both government and industry for the GOES-R system and their related broad scope of acquisition activities.

Huang, Hung-Lung

2005-08-01

215

Approaches to pre-formulation R and D for phytopharmaceuticals emanating from herb based traditional Ayurvedic processes  

PubMed Central

Botanicals constitute a large part of the drugs from the traditional medicine (TM) and ethno medicine (EM) known for their history of safe use (HOSU). Phytopharmaceuticals having a base of such origin offer high advantages as they come with safety profiles, and often allow extrapolation of the HOSU data, under certain circumstances. However, while current pharmaceutical technologies are being adopted by the industry to make phytopharmaceuticals with such origin, there is a need for preformulation research and development (R and D) during formulation. Some suggestions for R and D studies in case of aqueous extracts known in Ayurveda, converted on an industrial scale to obtain a phytopharmaceutical, and formulated as a solid dosage form (granules, tablets, or capsules) are discussed.

Anantha, Narayana D. B.

2013-01-01

216

A chemo-enzymatic process for sequential kinetic resolution of ( R, S)-2-octanol under microwave irradiation  

Microsoft Academic Search

A combination of the enzymatic resolution and chemical racemization for the heterogeneous sequential kinetic resolution (SKR) was employed to resolve (R,S)-2-octanol under microwave irradiation. Mesoporous molecular sieves SBA-15, alumina and strong basic styrene anion exchange resin were screened and selected as the optimum supports to immobilize the lipase from Pseudomonas sp. (PSL), oxidant-Chromium trioxide (CrO3) and reductant-Sodium borohydride (NaBH4), respectively.

Dahai Yu; Peng Chen; Lei Wang; Qiang Gu; Yan Li; Zhi Wang; Shugui Cao

2007-01-01

217

Electrical conduction processes in silicon nitride thin films prepared by r.f. magnetron sputtering using nitrogen gas  

Microsoft Academic Search

Silicon nitride (Si3N4) is an important VLSI material owing to its high resistivity and breakdown strength and its use in surface encapsulation during ion implantation and annealing. Previous work has focused on films prepared by low-pressure and plasma-enhanced chemical vapour deposition (LPCVD and PECVD), but in the present work the DC electrical properties of films prepared by r.f. magnetron sputtering

S. A. Awan; R. D. Gould; S. Gravano

1999-01-01

218

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

219

The charge excitation in the Raman process as correlated from a classical theory for Raman optical activity: The case study of (+)-(R)-methyloxirane  

NASA Astrophysics Data System (ADS)

We developed a classical algorithm to calculate the spectral signs in the Raman optical activity (ROA) spectrum. In this algorithm, the charge re-distributions among the bonds, which are associated to the bond polarizabilities, are included. For (+)-(R)-methyloxirane, we found that if these bond polarizabilities are attributed to the atoms and are properly scaled in order to be combined with the Mulliken charges on the atoms in the ground state, then the experimental ROA spectral signs can be well reproduced. Furthermore, in this process, we are able to determine that around 20% of the electrons in the molecule are excited in the Raman process.

Fang, Yan; Wu, Guozhen; Wang, Peijie

2012-03-01

220

First stars. XV. Third-peak r-process element and actinide abundances in the uranium-rich star CS31082-001  

NASA Astrophysics Data System (ADS)

Context. A small fraction of extremely metal-poor (EMP) stars exhibit moderate to extreme excesses of heavy neutron-capture elements produced in the r-process. The production site(s) of these elements in the early Galaxy remain(s) unclear, as is the reason for their occasional enhancement in the otherwise regular pattern of abundances of elements up to the iron peak. The detailed abundance pattern of the heaviest elements in EMP stars provides insight into their origin and role in the chemical enrichment of the early Galaxy and in radioactive nucleochronology. Aims: The EMP giant star CS 31082-001 ([Fe/H] ~ -2.9) exhibits an extreme enhancement of neutron-capture elements ([r/Fe] ~ +1.7) with U and Th enhanced by a further ~+0.7 dex, and a minimum of blending by molecular lines such as CH or CN. A rich inventory of r-process element abundances was established previously from optical spectra. Here we aim to supplement these data with abundances from near-UV spectroscopy of the third-peak neutron-capture elements, which are crucial for understanding the synthesis of the heaviest elements. Methods: Near-UV spectra from HST/STIS were analysed with LTE model atmospheres and spectrum synthesis calculations to derive new abundances of Os, Ir, Pt, Au, Bi and Pb in CS 31082-001. Results: Together with earlier data, the resulting abundance pattern for the r-process elements provides improved constraints on the nature of the r-process. The observed U and Th abundances and the initial production ratio place CS 31082-001 as one of the oldest stars in the Galaxy, consistent with its extreme metal deficiency. Comparison with the heaviest stable reference elements and with the daughter nuclides Pb and Bi provides a consistency check on this age determination. Finally, the existence of such r-element rich stars indicate that the early chemical evolution of the Galaxy was localised and inhomogeneous. Based on observations made with the NASA/ESA Hubble Space Telescope (HST) through the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555; and with the ESO Very Large Telescope at Paranal Observatory, Chile; Progr. ID 165.N-0276.

Barbuy, B.; Spite, M.; Hill, V.; Primas, F.; Plez, B.; Cayrel, R.; Spite, F.; Wanajo, S.; Siqueira Mello, C.; Andersen, J.; Nordström, B.; Beers, T. C.; Bonifacio, P.; François, P.; Molaro, P.

2011-10-01

221

Compact Ku-Band T/R Module for High-Resolution Radar Imaging of Cold Land Processes  

NASA Technical Reports Server (NTRS)

Global measurement of terrestrial snow cover is critical to two of the NASA Earth Science focus areas: (1) climate variability and change and (2) water and energy cycle. For radar backscatter measurements, Ku-band frequencies, scattered mainly within the volume of the snowpack, are most suitable for the SWE (snow-water equivalent) measurements. To isolate the complex effects of different snowpack (density and snowgrain size), and underlying soil properties and to distinctly determine SWE, the space-based synthetic aperture radar (SAR) system will require a dual-frequency (13.4 and 17.2 GHz) and dual polarization approach. A transmit/receive (T/R) module was developed operating at Ku-band frequencies to enable the use of active electronic scanning phased-array antenna for wide-swath, high-resolution SAR imaging of terrestrial snow cover. The T/R module has an integrated calibrator, which compensates for all environmental- and time-related changes, and results in very stable power and amplitude characteristics. The module was designed to operate over the full frequency range of 13 to 18 GHz, although only the two frequencies, 13.4 GHz and 17.2 GHz, will be used in this SAR radar application. Each channel of the transmit module produces > 4 W (35 dbm) over the operating bandwidth of 20 MHz. The stability requirements of <0.1 dB receive gain accuracy and <0.1 dB transmit power accuracy over a wide temperature range are achieved using a self-correction scheme, which does real-time amplitude calibration so that the module characteristics are continually corrected. All the calibration circuits are within the T/R module. The timing and calibration sequence is stored in a control FPGA (field-programmable gate array) while an internal 128K 8bit high-speed RAM (random access memory) stores all the calibration values. The module was designed using advanced components and packaging techniques to achieve integration of the electronics in a 2 x6.5x1-in. (5x17x2.5-cm) package. The module size allows 4 T/R modules to feed the 16 16-element subarray on an antenna panel. The T/R module contains four transmit channels and eight receive channels (horizontal and vertical polarizations).

Andricos, Constantine; Yueh, Simon H.; Krimskiy, Vladimir A.; Rahmat-Samii, Yahya

2010-01-01

222

Development of a process model to describe the synthesis of (R)-mandelonitrile by Prunus amygdalus hydroxynitrile lyase in an aqueous-organic biphasic reactor.  

PubMed

A process model for the enzymatic synthesis of (R)-cyanohydrins in an aqueous-organic biphasic-stirred tank reactor was developed. The conversion of benzal-dehyde into (R)-mandelonitrile, catalyzed by Prunus amygdalus hydroxynitrile lyase at 5 degrees C and pH 5.5, was chosen as a model system with methyl tert-butyl ether as the organic phase. The process model consisted of a description of the reaction kinetics, mass transfer kinetics, and the mass balances for both the aqueous and the organic phase. Values for the enzyme kinetic parameters, according to ordered bi-uni kinetics, the lumped mass transfer coefficient for benzaldehyde, and the partition coefficients were determined separately. The process model is validated by using 11 experimental data sets of batch conversions in the aqueous-organic biphasic-stirred tank reactor. In these 11 experiments, different enzyme concentrations and phase volume ratios were used. The model was found to be valid with respect to both the conversion and the enantiomeric excess. To synthesize cyanohydrins with a high enantiomeric excess, the enzyme is required to work at mass transfer limited conditions. The developed process model will be used to investigate other process concepts and other substrates. PMID:11753932

Willeman, Wouter F; Gerrits, Pieter Jan; Hanefeld, Ulf; Brussee, Johannes; Straathof, Adrie J J; van der Gen, Arne; Heijnen, Joseph J

2002-02-01

223

Activation of BlaR1 Protein of Methicillin-resistant Staphylococcus aureus, Its Proteolytic Processing, and Recovery from Induction of Resistance*  

PubMed Central

The fates of BlaI, the gene repressor protein for the bla operon, BlaR1, the ?-lactam sensor/signal transducer, and PC1 ?-lactamase in four strains of Staphylococcus aureus upon exposure to four different ?-lactam antibiotics were investigated as a function of time. The genes for the three proteins are encoded by the bla operon, the functions of which afford inducible resistance to ?-lactam antibiotics in S. aureus. BlaR1 protein is expressed at low copy number. Acylation of the sensor domain of BlaR1 by ?-lactam antibiotics initiates signal transduction to the cytoplasmic domain, a zinc protease, which is activated and degrades BlaI. This proteolytic degradation derepresses transcription of all three genes, resulting in inducible resistance. These processes take place within minutes of exposure to the antibiotics. The BlaR1 protein was shown to undergo fragmentation in three S. aureus strains within the time frame relevant for manifestation of resistance and was below the detection threshold in the fourth. Two specific sites of fragmentation were identified, one cytoplasmic and the other in the sensor domain. This is proposed as a means for turnover, a process required for recovery from induction of resistance in S. aureus in the absence of the antibiotic challenge. In S. aureus not exposed to ?-lactam antibiotics (i.e. not acylated by antibiotic) the same fragmentation of BlaR1 is still observed, including the shedding of the sensor domain, an observation that leads to the conclusion that the sites of proteolysis might have evolved to predispose the protein to degradation within a set period of time.

Llarrull, Leticia I.; Toth, Marta; Champion, Matthew M.; Mobashery, Shahriar

2011-01-01

224

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

225

C1D and hMtr4p associate with the human exosome subunit PM/Scl-100 and are involved in pre-rRNA processing  

PubMed Central

The exosome is a complex of 3?–5? exoribonucleases and RNA-binding proteins, which is involved in processing or degradation of different classes of RNA. Previously, the characterization of purified exosome complexes from yeast and human cells suggested that C1D and KIAA0052/hMtr4p are associated with the exosome and thus might regulate its functional activities. Subcellular localization experiments demonstrated that C1D and KIAA0052/hMtr4p co-localize with exosome subunit PM/Scl-100 in the nucleoli of HEp-2 cells. Additionally, the nucleolar accumulation of C1D appeared to be dependent on PM/Scl-100. Protein–protein interaction studies showed that C1D binds to PM/Scl-100, whereas KIAA0052/hMtr4p was found to interact with MPP6, a previously identified exosome-associated protein. Moreover, we demonstrate that C1D, MPP6 and PM/Scl-100 form a stable trimeric complex in vitro. Knock-down of C1D, MPP6 and KIAA0052/hMtr4p by RNAi resulted in the accumulation of 3?-extended 5.8S rRNA precursors, showing that these proteins are required for rRNA processing. Interestingly, C1D appeared to contain RNA-binding activity with a potential preference for structured RNAs. Taken together, our results are consistent with a role for the exosome-associated proteins C1D, MPP6 and KIAA052/hMtr4p in the recruitment of the exosome to pre-rRNA to mediate the 3? end processing of the 5.8S rRNA.

Schilders, Geurt; van Dijk, Erwin; Pruijn, Ger J.M.

2007-01-01

226

Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Affects Event-Related Potential Measures of Novelty Processing in Autism  

PubMed Central

In our previous study on individuals with autism spectrum disorder (ASD) (Sokhadze et al., Appl Psychophysiol Biofeedback 34:37–51, 2009a) we reported abnormalities in the attention-orienting frontal event-related potentials (ERP) and the sustained-attention centro-parietal ERPs in a visual oddball experiment. These results suggest that individuals with autism over-process information needed for the successful differentiation of target and novel stimuli. In the present study we examine the effects of low-frequency, repetitive Transcranial Magnetic Stimulation (rTMS) on novelty processing as well as behavior and social functioning in 13 individuals with ASD. Our hypothesis was that low-frequency rTMS application to dorsolateral prefrontal cortex (DLFPC) would result in an alteration of the cortical excitatory/inhibitory balance through the activation of inhibitory GABAergic double bouquet interneurons. We expected to find post-TMS differences in amplitude and latency of early and late ERP components. The results of our current study validate the use of low-frequency rTMS as a modulatory tool that altered the disrupted ratio of cortical excitation to inhibition in autism. After rTMS the parieto-occipital P50 amplitude decreased to novel distracters but not to targets; also the amplitude and latency to targets increased for the frontal P50 while decreasing to non-target stimuli. Low-frequency rTMS minimized early cortical responses to irrelevant stimuli and increased responses to relevant stimuli. Improved selectivity in early cortical responses lead to better stimulus differentiation at later-stage responses as was made evident by our P3b and P3a component findings. These results indicate a significant change in early, middle-latency and late ERP components at the frontal, centro-parietal, and parieto-occipital regions of interest in response to target and distracter stimuli as a result of rTMS treatment. Overall, our preliminary results show that rTMS may prove to be an important research tool or treatment modality in addressing the stimulus hypersensitivity characteristic of autism spectrum disorders.

Baruth, Joshua; Tasman, Allan; Mansoor, Mehreen; Ramaswamy, Rajesh; Sears, Lonnie; Mathai, Grace; El-Baz, Ayman; Casanova, Manuel F.

2009-01-01

227

Takagi-Sugeno Model Based Analysis of EWMA RtR Control of Batch Processes With Stochastic Metrology Delay and Mixed Products.  

PubMed

In many batch-based industrial manufacturing processes, feedback run-to-run control is used to improve production quality. However, measurements may be expensive and cannot always be performed online. Thus, the measurement delay always exists. The metrology delay will affect the stability and performance of the process. Moreover, since quality measurements are performed offline, delay is not fixed but is stochastic in nature. In this paper, a modeling approach Takagi-Sugeno (T-S) model is presented to handle stochastic metrology delay in both single-product and mixed-product processes. Based on the Markov characteristics of the delay, the membership of the T-S model is derived. Performance indices such as the mean and the variance of the closed-loop output of the exponentially weighted moving average (EWMA) control algorithm can be derived. A steady-state error of the process output always exists, which leads the output deviating from the target. To remove the steady-state error, an algorithm called compensatory EWMA run-to-run (COM-EWMA-RtR) algorithm is proposed. The validity of the T-S model analysis and the efficiency of the proposed COM-EWMA-RtR algorithm are confirmed by simulation. PMID:24235259

Zheng, Ying; Wong, David Shan-Hill; Wang, Yan-Wei; Fang, Huajing

2014-07-01

228

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...

229

Insertion, coupling and elimination processes in the reactions of the unsaturated alkyl-bridged complexes [Mo?(??-C?H?)?(?-CH?R)(?-PCy?)(CO)?] (R = H, Ph) with isocyanides and secondary phosphines.  

PubMed

The methyl-bridged complex [Mo2Cp2(?-Me)(?-PCy2)(CO)2] (Cp = ?(5)-C5H5) reacted with stoichiometric amounts of CN(t)Bu at 243 K to give the C,O:C,O-bridged acyl complex [Mo2Cp2{?-C,O:C,O-C(O)Me}(?-PCy2)(CN(t)Bu)(CO)], which at room temperature slowly rearranges into its iminoacyl-bridged isomer [Mo2Cp2(?-C,N:C,N-MeCN(t)Bu)(?-PCy2)(CO)2]. In contrast, the C:O-bridged acyl complex [Mo2Cp2{?-C:O-C(O)Me}(?-PCy2)(CN(t)Bu)(CO)] was the major product obtained when the above reaction was carried out at room temperature. Density Functional Theory (DFT) was used to find the most likely structures of all these isomers, of which the iminoacyl complex was the absolute minimum. In contrast to the above reactions, up to three molecules of the ligand added rapidly to the methyl complex when using the aryl isocyanides CNR (R = o-C6H4Me, p-C6H4OMe), triggering the coupling between the methyl ligand and one of the cyclopentadienyl groups to give the corresponding methylcyclopentadiene derivatives [Mo2Cp(?(4)-C5H5Me)(?-PCy2)(CNR)3(CO)]. Carbonylation of the latter complex (R = o-C6H4Me) induced the displacement of the ?(4)-bound ligand, but also gave small yields of the hydride derivative [Mo2Cp(?(5)-C5H4Me)(?-H)(?-PCy2){CN(o-C6H4Me)}(CO)3] (Mo-Mo = 3.2467(5) Å), the latter resulting from a C-H cleavage in the methylcyclopentadiene ligand. The reaction of the title complexes with phosphines HPR (R' = Et, Ph) gave two major products: the corresponding aldehyde complexes [Mo2Cp2(?-PCy2)(?-PR){?(2)-C(O)HR}(CO)] (Mo-Mo = 2.8288(5) Å when R = CH2Ph and R' = Et) and the dicarbonyl complexes [Mo2Cp2(?-PCy2)(?-PR)(CO)2], these following from alternative reductive elimination processes, from hydrogen and either acyl or alkyl ligands, respectively. PMID:24699932

Alvarez, M Angeles; García, M Esther; García-Vivó, Daniel; Martínez, M Eugenia; Ramos, Alberto; Ruiz, Miguel A

2014-06-01

230

EVALUATION OF DIFFERENT SIGNAL PROCESSING OPTIONS IN UNILATERAL AND BILATERAL COCHLEAR FREEDOM IMPLANT RECIPIENTS USING R-SPACE(TM) 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 recipient’s 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.

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

2013-01-01

231

Magnetocaloric effect of RM2 (R = rare earth, M = Ni, Al) intermetallic compounds made by centrifugal atomization process for magnetic refrigerator  

NASA Astrophysics Data System (ADS)

RM2 (R = rare earth, M = Al, Ni and Co) compounds have large entropy change and magnetic transition temperatures can be controlled by change of R and/or M so that are suitable to a magnetic refrigerator for hydrogen liquefaction under development. In order to improve refrigerator performance, spherical powdered HoAl2, DyAl2, and GdNi2 compounds with submillimeter diameter were synthesized by centrifugal atomization process. By measuring the magnetization and heat capacity, we obtained entropy change by magnetic fields and entropy as functions of temperature and magnetic field, which are essential for analysing the magnetic refrigeration cycle. All samples showed sharp magnetic transitions and had good potentials for use in magnetic refrigeration.

Matsumoto, K.; Asamato, K.; Nishimura, Y.; Zhu, Y.; Abe, S.; Numazawa, T.

2012-12-01

232

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

233

NOL11, Implicated in the Pathogenesis of North American Indian Childhood Cirrhosis, Is Required for Pre-rRNA Transcription and Processing  

PubMed Central

The fundamental process of ribosome biogenesis requires hundreds of factors and takes place in the nucleolus. This process has been most thoroughly characterized in baker's yeast and is generally well conserved from yeast to humans. However, some of the required proteins in yeast are not found in humans, raising the possibility that they have been replaced by functional analogs. Our objective was to identify non-conserved interaction partners for the human ribosome biogenesis factor, hUTP4/Cirhin, since the R565W mutation in the C-terminus of hUTP4/Cirhin was reported to cause North American Indian childhood cirrhosis (NAIC). By screening a yeast two-hybrid cDNA library derived from human liver, and through affinity purification followed by mass spectrometry, we identified an uncharacterized nucleolar protein, NOL11, as an interaction partner for hUTP4/Cirhin. Bioinformatic analysis revealed that NOL11 is conserved throughout metazoans and their immediate ancestors but is not found in any other phylogenetic groups. Co-immunoprecipitation experiments show that NOL11 is a component of the human ribosomal small subunit (SSU) processome. siRNA knockdown of NOL11 revealed that it is involved in the cleavage steps required to generate the mature 18S rRNA and is required for optimal rDNA transcription. Furthermore, abnormal nucleolar morphology results from the absence of NOL11. Finally, yeast two-hybrid analysis shows that NOL11 interacts with the C-terminus of hUTP4/Cirhin and that the R565W mutation partially disrupts this interaction. We have therefore identified NOL11 as a novel protein required for the early stages of ribosome biogenesis in humans. Our results further implicate a role for NOL11 in the pathogenesis of NAIC.

