bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Reassessment of the Role of Stress in Development of Radiation-Induced Microstructure
Authors: Garner FA , Wolfer WG , Brager HR 
Published: February 2009

Data are now accumulating which clearly demonstrate that the stress state plays a strong role in the development of void and dislocation microstructure in metals during neutron irradiation. In these experiments the application of a tensile biaxial stress state at constant fluence and temperature has been found to lead to a progressively decreasing metal density with increasing stress. The effect of stress on the concurrent development of voids, Frank interstitial loops, and dislocation networks has been studied with transmission electron microscopy. The results of these experiments clearly show that the densities of both Frank loops and voids are enhanced by a tensile stress field, with the relevant operating variable being the hydrostatic stress. More importantly it appears that any anisotropy in the stress field is reflected in a corresponding anisotropy that develops in the number of Frank loops that form on the various (111) planes. The loop density that develops on each plane exhibits a clear and direct dependence on the resolved normal stress component at each plane. Although the data from these experiments have been interpreted previously to support the existence of stress-assisted nucleation mechanisms for both loops and voids, further analysis has shown both of these explanations to be deficient in one or more respects, and both models have been replaced.
Whereas a previous analysis of these data invoked as the dominant process an effect of stress on the rate of thermal re-emission of vacancies by voids, this process has been found to be too slow at the temperature at which the experiments were conducted to account for the magnitude of the observed perturbation. The current model employs as the dominant process the effect of stress on changing the capture efficiency of voids for interstitials.
The stress-assisted nucleation model for Frank loops has been replaced with a stress-assisted growth model arising from the stress-induced preferential absorption (SIPA) mechanism of irradiation creep. Several previously unresolved problems arising from the earlier interpretation of the data set have been reconciled with the new model.
The current analysis of this data field yields two additional significant results that were not part of the original experimental objectives. For the first time the existence of the proposed SIPA mechanism of irradiation creep has been validated by a convincing microstructural record of its existence. The initially perplexing but consistent anisotropy of planar loop populations in the absence of externally applied stresses has also revealed the existence and magnitude of internal stresses generated in polycrystalline materials during irradiation.
An Empirical Evaluation of the Irradiation Sensitivity of Reactor Pressure Vessel Materials
Authors: Varsik JD , Byrne ST 
Published: February 2009

There is a general consensus that copper content increases the neutron irradiation sensitivity of reactor vessel materials. Within the past few years, several attempts have been made to introduce factors other than copper to explain the greater variance in irradiation sensitivity of weld metal compared with plate, such as the model presented in 1976 by Biemiller and Byrne (ASTM STP 611). This model implicated the role of the weld metal's major alloying elements with the use of a theoretically derived relation. The objective of this investigation was to further develop an improved and continuous correlation between irradiation-induced nil-ductility transition temperature (NDTT) shift and the residual and alloying elements in a typical reactor pressure vessel weldment. This correlation can be used for predicting, in advance to neutron exposure, a material's irradiation sensitivity.
Using the model developed by Biemiller and Byrne as the investigative basis, a comprehensive computerized data bank was used in performing a series of selected iterations to develop a best-fit chemistry relationship. The approach was to determine, by weighting the empirical chemistry relation, the synergistic role of residual and alloying elements with copper on weld irradiation sensitivity.
In the new empirical model, the alloying elements found to increase irradiation sensitivity were nickel, silicon, carbon, and manganese, while molybdenum was found to decrease sensitivity. A decreasing role of the carbide formers in acting beneficially toward weld irradiation sensitivity was noted.
Reactor vessel plate irradiation data were also evaluated using the empirical weld metal chemistry relationship. The results indicated that plate material exhibited a lower irradiation sensitivity than welds when their corresponding compositions were similar. As principal chemistry increased in content, the irradiation sensitivity of the plate and weld material became less distinguishable.
The most significant conclusion of this investigation is that the influence of alloying elements on weld irradiation sensitivity can be controlled provided a proper chemistry balance, especially copper content, is maintained. This model supports the assumption that, for a given copper content, specific alloying elements in the weld account for the large variation in weld irradiation behavior. The chemistry relationship developed provides a significantly improved method for predicting weld irradiation behavior than was possible with the earlier model as well as with relations involving residual elements alone.
Effect and Possibilities of Irradiation Results Error Correction (Demonstrated on the Results of the IAEA Coordinated Program)
Authors: Nagel G 
Published: February 2009

