Science.gov

Sample records for age class structure

  1. Age-class structure and variability of two populations of the bluemask darter etheostoma (Doration) sp.

    USGS Publications Warehouse

    Simmons, J.W.; Layzer, J.B.; Smith, D.D.

    2008-01-01

    The bluemask darter Etheostoma (Doration) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters (Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish 0.05). In both rivers, females were more abundant than males.

  2. Stage-structured models of intra- and inter-specific competition within age classes

    NASA Astrophysics Data System (ADS)

    Fang, Jian; Gourley, Stephen A.; Lou, Yijun

    2016-01-01

    In some species, larvae and adults experience competition in completely different ways. Simple stage-structured models without larval competition usually yield a single delay equation for the adults. Using an age structured system incorporating competition among both larvae and adults, we derive a system of distributed delay equations for the numbers of larvae and adults. The system is neither cooperative nor reducible to a single equation for either variable. Positivity, boundedness and uniform strong persistence are established. Linear stability analysis of equilibria is difficult due to the strong coupling, but results are proved for small delays using monotone systems theory and exponential ordering. For small delay we prove a theorem on generic convergence to equilibria, which does not directly follow from standard theory but can be proved indirectly using comparison arguments. Finally, we consider an extension to two-strain competition and prove theorems on the linear stability of the boundary equilibria.

  3. Divergent patterns of abundance and age-class structure of headwater stream tadpoles in burned and unburned watersheds

    USGS Publications Warehouse

    Hossack, B.R.; Corn, P.S.; Fagre, D.B.

    2006-01-01

    Wildfire is a potential threat to many species with narrow environmental tolerances like the Rocky Mountain tailed frog (Ascaphus montanus Mittleman and Myers, 1949), which inhabits a region where the frequency and intensity of wildfires are expected to increase. We compared pre- and post-fire counts of tadpoles in eight streams in northwestern Montana to determine the effects of wildfire on A. montanus. All streams were initially sampled in 2001, 2 years before four of them burned in a large wildfire, and were resampled during the 2 years following the fire. Counts of tadpoles were similar in the two groups of streams before the fire. After the fire, tadpoles were almost twice as abundant in unburned streams than in burned streams. The fire seemed to have the greatest negative effect on abundance of age-1 tadpoles, which was reflected in the greater variation in same-stream age-class structure compared with those in unburned streams. Despite the apparent effect on tadpoles, we do not expect the wildfire to be an extirpation threat to populations in the streams that we sampled. Studies spanning a chronosequence of fires, as well as in other areas, are needed to assess the effects of fires on streams with A. montanus and to determine the severity and persistence of these effects.

  4. Major Histocompatibility Complex class I proteins are critical for maintaining neuronal structural complexity in the aging brain.

    PubMed

    Lazarczyk, Maciej J; Kemmler, Julia E; Eyford, Brett A; Short, Jennifer A; Varghese, Merina; Sowa, Allison; Dickstein, Daniel R; Yuk, Frank J; Puri, Rishi; Biron, Kaan E; Leist, Marcel; Jefferies, Wilfred A; Dickstein, Dara L

    2016-01-01

    Major histocompatibility complex class I (MHCI) proteins have been implicated in neuronal function through the modulation of neuritogenesis, synaptogenesis, synaptic plasticity, and memory consolidation during development. However, the involvement of MHCI in the aged brain is unclear. Here we demonstrate that MHCI deficiency results in significant dendritic atrophy along with an increase in thin dendritic spines and a reduction in stubby spines in the hippocampus of aged (12 month old) mice. Ultrastructural analyses revealed a decrease in spine head diameter and post synaptic density (PSD) area, as well as an increase in overall synapse density, and non-perforated, small spines. Interestingly, we found that the changes in synapse density and morphology appear relatively late (after the age of 6 months). Finally, we found a significant age dependent increase in the levels of the glutamate receptor, GluN2B in aged MHCI knockout mice, with no change in GluA2/3, VGluT1, PSD95 or synaptophysin. These results indicate that MHCI may be also be involved in maintaining brain integrity at post-developmental stages notably in the modulation of neuronal and spine morphology and synaptic function during non-pathological aging which could have significant implications for cognitive function. PMID:27229916