Freed, Emily F.; Prieto, Jose-Luis; McCann, Kathleen L.; McStay, Brian; Baserga, Susan J.

2012-01-01

234

Static and fatigue testing of full-scale fuselage panels fabricated using a Therm-X(R) process  

NASA Technical Reports Server (NTRS)

Large, curved, integrally stiffened composite panels representative of an aircraft fuselage structure were fabricated using a Therm-X process, an alternative concept to conventional two-sided hard tooling and contour vacuum bagging. Panels subsequently were tested under pure shear loading in both static and fatigue regimes to assess the adequacy of the manufacturing process, the effectiveness of damage tolerant design features co-cured with the structure, and the accuracy of finite element and closed-form predictions of postbuckling capability and failure load. Test results indicated the process yielded panels of high quality and increased damage tolerance through suppression of common failure modes such as skin-stiffener separation and frame-stiffener corner failure. Finite element analyses generally produced good predictions of postbuckled shape, and a global-local modelling technique yielded failure load predictions that were within 7% of the experimental mean.

Dinicola, Albert J.; Kassapoglou, Christos; Chou, Jack C.

1992-01-01

235

The A20R Protein Is a Stoichiometric Component of the Processive Form of Vaccinia Virus DNA Polymerase  

PubMed Central

In vitro analysis of the catalytic DNA polymerase encoded by vaccinia virus has demonstrated that it is innately distributive, catalyzing the addition of <10 nucleotides per primer-template binding event in the presence of 8 mM MgCl2 or 40 mM NaCl (W. F. McDonald and P. Traktman, J. Biol. Chem. 269:31190–31197, 1994). In contrast, cytoplasmic extracts isolated from vaccinia virus-infected cells contain a highly processive form of DNA polymerase, able to catalyze the replication of a 7-kb template per binding event under similar conditions. To study this holoenzyme, we were interested in purifying and characterizing the vaccinia virus processivity factor (VPF). Our previous studies indicated that VPF is expressed early after infection and has a native molecular mass of ?48 kDa (W. F. McDonald, N. Klemperer, and P. Traktman, Virology 234:168–175, 1997). Using these criteria, we established a six-step chromatographic purification procedure, in which a prominent ?45-kDa band was found to copurify with processive polymerase activity. This species was identified as the product of the A20 gene. By use of recombinant viruses that direct the overexpression of A20 and/or the DNA polymerase, we verified the physical interaction between the two proteins in coimmunoprecipitation experiments. We also demonstrated that simultaneous overexpression of A20 and the DNA polymerase leads to a specific and robust increase in levels of processive polymerase activity. Taken together, we conclude that the A20 gene encodes a component of the processive DNA polymerase complex. Genetic data that further support this conclusion are presented in the accompanying report, which documents that temperature-sensitive mutants with lesions in the A20 gene have a DNA? phenotype that correlates with a deficit in processive polymerase activity (A. Punjabi et al, J. Virol. 75:12308–12318, 2001).

Klemperer, Nancy; McDonald, William; Boyle, Kathleen; Unger, Beth; Traktman, Paula

2001-01-01

236

WESTERN RESEARCH INSTITUTE CONTAINED RECOVERY OF OILY WASTES (CROW) PROCESS - ITER (EPA/540/R-00/500)  

EPA Science Inventory

This report summarizes the findings of an evaluation of the Contained Recovery of Oily Wastes (CROW) technology developed by the Western Research Institute. The process involves the injection of heated water into the subsurface to mobilize oily wastes, which are removed from the ...

237

Classroom Interpreting and Visual Information Processing in Mainstream Education for Deaf Students: Live or Memorex[R]?  

ERIC Educational Resources Information Center

This study examined visual information processing and learning in classrooms including both deaf and hearing students. Of particular interest were the effects on deaf students' learning of live (three-dimensional) versus video-recorded (two-dimensional) sign language interpreting and the visual attention strategies of more and less experienced…

Marschark, Marc; Pelz, Jeff B.; Convertino, Carol; Sapere, Patricia; Arndt, Mary Ellen; Seewagen, Rosemarie

2005-01-01

238

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...

239

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....

240

The Astrophysical r-Process: A Comparison of Calculations following Adiabatic Expansion with Classical Calculations Based on Neutron Densities and Temperatures  

NASA Astrophysics Data System (ADS)

The rapid neutron-capture process (r-process) encounters unstable nuclei far from ?-stability. Therefore its observable features, like the abundances, witness (still uncertain) nuclear structure as well as the conditions in the appropriate astrophysical environment. With the remaining lack of a full understanding of its astrophysical origin, parameterized calculations are still needed. We consider two approaches: (1) the classical approach is based on (constant) neutron number densities nn and temperatures T over duration timescales ? (2) recent investigations, motivated by the neutrino wind scenario from hot neutron stars after a supernova explosion, followed the expansion of matter with initial entropies S and electron fractions Ye over expansion timescales ?. In the latter case the freezeout of reactions with declining temperatures and densities can be taken into account explicitly. We compare the similarities and differences between the two approaches with respect to resulting abundance features and their relation to solar r-process abundances, applying for the first time different nuclear mass models in entropy-based calculations. Special emphasis is given to the questions of (a) whether the same nuclear properties far from stability lead to similar abundance patterns and possible deficiencies in (1) and (2), and (b) whether some features can also provide clear constraints on the astrophysical conditions in terms of permitted entropies, Ye values, and expansion timescales in (2). This relates mostly to the A<110 mass range, where a fit to solar r-abundances in high-entropy supernova scenarios seems to be hard to attain. Possible low-entropy alternatives are presented.

Freiburghaus, C.; Rembges, J.-F.; Rauscher, T.; Kolbe, E.; Thielemann, F.-K.; Kratz, K.-L.; Pfeiffer, B.; Cowan, J. J.

1999-05-01

241

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

242

Measuring Hospital Care from the Patients' Perspective: An Overview of the CAHPS(R) Hospital Survey Development Process  

PubMed Central

Objective To describe the developmental process for the CAHPS® Hospital Survey. Study Design A pilot was conducted in three states with 19,720 hospital discharges. Methods of Analysis A rigorous, multi-step process was used to develop the CAHPS Hospital Survey. It included a public call for measures, multiple Federal Register notices soliciting public input, a review of the relevant literature, meetings with hospitals, consumers and survey vendors, cognitive interviews with consumer, a large-scale pilot test in three states and consumer testing and numerous small-scale field tests. Findings The current version of the CAHPS Hospital Survey has survey items in seven domains, two overall ratings of the hospital and five items used for adjusting for the mix of patients across hospitals and for analytical purposes. Conclusions The CAHPS Hospital Survey is a core set of questions that can be administered as a stand-alone questionnaire or combined with a broader set of hospital specific items.

Goldstein, Elizabeth; Farquhar, Marybeth; Crofton, Christine; Darby, Charles; Garfinkel, Steven

2005-01-01

243

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

244

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

245

A Compendium of Causes and Effects of Processes at Transform Faults and Fracture Zones (Paper 7R0440)  

NASA Astrophysics Data System (ADS)

A flowchart has been constructed which consolidates into a single conceptual framework a large number of the phenomena and processes which have been observed or postulated at transform faults (TFs) and fracture zones (FZs). Oceanic ridge-ridge transform faults and their aseismic extensions are emphasized. The upstream end of the flowchart contains large-scale boundary conditions imposed by the position of a particular transform fault in space and time, for example, slip rate. The downstream end of the flowchart contains small-scale features characteristic of individual TFs or FZs, for example, the existence of a FZ-parallel ridge. Features of both the upstream and the downstream ends of the flowchart can be mapped, measured, or otherwise derived by direct observation. The middle of the flow chart includes processes and phenomena which are inferred to result from the upstream boundary conditions and to cause the downstream small-scale features, for example, thermal conduction across the plate boundary. Phenomena in this "black box" in the center of the flowchart cannot be directly observed with present technology but must be inferred. The advantages of ordering knowledge into such a flowchart are that inconsistancies, gaps in understanding, self-limiting phenomena (feedback loops), and previously unrecognized relationships stand out and that the boundary between inference and observation is clearly drawn.

Kastens, Kim A.

1987-08-01

246

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

247

Astrocytes and interneurons in memory processing in the chick hippocampus: roles for G-coupled protein receptors, GABA(B) and mGluR1.  

PubMed

Glutamate and GABA acting at mGluR1 and GABA(B) receptors, respectively, have roles in memory processing in the hippocampus up to 35 min after bead discrimination learning in the young chick. Activation of mGluR1 receptors is important at 2.5 and 30 min after training, but modulation of these receptors between these two times has no effect on memory. This timing is similar to the action of glutamate on NMDA receptors. The GABA(B) antagonist, phaclofen, and the inhibitor of astrocytic oxidative metabolism, fluoroacetate, inhibited memory when injected between 2.5 and 30 min. Paradoxically, a high dose of the GABA(B) agonist, baclofen, also inhibited memory, but a low dose promoted memory consolidation--an effect possibly caused by too much information and loss of the 'message'. These results are interpreted in terms interactions between interneurons, astrocytes and pyramidal cells and demonstrate the importance of all cell types in memory processing in the hippocampus. PMID:19415487

Gibbs, Marie E; Bowser, David N

2009-10-01

248

Hierarchical recruitment into nascent ribosomes of assembly factors required for 27SB pre-rRNA processing in Saccharomyces cerevisiae  

PubMed Central

To better define the roles of assembly factors required for eukaryotic ribosome biogenesis, we have focused on one specific step in maturation of yeast 60?S ribosomal subunits: processing of 27SB pre-ribosomal RNA. At least 14 assembly factors, the ‘B-factor’ proteins, are required for this step. These include most of the major functional classes of assembly factors: RNA-binding proteins, scaffolding protein, DEAD-box ATPases and GTPases. We have investigated the mechanisms by which these factors associate with assembling ribosomes. Our data establish a recruitment model in which assembly of the B-factors into nascent ribosomes ultimately leads to the recruitment of the GTPase Nog2. A more detailed analysis suggests that this occurs in a hierarchical manner via two largely independent recruiting pathways that converge on Nog2. Understanding recruitment has allowed us to better determine the order of association of all assembly factors functioning in one step of ribosome assembly. Furthermore, we have identified a novel subcomplex composed of the B-factors Nop2 and Nip7. Finally, we identified a means by which this step in ribosome biogenesis is regulated in concert with cell growth via the TOR protein kinase pathway. Inhibition of TOR kinase decreases association of Rpf2, Spb4, Nog1 and Nog2 with pre-ribosomes.

Talkish, Jason; Zhang, Jingyu; Jakovljevic, Jelena; Horsey, Edward W.; Woolford, John L.

2012-01-01

249

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...

250

Beta Decay Half-lives and Delayed Neutron Emission of r-process Neutron-Rich nuclei in the vicinity of 78Ni  

NASA Astrophysics Data System (ADS)

The region of neutron rich isotopes at and beyond the N=50 shell closure in the vicinity of ^78Ni has recently attracted major interest from experimental and theoretical nuclear physics community [1-4]. Moreover, as many nuclei in the region are predicted precursors of r-process nucleosynthesis, their most basic nuclear properties such as mass and beta decay half-life are required parameters in abundance calculations. The availability of hight purity and high quality radioactive beams of nuclei in this region at the Holifield Radioactive Ion Beam Facility has spurred a systematic campaign to study their properties through beta decay. Four new half-lives of ^82,83Zn, ^85Ga and ^86Ge were measured for the first time. The resulting values differ from the predictions of the Finite Range Droplet Model used in r-process abundance calculations. We presented a new model based on Density Functional Theory that correctly reproduced the new half-lives. 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. Continuing our effort to systematically understand decay properties in the region of beta-delayed neutron emission, 30 nuclei in the region were studied using the neutron energy Time-of-Flight detector VANDLE. Due to the shell structure in the region, most of the decay strength is expected to concentrate in states above neutron separation energy, in the so-called Pigmy Giant resonance. Precise knowledge of the position and strength of the resonance may help fine tune and develop existing models, with the aim of increasing their reliability beyond what can be experimentally measured. The data resulting from the experimental campaign at Holifield are still being analyzed. In a few species strong shell effects have already been identified and they will be presented. In particular, the decay of ^84Ga shows that more than half of the neutron strength concentrates in a single neutron transition at 2 MeV, suggesting the population of the Pigmy resonance.[4pt] [1] P. Hosmer et al., Phys. Rev. Lett. 94, 112501 (2005).[0pt] [2] T. Otsuka, T. Suzuki, R. Fujimoto, H. Grawe, and Y. Akaishi, Phys. Rev. Lett. 95, 232502 (2005).[0pt] [3] B. Cheal et al., Phys. Rev. Lett. 103, 142501 (2009).[0pt] [4] S. Padgett et al., Phys. Rev. C 82, 064314 (2010).

Madurga, M.

2012-10-01

251

The Dorsolateral Prefrontal Cortex Plays a Role in Self-Initiated Elaborative Cognitive Processing during Episodic Memory Encoding: rTMS Evidence  

PubMed Central

During episodic memory encoding, elaborative cognitive processing can improve later recall or recognition. While multiple studies examined the neural correlates of encoding strategies, few studies have explicitly focused on the self-initiation of elaborative encoding. Repetitive transcranial magnetic stimulation (rTMS), a method which can transiently disrupt neural activity, was administered during an associative encoding task. rTMS was either applied to the left dorsolateral prefrontal cortex (DLPFC) or to the vertex (a control region not involved in memory encoding) during presentation of pairs of words. Pairs could be semantically related or not related. Two encoding instructions were given, either cueing participants to analyze semantic relationships (cued condition), or to memorize the pair without any specific strategy cues (the self-initiated condition). Participants filled out a questionnaire regarding their use of memory strategies and performed a cued-recall task. We hypothesized that if the DLPFC plays a role in the self-initiation of elaborative encoding we would observe a reduction in memory performance in the self-initiated condition, particularly for related. We found a significant correlation between the effects of rTMS and strategy use, only in the self-initiated condition with related pairs. High strategy users showed reduced performance following DLPFC stimulation, while low strategy users tended to show increased recall following DLPFC stimulation during encoding. These results suggest the left DLPFC may be involved in the self-initiation of memory strategy use, and individuals may utilize different neural networks depending on their use of encoding strategies.

Hawco, Colin; Berlim, Marcelo T.; Lepage, Martin

2013-01-01

252

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

253

Comparative study on the degradation of I.C. Remazol Brilliant Blue R and I.C. Acid Black 1 by Fenton oxidation and Fe 0/air process and toxicity evaluation.  

PubMed

Degradation of Remazol Brilliant Blue R (anthraquinone dye) and Acid Black 1 (azo dye) by Fenton oxidation and low-cost Fe(0)/air process was compared. The doses of Fenton reagent needed for decolorization of Remazol Brilliant Blue R was much higher than for Acid Black 1. The Fe(0)/air process rapidly decolorized dyes within 5 min at the Fe(0) doses of 10 and 50 g L(-1) for Remazol Brilliant Blue R and Acid Black 1, respectively. COD removals of Remazol Brilliant Blue R and Acid Black 1 by the Fe(0)/air treatment were significantly higher than those by Fenton oxidation. 98% COD of Remazol Brilliant Blue R was removed by the Fe(0)/air process. The toxicity of Fe(0)/air-treated solution was significantly lower than that of Fenton-treated solution; no toxicity was detected after the treatment of Remazol Brilliant Blue R by the Fe(0)/air process. Fe(0)/air technique is a potential process for dye degradation. PMID:19157699

Chang, Shih-Hsien; Chuang, Shun-Hsing; Li, Heng-Ching; Liang, Hsiu-Hao; Huang, Lung-Chiu

2009-07-30

254

PV Manufacturing R&D Project Status and Accomplishments Under 'In-Line Diagnostics and Intelligent Processing' and 'Yield, Durability and Reliability'  

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 $2.73/Wp, and the capacity increased 18.5-fold (25% annualized) to 251 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. A.

2006-01-01

255

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

256

Direct and semi-direct capture in low-energy (n,{gamma}) reactions of neutron-rich tin isotopes and its implications for r-process nucleosynthesis  

SciTech Connect

The direct and semi-direct (DSD) components of the neutron capture cross sections are calculated for a series of tin isotopes by employing a single-particle potential (SPP) that gives a good reproduction of the known single-particle energies (SPEs) over a wide mass region. The results are compared with the Hauser-Feshbach (HF) contribution in the energy region of astrophysical interest. The calculated result shows that the HF component drops off rapidly for isotope {sup 132}Sn and toward more neutron-rich ones, whereas the DSD component decreases only smoothly and eventually becomes dominant. This result is consistent with those of previous studies, but the dependence of the DSD cross section on the target mass number is a feature of the present SPP that gives a smooth variation of SPEs. As a consequence, the direct portion of the DSD component gives the largest contribution to the total (n,{gamma}) cross section for neutron-rich isotopes below a few MeV. Therefore, the direct capture process modifies the astrophysical (n,{gamma}) reaction rates to a great extent. The semi-direct component, however, gives a negligible contribution to the astrophysical reaction rates, but its impact is significant above several MeV. The reason for the difference in isotopic dependence between the HF and DSD components is discussed, and its implication for r-process nucleosynthesis is given.

Chiba, S.; Koura, H.; Maruyama, T. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195 (Japan); Hayakawa, T. [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kawano, T. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Kajino, T. [National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan) and Department of Astronomy, School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2008-01-15

257

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.

2011-01-01

258

Ngl2p is a Ccr4p-like RNA nuclease essential for the final step in 3'-end processing of 5.8S rRNA in Saccharomyces cerevisiae.  

PubMed Central

Saccharomyces cerevisiae contains three nonessential genes (NGL1, NGL2, and NGL3) that encode proteins containing a domain with similarity to a Mg(2+)-dependent endonuclease motif present in the mRNA deadenylase Ccr4p. We have investigated a possible role of these proteins in rRNA processing, because for many of the pre-rRNA processing steps, the identity of the responsible nuclease remains elusive. Analysis of RNA isolated from cells in which the NGL2 gene has been inactivated (ngl2delta) demonstrates that correct 3'-end formation of 5.8S rRNA at site E is strictly dependent on Ngl2p. No role in pre-rRNA processing could be assigned to Ngl1p and Ngl3p. The 3'-extended 5.8S rRNA formed in the ngl2delta mutant is slightly shorter than the 6S precursor previously shown to accumulate upon combined deletion of the 3' --> 5' exonuclease-encoding REX1 and REX2 genes or upon depletion of the exosomal subunits Rrp40p or Rrp45p. Thus, our data add a further component to the set of nucleases required for correct 3'-end formation of yeast 5.8S rRNA.

Faber, Alex W; Van Dijk, Marie; Raue, Hendrik A; Vos, Jan C

2002-01-01

259

Effects of mixing between ordinary and exotic charged leptons in the process e sup + e sup minus r arrow Z sup 0 Z sup 0  

SciTech Connect

The process {ital e}{sup +}{ital e}{sup {minus}}{r arrow}{ital Z}{sup 0}{ital Z}{sup 0} is reexamined with the inclusion of mixing between ordinary and exotic charged leptons. Three types of exotic leptons, (i) mirror, (ii) vector doublet, and (iii) vector singlet, are considered. The effects of mixing are discussed in terms of the expected relative deviations in the differential decay parameters with respect to the standard-model results. These are presented as a function of the scattering angle as well as a function of the square of mixing, {vert bar}{ital U}{sub {ital Ee}}{vert bar}{sup 2}, between the ordinary ({ital e}) and exotic ({ital E}) leptons. At {radical}{ital s} =200 GeV, {ital m}{sub {ital E}}=100 GeV, and {vert bar}{ital U}{sub {ital Ee}}{vert bar}{sup 2}=0.02, for the mixing of the three types of leptons, the expected relative deviations are (i) between {minus}2.7% and {minus}7.6% in the differential cross sections with unpolarized {ital e}{sup +},{ital e}{sup {minus}} beams, (ii) between {similar to}{minus}6% and {similar to}{minus}8% in the inclusive angular distributions (for the production of polarized {ital Z}{sup 0}'s) with longitudinally polarized {ital e}{sup {minus}} and unpolarized {ital e}{sup +} beams, and (iii) between +10.4% and {minus}11% in the differential polarization asymmetry. The magnitudes of the relative deviations, in most of these decay parameters, increase with the increase in {ital m}{sub {ital E}}. We find that, in principle, measurements of relative deviations in the polarization asymmetry and inclusive angular distributions with {ital e}{sub {ital L}({ital R})}{sup {minus}},{ital e}{sup +} beams could help in distinguishing mirror, vector-doublet, and vector-singlet lepton mixings.