The material-state error is caused by the use of material property values, in the initial state unidentical and thus incomparable, for the determination of neutron irradiation damage. To correct the material-state error, the unirradiated-state property values must be normalized to the material location the irradiated specimens were taken from. Depending on the material property variation involved and on the effect of other error sources as well as on the purpose of the irradiation experiment, the correction of the material-state error will be a more or less necessary preparation to make irradiation results comparable.
A correction of the material-state error was performed on the results of the International Atomic Energy Agency (IAEA) Coordinated Research Programme (Steel, ASTM A533-B, Class 1, HSST Plate 03). The evaluation of the corrected results led to the separation of results apparently influenced by special irradiation conditions, thus narrowing the trend band of the results effectively.
The remaining trend band appears to be the collective result of the irradiation sensitivities of all individual material states, that is, material locations represented, and thus not subject to further reduction.
A correlation of irradiation sensitivity and initial material state could not be proved.
The results do not separate as such between heavy water and light water moderated test reactors.
Tensile Property Correlations for Highly Irradiated 20 Percent Cold-Worked Type 316 Stainless Steel
Authors: Fish RL , Cannon NS , Wire GL 
Published: February 2009

Recent experiments on developmental fast-flux test facility (FFTF) cladding (20 percent cold-worked Type 316 stainless steel) have extended the data base to a fast neutron fluence of 8.4 × 1022 neutrons (n)/cm2 (E &gt; 0.1 MeV). The specimens were irradiated in the experimental breeder reactor-II (EBR-II) at temperatures ranging from 371 to 816°C, although peak fluence levels were attained on specimens irradiated near 371 and 649°C only. Tension tests were performed at 232°C, near the irradiation temperature, and, in some cases, above the irradiation temperature. Test specimen strain rates ranged from 4 × 10 -5/s to 4 × 10-2/s.
The data generated on cladding irradiated near 371 °C established that the low-temperature strength and ductility are fluence independent beyond about 5 × 1022 n/cm2 (E &gt; 0.1 MeV). The strength behavior of the irradiated cladding at 538, 593, and 649 °C is essentially the same as exhibited by thermally aged developmental cladding at the same temperatures and times out of the reactor. Up to a fluence of ∼5 × 1022 n/cm2 (E &gt; 0.1 MeV), the 538°C ductility values remain relatively fluence independent after an initial decrease. Higher temperature (593 and 649 °C) ductilities decrease continually with increasing fluence.
Tensile parameter correlations were developed for the prediction of irradiation effects on the tensile properties of 20 percent cold-worked Type 316 stainless steel. These correlations are based on unirradiated tensile property correlations developed using Hart's equation-of-state approach. The basic premise is that the condition of plastic deformation of some materials such as 316 stainless steel can be characterized by a structure parameter (σ*) which describes the material's “hardness.” It is found that irradiation effects can be incorporated into this formulation by parameterizing the changes in σ* with irradiation temperature and fluence. The resulting correlations provide a description of strength and ductility over the temperature range of 371 to 871 °C and strain rates of 10-5 to 10 1/s.
Effects of Irradiation Temperature, Fluence, and Heating Rate on Postirradiation Flow Properties of Cladding Under Simulated Temperature Transient Heating and Deformation Conditions
Authors: Cannon NS , Duncan DR 
Published: February 2009