  5. Major Histocompatibility Complex class I proteins are critical for maintaining neuronal structural complexity in the aging brain

    PubMed Central

    Lazarczyk, Maciej J.; Kemmler, Julia E.; Eyford, Brett A.; Short, Jennifer A.; Varghese, Merina; Sowa, Allison; Dickstein, Daniel R.; Yuk, Frank J.; Puri, Rishi; Biron, Kaan E.; Leist, Marcel; Jefferies, Wilfred A.; Dickstein, Dara L.

    2016-01-01

    Major histocompatibility complex class I (MHCI) proteins have been implicated in neuronal function through the modulation of neuritogenesis, synaptogenesis, synaptic plasticity, and memory consolidation during development. However, the involvement of MHCI in the aged brain is unclear. Here we demonstrate that MHCI deficiency results in significant dendritic atrophy along with an increase in thin dendritic spines and a reduction in stubby spines in the hippocampus of aged (12 month old) mice. Ultrastructural analyses revealed a decrease in spine head diameter and post synaptic density (PSD) area, as well as an increase in overall synapse density, and non-perforated, small spines. Interestingly, we found that the changes in synapse density and morphology appear relatively late (after the age of 6 months). Finally, we found a significant age dependent increase in the levels of the glutamate receptor, GluN2B in aged MHCI knockout mice, with no change in GluA2/3, VGluT1, PSD95 or synaptophysin. These results indicate that MHCI may be also be involved in maintaining brain integrity at post-developmental stages notably in the modulation of neuronal and spine morphology and synaptic function during non-pathological aging which could have significant implications for cognitive function. PMID:27229916

  6. Chemical structure of cement aged at normal and elevated temperatures and pressures, Part II: Low permeability class G oilwell cement

    SciTech Connect

    Le Saout, Gwenn . E-mail: gwenn.lesaout@epfl.ch; Lecolier, Eric; Rivereau, Alain; Zanni, Helene

    2006-03-15

    Recently, Low Permeability Cement formulation has been developed for oilwell cementing. Therefore, it is important to understand the physical and chemical processes causing cement degradation in the downhole environment. In this study, we have characterised a Low Permeability Class G oilwell Cement immersed for one year in brine at T = 293 K, p = 10{sup 5} Pa and T = 353 K, p = 7 x 10{sup 6} Pa using {sup 29}Si, {sup 27}Al NMR and XRD techniques. Elevated temperature and pressure conditions increase the rate of the pozzolanic reaction and have significant effects on the polymerisation of C-S-H and on the incorporation of Al in the C-S-H structure. Leaching resulted in the formation of calcite and a more polymerised C-S-H with the appearance of tobermorite in the sample cured at elevated temperature and pressure.

  7. Age-class determination of canvasbacks

    USGS Publications Warehouse

    Serie, J.R.; Trauger, D.L.; Doty, H.A.; Sharp, D.E.

    1982-01-01

    A technique was developed to distinguish yearling from adult canvasbacks (Aythya valisineria) in the field during spring on the basis of white flecking on the distal ends of selected wing feathers. Covert feathers from adults had well-defined vermiculation patterns whereas feathers from yearlings lacked such markings. These age-related characters were confirmed by paired comparisons of feathers from the same captive birds in consecutive years and by discriminant analysis of feathers using densitometric measurements from known-age wild birds. Reflective densitometric measurements of greater secondary coverts for females and males were significantly different between 1- and 2-year-old and between 2- and 3-year-old canvasbacks. Greater secondary coverts were the best feathers for recognizing age-classes of males and females. Densitometric values indicate low variability among different observers and within samples.