Singh, S.; Nagawat, A.K.; Sharma, N.K. (Department of Physics, University of Rajasthan, Jaipur 302004, India (IN))

1990-03-01

260

Non-Canonical Processing of Arabidopsis pri-miR319a/b/c Generates Additional microRNAs to Target One RAP2.12 mRNA Isoform  

PubMed Central

Arabidopsis miR319a/b/c primary transcripts are unusual due to the presence of a long stem and loop structure containing functional miR319a/b/c molecules. In our experiments carried out using high throughput sequencing (HTS), we have shown that additional microRNAs (miRNAs), miR319a.2/b.2/c.2 are generated from the upper part of the same hairpin structure. We have also found cognate miRNAa.2*/b.2*/c.2* to be present in the HTS results with a considerably lower number of reads. Northern hybridization revealed that miR319b.2 is mainly expressed in 35-day-old plant rosette leaves, as well as in stem and inflorescences of 42- and 53-day-old plants. Moreover, it carries multiple signatures of a functional miRNA, including as follows: (i) its biogenesis is HYL1-dependent; (ii) it is incorporated in a substantial amount into RISC complexes containing AGO1, AGO2, or AGO4 protein; (iii) 24 nt-long species of miR319b.2 have been found in inflorescences to be more abundant than 21 nt miR319b.2 species; (iv) it is present in various ratios to miR319b during plant development, which suggests the existence of a regulatory mechanism responsible for its biogenesis/processing; (v) there is an observed cross-species conservation of the miR319a/b/c stem nucleotide sequence extending beyond mature miRNA region; and (vi) all evidence suggests that intron-containing RAP2.12 mRNA isoform is the target for miR319b.2. All these features prompt us to claim miR319b.2 as a functional miRNA molecule.

Sobkowiak, Lukasz; Karlowski, Wojciech; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

2012-01-01

261

EfaR Is a Major Regulator of Enterococcus faecalis Manganese Transporters and Influences Processes Involved in Host Colonization and Infection  

PubMed Central

Metal ions, in particular manganese, are important modulators of bacterial pathogenicity. However, little is known about the role of manganese-dependent proteins in the nosocomial pathogen Enterococcus faecalis, a major cause of bacterial endocarditis. The present study demonstrates that the DtxR/MntR family metalloregulator EfaR of E. faecalis controls the expression of several of its regulon members in a manganese-dependent way. We also show that efaR inactivation impairs the ability of E. faecalis to form biofilms, to survive inside macrophages, and to tolerate oxidative stress. Our results reveal that EfaR is an important modulator of E. faecalis virulence and link manganese homeostasis to enterococcal pathogenicity.

Abrantes, M. C.; Lopes, M. de F.

2013-01-01

262

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

263

Possible deviations due to exotic-lepton mixings in the process e sup + e sup minus r arrow W sup + W sup minus  

SciTech Connect

The process {ital e}{sup +}{ital e}{sup {minus}}{r arrow}{ital W}{sup +}{ital W}{sup {minus}} is reexamined with the inclusion of mixing between ordinary leptons and exotic leptons of the types (i) mirror, (ii) vector doublet, and (iii) vector singlet. The effects of mixings are discussed in terms of the expected relative deviations from the standard-model predictions for the total cross section, the forward-backward asymmetry, the differential angular distribution for unpolarized {ital W}'s, and the inclusive angular distributions for longitudinally ({ital L}) and transversely ({ital T}) polarized {ital W}'s with and without charge identification at energies of the CERN collider LEP II ({radical}{ital s} {approx}190 GeV). These deviations are evaluated for three extreme cases of mixing: (I) mixing in the neutral-lepton sector only, (II) mixing in the charged-lepton sector only, and (III) equal mixings in both sectors. The expected relative deviations are presented as a function of the scattering angle {theta} as well as the exotic-neutrino mass {ital m}{sub {ital N}} and the square of the mixing angle sin{sup 2}{psi}. For case (I), all three types of exotic leptons have identical mixing effects. For a run of 500-pb{sup {minus}1} data, with {ital m}{sub {ital N}}{ge}250 GeV and {psi}=10{degree}, the expected relative deviations are more than one standard deviation (SD) error in {ital d}{sigma}({theta}), {ital d}{sigma}{sub {ital T}}({theta}) for all values of {theta}, in {ital d}{sigma}{sub {ital T}{ital T}}({theta}) for cos{theta}{ge}0.4, and in {ital d}{sigma}{sub {ital L}}({theta}) for {vert bar}cos{theta}{vert bar}{le}0.6.

Nagawat, A.K.; Singh, S.; Sharma, N.K. (Department of Physics, University of Rajasthan, Jaipur-302004, India (IN))

1990-11-01

264

The Putative NTPase Fap7 Mediates Cytoplasmic 20S Pre-rRNA Processing through a Direct Interaction with Rps14†  

PubMed Central

One of the proteins identified as being involved in ribosome biogenesis by high-throughput studies, a putative P-loop-type kinase termed Fap7 (YDL166c), was shown to be required for the conversion of 20S pre-rRNA to 18S rRNA. However, the mechanism underlying this function has remained unclear. Here we demonstrate that Fap7 is strictly required for cleavage of the 20S pre-rRNA at site D in the cytoplasm. Genetic depletion of Fap7 causes accumulation of only the 20S pre-rRNA, which could be detected not only in 43S preribosomes but also in 80S-sized complexes. Fap7 is not a structural component of 43S preribosomes but likely transiently interacts with them by directly binding to Rps14, a ribosomal protein that is found near the 3? end of the 18S rRNA. Consistent with an NTPase activity, conserved residues predicted to be required for nucleoside triphosphate (NTP) hydrolysis are essential for Fap7 function in vivo. We propose that Fap7 mediates cleavage of the 20S pre-rRNA at site D by directly interacting with Rps14 and speculate that it is an enzyme that functions as an NTP-dependent molecular switch in 18S rRNA maturation.

Granneman, Sander; Nandineni, Madhusudan R.; Baserga, Susan J.

2005-01-01

265

Overexpression of interleukin-8 receptor 2 (IL-8R2) indicates better prognosis in esophageal adenocarcinoma and squamous cell carcinoma procession.  

PubMed

Researches have showed that interleukin family or receptors play a role in many human tumor progressions including esophageal carcinoma. In this study, we examined the expression of interleukin-8 receptor 2 (IL-8R2) and analyze the relationship between it and esophageal carcinoma clinical characteristics. IL-8R2 protein expression was confirmed by immunohistochemistry and immunofluorescence arrays and was analyzed further via Western blot and qRT-PCR analysis in frozen tissues. The correlation between their expression levels and clinical characteristics were evaluated by Mann-Whitney and Kruskal-Wallis test. Via Kaplan-Meier plots and Cox proportional hazard models, overall survival (OS) was analyzed. Compared with normal esophageal tissue, IL-8R2 protein was overexpressed significantly in esophageal cancer (p < 0.05) and was observed both in cytoplasm and nuclear. The lower expression of IL-8R2 protein was observed with higher p staging of esophageal cancer, and the significant association between them was confirmed (p = 0.000), and in advanced p T stage, the similar result was obtained (p = 0.015); however, compared with lymph node metastasis-negative group, it is no significant difference in positive group (p = 0.152). In a Kaplan-Meier analysis, compared with IL-8R2 low expression, IL-8R2 high expression identified a group of patients with the longest OS. Cox proportional hazard models revealed that IL-8R2 predicted long time to OS. The higher expression of IL-8R2 was found in early esophageal carcinoma, which may indicate that IL-8R2 plays an important role and is better prognostic factor in esophageal cancer development. PMID:24972913

Liang, Bing; Zhao, Hui; Che, Jian-Bo; Wang, Hao-Jie; Shi, Gong-Ning

2014-08-01

266

Imp3 unfolds stem structures in pre-rRNA and U3 snoRNA to form a duplex essential for small subunit processing.  

PubMed

Eukaryotic ribosome biogenesis requires rapid hybridization between the U3 snoRNA and the pre-rRNA to direct cleavages at the A0, A1, and A2 sites in pre-rRNA that liberate the small subunit precursor. The bases involved in hybridization of one of the three duplexes that U3 makes with pre-rRNA, designated the U3-18S duplex, are buried in conserved structures: box A/A' stem-loop in U3 snoRNA and helix 1 (H1) in the 18S region of the pre-rRNA. These conserved structures must be unfolded to permit the necessary hybridization. Previously, we reported that Imp3 and Imp4 promote U3-18S hybridization in vitro, but the mechanism by which these proteins facilitate U3-18S duplex formation remained unclear. Here, we directly addressed this question by probing base accessibility with chemical modification and backbone accessibility with ribonuclease activity of U3 and pre-rRNA fragments that mimic the secondary structure observed in vivo. Our results demonstrate that U3-18S hybridization requires only Imp3. Binding to each RNA by Imp3 provides sufficient energy to unfold both the 18S H1 and the U3 box A/A' stem structures. The Imp3 unfolding activity also increases accessibility at the U3-dependent A0 and A1 sites, perhaps signaling cleavage at these sites to generate the 5' mature end of 18S. Imp4 destabilizes the U3-18S duplex to aid U3 release, thus differentiating the roles of these proteins. Protein-dependent unfolding of these structures may serve as a switch to block U3-pre-rRNA interactions until recruitment of Imp3, thereby preventing premature and inaccurate U3-dependent pre-rRNA cleavage and folding events in eukaryotic ribosome biogenesis. PMID:23980203

Shah, Binal N; Liu, Xin; Correll, Carl C

2013-10-01

267

Imp3 unfolds stem structures in pre-rRNA and U3 snoRNA to form a duplex essential for small subunit processing  

PubMed Central

Eukaryotic ribosome biogenesis requires rapid hybridization between the U3 snoRNA and the pre-rRNA to direct cleavages at the A0, A1, and A2 sites in pre-rRNA that liberate the small subunit precursor. The bases involved in hybridization of one of the three duplexes that U3 makes with pre-rRNA, designated the U3-18S duplex, are buried in conserved structures: box A/A? stem–loop in U3 snoRNA and helix 1 (H1) in the 18S region of the pre-rRNA. These conserved structures must be unfolded to permit the necessary hybridization. Previously, we reported that Imp3 and Imp4 promote U3-18S hybridization in vitro, but the mechanism by which these proteins facilitate U3-18S duplex formation remained unclear. Here, we directly addressed this question by probing base accessibility with chemical modification and backbone accessibility with ribonuclease activity of U3 and pre-rRNA fragments that mimic the secondary structure observed in vivo. Our results demonstrate that U3-18S hybridization requires only Imp3. Binding to each RNA by Imp3 provides sufficient energy to unfold both the 18S H1 and the U3 box A/A? stem structures. The Imp3 unfolding activity also increases accessibility at the U3-dependent A0 and A1 sites, perhaps signaling cleavage at these sites to generate the 5? mature end of 18S. Imp4 destabilizes the U3-18S duplex to aid U3 release, thus differentiating the roles of these proteins. Protein-dependent unfolding of these structures may serve as a switch to block U3-pre-rRNA interactions until recruitment of Imp3, thereby preventing premature and inaccurate U3-dependent pre-rRNA cleavage and folding events in eukaryotic ribosome biogenesis.

Shah, Binal N.; Liu, Xin; Correll, Carl C.

2013-01-01

268

(R)-Doxylaminium (R,R)-tartrate  

PubMed Central

In the title compound (systematic name: (R)-dimeth­yl{2-[1-phenyl-1-(pyridin-2-yl)eth­oxy]eth­yl}aza­nium (R,R)-3-carb­oxy-2,3-dihy­droxy­propano­ate), C17H23N2O+·C4H5O6 ?, the doxylaminium cation is protonated at the N atom. The tartrate monoanions are linked by short, almost linear O—H?O hydrogen bonds into chains extended along [100]. These chains are inter­linked by anion–pyridine O—H?N hydrogen bonds into a two-dimensional grid structure. WeakC—H?O inter­actions also play a role in the crystal packing. An intra­molecular hy­droxy–carboxyl­ate O—H?O hydrogen bond influences the conformation of the anion: the hydrogen-bonded fragment is almost planar, the maximum deviation from the mean plane being 0.059?(14)?Å. In the cation, the aromatic rings are almost perpendicular [dihedral angle = 84.94?(8)°] and the conformation of the O—C—C—N chain is gauche(?), the dihedral angle is ?76.6?(2)°. The absolute configuration was assigned on the basis of known chirality of the parent compound.

Dayananda, A.S.; Dutkiewicz, Grzegorz; Yathirajan, H. S.; Kubicki, Maciej

2012-01-01

269

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

270

On the Applicability of the Concept of Control Wave Process to the B 2? R Martensitic Transformation in B 2 Titanium Nickelide Alloys  

NASA Astrophysics Data System (ADS)

Within the framework of the dynamic theory based on the synthesis of concepts of heterogeneous nucleation and wave growth of martensite crystals, the possibility of description of morphological parameters during the ? 2? R transformation is analyzed. It is demonstrated that the calculated and observed orientations of the habit planes can be matched. The calculated orientation relationships are given and the results obtained are discussed.

Kashchenko, M. P.; Chashchina, V. G.

2013-12-01

271

Elucidating the role of H/ACA-like RNAs in trans-splicing and rRNA processing via RNA interference silencing of the Trypanosoma brucei CBF5 pseudouridine synthase.  

PubMed

Most pseudouridinylation in eukaryotic rRNA and small nuclear RNAs is guided by H/ACA small nucleolar RNAs. In this study, the Trypanosoma brucei pseudouridine synthase, Cbf5p, a snoRNP protein, was identified and silenced by RNAi. Depletion of this protein destabilized all small nucleolar RNAs of the H/ACA-like family. Following silencing, defects in rRNA processing, such as accumulation of precursors and inhibition of cleavages to generate the mature rRNA, were observed. snR30, an H/ACA RNA involved in rRNA maturation, was identified based on prototypical conserved domains characteristic of this RNA in other eukaryotes. The silencing of CBF5 also eliminated the spliced leader-associated (SLA1) RNA that directs pseudouridylation on the spliced leader RNA (SL RNA), which is the substrate for the trans-splicing reaction. Surprisingly, the depletion of Cbf5p not only eliminated the pseudouridine on the SL RNA but also abolished capping at the fourth cap-4 nucleotide. As a result of defects in the SL RNA and decreased modification on the U small nuclear RNA, trans-splicing was inhibited at the first step of the reaction, providing evidence for the essential role of H/ACA RNAs and the modifications they guide on trans-splicing. PMID:16107339

Barth, Sarit; Hury, Avraham; Liang, Xue-Hai; Michaeli, Shulamit

2005-10-14

272

Copy number control and incompatibility of plasmid R1: Identification of a protein that seems to be involved in both processes  

Microsoft Academic Search

Investigations into the genetic determinants for incompatibility of miniplasmids and hybrid replicons constructed from wild type and mutant R1 revealed the presence of an incompatibility function at the junction of two small PstI fragments. These two fragments were not distinguished in earlier experiments since they have the same mobility on agarose gels. This incompatibility function is distinct from other inc-determinants

K. J. Burger; J. Steinbauer; G. Röllich; R. Kollek; W. Goebel

1981-01-01

273

Rpp2, an essential protein subunit of nuclear RNase P, is required for processing of precursor tRNAs and 35S precursor rRNA in Saccharomyces cerevisiae.  

PubMed

RPP2, an essential gene that encodes a 15.8-kDa protein subunit of nuclear RNase P, has been identified in the genome of Saccharomyces cerevisiae. Rpp2 was detected by sequence similarity with a human protein, Rpp20, which copurifies with human RNase P. Epitope-tagged Rpp2 can be found in association with both RNase P and RNase mitochondrial RNA processing in immunoprecipitates from crude extracts of cells. Depletion of Rpp2 protein in vivo causes accumulation of precursor tRNAs with unprocessed introns and 5' and 3' termini, and leads to defects in the processing of the 35S precursor rRNA. Rpp2-depleted cells are defective in processing of the 5.8S rRNA. Rpp2 immunoprecipitates cleave both yeast precursor tRNAs and precursor rRNAs accurately at the expected sites and contain the Rpp1 protein orthologue of the human scleroderma autoimmune antigen, Rpp30. These results demonstrate that Rpp2 is a protein subunit of nuclear RNase P that is functionally conserved in eukaryotes from yeast to humans. PMID:9618478

Stolc, V; Katz, A; Altman, S

1998-06-01

274

Glossary Terms [R  

Cancer.gov

In the instances when these applications are reviewed by CSR study sections, they are processed in the same manner as the other applications. DHHS policies concerning assurances of protection of human subjects involved in research also apply to R84s. Pertinent background information may be obtained from the Fogarty International Center.

275

The effects of exchange and interfacial reaction in two-phase systems on N.M.R. lineshapes and relaxation processes  

NASA Astrophysics Data System (ADS)

The effects of molecular exchange between two immiscible fluid phases are of considerable importance when interpreting N.M.R. lineshapes and relaxation times in systems such as emulsions or coacervates, but have not been fully explored theoretically. In general the nuclei in each phase must be considered as belonging to distinct chemical species which are interchanged by chemical reaction localized at the interface between the two fluids. By solving the Bloch-Torrey equations with new generalized boundary conditions describing this localized interfacial reaction we show how the N.M.R. spectral lineshape and relaxation times depend on the morphology of the system as well as on the rates of diffusion and interfacial reaction. Our results differ fundamentally from the traditional phenomenological description of exchange based on the Bloch-McConnell or Zimmerman-Brittin equations which take no explicit account of these factors. In order to illustrate these differences exact analytical solutions are derived for the simplest geometry where the two phases are lamellar. More complicated geometries can be treated by numerical methods.

Belton, P. S.; Hills, B. P.

276

Report on the results of the fiscal 1997 R and D under consignment from NEDO of photon measuring/processing technology (development of high-efficiency production process technology).  

National Technical Information Service (NTIS)

Development is made of high energy-efficiency laser processing technology and high efficiency/high grade photon generation/control technology as laser light source, for the purpose of energy conservation/efficiency heightening of production processes whic...

1998-01-01

277

Test Review: R. W. Keith "SCAN-3 for Adolescents and Adults--Tests for Auditory Processing Disorders". San Antonio, TX: Pearson, 2009  

ERIC Educational Resources Information Center

The SCAN-3 is a battery of tasks used for the screening and diagnosis of auditory processing disorder. It is available in two versions, one for children (the SCAN-3: C) and one for adolescents and adults (the SCAN-3: A); the latter version of the SCAN-3 is reviewed in this article, although it is very similar to the child version. The primary…

Lovett, Benjamin J.; Johnson, Theodore L.

2010-01-01

278

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...

279

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

280

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

281

The Earth's magnetosphere is 165 R(sub E) long: Self-consistent currents, convection, magnetospheric structure, and processes for northward interplanetary magnetic field  

NASA Technical Reports Server (NTRS)

The subject of this paper is a self-consistent, magnetohydrodynamic numerical realization for the Earth's magnetosphere which is in a quasi-steady dynamic equilibrium for a due northward interplanetary magnetic field (IMF). Although a few hours of steady northward IMF are required for this asymptotic state to be set up, it should still be of considerable theoretical interest because it constitutes a 'ground state' for the solar wind-magnetosphere interaction. Moreover, particular features of this ground state magnetosphere should be observable even under less extreme solar wind conditions. Certain characteristics of this magnetosphere, namely, NBZ Birkeland currents, four-cell ionospheric convection, a relatively weak cross-polar potential, and a prominent flow boundary layer, are widely expected. Other characteristics, such as no open tail lobes, no Earth-connected magnetic flux beyond 155 R(sub E) downstream, magnetic merging in a closed topology at the cusps, and a 'tadpole' shaped magnetospheric boundary, might not be expected. In this paper, we will present the evidence for this unusual but interesting magnetospheric equilibrium. We will also discuss our present understanding of this singular state.

Fedder, J. A.; Lyon, J. G.