Irradiation temperature, fluence, and heating rate effects on plastic flow and failure properties of fast reactor cladding were investigated by heating internally pressurized specimens until failure occurred. Specimens tested were from 20 percent cold-worked Type 316 stainless steel cladding, irradiated in the experimental breeder reactor II (EBR-II) at temperatures to 720°C and fluences to 1023 neutrons (n)/cm2 (E &gt; 0.1 MeV).
A decrease of transient failure temperature with increasing irradiation temperature was observed at the “standard” heating rate of 5.6 C°/s. This effect became more pronounced for irradiation temperatures above 600°C. Transient failure temperatures also generally decreased with increasing fluence for tests performed at the standard heating rate. Irradiated and unirradiated specimens were tested at several heating rates. For equal stress, fluence, and irradiation temperature, decreasing the heating rate decreased failure temperatures by as much as 170 deg C for irradiated specimens and 150 deg C for unirradiated specimens. The data reported herein fall well within fast-flux test facility (FFTF) design limits for transient conditions and serve to confirm the material properties currently used in the design analyses.
In-Reactor Deformation and Fracture of Austenitic Stainless Steels
Authors: Bloom EE , Wolfer WG 
Published: February 2009

An experimental technique for determining in-reactor fracture strain was developed and demonstrated. Differential swelling between a specimen holder and a test specimen with a lower swelling rate produced uniaxial deformation in 304 and cold-worked 316 stainless steel specimens. In-reactor deformations of 0.7 to 2.1 percent were achieved in Type 304 stainless steel previously irradiated to fluences up to 8.8 × 1026 neutrons (n)/m2 without fracture. These strains are significantly higher than found in postirradiation creep-rupture tests on similar specimens. From the measured strain values and published irradiation creep data and correlations, the stress levels during the irradiation were calculated. On the basis of previous postirradiation creep-rupture results, many of the specimens that did not fail would be predicted to fail. Thus we conclude that the in-reactor rupture life is longer than predicted by postirradiation tests.
Strain in a fractured specimen was estimated to be less than 3.8 percent, and the in-reactor fractures were intergranular—the same fracture mode as found in postirradiation tests. Irradiation creep may relax stresses at crack tips and sliding boundaries, thus retarding the initiation or growth of cracks, or both, and leading to longer rupture lives in-reactor. However, the very high ductility or superplastic behavior predicted by the strain-rate sensitivity of irradiation creep is not achieved because of the eventual interruption of the deformation process by grain boundary fracture.
Uncle Sam Wants Them
Authors: McCoy Katherine 
Published: February 2009

Throughout most of the 20th century, warring nation—states generally had two options to increase their military strength. They could create a coalition—as the United States did in World War II—or institute a draft—as it did in Vietnam. Today, though, countries have a third option. Rent. Hiring private military corporations, sometimes called private security corporations or private security firms, has fast become a popular way for nations to fight wars.
Community Organizing and Social Change
Authors: Stoecker Randy 
Published: February 2009

It was 2008, early in the presidential campaign season. Everyone was talking about whether a woman or an African American would be the Democratic party nominee for president. And then they began talking about community organizing. In the early days of the Democratic primary we learned that both Hillary Clinton and Barack Obama had connections to it. Clinton had written her undergraduate thesis on the famous community organizer Saul Alinsky. Obama had actually done it in Chicago through the Gamaliel Foundation, one of the national faith-based community organizing networks.
Communities That Don't bowl in the fog
Authors: Martinrogers Nicole , Rausch Ela , Mattessich Paul 
Published: February 2009

Early one morning, members of a Santa Cruz business owners' association discussed a request for a contribution to an affordable housing development. They considered making the donation, but couldn't agree about the need for this type of housing in their community. Later that afternoon, the director of a Boston nonprofit searched for information about labor market conditions in her agency's service area. She wanted to demonstrate the need for more employment training in a grant proposal. The same day in St. Paul, city council members struggled to prioritize funding for a ride share initiative, a crime prevention program, and a teen center's homework help program. Each had different perceptions of the needs for these services and thus advocated different priorities.
Mutations in Genes Encoding Sorting Nexins Alter Production ofIntracellular and Extracellular Proteases in Aspergillus nidulans
Authors: Katz Margaret E , Evans Cara J , Heagney Emma E , vanKuyk Patricia A , Kelly Joan M , Cheetham Brian F 
Published: February 2009

