252 research outputs found

    Silo Storage Preconceptual Design

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    The National Nuclear Security Administration (NNSA) has a need to develop and field a low-cost option for the long-term storage of a variety of radiological material. The storage option’s primary requirement is to provide both environmental and physical protection of the materials. Design criteria for this effort require a low initial cost and minimum maintenance over a 50-year design life. In 1999, Argonne National Laboratory-West was tasked with developing a dry silo storage option for the BN-350 Spent Fuel in Aktau Kazakhstan. Argon’s design consisted of a carbon steel cylinder approximately 16 ft long, 18 in. outside diameter and 0.375 in. wall thickness. The carbon steel silo was protected from corrosion by a duplex coating system consisting of zinc and epoxy. Although the study indicated that the duplex coating design would provide a design life well in excess of the required 50 years, the review board was concerned because of the novelty of the design and the lack of historical use. In 2012, NNSA tasked Idaho National Laboratory (INL) with reinvestigating the silo storage concept and development of alternative corrosion protection strategies. The 2012 study, “Silo Storage Concepts, Cathodic Protection Options Study” (INL/EST-12-26627), concludes that the option which best fits the design criterion is a passive cathotic protection scheme, consisting of a carbon steel tube coated with zinc or a zinc-aluminum alloy encapsulated in either concrete or a cement grout. The hot dipped zinc coating option was considered most efficient, but the flame-sprayed option could be used if a thicker zinc coating was determined to be necessary

    Change and Aging Senescence as an adaptation

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    Understanding why we age is a long-lived open problem in evolutionary biology. Aging is prejudicial to the individual and evolutionary forces should prevent it, but many species show signs of senescence as individuals age. Here, I will propose a model for aging based on assumptions that are compatible with evolutionary theory: i) competition is between individuals; ii) there is some degree of locality, so quite often competition will between parents and their progeny; iii) optimal conditions are not stationary, mutation helps each species to keep competitive. When conditions change, a senescent species can drive immortal competitors to extinction. This counter-intuitive result arises from the pruning caused by the death of elder individuals. When there is change and mutation, each generation is slightly better adapted to the new conditions, but some older individuals survive by random chance. Senescence can eliminate those from the genetic pool. Even though individual selection forces always win over group selection ones, it is not exactly the individual that is selected, but its lineage. While senescence damages the individuals and has an evolutionary cost, it has a benefit of its own. It allows each lineage to adapt faster to changing conditions. We age because the world changes.Comment: 19 pages, 4 figure

    Altered growth characteristics of skin fibroblasts from wild-derived mice, and genetic loci regulating fibroblast clone size

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    Mouse fibroblast senescence in vitro is an important model for the study of aging at cellular level. However, common laboratory mouse strains may have lost some important allele variations related to aging processes. In this study, growth in vitro of tail skin fibroblasts (TSFs) derived from a wild-derived stock, Pohnpei (Pohn) mice, differed from growth of control C57BL/6 J (B6) TSFs. Pohn TSFs exhibited higher proliferative ability, fewer apoptotic cells, decreased expression of Cip1 , smaller surface areas, fewer cells positive for senescence associated-β-galactosidase (SA-β-gal) and greater resistance to H 2 O 2 -induced SA-β-gal staining and Cip1 expression. These data suggest that TSFs from Pohn mice resist cellular senescence-like changes. Using large clone ratio (LCR) as the phenotype, a quantitative trait locus (QTL) analysis in a Pohn/B6 backcross population found four QTLs for LCR: Fcs1 on Chr 3 at 55 cm; Fcs2 on Chr X at 50 cm; Fcs3 on Chr 4 at 51 cm and Fcs4 on Chr 10 at 25 cm. Together, these four QTLs explain 26.1% of the variations in LCRs in the N2 population. These are the first QTLs reported that regulate fibroblast growth. Glutathione S transferase mu ( GST-mu ) genes are overrepresented in the 95% confidence interval of Fcs1 , and Pohn TSFs have higher H 2 O 2 -induced GST-mu 4 , 5 and 7 mRNA levels than B6 TSFs. These enzymes may protect Pohn TSFs from oxidation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71416/1/j.1474-9726.2006.00208.x.pd

    New species longevity record for the northern quahog (=hard clam), Mercenaria mercenaria

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    Author Posting. © National Shellfisheries Association, 2011. This article is posted here by permission of National Shellfisheries Association for personal use, not for redistribution. The definitive version was published in Journal of Shellfish Research 30 (2011): 35-38, doi:10.2983/035.030.0106.Twenty-two large shells (>90 mm shell height) from a sample of live collected hard shell clams, Mercenaria mercenaria, from Buzzards Bay, Woods Hole, Cape Cod, MA, were subjected to sclerochronological analysis. Annually resolved growth lines in the hinge region and margin of the shell were identified and counted; the age of the oldest clam shell was determined to be at least 106 y. This age represents a considerable increase in the known maximum life span for M. mercenaria, more than doubling the maximum recorded life span of the species (46 y). More than 85% of the clam shells aged had more than 46 annual increments, the previous known maximum life span for the species. In this article we present growth rate and growth performance indicators (the overall growth performance and phi prime) for this record-breaking population of M. mercenaria. Recently discovered models of aging require accurate age records and growth parameters for bivalve populations if they are to be utilized to their full potential.This work was supported by grants from the American Diabetes Association (to Z. U.), American Federation for Aging Research (to A. C.), the University of Oklahoma College of Medicine Alumni Association (to A. C.), the BBSRC (to C. A. R.),the National Institutes of Health (AT006526 and HL077256 to Z. U.; AG022873 and AG025063 to S. N. A.), and the DFG Cluster of Excellence ‘‘Future Ocean’’ (to E. P.)