1995-01-01

282

The process of displacing the single-stranded DNA-binding protein from single-stranded DNA by RecO and RecR proteins  

Microsoft Academic Search

The regions of single-stranded (ss) DNA that result from DNA damage are immediately coated by the ssDNA-binding protein (SSB). RecF pathway pro- teins facilitate the displacement of SSB from ssDNA, allowing the RecA protein to form protein filaments on the ssDNA region, which facilitates the process of recombinational DNA repair. In this study, we examined the mechanism of SSB displacement

Jin Inoue; Masayoshi Honda; S. Ikawa; Takehiko Shibata; Tsutomu Mikawa

2007-01-01

283

Uniform and High-Power Characteristics of AlGaInP-based Laser Diodes by 4-inch Wafer Process Technology for DVD-R\\/RW\\/RAM  

Microsoft Academic Search

In this study, we demonstrate the high-power (over 400 mW) at 75 degC single-lateral-mode operation of a 650-nm band LD, and we present the excellent uniformity of LD characteristics in 4-inch wafer. In summary, we have successfully fabricated high-power and single-lateral-mode 650-nm band AlGaInP LDs by using the 4-inch wafer process technology for the first time. The results confer the

H. Sumitomo; S. Kajiyama; H. Oguri; T. Sakashita; S. Domoto; K. Nakao; T. Yamamoto; T. Kita; T. Komatani; H. Kawakubo; M. Ono; S. Izumi

2006-01-01

284

Prospects for Using High Neutron Fluxes in Igniting Capsules to Probe the Contributions of Excited Nuclear State Reactions to R, P, and S Process Nucleosynthesis  

NASA Astrophysics Data System (ADS)

The standard capsule design^1 for the National Ignition Facility offers the possibility of producing neutron fluxes that are high enough to explore a variety of multiple-step nuclear reactions that are relevant to astrophysical nucleosynthesis.^2 Calculations show that target nuclei seeded between the ablator and ice would see a neutron flux high enough to drive 10-20% into excited states via (n, n) reactions. Multiple-step reactions, including branches that pass through excited states with t > 1 ps can be studied using radiochemistry.^3 The 14 MeV neutrons due to the major D+T>? + n burn reaction drive the (n, n) excitations and (n, 2n) nuclear kinetics, while the ~ 2% minority D + D 3He + n, or T + p can drive (n,? ) or (p, ? ) reactions. Radiochemistry measurements of noble gas end species can be made with very high efficiency with only ~ 10^4 atoms required. Solid collection systems are being developed as well (with 10^7-8 atoms required at present). Spatially, temporally, and spectrally resolved x-ray emission as well neutron time-of-flight measurements offer the promise of constraining the distribution of doped nuclei and the temperature and therefore local rate of the thermonuclear burn. It should also be noted that the class of experiments proposed here involving short-lived intermediate states are complementary to those naturally studied at the proposed Rare Isotope Accelerator which is suited to probing reactions on states with much longer half lives. 1. Haan, S. W. et. al., Physics of Plasmas, 2 (6), 2480, part 2, 1995 2. Hoffman, R.D. et.al., Astrophysical Journal, 521 (2), 735, part 1, 1999. 3. Stoyer, M..A. et. al., in the 42nd Annual Meeting of the Division of Plasma Physics Meeting, Quebec City, Canada, October 23-27, 2000 *The work at LLNL was performed under the auspices of the U. S. Department of Energy by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

Libby, Stephen; Tabak, Max; Hoffman, Robert; Stoyer, Mark; McNabb, Dennis; Ormand, Erich; Weiss, Morton; Mustafa, Mohammed; Ward, Richard

2001-10-01

285

Dynamics of R1 and R2 elements in the rDNA locus of Drosophila simulans.  

PubMed Central

The mobile elements R1 and R2 insert specifically into the rRNA gene locus (rDNA locus) of arthropods, a locus known to undergo concerted evolution, the recombinational processes that preserve the sequence homogeneity of all repeats. To monitor how rapidly individual R1 and R2 insertions are turned over in the rDNA locus by these processes, we have taken advantage of the many 5' truncation variants that are generated during the target-primed reverse transcription mechanism used by these non-LTR retrotransposons for their integration. A simple PCR assay was designed to reveal the pattern of the 5' variants present in the rDNA loci of individual X chromosomes in a population of Drosophila simulans. Each rDNA locus in this population was found to have a large, unique collection of 5' variants. Each variant was present at low copy number, usually one copy per chromosome, and was seldom distributed to other chromosomes in the population. The failure of these variants to spread to other units in the same rDNA locus suggests a strong recombinational bias against R1 and R2 that results in the individual copies of these elements being rapidly lost from the rDNA locus. This bias suggests a significantly higher frequency of R1 and R2 retrotransposition than we have previously suggested.

Perez-Gonzalez, C E; Eickbush, T H

2001-01-01

286

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

287

Viscosity of gaseous R404A, R407C, R410A, and R507  

SciTech Connect

This paper presents new measurements of the viscosity of gaseous R404A (52 wt% R143a, 44 wt% R125, 4 wt% R134a), R407C (23 wt% R32, 25 wt% R125, 52 wt% R143a), R410A (50 wt% R32, 50 wt% R125), and R507 (50 wt% R143a, 50 wt% R125). These mixtures are recommended as substitutes for the refrigerants R22, R502, and R13B1. Measurements were carried out in an oscillating-disk viscometer. The obtained values of the viscosity are relative to the viscosity of nitrogen. The experiments were performed at atmospheric pressure over the temperature range 297 to 403 K and near the saturation line up to pressures of 0.6 P{sub crit}. The estimated uncertainty of the reported viscosities are {+-}0.5% for the viscosities at atmospheric pressure and {+-}15 along the saturation line, being limited by the accuracy of the available vapor pressure and density data. The experimental viscosities at atmospheric pressure are employed to determine the intermolecular potential parameters, {sigma} and {epsilon}, which provide the optimum representation of the data with the aid of the extended law of corresponding states developed by Kestin et al. A comparison of the experimental viscosity data with the values calculated by REFPROP, both at atmospheric pressure and along the saturation line, is presented.

Nabizadeh, H.; Mayinger, F.

1999-05-01

288

The alpha Process and the rProcess  

Microsoft Academic Search

If material initially in nuclear statistical equilibrium (NSE) at high temperature and containing a large fraction of alpha -particles (or nucleons) is expanded and cooled so rapidly that not all the alpha -particles have time to reassemble, its final composition will differ substantially from what is traditionally calculated for particle-deficient freeze-outs. It has long been known that this phenomenon, the

S. E. Woosley; R. D. Hoffman

1992-01-01

289

The Mips R4000 processor  

Microsoft Academic Search

The R4000, a highly integrated, 64-b RISC microprocessor that provides a simple solution to the increasing demands on the size of address space while maintaining full compatibility with previous Mips processors, is described. The microprocessor's on-chip central processing unit, floating point unit, memory management unit, primary caches, system interface logic, secondary cache control logic with flexible interface, the programmable system

Sunil Mirapuri; Michael Woodacre; N. Vasseghi

1992-01-01

290

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

291

R+?R2 loop quantum cosmology  

NASA Astrophysics Data System (ADS)

Working in Einstein frame, we introduce, in order to avoid singularities, holonomy corrections to the f(R)=R +?R2 model. We perform a detailed analytical and numerical study when holonomy corrections are taken into account in both Jordan and Einstein frames, obtaining, in Jordan frame, a dynamics which differs qualitatively, at early times, from the one of the original model. More precisely, when holonomy corrections are taken into account, the Universe is not singular, starting at early times in the contracting phase and bouncing to enter the expanding one where, as in the original model, it inflates. This dynamics is completely different from the one obtained in the original R +?R2 model, where the Universe is singular at early times and never bounces. Moreover, we show that these holonomy corrections may lead to better predictions for the inflationary phase as compared with current observations.

Amorós, Jaume; de Haro, Jaume; Odintsov, Sergei D.

2014-05-01

292

Subsurface damage in precision ground ULE(R) and Zerodur(R) surfaces.  

PubMed

The total process cycle time for large ULE((R)) and Zerodur((R))optics can be improved using a precise and rapid grinding process, with low levels of surface waviness and subsurface damage. In this paper, the amounts of defects beneath ULE((R)) and Zerodur((R) )surfaces ground using a selected grinding mode were compared. The grinding response was characterised by measuring: surface roughness, surface profile and subsurface damage. The observed subsurface damage can be separated into two distinct depth zones, which are: 'process' and 'machine dynamics' related. PMID:19547587

Tonnellier, X; Morantz, P; Shore, P; Baldwin, A; Evans, R; Walker, D D

2007-09-17

293

Coal Dewatering: Australian R&D Trends  

Microsoft Academic Search

Coal (and tailings) dewatering is a major R&D priority in Australia and other coal producing countries. Improved dewatering involves understanding and manipulating feed suspension and filter cake characteristics; judicious selection, modification and application of dewatering technology; and control of the process in respect of feed material, operational parameters, and product characteristics. For these areas, this paper analyses R&D needs, summarises

N. C. LOCKHART; C. J. VEAL

1996-01-01

294

Factor Analysis Using "R"  

ERIC Educational Resources Information Center

"R" (R Development Core Team, 2011) is a very powerful tool to analyze data, that is gaining in popularity due to its costs (its free) and flexibility (its open-source). This article gives a general introduction to using "R" (i.e., loading the program, using functions, importing data). Then, using data from Canivez, Konold, Collins, and Wilson…

Beaujean, A. Alexander

2013-01-01

295

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

296

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

...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

297

Yeast snR30 is a small nucleolar RNA required for 18S rRNA synthesis.  

PubMed Central

Subnuclear fractionation and coprecipitation by antibodies against the nucleolar protein NOP1 demonstrate that the essential Saccharomyces cerevisiae RNA snR30 is localized to the nucleolus. By using aminomethyl trimethyl-psoralen, snR30 can be cross-linked in vivo to 35S pre-rRNA. To determine whether snR30 has a role in rRNA processing, a conditional allele was constructed by replacing the authentic SNR30 promoter with the GAL10 promoter. Repression of snR30 synthesis results in a rapid depletion of snR30 and a progressive increase in cell doubling time. rRNA processing is disrupted during the depletion of snR30; mature 18S rRNA and its 20S precursor underaccumulate, and an aberrant 23S pre-rRNA intermediate can be detected. Initial results indicate that this 23S pre-rRNA is the same as the species detected on depletion of the small nucleolar RNA-associated proteins NOP1 and GAR1 and in an snr10 mutant strain. It was found that the 3' end of 23S pre-rRNA is located in the 3' region of ITS1 between cleavage sites A2 and B1 and not, as previously suggested, at the B1 site, snR30 is the fourth small nucleolar RNA shown to play a role in rRNA processing. Images

Morrissey, J P; Tollervey, D

1993-01-01

298

Computation & communication in R: a distributed database manager  

Microsoft Academic Search

R* is an experimental prototype distributed database management system. The computation needed to perform a sequence of multisite user transactions in R* is structured as a tree of processes communicating over virtual circuit communication links. Distributed computation can be supported by providing a server process per site which performs requests on behalf of remote users. Alternatively, a new process could

Bruce G. Lindsay; Laura M. Haas; Paul F. Wilms; Robert A. Yost

1983-01-01

299

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

300

Phototype Plant for Nuclear Process Heat (Nph), Reference Phase. R and D Work on Hydrogenated Coal Gasification (Hcg). Further Operation of Semi-Industrial Plant for Hydrogenated Coal Gasification.  

National Technical Information Service (NTIS)

In view of a scale up, leading to a commercial HCG, futher R and D work was performed on the 100 kg C/hr prototype plant. The inclined tube for feeding coal into the fluidized bed, the raw gas/hydrogenation gas heat exchanger, and the modified hydrogen so...

R. Fladerer L. Schrader

1982-01-01

301

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

302

Pharmacokinetics and Metabolism of (R,R)-Methoxyfenoterol in Rat  

PubMed Central

(R,R)-Fenoterol (Fen), a ?2-adrenoceptor agonist, is under clinical investigation in the treatment of congestive heart disease. The pharmacokinetics and metabolism of the 4-methoxyphenyl derivative of (R,R)-Fen, (R,R)-MFen, have been determined following intravenous and oral administration to the rat and compared with corresponding results obtained with (R,R)-Fen. Results of the study suggest that (R,R)-MFen can offer pharmacokinetic and metabolic advantages in comparison to an earlier (R,R)-Fen.The oral administration revealed that the net exposure of (R,R)-MFen was about three-fold higher than that of (R,R)-Fen (7.2 versus 2.3 min × nmol ml-1), while intravenous administration proved that the clearance was significantly reduced, 48 versus 146 ml min-1 kg-1, the T1/2 was significantly longer, 152.9 versus 108.9 min and the area under the curve (AUC) was significantly increased, 300 versus 119 min × nmol ml-1.(R,R)-MFen was primarily cleared by glucuronidation associated with significant presystemic glucuronidation of the compound. After intravenous and oral administration of (R,R)-MFen, (R,R)-Fen and (R,R)-Fen-G were detected in the urine samples indicating that (R,R)-MFen was O-demethylated and subsequently conjugated to (R,R)-Fen-G. The total (R,R)-Fen and (R,R)-Fen-G as a percentage of the dose after intravenous administration was 3.6% while after oral administration was 0.3%, indicating that only a small fraction of the drug escaped presystemic glucuronidation and was available for O-demethylation.The glucuronidation pattern was confirmed by the results from in vitro studies where incubation of (R,R)-MFen with rat hepatocytes produced (R,R)-MFen-G, (R,R)-Fen and (R,R)-Fen-G, while incubation with rat intestinal microsomes only resulted in the formation of (R,R)-MFen-G.

Siluk, Danuta; Mager, Donald E.; Kim, Hee Seung; Wang, Yan; Furimsky, Anna M.; Ta, Amy; Iyer, Lalitha V.; Green, Carol E.; Wainer, Irving W.

2010-01-01

303

Dynamical R-Parity Violation  

NASA Astrophysics Data System (ADS)

We present a new paradigm for supersymmetric theories with R-parity violation (RPV). At high scale, R parity is conserved in the visible sector but spontaneously broken in the supersymmetry-breaking sector. The breaking is then dynamically mediated to the visible sector and is manifested via nonrenormalizable operators at low energy. Consequently, RPV operators originate from the Kähler potential rather than the superpotential, and are naturally suppressed by the supersymmetry-breaking scale, explaining their small magnitudes. A new set of nonholomorphic RPV operators is identified and found to often dominate over the standard RPV ones. We study the relevant low-energy constraints arising from baryon-number violating processes, proton decay, and flavor changing neutral currents, which may all be satisfied if a solution to the standard model flavor puzzle is incorporated. The chiral structure of the RPV operators implies new and distinct collider signatures, indicating the need to alter current techniques in searching for RPV at the LHC.

Csáki, Csaba; Kuflik, Eric; Volansky, Tomer

2014-04-01

304

A novel nickel responsive MerR-like regulator, NimR, from Haemophilus influenzae.  

PubMed

We have identified a novel regulator from the MerR family of transcription factors in the bacterial pathogen Haemophilus influenzae (HI1623; nickel-associated merR-like Regulator--NimR). NimR regulates the expression of a Ni(2+) uptake transporter (NikKLMQO). The promoters for nimR and the nik operon are divergent and overlapping and NimR binds at a site between the promoter elements for nikKLMQO. Expression of this operon requires NimR and depends on Ni(2+). Growth rates of the H. influenzae nimR and nikQ mutants were reduced in chemically defined media compared to the wild type and the mutants were unable to grow in the presence of EDTA. The mutant strains were less tolerant of acidic pH and the wild type Rd KW20 could not tolerate low pH in the presence of fluoramide, a urease specific inhibitor, confirming that both nickel transport and urea hydrolysis are a central process in pH control. H. influenzae nimR and nikQ strains were deficient in urease activity, but this could be specifically restored by the addition of excess Ni(2+). NimR did not directly regulate the expression of urease genes but the activity of urease requires both nimR and nikQ. Purified NimR is a dimer that binds 1 Ni(2+)ion. NimR is the first example of a Ni-dependent regulator from the MerR family and targeting a metal ion uptake system; it is distinct from NikR the Ni-responsive regulators of the ribbon-helix-helix family. PMID:21952667

Kidd, Stephen P; Djoko, Karrera Y; Ng, JiaQi; Argente, M Pilar; Jennings, Michael P; McEwan, Alastair G

2011-10-01

305

AphA and LuxR/HapR reciprocally control quorum sensing in vibrios  

PubMed Central

Bacteria cycle between periods when they perform individual behaviors and periods when they perform group behaviors. These transitions are controlled by a cell–cell communication process called quorum sensing, in which extracellular signal molecules, called autoinducers (AIs), are released, accumulate, and are synchronously detected by a group of bacteria. AI detection results in community-wide changes in gene expression, enabling bacteria to collectively execute behaviors such as bioluminescence, biofilm formation, and virulence factor production. In this study, we show that the transcription factor AphA is a master regulator of quorum sensing that operates at low cell density (LCD) in Vibrio harveyi and Vibrio cholerae. In contrast, LuxR (V. harveyi)/HapR (V. cholerae) is the master regulator that operates at high cell density (HCD). At LCD, redundant small noncoding RNAs (sRNAs) activate production of AphA, and AphA and the sRNAs repress production of LuxR/HapR. Conversely, at HCD, LuxR/HapR represses aphA. This network architecture ensures maximal AphA production at LCD and maximal LuxR/HapR production at HCD. Microarray analyses reveal that 300 genes are regulated by AphA at LCD in V. harveyi, a subset of which is also controlled by LuxR. We propose that reciprocal gradients of AphA and LuxR/HapR establish the quorum-sensing LCD and HCD gene expression patterns, respectively.

Rutherford, Steven T.; van Kessel, Julia C.; Shao, Yi; Bassler, Bonnie L.

2011-01-01

306

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

307

R Tricks for Kids  

ERIC Educational Resources Information Center

Real-world phenomena simulation models, which can be used to engage middle-school students with probability, are described. Links to R instructional material and easy-to-use code are provided to facilitate implementation in the classroom.

Braun, W. John; White, Bethany J. G.; Craig, Gavin

2014-01-01

308

Generation and analysis of GluR5(Q636R) kainate receptor mutant mice.  

PubMed

The physiological significance of RNA editing of transcripts that code for kainate-preferring glutamate receptor subunits is unknown, despite the fact that the functional consequences of this molecular modification have been well characterized in cloned receptor subunits. RNA editing of the codon that encodes the glutamine/arginine (Q/R) site in the second membrane domain (MD2) of glutamate receptor 5 (GluR5) and GluR6 kainate receptor subunits produces receptors with reduced calcium permeabilities and single-channel conductances. Approximately 50% of the GluR5 subunit transcripts from adult rat brain are edited at the Q/R site in MD2. To address the role of glutamate receptor mRNA editing in the brain, we have made two strains of mice with mutations at amino acid 636, the Q/R-editing site in GluR5, using embryonic stem cell-mediated transgenesis. GluR5(RloxP/RloxP) mice encode an arginine at the Q/R site of the GluR5 subunit, whereas GluR5(wt(loxP)/wt(loxP)) mice encode a glutamine at this site, similar to wild-type mice. Mutant animals do not exhibit developmental abnormalities, nor do they show deficits in the behavioral paradigms tested in this study. Kainate receptor current densities were reduced by a factor of six in acutely isolated sensory neurons of dorsal root ganglia from GluR5(RloxP/RloxP) mice compared with neurons from wild-type mice. However, the editing mutant mice did not exhibit altered responses to thermal and chemical pain stimuli. Our investigations with the GluR5-editing mutant mice have therefore defined a set of physiological processes in which editing of the GluR5 subunit is unlikely to play an important role. PMID:10516295

Sailer, A; Swanson, G T; Pérez-Otaño, I; O'Leary, L; Malkmus, S A; Dyck, R H; Dickinson-Anson, H; Schiffer, H H; Maron, C; Yaksh, T L; Gage, F H; O'Gorman, S; Heinemann, S F

1999-10-15

309

Making Superfund documents available to the public throughout the cleanup process, and discussing site findings and decisions as they are developed (Superfund Management Review: No. 43 G, H, Q, R, T). Directive  

SciTech Connect

The directive summarizes five recommendations for improving Superfund efforts towards timely release of information to the public during site cleanup activities. It provides guidance for the Regions to make documents available to the public throughout the cleanup process and to discuss site findings and decisions as they are developed for the sake of more fully involving citizens in the cleanup process and ensuring two way communication between Superfund staff and local communities.

Not Available

1990-11-05

310

Systems factorial technology with R.  

PubMed

Systems factorial technology (SFT) comprises a set of powerful nonparametric models and measures, together with a theory-driven experiment methodology termed the double factorial paradigm (DFP), for assessing the cognitive information-processing mechanisms supporting the processing of multiple sources of information in a given task (Townsend and Nozawa, Journal of Mathematical Psychology 39:321-360, 1995). We provide an overview of the model-based measures of SFT, together with a tutorial on designing a DFP experiment to take advantage of all SFT measures in a single experiment. Illustrative examples are given to highlight the breadth of applicability of these techniques across psychology. We further introduce and demonstrate a new package for performing SFT analyses using R for statistical computing. PMID:24019062

Houpt, Joseph W; Blaha, Leslie M; McIntire, John P; Havig, Paul R; Townsend, James T

2014-06-01

311

Phototype plant for Nuclear Process Heat (NPH), reference phase. R and D work on Hydrogenated Coal Gasification (HCG). Further operation of semi-industrial plant for hydrogenated coal gasification  

NASA Astrophysics Data System (ADS)

In view of a scale up, leading to a commercial HCG, futher R and D work was performed on the 100 kg C/hr prototype plant. The inclined tube for feeding coal into the fluidized bed, the raw gas/hydrogenation gas heat exchanger, and the modified hydrogen source were tested. Influence on carbon gasification efficiency of dimension of coal particles, humidity of coal, hydrogen content of gasification gas, introduction place of coal in gasifier, height of fluidized bed, and ash content of coal were studied. The plant was operated for 19,400 hr, of which more than 7400 hr under gasification conditions. Carbon gasification rates up to 82% with methane content up to 48% were obtained.