Abstract
XprG, a putative p53-like transcriptional activator, regulates production of extracellular proteases in response to nutrient limitation and may also have a role in programmed cell death. To identify genes that may be involved in the XprG regulatory pathway, xprG2 revertants were isolated and shown to carry mutations in genes which we have named sogA-C (suppressors of xprG). The translocation breakpoint in the sogA1 mutant was localized to a homolog of Saccharomyces cerevisiae VPS5 and mapping data indicated that sogB was tightly linked to a VPS17 homolog. Complementation of the sogA1 and sogB1 mutations and identification of nonsense mutations in the sogA2 and sogB1 alleles confirmed the identification. Vps17p and Vps5p are part of a complex involved in sorting of vacuolar proteins in yeast and regulation of cell-surface receptors in mammals. Protease zymograms indicate that mutations in sogA-C permit secretion of intracellular proteases, as in S. cerevisiae vps5 and vps17 mutants. In contrast to S. cerevisiae, the production of intracellular protease was much higher in the mutants. Analysis of serine protease gene expression suggests that an XprG-independent mechanism for regulation of extracellular protease gene expression in response to carbon starvation exists and is activated in the pseudorevertants.
Germline Expression Influences Operon Organization in theCaenorhabditis elegansGenome
Authors: Reinke Valerie , Cutter Asher D 
Published: February 2009

AbstractOperons are found across multiple kingdoms and phyla, from prokaryotes to chordates. In the nematode Caenorhabditis elegans, the genome contains &gt;1000 operons that compose ∼15% of the protein-coding genes. However, determination of the force(s) promoting the origin and maintenance of operons in C. elegans has proved elusive. Compared to bacterial operons, genes within a C. elegans operon often show poor coexpression and only sometimes encode proteins with related functions. Using analysis of microarray and large-scale in situ hybridization data, we demonstrate that almost all operon-encoded genes are expressed in germline tissue. However, genes expressed during spermatogenesis are excluded from operons. Operons group together along chromosomes in local clusters that also contain monocistronic germline-expressed genes. Additionally, germline expression of genes in operons is largely independent of the molecular function of the encoded proteins. These analyses demonstrate that mechanisms governing germline gene expression influence operon origination and/or maintenance. Thus, gene expression in a specific tissue can have profound effects on the evolution of genome organization.
Detecting Selective Sweeps: A New Approach Based on Hidden Markov Models
Authors: Boitard Simon , Schlötterer Christian , Futschik Andreas 
Published: February 2009

Abstract
Detecting and localizing selective sweeps on the basis of SNP data has recently received considerable attention. Here we introduce the use of hidden Markov models (HMMs) for the detection of selective sweeps in DNA sequences. Like previously published methods, our HMMs use the site frequency spectrum, and the spatial pattern of diversity along the sequence, to identify selection. In contrast to earlier approaches, our HMMs explicitly model the correlation structure between linked sites. The detection power of our methods, and their accuracy for estimating the selected site location, is similar to that of competing methods for constant size populations. In the case of population bottlenecks, however, our methods frequently showed fewer false positives.
Both the RGS Domain and the Six C-Terminal Amino Acids of Mouse Axin Are Required for Normal Embryogenesis
Authors: Chia Ian V , Kim Min Jung , Itoh Keiji , Sokol Sergei Y , Costantini Frank 
Published: February 2009