    Demography and Life Histories of Sympatric Patas Monkeys, Erythrocebus patas, and Vervets, Cercopithecus aethiops, in Laikipia, Kenya

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    Mortality patterns are thought to be strong selective forces on life history traits, with high adult mortality and low immature mortality favoring early and rapid reproduction. Patas monkeys (Erythrocebus patas) have the highest potential rates of population increase for their body size of any haplorhine primate because they reproduce both earlier and more often. We report here 10 yr of comparative demographic data on a population of patas monkeys and a sympatric population of vervet monkeys (Cercopithecus aethiops), a closely related species differing in aspects of social system, ecology, and life history. The data reveal that 1) adult female patas monkeys have significantly higher mortality than adult female vervets; 2) infant mortality in patas monkeys is relatively low compared to the norm for mammals because it is not significantly different from that of adult female patas monkeys; and 3) infant mortality is significantly higher than adult female mortality in vervets. For both species, much of the mortality could be attributed to predation. An epidemic illness was also a major contributor to the mortality of adult female patas monkeys whereas chronic exposure to pathogens in a cold and damp microenvironment may have contributed to the mortality of infant vervets. Both populations experienced large fluctuations during the study period. Our results support the prediction from demographic models of life history evolution that high adult mortality relative to immature mortality selects for early maturation

    The Portuguese Rheumatoid Arthritis Impact of Disease (RAID) score and its measurement equivalence in three countries: validation study using Rasch Models

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    © 2018, The Author(s). Purpose: The Rheumatoid Arthritis Impact of Disease (RAID) score assesses seven impact domains of interest for people with RA. This study aimed to test patients’ understanding of the Portuguese RAID and evaluate its cross-cultural validity for use in Portugal. Methods: This was a mixed methods study comprising two phases: (i) cognitive debriefing to determine patient’s comprehension of the Portuguese RAID and (ii) cross-cultural validation using Rasch analysis. Construct validity was determined by fit to the model, invariance culture (compared with France and UK datasets) and evidence of convergent and divergent validity. Results: Patients’ input (n = 38) led to minor changes in the phrasing of two items to ensure conceptual equivalence between the Portuguese and the original RAID. In Rasch analysis (n = 288), two items ‘Sleep’ and ‘Physical well-being’ in the Portuguese dataset did not adequately fit the model specifications, suggesting multidimensionality (sleep—not necessarily associated with RA) and redundancy (physical well-being overlapping with functional disability). Despite the imperfections, the scale had high internal consistency, evidence of convergent and divergent validity and invariance to culture (compared to France n = 195 and UK n = 205 datasets). The scale was well targeted for patients with different levels of disease impact. Conclusions: The RAID has been successfully adapted into Portuguese and it can be used with confidence in clinical practice. Further research will be required to ensure it captures the full range of sleep problems in RA. Meanwhile, data across the three countries (Portugal, France and the UK) are comparable except for the two items (sleep and physical well-being)

    Management of patients with persistent medically unexplained symptoms: a descriptive study

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    Background: In 2013 the Dutch guideline for management of medically unexplained symptoms (MUS) was published. The aim of this study is to assess medical care for patients with persistent MUS as recorded in their electronic medical records, to investigate if this is in line with the national guideline for persistent MUS and whether there are changes in care over time. Methods: We conducted an observational study of adult primary care patients with MUS. Routinely recorded health care data were extracted from electronic medical records of patients participating in an ongoing randomised controlled trial in 30 general practices in the Netherlands. Data on general practitioners’ (GPs’) management strategies during MUS consultations were collected in a 5-year period for each patient prior. Management strategies were categorised according to the options offered in the Dutch guideline. Changes in management over time were analysed. Results: Data were collected from 1035 MUS consultations (77 patients). Beside history-taking, the most frequently used diagnostic strategies were physical examination (24.5%) and additional investigations by the GP (11.1%). Frequently used therapeutic strategies were prescribing medication (24.6%) and providing explanations (11.2%). As MUS symptoms persisted, GPs adjusted medication, discussed progress and scheduled follow-up appointments more frequently. The least frequently used strategies were exploration of all complaint dimensions (i.e. somatic, cognitive, emotional, behavioural and social) (3.5%) and referral to a psychologist (0.5%) or psychiatrist (0.1%). Conclusions: Management of Dutch GPs is partly in line with the Dutch guideline. Medication was possibly prescribed more frequently than recommended, whereas exploration of all complaint dimensions, shared problem definition and referral to mental health care were used less
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