Fladerer, R.; Schrader, L.

1982-07-01

312

Interactions of miR-323/miR-326/miR-329 and miR-130a/miR-155/miR-210 as prognostic indicators for clinical outcome of glioblastoma patients  

PubMed Central

Background Glioblastoma multiforme (GBM) is the most common and aggressive brain tumor with poor clinical outcome. Identification and development of new markers could be beneficial for the diagnosis and prognosis of GBM patients. Deregulation of microRNAs (miRNAs or miRs) is involved in GBM. Therefore, we attempted to identify and develop specific miRNAs as prognostic and predictive markers for GBM patient survival. Methods Expression profiles of miRNAs and genes and the corresponding clinical information of 480 GBM samples from The Cancer Genome Atlas (TCGA) dataset were downloaded and interested miRNAs were identified. Patients’ overall survival (OS) and progression-free survival (PFS) associated with interested miRNAs and miRNA-interactions were performed by Kaplan-Meier survival analysis. The impacts of miRNA expressions and miRNA-interactions on survival were evaluated by Cox proportional hazard regression model. Biological processes and network of putative and validated targets of miRNAs were analyzed by bioinformatics. Results In this study, 6 interested miRNAs were identified. Survival analysis showed that high levels of miR-326/miR-130a and low levels of miR-323/miR-329/miR-155/miR-210 were significantly associated with long OS of GBM patients, and also showed that high miR-326/miR-130a and low miR-155/miR-210 were related with extended PFS. Moreover, miRNA-323 and miRNA-329 were found to be increased in patients with no-recurrence or long time to progression (TTP). More notably, our analysis revealed miRNA-interactions were more specific and accurate to discriminate and predict OS and PFS. This interaction stratified OS and PFS related with different miRNA levels more detailed, and could obtain longer span of mean survival in comparison to that of one single miRNA. Moreover, miR-326, miR-130a, miR-155, miR-210 and 4 miRNA-interactions were confirmed for the first time as independent predictors for survival by Cox regression model together with clinicopathological factors: Age, Gender and Recurrence. Plus, the availability and rationality of the miRNA-interaction as predictors for survival were further supported by analysis of network, biological processes, KEGG pathway and correlation analysis with gene markers. Conclusions Our results demonstrates that miR-326, miR-130a, miR-155, miR-210 and the 4 miRNA-interactions could serve as prognostic and predictive markers for survival of GBM patients, suggesting a potential application in improvement of prognostic tools and treatments.

2013-01-01

313

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

Microsoft Academic Search

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

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

1981-01-01

314

f(R) Theories  

NASA Astrophysics Data System (ADS)

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.

de Felice, Antonio; Tsujikawa, Shinji

2010-06-01

315

R-values  

SciTech Connect

I'll try to keep this short and simple. R{sub LANL} = (beta cpm of X{sub exp} on system 'A')/ (beta cpm of {sup 99}Mo{sub exp} on system 'A')/ (beta cpm of X on system 'A', from thermal on {sup 235}U)/ (beta cpm of {sup 99}Mo on system 'A', from thermal on {sup 235}U). As I understand it, the above equation is the historical (as well as current) way of determining R-values using data from beta counting at LANL. The ratio in the denominator, a little 'r', is the 'baseline' or 'calibration' value for a specific beta detector. Over time, if the detector 'drifts' one would see a variation in this 'r' during a thermal calibration measurement. This baseline is what LANL likes to track to monitor specific detector performance - this is not relevant to LLNL where gamma detection is used for determining R-values. LANL states that uncertainty is only dependent upon the count statistics for the isotopes measured. If one tries to convert this to an atom basis, the uncertainties will increase due to the incorporation of the uncertainties in the nuclear data used to convert the cpm to atoms. LLNL switched to gamma detection methods in the 1970s thus replacing our beta counting effort. The equation below is how we have since determined R-values. The numerator ratios atom values of isotopes that are determined by measuring gamma cpm (usually? using several peaks per isotope) and then converting to particle decay in dpm using detector efficiency for each peak and the appropriate branch ratio for each gamma emission. Isotope decay is then converted to atoms using specific activity, mass or volume?, and Avogadro's number. The denominator is simply the ratio of published, cumulative fission product chain yields for isotopes produced in a thermal irradiation on 235U - values of England & Ryder are used by LLNL for the NTNF program. Uncertainties in LLNL R-values are dependent upon gamma counting statistics as well as the nuclear data for each isotope. R{sub LLNL} = (Atoms of X{sub exp})/(Atoms of {sup 99}Mo{sub exp})/(Cumulative Fission Chain Yield of X, from thermal on {sup 235}U)/(Cumulative Fission Chain Yield of {sup 99}Mo, from thermal on {sup 235}U). The next page tabulates fission chain yields and 'atoms per gram' amounts measured in a recent NTNF Thermal Calibration. The R-values in the table are calculated using the LLNL method of determining R. The measure of success is demonstrated by how close to 1.00 the R-value is when determined during a Thermal Calibration. A value of 1.00 is the desired value. In the example below, only four isotopes lie outside of 1.00 by more than 3 percent. These are the four isotopic measurements that obviously need to be improved.

Roberts, K

2009-03-03

316

76 FR 72869 - Proposed Establishment of Restricted Areas R-5402, R-5403A, R-5403B, R-5403C, R-5403D, R-5403E...  

Federal Register 2010, 2011, 2012, 2013

...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 would...

2011-11-28

317

Hydrologic Tests at Characterization Wells R-9i, R-13, R-19, R-22, and R-31  

SciTech Connect

Hydrologic information is essential for environmental efforts at Los Alamos National Laboratory. Testing at new characterization wells being drilled to the regional aquifer (''R wells'') to improve the conceptual hydrogeologic model of the Pajarito Plateau is providing such information. Drilling has been by air-rotary casing-advance or open-hole methods. Most wells are completed with multiple screens. After their construction, wells were rigorously developed by wire-brushing, bailing, followed by surging, swabbing, or jetting, and finally by pumping. These methods are effective based on field-parameter measurements and comparison of results of hydrologic testing at well R-31 before and after complete well development. We conducted field tests on various zones of saturation penetrated by the R wells to collect data needed for determining hydraulic properties. This document provides details of the design and execution of testing as well as an analysis of data for five of the new wells: R-9i, R-13, R-19, R-22, and R-31. One well was evaluated by a pumping test (R-13), another was evaluated by both straddle-packer/injection and pumping tests (R-9i), and the rest were evaluated by injection tests alone (R-19, R-22, R-31). Testing was constrained by the regional setting (complex geology and multiple zones of saturation) and well construction (multiscreen completion and the small diameter of the production casing). Packers are required for testing multiscreen wells. The small diameter of the production casing not only precludes the use of a slugger but also limits the capacity of pumps that can be used in testing, especially for the depths involved in the R wells. For example, pumping at a maximum rate of 19 gallons per minute did not significantly stress the regional aquifer at R-13. Although not slug tests, the injection tests are comparable in several ways, and analysis of data by slugtest methods is appropriate. Despite constraints, the results obtained appear valid based on (1) the care taken during test implementation and data analysis, (2) comparison of results for initial and repeated tests obtained by the same analytical method, (3) comparison of results obtained for a given test by different analytical methods, (4) comparison of results with values determined by geophysical logging in the wells and pumping tests of the same geologic units elsewhere on the plateau, and (5) comparison with hydraulic properties commonly reported for similar geologic materials outside the area. Significant contributions of this report are not only the documentation of test design, implementation, and analysis but also a comprehensive table showing the distribution of hydraulic properties for the saturated geologic units tested beneath the Pajarito Plateau. We also offer several recommendations based on testing to date. Placing screens across the water table and geologic contacts as well as employing oversized filter packs hinders testing and should be avoided. In addition, we recommend that future testing include some alternative designs and methods. Multiple methods and routine repeat testing for a given screened interval would permit comparison of results.

W.J. Stone; S. McLin

2003-03-01

318

miR-214 coordinates melanoma progression by upregulating ALCAM through TFAP2 and miR-148b downmodulation.  

PubMed

Malignant melanoma is one of the most aggressive human cancers, but the mechanisms governing its metastatic dissemination are not fully understood. Upregulation of miR-214 and ALCAM and the loss of TFAP2 expression have been implicated in this process, with TFAP2 a direct target of miR-214. Here, we link miR-214 and ALCAM as well as identify a core role for miR-214 in organizing melanoma metastasis. miR-214 upregulated ALCAM, acting transcriptionally through TFAP2 and also posttranscriptionally through miR-148b (itself controlled by TFAP2), both negative regulators of ALCAM. We also identified several miR-214-mediated prometastatic functions directly promoted by ALCAM. Silencing ALCAM in miR-214-overexpressing melanoma cells reduced cell migration and invasion without affecting growth or anoikis in vitro, and it also impaired extravasation and metastasis formation in vivo. Conversely, cell migration and extravasation was reduced in miR-214-overexpressing cells by upregulation of either miR-148b or TFAP2. These findings were consistent with patterns of expression of miR-214, ALCAM, and miR-148b in human melanoma specimens. Overall, our results define a pathway involving miR-214, miR-148b, TFAP2, and ALCAM that is critical for establishing distant metastases in melanoma. PMID:23667173

Penna, Elisa; Orso, Francesca; Cimino, Daniela; Vercellino, Irene; Grassi, Elena; Quaglino, Elena; Turco, Emilia; Taverna, Daniela

2013-07-01

319

Synthesis of Tritium Labeled (R,R)-4-Methoxyfenoterol  

PubMed Central

The preparation of 2?,4?,6?-[3H3]-(R,R)-4-methoxyfenoterol, a tritium-labeled derivative of (R,R)-4-methoxyfenoterol was demonstrated on a 15 mCi scale providing material with a specific activity of 57 Ci/mmol.

Kozocas, Joseph A.; Bupp, James E.; Tanga, Mary J.; Pluhar, Joseph T.; Wainer, Irving W.

2009-01-01

320

Calibration and R&R Practices for Reliable Temperature Measurements  

Microsoft Academic Search

There are many resources available to help one learn about calibration but few that talk to the practical issues, the practices involved. This talk will discuss traceability and practices used in establishing reasonable calibration uncertainties for temperature- measuring Thermal Imagers and IR Thermometers. The related, very important subject of R&R testing (automotive QA people know the practice as Gage R&R)

G. Raymond

321

Sampling Distribution of r  

NSDL National Science Digital Library

This page, created by Richard Lowry of Vassar College, generates a graph of the sampling distribution of r, the Pearson correlation coefficient. Upon opening, the applet prompts for sample size greater than 6. The applet also displays the probabilities associated with the distribution.

Lowry, Richard

2009-10-13

322

Simulation Insights Using "R"  

ERIC Educational Resources Information Center

This article attempts to introduce the reader to computational thinking and solving problems involving randomness. The main technique being employed is the Monte Carlo method, using the freely available software "R for Statistical Computing." The author illustrates the computer simulation approach by focusing on several problems of…

Kostadinov, Boyan

2013-01-01

323

R. Burl Yarberry  

ERIC Educational Resources Information Center

R. Burl Yarberry was born in 1920 in Pueblo, Colorado. He attended public schools in Pueblo and graduated from high school in 1938. After a year attending the Colorado School of Mines, he enlisted in the U.S. Marine Corps and served in the Pacific during World War II. Following his discharge, he earned a BA in English from Western State College of…

Nishimoto, Warren

2007-01-01

324

Bioassay Analysis using R  

Microsoft Academic Search

We describe an add-on package for the language and environment R which allows simulta- neous fitting of several non-linear regression models. The focus is on analysis of dose response curves, but the functionality is applicable to arbitrary non-linear regression models. Features of the package is illustrated in examples.

Christian Ritz; Jens C. Streibig

2006-01-01

325

Rpp2, an Essential Protein Subunit of Nuclear RNase P, is Required for Processing of Precursor tRNAs and 35S Precursor rRNA in Saccharomyces cerevisiae  

Microsoft Academic Search

RPP2, an essential gene that encodes a 15.8-kDa protein subunit of nuclear RNase P, has been identified in the genome of Saccharomyces cerevisiae. Rpp2 was detected by sequence similarity with a human protein, Rpp20, which copurifies with human RNase P. Epitope-tagged Rpp2 can be found in association with both RNase P and RNase mitochondrial RNA processing in immunoprecipitates from crude

Viktor Stolc; Alexander Katz; Sidney Altman

1998-01-01

326

75 FR 41104 - Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta...  

Federal Register 2010, 2011, 2012, 2013

...RIN 2120-AA64 Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta, and R22 Mariner Helicopters, and Model R44, and R44 II Helicopters AGENCY: Federal Aviation Administration, DOT....

2010-07-15

327

75 FR 71532 - Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta...  

Federal Register 2010, 2011, 2012, 2013

...RIN 2120-AA64 Airworthiness Directives; Robinson Helicopter Company (Robinson) Model R22, R22 Alpha, R22 Beta, and R22 Mariner Helicopters, and Model R44, and R44 II Helicopters AGENCY: Federal Aviation Administration, DOT....

2010-11-24

328

Embedding R+R{sup 2} inflation in supergravity  

SciTech Connect

We find the natural embedding of the (R+R{sup 2}) inflationary model into the recently constructed F(R) supergravity. It gives a simple and viable realization of chaotic inflation in supergravity. The only requirement for a slow-roll inflation is the existence of the R{sup 3} term with an anomalously large coefficient in Taylor expansion of the F(R) function.

Ketov, Sergei V. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa 1-1, Hachioji-shi, Tokyo 192-0397 (Japan); Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Starobinsky, Alexei A. [Landau Institute for Theoretical Physics, Moscow 119334 (Russian Federation); Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan)

2011-03-15

329

TGF?R2 is a major target of miR-93 in nasopharyngeal carcinoma aggressiveness  

PubMed Central

Background MiR-17-92 cluster and its paralogues have emerged as crucial regulators of many oncogenes and tumor suppressors. Transforming growth factor-? receptor II (TGF?R2), as an important tumor suppressor, is involved in various cancer types. However, it is in cancer that only two miRNAs of this cluster and its paralogues have been reported so far to regulate TGF?R2. MiR-93 is oncogenic, but its targetome in cancer has not been fully defined. The role of miR-93 in nasopharyngeal carcinoma (NPC) still remains largely unknown. Methods We firstly evaluated the clinical signature of TGF?R2 down-regulation in clinical samples, and next used a miRNA expression profiling analysis followed by multi-validations, including Luciferase reporter assay, to identify miRNAs targeting TGF?R2 in NPC. In vitro and in vivo studies were performed to further investigate the effects of miRNA-mediated TGF?R2 down-regulation on NPC aggressiveness. Finally, mechanism studies were conducted to explore the associated pathway and genes influenced by this miRNA-mediated TGF?R2 down-regulation. Results TGF?R2 was down-regulated in more than 50% of NPC patients. It is an unfavorable prognosis factor contributing to clinical NPC aggressiveness. A cluster set of 4 TGF?R2-associated miRNAs was identified; they are all from miR-17-92 cluster and its paralogues, of which miR-93 was one of the most significant miRNAs, directly targeting TGF?R2, promoting cell proliferation, invasion and metastasis in vitro and in vivo. Moreover, miR-93 resulted in the attenuation of Smad-dependent TGF-? signaling and the activation of PI3K/Akt pathway by suppressing TGF?R2, further promoting NPC cell uncontrolled growth, invasion, metastasis and EMT-like process. Impressively, the knockdown of TGF?R2 by siRNA displayed a consentaneous phenocopy with the effect of miR-93 in NPC cells, supporting TGF?R2 is a major target of miR-93. Our findings were also substantiated by investigation of the clinical signatures of miR-93 and TGF?R2 in NPC. Conclusion The present study reports an involvement of miR-93-mediated TGF?R2 down-regulation in NPC aggressiveness, thus giving extended insights into molecular mechanisms underlying cancer aggressiveness. Approaches aimed at blocking miR-93 may serve as a promising therapeutic strategy for treating NPC patients.

2014-01-01

330

James R. Thompson  

NASA Technical Reports Server (NTRS)

James R. Thompon served as director of the Marshall Space Flight Center from September 29, 1986 until July 6, 1989, when he was appointed as NASA Deputy Administrator. Prior to his tenure as Marshall's Director, Thompson served from March to June 1986 as the vice-chairman of the NASA task force investigating the cause of the Space Shuttle Challenger accident. He was credited with playing a significant role in returning the Space Shuttle to flight following the Challenger disaster.

1986-01-01

331

R-Factor  

NSDL National Science Digital Library

The amount of energy used in a home is greatly impacted by the type of materials used in constructing the home. In particular, the thermal conductivity of the materials will affect how quickly heat is allowed to enter or leave the home. In this hands-on activity, students will measure the ability of various materials to resist heat flow (R-factor) by placing a light bulb inside boxes made of the materials and monitoring the temperatures both inside and outside.

Pratte, John

332

Hydrologic Tests at Characterization Wells R-9i, R-13, R-19, R-22, and R-31, Revision 1  

SciTech Connect

Hydrologic information is essential for environmental efforts at Los Alamos National Laboratory. Testing at new characterization wells being drilled to the regional aquifer (''R wells'') to improve the conceptual hydrogeologic model of the Pajarito Plateau is providing such information. Field tests were conducted on various zones of saturation penetrated by the R wells to collect data needed for determining hydraulic properties. This document provides details of the design and execution of testing as well as an analysis of data for five new wells: R-9i, R-13, R-19, R-22, and R-31. One well (R-13) was evaluated by a pumping test and the rest (R-9i, R-19, R-22, and R-31) were evaluated by injection tests. Characterization well R-9i is located in Los Alamos Canyon approximately 0.3 mi west of the Route 4/Route 502 intersection. It was completed at a depth of 322 ft below ground surface (bgs) in March 2000. This well was constructed with two screens positioned below the regional water table. Both screens were tested. Screen 1 is completed at about 189-200 ft bgs in fractured basalt, and screen 2 is completed at about 270-280 ft bgs in massive basalt. Specific capacity analysis of the screen 1 data suggests that the fractured basalt has a transmissivity (T) of 589 ft{sup 2}/day and corresponds to a hydraulic conductivity (K) of 7.1 ft/day based on a saturated thickness of 83 ft. The injection test data from the massive basalt near screen 2 were analyzed by the Bouwer-Rice slug test methodology and suggest that K is 0.11 ft/day, corresponding to a T of about 2.8 ft{sup 2}/day based on a saturated thickness of 25 ft. Characterization well R-13 is located in Mortandad Canyon just west of the eastern Laboratory boundary. It was completed at a depth of 1029 ft bgs in February 2002. This well was constructed with one 60-ft long screen positioned about 125 ft below the regional water table. This screen is completed at about 958-1019 ft bgs and straddles the geologic contact between the Puye fanglomerate and unassigned pumiceous units. The specific capacity analysis of a 12 minute pumping test indicates that the Puye fanglomerates near the R-13 screen have a T of 5269 ft{sup 2}/day and correspond to a hydraulic conductivity (K) of 17.6 ft/day based on a saturated thickness of 300 ft. Characterization well R-19 is located east of firing site IJ in Technical Area (TA) 36 on the mesa between Three-mile and Potrillo Canyons. It was completed at a depth of 1885 ft bgs in April 2000. This well was constructed with two screens positioned above the regional water table and five screens positioned below the regional water table. Only the bottom two screens were tested. Screen 6 is completed at about 1727-1734 ft bgs in Puye fanglomerate, and screen 7 is completed at about 1832-1849 ft bgs in Puye fanglomerate. Specific capacity analysis of the screen 6 data suggests that T is about 6923 ft{sup 2}/day and corresponds to a K of 18.6 ft/day based on a saturated thickness of 373 ft. Specific capacity analysis of the screen 7 data suggests that T is about 8179 ft{sup 2}/day and corresponds to a K of 22.0 ft/day based on a saturated thickness of 373 ft. Characterization well R-22 is located on Mesita del Buey between Canada del Buey and Pajarito Canyons immediately east of Material Disposal Area (MDA) G in TA-54. It was completed at a depth of 1489 ft bgs in October 2000. This well was constructed with five screens positioned at or below the regional water table; however, only screens 2-5 were tested. Screen 1 is completed at the regional water table at about 872-914 ft bgs in Cerros del Rio basalt. Screen 2 is completed at about 947-989 ft bgs in Cerros del Rio basalt. Screen 3 is completed at about 1272-1279 ft bgs in Puye fanglomerate. Screen 4 is completed at about 1378-1452 ft bgs in older basalt. Screen 5 is completed at about 1447-1452 ft bgs in older fanglomerate. Bouwer-Rice analyses of the injection-test recovery data suggest K values of 0.04, 0.32, 0.54, and 0.27 ft/day for screens 2, 3, 4, and 5, respectively. These values correspond to

S.G.McLin; W.J. Stone

2004-06-01

333

Roll-to-Roll Processing of Flexible Heterogeneous Electronics With Low Interfacial Residual Stress  

Microsoft Academic Search

The roll-to-roll (R2R) processing plays an increas- ingly important role in the high-throughput fabrication of flexible electronics. This paper highlights the dramatic influence of material properties, geometrical dimensions of film-on-substrate structure, process temperatures, and web tension of the R2R processing. A co-optimization approach has been presented for the R2R processing, and all the design and process parameters are to be

Yongan Huang; Jiankui Chen; Zhouping Yin; Youlun Xiong

2011-01-01

334

Vapour-liquid equilibrium of ternary mixtures of the refrigerants R32, R125 and R134a  

Microsoft Academic Search

Ternary mixtures of R32, R125 and R134a of different compositions are recommended for replacing refrigerants R22 and R502. As a prerequisite for reliably calculating vapour pressure and phase equilibria of ternary mixtures within the relevant range of temperature and composition, VLE data of the three binary systems R32\\/R134a, R125\\/R134a and R32\\/R125 have been measured from ?70°C up to the critical

M Nagel; K Bier

1995-01-01

335

Transparent runtime parallelization of the R scripting language  

SciTech Connect

Scripting languages such as R and Matlab are widely used in scientific data processing. As the data volume and the complexity of analysis tasks both grow, sequential data processing using these tools often becomes the bottleneck in scientific workflows. We describe pR, a runtime framework for automatic and transparent parallelization of the popular R language used in statistical computing. Recognizing scripting languages interpreted nature and data analysis codes use pattern, we propose several novel techniques: (1) applying parallelizing compiler technology to runtime, whole-program dependence analysis of scripting languages, (2) incremental code analysis assisted with evaluation results, and (3) runtime parallelization of file accesses. Our framework does not require any modification to either the source code or the underlying R implementation. Experimental results demonstrate that pR can exploit both task and data parallelism transparently and overall has better performance as well as scalability compared to an existing parallel R package that requires code modification.