Abstract
Axin is a negative regulator of canonical Wnt signaling, which promotes the degradation of β-catenin, the major effector in this signaling cascade. While many protein-binding domains of Axin have been identified, their significance has not been evaluated in vivo. Here, we report the generation and analysis of mice carrying modified Axin alleles in which either the RGS domain or the six C-terminal amino acids (C6 motif) were deleted. The RGS domain is required for APC-binding, while the C6 motif has been implicated in the activation of c-Jun N-terminal kinase, but is not required for the effects of Axin on the Wnt/β-catenin pathway, in vitro. Both mutant Axin alleles caused recessive embryonic lethality at E9.5–E10.5, with defects indistinguishable from those caused by a null allele. As Axin-ΔRGS protein was produced at normal levels, its inability to support embryogenesis confirms the importance of interactions between Axin and APC. In contrast, Axin-ΔC6 protein was expressed at only 25–30% of the normal level, which may account for the recessive lethality of this allele. Furthermore, many AxinΔC6/ΔC6 embryos that were heterozygous for a β-catenin null mutation survived to term, demonstrating that early lethality was due to failure to negatively regulate β-catenin.
An Implant-Retained Maxillary Overdenture to Obturate a Patent Oronasal Communication: A Case Report
Authors: Flanagan Dennis 
Published: February 2009

Abstract
This is a case report of dental prosthetic treatment of a 72-year-old patient with cleft palate with a persisting oral nasal communication in the anterior hard palate. The remaining teeth were extracted, and dental implants were surgically placed in the maxilla and mandible to retain removable overdentures. The maxillary complete overdenture had full palatal coverage as opposed to partial coverage. It was retained by 5 implants with low-profile light retentive retainers. The mandibular overdenture was retained with 4 implants of different diameters and brands. Apparent parameters for successful treatment of a removable maxillary overdenture are as follows: denture flanges, flat or lingualized occlusal scheme, light low-profile retainer retention, maximum implant positional spread with parallel placement, and a minimum of 4 rough-surfaced, long, wide implants placed in denser-type bone sites.
Early Implant Placement in Bilateral Sinus Floor Augmentation Using Iliac Bone Block Grafts in Severe Maxillary Atrophy: A Clinical, Histological, and Radiographic Case Report
Authors: Acocella Alessandro , Sacco Roberto , Nardi Paolo , Agostini Tommaso 
Published: February 2009

Abstract
Effectively restoring a grossly atrophic maxilla can be difficult for the implant surgeon. The placement of dental implants in patients who are edentulous in the posterior maxilla can present difficulties because of deficient posterior alveolar ridge and increased pneumatization of the maxillary sinus, resulting in a minimal hard tissue bed. Implant placement requires adequate quality and quantity of bone, especially in the posterior maxilla. Insufficient bone height and width in this area of the maxilla, because of expansion of the maxillary sinus and atrophic reduction of the alveolar ridge, represents a contraindication for conventional insertion of dental implants. The reconstruction of edentulous patients with adequate bone volume and density by the use of bone graft and, subsequently, the placement of dental implants has become a viable treatment option with high predictability. It is commonly shared that autologous bone graft is the gold standard grafting method in the augmentation of Higmoro antrum and in any kinds of guided bone regeneration. In this article, the authors report a case of severe maxillary atrophy that is augmented by block bone graft harvested from iliac crest. An early placement of implants is possible due to the quick healing of the site, as proven by histologic examinations.
The Use of Laser Technology (Er;Cr:YSGG) and Stereolithography to Aid in the Placement of a Subperiosteal Implant: Case Study
Authors: Kusek Edward R. 
Published: February 2009

AbstractThe use of laser technology has helped this clinician to provide treatment with less postoperative pain and increased healing. The subperiosteal implant is a modality that has been used for several decades, although its popularity has declined in favor of endosseous dental implants. In some instances, however, it remains the treatment of choice, specifically in the atrophic mandible (where placement of endosseous implants is not possible) or when placement would increase the chances of jaw fracture. This article reports the case of a patient rehabilitated using a simplified surgical protocol involving laser surgery and stereolithography.