Yoginath, Srikanth B [ORNL

2011-01-01

336

MiR-223 deficiency increases eosinophil progenitor proliferation  

PubMed Central

Recently, microRNAs (miRNAs) have been shown to be involved in hematopoietic cell development but their role in eosinophilopoeisis has not yet been described. Here we show that miR-223 is up-regulated during eosinophil differentiation in an ex vivo bone marrow derived eosinophil culture system. Targeted ablation of miR-223 leads to an increased proliferation of eosinophil progenitors. We found up-regulation of a miR-223 target gene – IGF1R in the eosinophil progenitor cultures derived from miR-223-/- mice compared to miR-223+/+ littermate controls. The increased proliferation of miR-223-/- eosinophil progenitors was reversed by treatment with the IGF1R inhibitor (picropodophyllin). Whole genome microarray analysis of differentially regulated genes between miR-223+/+ and miR-223-/- eosinophil progenitor cultures identified a specific enrichment in genes that regulate hematologic cell development. Indeed, miR-223-/- eosinophil progenitors had a delay in differentiation. Our results demonstrate that miRNAs regulate the development of eosinophils by influencing eosinophil progenitor growth and differentiation and identify a contributory role for miR-223 in this process.

Lu, Thomas X.; Lim, Eun-Jin; Besse, John A.; Itskovich, Svetlana; Plassard, Andrew J.; Fulkerson, Patricia C.; Aronow, Bruce J.; Rothenberg, Marc E.

2012-01-01

337

MiR-223 deficiency increases eosinophil progenitor proliferation.  

PubMed

Recently, microRNAs have been shown to be involved in hematopoietic cell development, but their role in eosinophilopoiesis has not yet been described. In this article, we show that miR-223 is upregulated during eosinophil differentiation in an ex vivo bone marrow-derived eosinophil culture system. Targeted ablation of miR-223 leads to an increased proliferation of eosinophil progenitors. We found upregulation of a miR-223 target gene, IGF1R, in the eosinophil progenitor cultures derived from miR-223(-/-) mice compared with miR-223(+/+) littermate controls. The increased proliferation of miR-223(-/-) eosinophil progenitors was reversed by treatment with an IGF1R inhibitor (picropodophyllin). Whole-genome microarray analysis of differentially regulated genes between miR-223(+/+) and miR-223(-/-) eosinophil progenitor cultures identified a specific enrichment in genes that regulate hematologic cell development. Indeed, miR-223(-/-) eosinophil progenitors had a delay in differentiation. Our results demonstrate that microRNAs regulate the development of eosinophils by influencing eosinophil progenitor growth and differentiation and identify a contributory role for miR-223 in this process. PMID:23325891

Lu, Thomas X; Lim, Eun-Jin; Besse, John A; Itskovich, Svetlana; Plassard, Andrew J; Fulkerson, Patricia C; Aronow, Bruce J; Rothenberg, Marc E

2013-02-15

338

Large Deviations for the Fermion Point Process Associated with the Exponential Kernel  

NASA Astrophysics Data System (ADS)

For the fermion point process on the whole complex plane associated with the exponential kernel e^{zbar{w}}, we show the central limit theorem for the random variable ?( D r , the number of points inside the ball D r of radius r, as r ? ? and we establish the large deviation principle for the random variables { r -2? ( D r ), r > 0}.

Shirai, Tomoyuki

2006-05-01

339

AMP-Activated Kinase Regulates Cytoplasmic HuR  

Microsoft Academic Search

While transport of RNA-binding protein HuR from nucleus to cytoplasm is emerging as a key regulatory step for HuR function, the mechanisms underlying this process remain poorly understood. Here, we report that the AMP-activated kinase (AMPK), an enzyme involved in responding to metabolic stresses, potently regulates the levels of cytoplasmic HuR. Inhibition of AMPK, accomplished either through cell treatment or

Wengong Wang; Jinshui Fan; Xiaoling Yang; S. Furer-Galban; Isabel Lopez de Silanes; Cayetano von Kobbe; Jia Guo; Steve N. Georas; Fabienne Foufelle; D. Grahame Hardie; David Carling; Myriam Gorospe

2002-01-01

340

The Hobbit by J.R.R. Tolkien  

NSDL National Science Digital Library

A collection of resources for use in the study of The Hobbit by J.R.R. Tolkien. Introduction During the past few weeks we will be reading The Hobbit by J.R.R. Tolkien. Before Reading First, you need to be introduced to Hero s Journey. Also called the Monomyth, this is a concept explored by Joseph Campbell. We will talk about it in class, but you can get a nice ...

Cook, Miss

2009-06-25

341

R.Science Podcast  

NSDL National Science Digital Library

The Royal Society, based in the United Kingdom, is not only 350 years old, but is also not about the royal family. Rather, The Royal Society is all about science--influencing science policy and debating scientific issues, with other scientists and the public. Their website is loaded with resources, including the R.Science Podcast, the main podcast of the Royal Society. Monthly episodes include topics from nanotechnology to neuroscience to climate change. Visitors can subscribe to the RSS feed to be updated right away when a new episode is published.

2009-06-22

342

R.Science Podcast  

NSDL National Science Digital Library

The Royal Society, based in the United Kingdom, is not only 350 years old, but is also not about the royal family. Rather, The Royal Society is all about science--influencing science policy and debating scientific issues, with other scientists and the public. Their website is loaded with resources, including the R.Science Podcast, the main podcast of the Royal Society. Monthly episodes include topics from nanotechnology to neuroscience to climate change. Visitors can subscribe to the RSS feed to be updated right away when a new episode is published.

343

Insilico study of the A(2A)R-D (2)R kinetics and interfacial contact surface for heteromerization.  

PubMed

G-protein-coupled receptors (GPCRs) are cell surface receptors. The dynamic property of receptor-receptor interactions in GPCRs modulates the kinetics of G-protein signaling and stability. In the present work, the structural and dynamic study of A(2A)R-D(2)R interactions was carried to acquire the understanding of the A(2A)R-D(2)R receptor activation and deactivation process, facilitating the design of novel drugs and therapeutic target for Parkinson's disease. The structure-based features (Alpha, Beta, SurfAlpha, and SurfBeta; GapIndex, Leakiness and Gap Volume) and slow mode model (ENM) facilitated the prediction of kinetics (K (off), K (on), and K (d)) of A(2A)R-D(2)R interactions. The results demonstrated the correlation coefficient 0.294 for K (d) and K (on) and the correlation coefficient 0.635 for K (d) and K (off), and indicated stable interfacial contacts in the formation of heterodimer. The coulombic interaction involving the C-terminal tails of the A(2A)R and intracellular loops (ICLs) of D(2)R led to the formation of interfacial contacts between A(2A)R-D(2)R. The properties of structural dynamics, ENM and KFC server-based hot-spot analysis illustrated the stoichiometry of A(2A)R-D(2)R contact interfaces as dimer. The propensity of amino acid residues involved in A(2A)R-D(2)R interaction revealed the presence of positively (R, H and K) and negatively (E and D) charged structural motif of TMs and ICL3 of A(2A)R and D(2)R at interface of dimer contact. Essentially, in silico structural and dynamic study of A(2A)R-D(2)R interactions will provide the basic understanding of the A(2A)R-D(2)R interfacial contact surface for activation and deactivation processes, and could be used as constructive model to recognize the protein-protein interactions in receptor assimilations. PMID:22278740

Prakash, Amresh; Luthra, Pratibha Mehta

2012-10-01

344

Model for R&D planning in energy  

Microsoft Academic Search

Optimal allocation of resources for R&D on new energy technologies is an important issue in the process of development of energy system models. In this study, a model of R&D planning in energy sector has been developed and it is then linked to the energy system model. Energy system model is used as a tool for the technology assessment and

E. Shafiei; Y. Saboohi; M. B. Ghofrani

2005-01-01

345

Integrative knowledge management to enhance pharmaceutical R&D.  

PubMed

Information technologies already have a key role in pharmaceutical research and development (R&D), but achieving substantial advances in their use and effectiveness will depend on overcoming current challenges in sharing, integrating and jointly analysing the range of data generated at different stages of the R&D process. PMID:24687050

Marti-Solano, Maria; Birney, Ewan; Bril, Antoine; Della Pasqua, Oscar; Kitano, Hiroaki; Mons, Barend; Xenarios, Ioannis; Sanz, Ferran

2014-04-01

346

R-UNSAT  

EPA Science Inventory

Natural attenuation, a remediation strategy that relies on intrinsic physical, chemical, and biological processes to decrease contaminant concentrations, is gaining widespread acceptance in aquifer restoration efforts. The potential for successful remediation by natural attenuati...

347

Hydrologic Tests at Characterization Wells R-9i, R-13, R-19, R-22, and R-31  

Microsoft Academic Search

Hydrologic information is essential for environmental efforts at Los Alamos National Laboratory. Testing at new characterization wells being drilled to the regional aquifer (''R wells'') to improve the conceptual hydrogeologic model of the Pajarito Plateau is providing such information. Drilling has been by air-rotary casing-advance or open-hole methods. Most wells are completed with multiple screens. After their construction, wells were

W. J. Stone; S. McLin

2003-01-01

348

First molecular detection of R. conorii, R. aeschlimannii, and R. massiliae in ticks from Algeria.  

PubMed

Ticks collected in Northern Algeria between May 2001 and November 2003 were tested by PCR for the presence of Rickettsia spp. DNA using primer amplifying gltA and OmpA genes. Three different spotted fever group rickettsias were amplified from these ticks: R. Conorii subsp. P. conorii strain Malish in Rhipicephalus sanguineus, R. aeschlimannii in Hyalomma marginatum, and R. massiliae in Rhipicephalus turanicus. Our results confirm the presence of R. conorii in ticks in Algeria and provide the first detection of R. aeschlimannii and R. massiliae in Algeria. PMID:17114743

Bitam, I; Parola, P; Matsumoto, K; Rolain, J M; Baziz, B; Boubidi, S C; Harrat, Z; Belkaid, M; Raoult, Didier

2006-10-01

349

Thermal Conductivity of the Refrigerant Mixtures R404A, R407C, R410A, and R507A  

Microsoft Academic Search

New thermal conductivity data of the refrigerant mixtures R404A, R407C, R410A, and R507C are presented. For all these refrigerants, the thermal conductivity was measured in the vapor phase at atmospheric pressure over a temperature range from 250 to 400 K and also at moderate pressures. A modified steady-state hot-wire method was used for these measurements. The cumulative correction for end

V. Z. Geller; B. V. Nemzer; U. V. Cheremnykh

2001-01-01

350

Thermodynamic Properties of the Mixtures R23\\/R744 and R41\\/R744 and their Efficiency as Refrigerants  

Microsoft Academic Search

Mixtures of refrigerants are widely used as working substances for refrigerating plants. Among them, mixtures of ozone-safe and natural refrigerants, in particular R23\\/R744 and R41\\/R744, are important. For calculating their thermodynamic properties, we compiled equations of state on the basis of the method in (1). According to this reference, the equation of state for a mixture is presented as a

Aleksandr Vasserman C; Valentine Malchevsky S

351

Ceramic fabrication R D  

SciTech Connect

This project is separated into three tasks. The first task is a design and modeling effort to be carried out by MSE, Inc. The purpose of this task is to develop and analyze designs for various cohesive ceramic fabrication (CCF) components. This quarter, the advanced molybdenum disicilide MHD electrode design was essentially completed. Final refinements will be made after molybdenum disilicide processing results are available and the final layer compositions are established. Work involving whisker incorporation was initiated on the high stress component. It is unlikely that whiskers will become low cost, so particulate reinforcement will be pursued. Modeling work will resume once a suitable aluminum oxide/silicon carbide composition is selected that can be fired to acceptable densities by pressureless sintering. Task 2, subcontracted to Applied Technology Laboratories (ATL), is principally directed at establishing a property data base for monolithic and laminated alumina fabricated using the CCF process. This quarter, ATL demonstrated that the CCF process does not compromise the flexure strength of alumina. Task 3, subcontracted to Ceramics Binder Systems, Inc., focused on CCF silicon carbide particulate reinforced alumina and on the development of processing procedures for nonoxide molybdenum disilicide. Preliminary results indicate that achieving high densities in silicon carbide particulate reinforced aluminum oxide will be difficult. Molybdenum disilicide results are encouraging, and it is clear that the CCF process will work with this nonoxide material. 3 refs., 18 figs., 4 tabs.

Not Available

1990-01-01

352

Three small RNAs within the 10 kb trypanosome rRNA transcription unit are analogous to domain VII of other eukaryotic 28S rRNAs.  

PubMed Central

We have localized the six ribosomal RNAs (rRNAs) which encode the 28S rRNA region of Trypanosoma brucei. These six rRNAs include two large rRNAs, 28S alpha (approx. 1840 nt) and 28S beta (approx. 1570 nt), and four small rRNAs of approximate sizes 220, 180, 140 and 70 nt. Three of these four small rRNAs (180, 70 and 140) are found at the 3' end of the 28S rRNAs region. Sequence analysis of this area shows that these three small rRNAs encode Domain VII, the last domain of secondary structure in the 28S rRNAs of eukaryotes. Hybridization of labeled nascent RNA to the cloned repeat unit and S1 nuclease protection analysis of putative precursors show that transcription initiates approximately 1.2 kb upstream of the 18S rRNA and terminates after the last small rRNA (140) at the 3' end of the 28S rRNA region. Analysis of three putative rRNA precursors suggests that the small rRNAs are not processed from the primary transcript until after the usual processing of the 5.8S rRNA region. Images

White, T C; Rudenko, G; Borst, P

1986-01-01

353

Algebraic treatment of the potential V(r)=-v/r[1-r?(1-1/Z)/(1+r?)  

NASA Astrophysics Data System (ADS)

The discrete energy levels Enl of the Schrödinger Hamiltonian H=-(1/2?+V(r), where V(r)=-(v/r)[1-r?(1-1/Z)/(1+r?)] have been analyzed using the dynamical group formulation of the scaling variational method. A simple analytical formula has been obtained which gives the energy value of different states for various values of Z. We have also found out the exact numerical eigenvalues for the above potential for the 1S, 2S, 2P, 3S, 3P, and 3D cases, and the energy values given by the dynamical group method are in excellent agreement with the exact numerical ones.

Roychoudhury, Rajkumar; Roy, Barnana; Varshni, Y. P.

1988-10-01

354

Comparative energy and exergy analysis of R744, R404A and R290 refrigeration cycles  

Microsoft Academic Search

A detailed energy and exergy analysis of the low global warming potential refrigerants R744 and R290 was preformed and compared against the commercial refrigerant R404A in a single-stage vapour compression cycle and R744 in a two-stage vapour compression cycle with an internal heat exchanger. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email:

J. A. Shilliday; S. A. Tassou; N. Shilliday

2009-01-01

355

Magnetic properties of (R, R', R",...)Ni2Ge2 solid solutions  

NASA Astrophysics Data System (ADS)

Anisotropic magnetic properties of single crystals of (R, R', R",...)Ni2Ge2 (R = rare earth) solid solutions will be presented. Whereas the magnetic ordering temperatures and the paramagnetic ?'s broadly follow de Gennes scaling there are some systematic deviations from this oversimplfied trend. In this talk we will examine these deviations and also discuss the apparent absence of a spin-glass state induced by random magnetic anisotropy for the most highly mixed samples.

Law, S. A.; Bud'Ko, S. L.; Canfield, P. C.

2006-03-01

356

Transport properties of refrigerants R32, R125, R134a, and R125+R32 mixtures in and beyond the critical region  

Microsoft Academic Search

A practical representation for the transport coefficients of pure refrigerants R32, R125, R134a, and R125+R32 mixtures is presented which is valid in the vapor–liquid critical region. The crossover expressions for the transport coefficients incorporate scaling laws near the critical point and are transformed to regular background values far away from the critical point. The regular background parts of the transport

S. B Kiselev; R. A Perkins; M. L Huber

1999-01-01

357

RCircos: an R package for Circos 2D track plots  

PubMed Central

Background Circos is a Perl language based software package for visualizing similarities and differences of genome structure and positional relationships between genomic intervals. Running Circos requires extra data processing procedures to prepare plot data files and configure files from datasets, which limits its capability of integrating directly with other software tools such as R. Recently published R Bioconductor package ggbio provides a function to display genomic data in circular layout based on multiple other packages, which increases its complexity of usage and decreased the flexibility in integrating with other R pipelines. Results We implemented an R package, RCircos, using only R packages that come with R base installation. The package supports Circos 2D data track plots such as scatter, line, histogram, heatmap, tile, connectors, links, and text labels. Each plot is implemented with a specific function and input data for all functions are data frames which can be objects read from text files or generated with other R pipelines. Conclusion RCircos package provides a simple and flexible way to make Circos 2D track plots with R and could be easily integrated into other R data processing and graphic manipulation pipelines for presenting large-scale multi-sample genomic research data. It can also serve as a base tool to generate complex Circos images.

2013-01-01

358

Synthesis and decomposition studies of dialkyltellurides of type RTeR'  

NASA Astrophysics Data System (ADS)

Unsymmetrical dialkyltellurides of type RTeR' suitable for use as precursors in the metalorganic vapour phase epitaxy (MOVPE) of cadmium mercury telluride (CMT) can be prepared by an alkyl exchange process. For certain organotellurium compounds, reaction of R 2Te (R = alkyl, allyl) with R' 2Te 2 (R' = alkyl) produces an equilibrium mixture containing RTeR' and RTe 2R'. Suitable selection of R and R' allows good yields of RTeR' to be prepared in high purity. ESR studies show that free radicals are formed on thermal or photochemical decomposition of R 2Te and that the stability of (allyl)TeMe is very similar to that of (allyl) 2Te but quite different from that of Me 2Te.

McQueen, A. Ewan D.; Culshaw, Peter N.; Walton, John C.; Shenai-Khatkhate, D. V.; Cole-Hamilton, David J.; Mullin, J. Brian

1991-01-01

359

Thoughts on VaR and CVaR  

Microsoft Academic Search

Value at Risk (VaR) is an important issue for banks since its adoption as a primary risk metric in the Basel Accords and the requirement that it is calculated on a daily basis. VaR calculates maximum expected losses over a given time period at a given tolerance level. Conditional Value at Risk (CVaR) measures extreme risk. It calculates the risk

David E Allen; Robert J Powell

2007-01-01

360

CALCIUM TRANSPORT PROCESSES OF LOBSTER HEPATOPANCREATIC MITOCHONDRIA. (R823068)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

361

Stability of r-minimal cones in R  

NASA Astrophysics Data System (ADS)

The study of minimal cones C(M) in R construed over compact minimal hypersurface M of a unit Euclidean sphere Sn has an important link with the Bernstein problem, see e.g. Bombieri et al. [E. Bombieri, E. de Giorgi, E. Giusti, Minimal cones and Bernstein problem, Invent. Math. 7 (1969) 243-268]. It was studied by many authors with a remarkable paper due to Simmons [J. Simmons, Minimal varieties in Riemannian manifolds, Ann. of Math. 88 (1968) 62-105]. In a recent work Barbosa and Do Carmo [J.L.M. Barbosa, M.P. Do Carmo, On the stability of cones in R with zero scalar curvature, Ann. Global Anal. Geom. 28 (2005) 107-122] treated cones in R with the second function of curvature S2=0 and S3?=0. In these papers the authors showed the existence of a truncated cone which is unstable as well as truncated cones over Clifford tori that are stable. Here we partially extend such results for cones construed over compact hypersurfaces M of the unit sphere Sn with Sr=0 and S?=0 by showing that there exists ?>0 for which the truncated cone C( is (r-1)-unstable provided n?r+5. Moreover, we also show that for n?r+6 there exists a Clifford torus Sp(r1)×Sq(r2)?Sn with Sr=0 and S?=0, for which all truncated cones based on such a torus are (r-1)-stable.

Barros, A.; Sousa, P.

2008-10-01

362

Lee R. Scherer  

NASA Technical Reports Server (NTRS)

Lee R. Scherer was appointed Director of the NASA Flight Research Center on October 11, 1971, a position he held until January 28, 1975. Mr. Scherer first worked with NASA in 1962 while still on active duty with the U.S. Navy as a Captain. Prior to his arriving at the Flight Research Center he was at NASA Headquarters' Office of Space Science and Applications, as Director of the Apollo Program for the scientific aspects of lunar explorations, Assistant Director of Lunar Programs, and Manager of the Lunar Orbiter Program from its inception in 1963 through its successful completion in 1967. Scherer graduated from the U.S. Naval Academy in 1942. Most of Lee's 25-year Naval career was spent in aviation, including a tour flying carrier-based fighters and flight test experience with helicopters. Prior to entering the Naval Academy, he attended the University of Kentucky for one year. He received a second Bachelor of Science degree in aeronautical engineering in 1949 from the U.S. Naval Postgraduate School and his Master's degree in aeronautical engineering from the California Institute of Technology (Caltech) in 1950. Lee also attended the Summer of Industrial Management Studies program at the University of California at Los Angeles in 1949. Awards he has received include the NASA's Exceptional Service Medal in 1967 and NASA's Exceptional Scientific Achievement Medal in 1969.

1980-01-01

363

Lauren R. Donaldson Collection  

NSDL National Science Digital Library

In 1946, Lauren R. Donaldson and several of his scientific colleagues were selected as radiation monitors for Operation Crossroads, which was the codename for the first atomic bomb tests at Bikini Atoll. During this operation, two nuclear bombs were detonated above and below the ocean surface, contaminating the organs and tissues of living creatures and plants with large doses of radioactivity. Over the next twelve years, Dr. Donaldson and his colleagues would return a number of times to perform research related to these activities. Recently, the University of Washington Libraries Digital Collections team digitized selected personal logs, photo albums, papers, and ephemera from the surveys undertaken by this team of researchers. Visitors can browse the collection, or they may wish to get started by looking over the sample searches which include "1946 Operation Crossroads" and "1947 Bikini Atoll Radiological Survey". Also, visitors can learn more about Dr. Donaldson and peruse a finding aid for his own personal and academic papers which are also held by the University of Washington.

364

MSDS R115777.rtf  

Cancer.gov

Evacuate area. Next, use disposable towels moistened with an appropriate cleaning agent (i.e. solvent, detergent and water, etc.) to complete cleaning process. A designated HEPA vacuum can be used as an alternative cleaning method for large spills. All waste must be placed in a sealable, properly labeled waste disposal bag. Over bag into a sealable, properly labeled waste disposal bag. Material must be disposed of as hazardous drug waste.

365

Glossary Acronyms [R  

Cancer.gov

All research activities, both basic and applied, and all development activities that are supported at universities and other institutions. "Research" is the systematic study directed toward fuller scientific knowledge or understanding of the subject studied. "Development" is the systematic use of knowledge and understanding gained from research directed toward the production of useful materials, devices, systems, or methods, including design and development of prototypes and processes.

366

Antiausterity activity of arctigenin enantiomers: importance of (2R,3R)-absolute configuration.  

PubMed

From a MeOH extract of powdered roots of Wikstroemia indica, six dibenzyl-gamma-butyrolactone-type lignans with (2S,3S)-absolute configuration [(+)-arctigenin (1), (+)-matairesinol (2), (+)-trachelogenin (3), (+)-nortrachelogenin (4), (+)-hinokinin (5), and (+)-kusunokinin (6)] were isolated, whereas three dibenzyl-gamma-butyrolactone-type lignans with (2R,3R)-absolute configuration [(-)-arctigenin (1*), (-)-matairesinol (2*), (-)-trachelogenin (3*)] were isolated from Trachelospermum asiaticum. The in vitro preferential cytotoxic activity of the nine compounds was evaluated against human pancreatic PANC-1 cancer cells in nutrient-deprived medium (NDM), but none of the six lignans (1-6) with (2S,3S)-absolute configuration showed preferential cytotoxicity. On the other hand, three lignans (1*-3*) with (2R,3R)-absolute configuration exhibited preferential cytotoxicity in a concentration-dependent manner with PC50 values of 0.54, 6.82, and 5.85 microM, respectively. Furthermore, the effect of (-)- and (+)-arctigenin was evaluated against the activation of Akt, which is a key process in the tolerance to nutrition starvation. Interestingly, only (-)-arctigenin (1*) strongly suppressed the activation of Akt. These results indicate that the (2R,3R)-absolute configuration of (-)-enantiomers should be required for the preferential cytotoxicity through the inhibition of Akt activation. PMID:24660468

Awale, Suresh; Kato, Mamoru; Dibwe, Dya Fita; Li, Feng; Miyoshi, Chika; Esumi, Hiroyasu; Kadota, Shigetoshi; Tezuka, Yasuhiro

2014-01-01

367

The anti-miR21 antagomir, a therapeutic tool for colorectal cancer, has a potential synergistic effect by perturbing an angiogenesis-associated miR30  

PubMed Central

Colon cancer has the third highest incidence and mortality among cancers in the United States. MicroRNA-21 (miR21) has been described as an oncomir that is highly overexpressed in tumor tissue from colorectal cancer. Recent studies showed that silencing of miR21 through use of a miR21 inhibitor (anti-miR21) affected viability, apoptosis and the cell cycle in colon cancer cells. We identified an anti-miR21 that targets miR21 to inhibit genes by both post-transcriptional gene silencing and transcriptional gene silencing in the cytoplasm and nucleus, respectively. Overexpression of anti-miR21 in colon cancer cells caused changes in miRNA expression levels. We found that treatment with anti-miR21 down-regulated expression of miR30, which is involved in angiogenesis. In an in vitro angiogenesis assay, network formation induced by an angiogenesis activator was reduced upon treatment with anti-miR21. Sequence analysis of anti-miR21 and pri-miR30 revealed homology between anti-miR21 and the 3? end of pri-miR30, suggesting that anti-miR21 may bind to pri-miR30 and block processing of the miRNA processing. These results suggest anti-miR21 has a role not only in tumor growth but also in angiogenesis. Therefore, treatment with the anti-miR21 antagomir may have a synergistic effect mediated through suppression of miR30.

Song, Min-Sun; Rossi, John J.

2014-01-01

368

Craig R. Bomben  

NASA Technical Reports Server (NTRS)

Craig R. Bomben became a pilot in the Flight Crew Branch of NASA's Dryden Flight Research Center, Edwards, Calif., in June 2001. His flying duties include a variety of research and support activities while piloting the F/A-18, DC-8, T-34C and King Air aircraft. He has more than 17 years and 3,800 hours of military and civilian flight experience in over 50 different aircraft types. Bomben came to NASA Dryden from a U.S. Navy assignment to the Personnel Exchange Program, Canada. He served as a test pilot in the Canadian Armed Forces located in Cold Lake, Alberta. He participated in numerous developmental programs to include CT-133 airborne ejection seat testing, F/A-18 weapons flutter testing and F/A-18 night vision goggles integration. Bomben performed U.S. Navy fleet service in 1995 as a strike-fighter department head. He completed two overseas deployments onboard the USS George Washington and USS Stennis. As a combat strike leader, he headed numerous multi-national missions over Iraq in support of Operation Southern Watch. Bomben graduated from the U.S. Naval Test Pilot School in 1992 and was subsequently assigned to the Naval Weapons Test Squadron at Pt. Mugu, Calif. During this tour he developed the F-14D bombsight and worked on various other F-14D and F/A-18 weapon systems developmental programs. Bomben is a 1985 graduate of Washington State University with a bachelor of science degree in electrical engineering. He graduated from naval flight training in 1987 and was recognized as a Commodore List graduate. His first assignment was to Naval Air Station Pensacola, Fla., where he was an instructor in the T-2B Buckeye. When selected to fly the F/A-18 in 1989, he joined a fleet squadron and deployed aboard the USS Forrestal. Bomben is married to the former Aissa Asuncion. They live in Lancaster, Calif., with their 3 children.

2001-01-01

369

HuR/Methyl-HuR and AUF1 regulate the MAT expressed during liver proliferation, differentiation and carcinogenesis  

PubMed Central

Background & Aims Hepatic de-differentiation, liver development, and malignant transformation are processes in which the levels of hepatic S-adenosylmethionine (SAMe) are tightly regulated by two genes, MAT1A and MAT2A. MAT1A is expressed in the adult liver, whereas MAT2A expression is primarily extra-hepatic and is strongly associated with liver proliferation. The mechanisms that regulate these expression patterns are not completely understood. In silico analysis of the 3? untranslated region of MAT1A and MAT2A revealed putative binding sites for the RNA-binding proteins AUF1 and HuR, respectively. We investigated the post-transcriptional regulation of MAT1A and MAT2A by AUF1, HuR and methyl-HuR in the aforementioned biological processes. Results During hepatic de-differentiation, the switch between MAT1A and MAT2A coincided with an increase in HuR and AUF1 expression. SAMe treatment altered this homeostasis by shifting the balance of AUF1 and methyl-HuR/HuR, which was identified for the first time as an inhibitor of MAT2A mRNA stability. We also observed a similar temporal distribution and a functional link between HuR, methyl-HuR, AUF1, and MAT1A and MAT2A during the fetal liver development. Immunofluorescent analysis revealed increased levels of HuR and AUF1, and a decrease in methyl-HuR levels in human livers with hepatocellular carcinoma (HCC). Conclusions Our data strongly support a role for AUF1 and HuR/methyl-HuR in liver de-differentiation, development and human HCC progression through the post-translational regulation of MAT1A and MAT2A mRNAs.

Vazquez-Chantada, Mercedes; Fernandez-Ramos, David; Embade, Nieves; Martinez-Lopez, Nuria; Varela-Rey, Marta; Woodhoo, Ashwin; Luka, Zigmund; Wagner, Conrad; Anglim, Paul P.; Finnell, Richard H.; Caballeria, Juan; Laird-Offringa, Ite A.; Gorospe, Myriam; Lu, Shelly C; Mato, Jose M; Martinez-Chantar, M Luz

2010-01-01

370

Retrotransposable elements R1 and R2 interrupt the rRNA genes of most insects.  

PubMed Central

A large number of insect species have been screened for the presence of the retrotransposable elements R1 and R2. These elements integrate independently at specific sites in the 28S rRNA genes. Genomic blots indicated that 43 of 47 insect species from nine orders contained insertions, ranging in frequency from a few percent to greater than 50% of the 28S genes. Sequence analysis of these insertions from 8 species revealed 22 elements, 21 of which corresponded to R1 or R2 elements. Surprisingly, many species appeared to contain highly divergent copies of R1 and R2 elements. For example, a parasitic wasp contained at least four families of R1 elements; the Japanese beetle contained at least five families of R2 elements. The presence of these retrotransposable elements throughout Insecta and the observation that single species can harbor divergent families within its rRNA-encoding DNA loci present interesting questions concerning the age of these elements and the possibility of cross-species transfer. Images

Jakubczak, J L; Burke, W D; Eickbush, T H

1991-01-01

371

Experimental analysis of a window air conditioner with a R-22 and R32/R125/R134a mixture  

SciTech Connect

Much experimental and theoretical analysis of potential R-22 replacements has been accomplished. However, published information about the experimental analysis of any off-the-shelf air conditioner with a potential R-22 replacement at realistic, operating conditions is still rare. This type of work could be useful because it provides baseline data for comparing the performance of R-22 and its potential replacement at drop-in conditions. In this study, an off-the-shelf window air conditioner was tested at Air Conditioning and Refrigeration Institute (ARI)-rated indoor conditions and at different ambient temperatures, including the ARI-rated outdoor condition, with R-22 and with its potential replacement, a ternary mixture of R-32(30%)/R-125(10%)/R-134a(60%) (the ternary mixture). A test rig was built that provided for baseline operation and for the option of operating the system with a flooded evaporator by means of liquid over-feeding (LOF). The test results indicated the cooling capacity of the ternary mixture was 7.7% less than that of R-22 at 95{degrees}F ambient for baseline operation. The cooling capacity for both refrigerants improved when a flooded evaporator, or LOF, was used. For LOF operation, the cooling capacity of the ternary mixture was only 1.1% less than that of R-22. The ternary mixture had slightly higher compressor discharge pressure, a lower compressor discharge temperature, slightly lower compressor power consumption, and a higher compressor high/low pressure ratio.

Mei, V.C.; Chen, F.C.; Chen, D.T. [Oak Ridge National Lab., TN (United States); HuangFu, E.P. [USDOE, Washington, DC (United States)

1995-07-01

372

Regulation of the response regulator gene degU through the binding of SinR/SlrR and exclusion of SinR/SlrR by DegU in Bacillus subtilis.  

PubMed

Bacillus subtilis DegU is a response regulator of the DegS-DegU two-component regulatory system. Phosphorylated DegU (DegU-P) controls many genes and biological processes, such as exoprotease and ?-polyglutamic acid production, in addition to the degU gene, by binding to target gene promoters. Nonphosphorylated DegU and low levels of DegU-P are required for swarming motility and genetic competence. The DNA-binding repressors SinR and SlrR are part of a double-negative feedback loop and comprise the epigenetic switch governing biofilm formation. In this study, we found that SinR repressed degU. Furthermore, SlrR, which interacts with SinR through protein-protein interaction, seems to have an active role in degU expression in in vivo lacZ analysis. An in vitro transcription assay supported this observation. An electrophoretic mobility shift assay (EMSA) showed that SinR bound to the degU promoter and that SlrR formed a complex with SinR on the degU promoter. In EMSA, DegU-P excluded the SinR/SlrR complex but not SinR from the degU promoter in the presence of RNA polymerase. These findings suggest that DegU-P interacts with SlrR. In support of this hypothesis, disruption of the slrR gene resulted in decreased degU expression. This newly identified regulatory mechanism for degU is considered to be sequential transcription factor replacement. PMID:24317403

Ogura, Mitsuo; Yoshikawa, Hirofumi; Chibazakura, Taku

2014-02-01

373

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

374

Thermal conductivity of refrigerants R123, R134a, and R125 at low temperatures  

Microsoft Academic Search

Using a transient coaxial cylinder technique, thermal conductivities were measured for liquid 1,1,1-trifluoro-2,2-dichloroethane (refrigerant R123), 1,1,1,2-tetrafluoroethane (refrigerant R134a). and pentalluoroethane (refrigerant R 125). The uncertainty of the experimental data is estimated to be within 2–3 %. Thermal conductivities of refrigerants were measured at temperatures ranging from -114 to 20°C under pressures up to IOMPa. The apparatus was calibrated with four

O. B. Tsvetkov; Yu. A. Laptev; A. G. Asambaev

1994-01-01

375

Text Mining Infrastructure in R  

Microsoft Academic Search

During the last decade text mining has become a widely used discipline utilizing sta- tistical and machine learning methods. We present the tm package which provides a framework for text mining applications within R. We give a survey on text mining facili- ties in R and explain how typical application tasks can be carried out using our framework. We present

Ingo Feinerer; Kurt Hornik; David Meyer

2008-01-01

376

Analyzing biosignals using the R freeware (open source) tool  

Microsoft Academic Search

For researchers in electromyography (EMG), and similar biosginals, signal processing is naturally an essential topic. There are a number of excellent tools available. To these one may add the freely available open source statistical software package R, which is in fact also a programming language. It is becoming one the standard tools for scientists to visualize and process data. A

Frank Borg

2011-01-01

377

High Efficiency R-744 Commercial Heat Pump Water Heaters.  

National Technical Information Service (NTIS)

The project investigated the development and improvement process of a R744 (CO2) commercial heat pump water heater (HPWH) package of approximately 35 kW. The improvement process covered all main components of the system. More specific the heat exchangers ...

S. Elbel

2013-01-01

378

Representation of weakly harmonizable processes  

PubMed Central

Weakly harmonizable processes are represented by a family of positive definite contractive linear operators in a Hilbert space. This generalizes the known result on weakly stationary processes involving a unitary family. A characterization of the vector Fourier integral of a measure on R ? [unk], a reflexive space, is given, and this yields another characterization of weakly harmonizable processes when [unk] is a Hilbert space. Also these processes are shown to have associated spectra, yielding a positive solution to a problem of Rozanov.

Rao, M. M.

1981-01-01

379

Clementine sensor processing system  

NASA Technical Reports Server (NTRS)

The design of the DSPSE Satellite Controller (DSC) is baselined as a single-string satellite controller. The DSC performs two main functions: health and maintenance of the spacecraft; and image capture, storage, and playback. The DSC contains two processors: a radiation-hardened Mil-Std-1750, and a commercial R3000. The Mil-Std-1750 processor performs all housekeeping operations, while the R3000 is mainly used to perform the image processing functions associated with the navigation functions, as well as performing various experiments. The DSC also contains a data handling unit (DHU) used to interface to various spacecraft imaging sensors and to capture, compress, and store selected images onto the solid-state data recorder. The development of the DSC evolved from several key requirements; the DSPSE satellite was to do the following: (1) have a radiation-hardened spacecraft control system and be immune to single-event upsets (SEU's); (2) use an R3000-based processor to run the star tracker software that was developed by SDIO (due to schedule and cost constraints, there was no time to port the software to a radiation-hardened processor); and (3) fly a commercial processor to verify its suitability for use in a space environment. In order to enhance the DSC reliability, the system was designed with multiple processing paths. These multiple processing paths provide for greater tolerance to various component failures. The DSC was designed so that all housekeeping processing functions are performed by either the Mil-Std-1750 processor or the R3000 processor. The image capture and storage is performed either by the DHU or the R3000 processor.

Feldstein, A. A.

1993-01-01

380

Flow-boiling of R22, R134a, R507, R404A and R410A inside a smooth horizontal tube  

Microsoft Academic Search

Flow boiling heat transfer coefficients of R22, R134a, R507, R404A and R410A inside a smooth horizontal tube (6mm I.D., 6m length) were measured at a refrigerant mass flux of about 360kg\\/m2s varying the evaporating pressure within the range 3–12bar, with heat fluxes within the range 11–21kW\\/m2. The experimental data are discussed in terms of the heat transfer coefficients as a

A. Greco; G. P. Vanoli

2005-01-01

381

A Research Guide on National Board Certification[R] of Teachers  

ERIC Educational Resources Information Center

The National Board for Professional Teaching Standards[R] (NBPTS) has always welcomed scrutiny of the National Board Certification[R] process and the impact that National Board Certified Teachers[R] (NBCTs) have on teaching and learning. As a result, in the 20 years since NBPTS was founded, National Board Certification has become one of the most…

National Board for Professional Teaching Standards, 2007

2007-01-01

382

Rolling Deck to Repository (R2R): Research Cruise Event Logger  

NASA Astrophysics Data System (ADS)

Scientific event logs, used by the science party to record scientific sampling events that occur during a research cruise, have been used in various ways for decades. An event log is very important for documenting the occurrence of a sampling event and its location, time, relative sequence, and related details. Event logging, done well, can provide important documentation about scientific data collected during a cruise, and enable more efficient use of those data by cruise participants and future researchers. When the resultant event log is a digital data file, with content generated programmatically and controlled by term vocabularies, it becomes an even more valuable addition to the full complement of data sets generated during the cruise. However, such a tool is only effective if it is used. Through field testing, several key factors were identified that encourage the use of such a tool: the ability to customize the tool to represent the science implementation plan, proposed sampling scheme, cruise personnel and instrumentation; the ability to retrieve date, time and location data automatically from the shipboard network and the ability to enter events quickly and from any location on the ship. This presentation provides an overview of both the current version 1 and soon to be released version 2 of the Rolling Deck to Repository (R2R) research cruise Event Logger system. The R2R Event Logger application is built upon a pre-existing, open-source, weblog product called ELOG (ELOG URL: http://midas.psi.ch/elog/). We provide an oceanographer's view of the full process by which: 1) the R2R Event Logger application is configured and tested to meet the unique needs of a research cruise; 2) the R2R project works with the ship operator to install the Event Logger on the ship designated for the cruise, 3) the Event Logger is configured to automatically retrieve location, time, and other pertinent information from the shipboard network; 4) a copy of the event log file is made available to the science party at the end of the cruise and incorporated into the official shipboard data distribution; and 5) such event logs can be incorporated, accessed, and reviewed as part of scientific data holdings found in repositories such as the NSF funded Biological and Chemical Oceanography Data Management Office (BCO-DMO). A demonstration instance of the R2R Event Logger application, including a Web-based system for generating the custom configuration files (part of version 2 development), will be made available for researcher examination, evaluation and feedback.

Chandler, C. L.; Maffei, A. R.; Stolp, L.; Dubois, D. L.

2011-12-01

383

PaR-PaR laboratory automation platform.  

PubMed

Labor-intensive multistep biological tasks, such as the construction and cloning of DNA molecules, are prime candidates for laboratory automation. Flexible and biology-friendly operation of robotic equipment is key to its successful integration in biological laboratories, and the efforts required to operate a robot must be much smaller than the alternative manual lab work. To achieve these goals, a simple high-level biology-friendly robot programming language is needed. We have developed and experimentally validated such a language: Programming a Robot (PaR-PaR). The syntax and compiler for the language are based on computer science principles and a deep understanding of biological workflows. PaR-PaR allows researchers to use liquid-handling robots effectively, enabling experiments that would not have been considered previously. After minimal training, a biologist can independently write complicated protocols for a robot within an hour. Adoption of PaR-PaR as a standard cross-platform language would enable hand-written or software-generated robotic protocols to be shared across laboratories. PMID:23654257

Linshiz, Gregory; Stawski, Nina; Poust, Sean; Bi, Changhao; Keasling, Jay D; Hillson, Nathan J

2013-05-17

384

Downregulation of rRNA Transcription Triggers Cell Differentiation  

PubMed Central

Responding to various stimuli is indispensable for the maintenance of homeostasis. The downregulation of ribosomal RNA (rRNA) transcription is one of the mechanisms involved in the response to stimuli by various cellular processes, such as cell cycle arrest and apoptosis. Cell differentiation is caused by intra- and extracellular stimuli and is associated with the downregulation of rRNA transcription as well as reduced cell growth. The downregulation of rRNA transcription during differentiation is considered to contribute to reduced cell growth. However, the downregulation of rRNA transcription can induce various cellular processes; therefore, it may positively regulate cell differentiation. To test this possibility, we specifically downregulated rRNA transcription using actinomycin D or a siRNA for Pol I-specific transcription factor IA (TIF-IA) in HL-60 and THP-1 cells, both of which have differentiation potential. The inhibition of rRNA transcription induced cell differentiation in both cell lines, which was demonstrated by the expression of the common differentiation marker CD11b. Furthermore, TIF-IA knockdown in an ex vivo culture of mouse hematopoietic stem cells increased the percentage of myeloid cells and reduced the percentage of immature cells. We also evaluated whether differentiation was induced via the inhibition of cell cycle progression because rRNA transcription is tightly coupled to cell growth. We found that cell cycle arrest without affecting rRNA transcription did not induce differentiation. To the best of our knowledge, our results demonstrate the first time that the downregulation of rRNA levels could be a trigger for the induction of differentiation in mammalian cells. Furthermore, this phenomenon was not simply a reflection of cell cycle arrest. Our results provide a novel insight into the relationship between rRNA transcription and cell differentiation.

Hayashi, Yuki; Kuroda, Takao; Kishimoto, Hiroyuki; Wang, Changshan; Iwama, Atsushi; Kimura, Keiji

2014-01-01

385

FcR and autoimmunity  

Microsoft Academic Search

\\u000a Human immunoglobulin receptors (FcR) provide an important link between the humoral and cellular branches of the immune response.\\u000a FcR engagement in autoimmune diseases may result in many biological responses including phagocytosis, endocytosis, antibody-dependent\\u000a cellular cytotoxicity (ADCC), release of inflammatory mediators, facilitation of antigen presentation and clearance of immune\\u000a complexes (IC). Most FcR belong to the family of multi-chain immune recognition

R. Repp; J. G. J. Winkel

386

Trends and determinants of managing virtual R&D teams  

Microsoft Academic Search

The past years have seen a decentralization of R&D to local markets and centres-of-excellence. Supported by modern information and communication technologies, 'virtual project teams' were formed to facilitate transnational innovation processes. With their boundaries expanding and shrinking flexibly with changing project necessities, virtual teams are believed to be an important element in future R&D organization. Based on 204 interviews with

Oliver Gassmann; Maximilian von Zedtwitz

2003-01-01

387

MarcoPolo-R near earth asteroid sample return mission  

Microsoft Academic Search

MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) proposed in collaboration with NASA. It will\\u000a rendezvous with a primitive NEA, scientifically characterize it at multiple scales, and return a unique sample to Earth unaltered\\u000a by the atmospheric entry process or terrestrial weathering. MarcoPolo-R will return bulk samples (up to 2 kg) from an organic-rich\\u000a binary asteroid to

Maria Antonietta Barucci; A. F. Cheng; P. Michel; L. A. M. Benner; R. P. Binzel; P. A. Bland; H. Böhnhardt; J. R. Brucato; A. Campo Bagatin; P. Cerroni; E. Dotto; A. Fitzsimmons; I. A. Franchi; S. F. Green; L.-M. Lara; J. Licandro; B. Marty; K. Muinonen; A. Nathues; J. Oberst; A. S. Rivkin; F. Robert; R. Saladino; J. M. Trigo-Rodriguez; S. Ulamec; M. Zolensky

2011-01-01

388

Virtual R&D team: Technology Transfer Facilitator  

Microsoft Academic Search

A conceptual model is proposed which facilitate the process of technology transfer by applying a virtual R&D team. The underlying hypothesis is responded to competitive challenges, the complex customer requirements and the high instability on the market. The context of the knowledge-based economy introduces a major shift from serial to simultaneous R&D activities in the way technology transfer is conceived.

Nader Ale Ebrahim; Mohammad Ali Shafia; Hamid Tahbaz Tavakoli

2009-01-01

389

[In Process Citation].  

PubMed

M. J. S. Belton, (*) J. W. Head III, A. P. Ingersoll, R. Greeley, A. S. McEwen, K. P. Klaasen, D. Senske, R. Pappalardo, G. Collins, A. R. Vasavada, R. Sullivan, D. Simonelli, P. Geissler, M. H. Carr, M. E. Davies, J. Veverka, P. J. Gierasch, D. Banfield, M. Bell, C. R. Chapman, C. Anger, R. Greenberg, G. Neukum, C. B. Pilcher, R. F. Beebe, J. A. Burns, F. Fanale, W. Ip, T. V. Johnson, D. Morrison, J. Moore, G. S. Orton, P. Thomas, R. A. West The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on Io. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution. M. J. S. Belton, National Optical Astronomy Observatories, 950 North Cherry Ave, Tucson, AZ 85719, USA. J. W. Head III, R. Pappalardo, G. Collins, Department of Geological Science, Brown University, Providence, RI 02912, USA. A. P. Ingersoll and A. R. Vasavada, Department of Geology and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. R. Greeley and R. Sullivan, Department of Geology, Arizona State University, Tempe, AZ 85287-1414, USA. A. S. McEwen, P. Geissler, R. Greenberg, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 87721, USA. K. P. Klaasen, D. Senske, T. V. Johnson, G. S. Orton, R. A. West, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. D. Simonelli, J. Veverka, P. J. Gierasch, D. Banfield, M. Bell, J. A. Burns, P. Thomas, Department of Astronomy, Cornell University, Ithaca, NY 14853, USA. M. H. Carr, U.S. Geological Survey, Menlo Park, CA 94025, USA. M. E. Davies, RAND, Santa Monica, CA 90406, USA. C. R. Chapman, Southwest Research Institute, Boulder, CO 80302, USA. C. Anger, ITTRES Ltd, Calgary, Alberta TIY 5Z6, Canada. G. Neukum, Institute for Planetary Exploration, Deutsche Forschunganstalt für Luft und Raumfahrt, Berlin, Germany. C. B. Pilcher, National Aeronautical and Space Administration, Washington, DC 20546, USA. R. F. Beebe, Department of Astronomy, New Mexico State University, Las Cruces, NM 88003, USA. F. Fanale, Institute for Geophysics, University of Hawaii, Honolulu, HI 96822, USA. W. Ip, Max Planck Institute für Aeronomie, Lindau, Germany. D. Morrison and J. Moore, NASA Ames Research Center, Moffett Field, CA 94035, USA. (*) To whom correspondence should be addressed. E-mail: belton@noao.edu. PMID:17813508

1996-10-18

390

GOES-R user data transfer mechanisms and structure  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly developing the next-generation series of Geostationary Operational Environmental Satellites (GOES), known as the GOES-R Series. GOES-R meteorological data is provided to the operational and science user community through four main distribution mechanisms. GOES-R generates a set of data from each of the six primary satellite instruments and formats the data into a direct broadcast stream known as GOES Rebroadcast (GRB) for hemispheric distribution via L-band satellite downlink. Terrestrially, meteorological data is provided to forecasters at the National Weather Service (NWS) through a direct interface to the Advanced Weather Interactive Processing System (AWIPS). A secondary pathway for the user community to receive data terrestrially is via the GOES-R Access Subsystem (GAS), which is being developed as a part of NOAA's Environmental Satellite Processing and Distribution System (ESPDS) Product Distribution and Access (PDA) capability. Finally, GOES-R data is made available to NOAA's Comprehensive Large Array-Data Stewardship System (CLASS) for long-term archive. This paper will provide a summary description of the data types and formats associated with each of the four primary distribution pathways for user data from GOES-R. It will discuss the resources that are being developed by GOES-R to document the data structures and formats. It will also provide a brief introduction to the types of metadata associated with each of the primary data flows.

Royle, A. W.

391

INVESTIGATION FOR THE ENRICHMENT PATTERN OF THE ELEMENT ABUNDANCES IN r+s STAR HE 0338 - 3945: A SPECIAL r-II STAR?  

SciTech Connect

The very metal-poor star HE 0338 - 3945 shows a double-enhanced pattern of the neutron-capture elements. The study of this sample could help people gain a better understanding of s- and r-process nucleosynthesis at low metallicity. Using a parametric model, we find that the abundance pattern of the neutron-capture elements could be best explained by a binary system formed in a molecular cloud that had been polluted by r-process material. The observed abundance pattern of C and N can be explained by an asymptotic giant branch (AGB) model. Combined with the parameters obtained from Cui and Zhang, we suggest that the initial mass of the AGB companion is most likely to be about 2.5 M{sub sun}, which excludes the possibility of forming a Type 1.5 supernova. By comparing with the observational abundance pattern of CS 22892 - 052, we find that the dominant production of O should accompany the production of the heavy r-process elements of r+s stars. Similar to r-II stars, the heavy r-process elements are not produced in conjunction with all the light elements from the Na to Fe group. The abundance pattern of the light and r-process elements for HE 0338 - 3945 is very close to the pattern of the r-II star CS 22892 - 052. Therefore, we suggest that HE 0338 - 3945 should be a special r-II star.

Cui Wenyuan; Zhang Jiang; Zhu Zizhong; Zhang Bo, E-mail: wenyuancui@126.co, E-mail: zhangbo@hebtu.edu.c [Department of Physics, Hebei Normal University, 113 Yuhua Dong Road, Shijiazhuang 050016 (China)

2010-01-01

392

DOE R and D data tracking base  

SciTech Connect

This document consists of DOE R and D tracking information for the following topics: Stockpile Readiness Program; Stockpile Reduction Program; Enduring Stockpile Program; Future Stockpile Program; Archiving; Nuclear Component Assessment; Advanced Application; Validation and Verification; Distance and Distributed Computing; DOD Munitions; Performance Assessment; Physics; Los Alamos Meson Physics Facility/Los Alamos Neutron Science Center; Advanced Hydrodynamic Radiography; Systems Engineering; Advanced Manufacturing; Chemistry and Materials; High Explosives; Special Nuclear Mateirals; Tritium; Collaboration with ASCI; Numeric Environment for Weapons Simulation; Target Physics; Theory and Modeling; Target Development; Fabrication and Handling; Other ICF Activities; Development of Predictive Capabilities--Nuclear; Development of Diagnostic Tools--Nuclear; Process Development; and IPPD/Agile Manufacturing.

Horpedahl, L.; Brooks, M.

2000-12-01

393

Solving Differential Equations in R  

EPA Science Inventory

Although R is still predominantly applied for statistical analysis and graphical representation, it is rapidly becoming more suitable for mathematical computing. One of the fields where considerable progress has been made recently is the solution of differential equations. Here w...

394

miR-335 and miR-34a Promote Renal Senescence by Suppressing Mitochondrial Antioxidative Enzymes  

PubMed Central

The molecular basis for aging of the kidney is not well understood. MicroRNAs (miRNAs) contribute to processes such as development, differentiation, and apoptosis, but their contribution to the aging process is unknown. Here, we analyzed the miRNA expression profile of young (3-month) and old (24-month) rat kidneys and identified the biologic pathways and genes regulated by differentially expressed miRNAs. We observed upregulation of 18 miRNAs with aging, mainly regulating the genes associated with energy metabolism, cell proliferation, antioxidative defense, and extracellular matrix degradation; in contrast, we observed downregulation of 7 miRNAs with aging, principally targeting the genes associated with the immune inflammatory response and cell-cycle arrest. Bioinformatics analysis suggested that superoxide dismutase 2 (SOD2) and thioredoxin reductase 2 (Txnrd2), located in the mitochondria, are potential targets of miR-335 and miR-34a, respectively. Aging mesangial cells exhibited significant upregulation of miR-335 and miR-34a and marked downregulation of SOD2 and Txnrd2. miR-335 and miR-34a inhibited expression of SOD2 and Txnrd2 by binding to the 3?-untranslated regions of each gene, respectively. Overexpression of miR-335 and miR-34a induced premature senescence of young mesangial cells via suppression of SOD2 and Txnrd2 with a concomitant increase in reactive oxygen species (ROS). Conversely, antisense miR-335 and miR-34a inhibited senescence of old mesangial cells via upregulation of SOD2 and Txnrd2 with a concomitant decrease in ROS. In conclusion, these results suggest that miRNAs may contribute to renal aging by inhibiting intracellular pathways such as those involving the mitochondrial antioxidative enzymes SOD2 and Txnrd2.

Bai, Xue-Yuan; Ma, Yuxiang; Ding, Rui; Fu, Bo; Shi, Suozhu

2011-01-01

395

The impact of myopic loss aversion on continuing a troubled R&D project  

Microsoft Academic Search

R&D projects involve much risk and uncertainty. Failure of a R&D project is a common and dreaded question in innovation processes as a result of causing large losses to of businesses. This study explored whether shortening evaluation periods could reduce the willingness of managers of R&D projects in continuing a troubled R&D project. We employed 180 senior managers of high-tech

Kuo-Chih Cheng; Mei-Ling Yang; Chin-Chun Su; Feng-Yu Ni

396

On packing R-trees  

Microsoft Academic Search

We propose new R-tree packing techniques for static databases. Given a collection of rectangles, we sort them and build the R-tree bottom-up. There are several ways to sort the rectangles; the innovation of this work is the use of fractals, and specifically the hilbert curve, to achieve better ordering of the rectangles and eventually better pack- ing. We proposed and

Ibrahim Kamel; Christos Faloutsos

1993-01-01

397

Stuart R. Stidolph diatom atlas  

USGS Publications Warehouse

The "Stuart R. Stidolph Diatom Atlas" is a comprehensive volume of diatom taxa identified and micrographed by Stuart R. Stidoph during the 1980s and 1990s. The samples were collected from marine coasts of various geographic regions within tropical and subtropical climates. The plates included within this report have never been published and are being published by the USGS as an online reference so that others may have access to this incredible collection.

Stidolph, S. R.; Sterrenburg, F. A. S.; Smith, K. E. L.; Kraberg, A.

2012-01-01

398

The emerging role of miR-375 in cancer.  

PubMed

MicroRNAs (miRNAs) are evolutionarily conserved, small noncoding RNAs that are believed to play fundamental roles in various biological processes through regulation of gene expression at the level of posttranscription. MiR-375 was first identified as a pancreatic islet-specific miRNA regulating insulin secretion. However, further study revealed that miR-375 is a multifunctional miRNA participating in pancreatic islet development, glucose homeostasis, mucosal immunity, lung surfactant secretion and more importantly, tumorigenesis. Recently, miR-375 has been found significantly downregulated in multiple types of cancer, and suppresses core hallmarks of cancer by targeting several important oncogenes like AEG-1, YAP1, IGF1R and PDK1. The alteration of miR-375 in cancer is caused by a variety of mechanisms, including the dysregulation of transcription factors, aberrant promoter methylation and so on. Reduced expression of miR-375 in tissue or circulation may indicate the presence of neoplasia as well as a poor prognosis of many malignant cancers. Moreover, miR-375 stands for a promising direction for developing targeted therapies due to its capacity to inhibit tumor cell growth in vitro and in vivo. Here, we summarize the present understanding of the tumor suppressive role of miR-375 in cancer progression; the mechanisms underlying the dysregulation of miR-375; the potential use of miR-375 in prognosis and diagnosis and the therapeutic prospects of miR-375 in cancer. PMID:24166096

Yan, Jun-Wei; Lin, Ju-Sheng; He, Xing-Xing

2014-09-01

399

GluR5 kainate receptors, seizures, and the amygdala.  

PubMed

The amygdala is a critical brain region for limbic seizure activity, but the mechanisms underlying its epileptic susceptibility are obscure. Several lines of evidence implicate GluR5 (GLU(K5)) kainate receptors, a type of ionotropic glutamate receptor, in the amygdala's vulnerability to seizures and epileptogenesis. GluR5 mRNA is abundant in temporal lobe structures including the amygdala. Brain slice recordings indicate that GluR5 kainate receptors mediate a portion of the synaptic excitation of neurons in the rat basolateral amygdala. Whole-cell voltage-clamp studies demonstrate that GluR5 kainate receptor-mediated synaptic currents are inwardly rectifying and are likely to be calcium permeable. Prolonged activation of basolateral amygdala GluR5 kainate receptors results in enduring synaptic facilitation through a calcium-dependent process. The selective GluR5 kainate receptor agonist ATPA induces spontaneous epileptiform bursting that is sensitive to the GluR5 kainate receptor antagonist LY293558. Intra-amygdala infusion of ATPA in the rat induces limbic status epilepticus; in some animals, recurrent spontaneous seizures occur for months after the ATPA treatment. Together, these observations indicate that GluR5 kainate receptors have a unique role in triggering epileptiform activity in the amygdala and could participate in long-term plasticity mechanisms that underlie some forms of epileptogenesis. Accordingly, GluR5 kainate receptors represent a potential target for antiepileptic and antiepileptogenic drug treatments. Most antiepileptic drugs do not act through effects on glutamate receptors. However, topiramate at low concentrations causes slow inhibition of GluR5 kainate receptor-mediated synaptic currents in the basolateral amygdala, indicating that it may protect against seizures, at least in part, through suppression of GluR5 kainate receptor responses. PMID:12724156

Rogawski, Michael A; Gryder, Divina; Castaneda, Dora; Yonekawa, Wayne; Banks, Melissa K; Lia, He

2003-04-01

400

Viscosity of R134a, R32, and R125 at saturation  

SciTech Connect

This paper reports the results of the measurement of the viscosity of R134a close to the saturation time in the vapor phase. The new measurements were carried out in a vibrating-wire viscometer specially constructed for the purpose, and the results have an accuracy of {+-}2%. In addition, the opportunity is taken to present a reevaluation of earlier measurements along the saturation line of the viscosity of R32 and R125. Improved equations of state for these fluids are now available and can be employed to generate improved values for the viscosity.

Oliveira, C.M.B.P. [Univ. Aberta, Lisboa (Portugal)] [Univ. Aberta, Lisboa (Portugal); [Instituto Superior Tecnico, Lisboa (Portugal). Centro de Quimica Estrutural; Wakeham, W.A. [Imperial Coll., London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology] [Imperial Coll., London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology

1999-03-01

401

Studsvik Processing Facility Update  

SciTech Connect

Studsvik has completed over four years of operation at its Erwin, TN facility. During this time period Studsvik processed over 3.3 million pounds (1.5 million kgs) of radioactive ion exchange bead resin, powdered filter media, and activated carbon, which comprised a cumulative total activity of 18,852.5 Ci (6.98E+08 MBq). To date, the highest radiation level for an incoming resin container has been 395 R/hr (3.95 Sv/h). The Studsvik Processing Facility (SPF) has the capability to safely and efficiently receive and process a wide variety of solid and liquid Low Level Radioactive Waste (LLRW) streams including: Ion Exchange Resins (IER), activated carbon (charcoal), graphite, oils, solvents, and cleaning solutions with contact radiation level