  8. The Effect of Mixed-Age Classes in Sweden

    ERIC Educational Resources Information Center

    Lindstrom, Elly-Ann; Lindahl, Erica

    2011-01-01

    Mixed-aged (MA) classes are a common phenomenon around the world. In Sweden, these types of classes increased rapidly during the 1980s and 1990s, despite the fact that existing empirical support for MA classes is weak. In this paper, the effect of attending an MA class during grades 4-6 on students' cognitive skills is estimated. Using a unique…

  9. Food item use by coyote sex and age classes

    SciTech Connect

    Cypher, B.L.; Spencer, K.A.; Scrivner, J.H.

    1995-10-01

    Food item use by coyotes was compared between sexes and among age classes at the Naval Petroleum Reserves, California. Item use did not differ significantly between males and females. Although leporid was the item most frequently used by all age classes, item use differed significantly between pups (< 1 year), yearlings (1 year), and adults (> 1 year), probably due to differential use of secondary items. Variation in item use among age classes could potentially bias results of coyote food habit studies.

  10. Dance Class Structure Affects Youth Physical Activity and Sedentary Behavior: A Study of Seven Dance Types

    ERIC Educational Resources Information Center

    Lopez Castillo, Maria A.; Carlson, Jordan A.; Cain, Kelli L.; Bonilla, Edith A.; Chuang, Emmeline; Elder, John P.; Sallis, James F.

    2015-01-01

    Purpose: The study aims were to determine: (a) how class structure varies by dance type, (b) how moderate-to-vigorous physical activity (MVPA) and sedentary behavior vary by dance class segments, and (c) how class structure relates to total MVPA in dance classes. Method: Participants were 291 boys and girls ages 5 to 18 years old enrolled in 58…

  11. Aging evaluation of class 1E batteries: Seismic testing

    SciTech Connect

    Edson, J.L. )

    1990-08-01

    This report presents the results of a seismic testing program on naturally aged class 1E batteries obtained from a nuclear plant. The testing program is a Phase 2 activity resulting from a Phase 1 aging evaluation of class 1E batteries in safety systems of nuclear power plants, performed previously as a part of the US Nuclear Regulatory Commission's Nuclear Plant Aging Research Program and reported in NUREG/CR-4457. The primary purpose of the program was to evaluate the seismic ruggedness of naturally aged batteries to determine if aged batteries could have adequate electrical capacity, as determined by tests recommended by IEEE Standards, and yet have inadequate seismic ruggedness to provide needed electrical power during and after a safe shutdown earthquake (SSE) event. A secondary purpose of the program was to evaluate selected advanced surveillance methods to determine if they were likely to be more sensitive to the aging degradation that reduces seismic ruggedness. The program used twelve batteries naturally aged to about 14 years of age in a nuclear facility and tested them at four different seismic levels representative of the levels of possible earthquakes specified for nuclear plants in the United States. Seismic testing of the batteries did not cause any loss of electrical capacity. 19 refs., 29 figs., 7 tabs.

  12. Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment

    ERIC Educational Resources Information Center

    Tueller, Stephen; Lubke, Gitta

    2010-01-01

    Structural equation mixture models (SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from 1 wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are…

  13. Population density, biomass, and age-class structure of the invasive clam Corbicula fluminea in rivers of the lower San Joaquin River watershed, California

    USGS Publications Warehouse

    Brown, L.R.; Thompson, J.K.; Higgins, K.; Lucas, L.V.

    2007-01-01

    Corbicula fluminea is well known as an invasive filter-feeding freshwater bivalve with a variety of effects on ecosystem processes. However. C. fluminea has been relatively unstudied in the rivers of the western United States. In June 2003, we sampled C. fluminea at 16 sites in the San Joaquin River watershed of California, which was invaded by C. fluminea in the 1940s. Corbicula fluminea was common in 2 tributaries to the San Joaquin River, reaching densities of 200 clams??m-2, but was rare in the San Joaquin River. Biomass followed a similar pattern. Clams of the same age were shorter in the San Joaquin River than in the tributaries. Distribution of clams was different in the 2 tributaries, but the causes of the difference are unknown. The low density and biomass of clams in the San Joaquin River was likely due to stressful habitat or to water quality, because food was abundant. The success of C. fluminea invasions and subsequent effects on trophic processes likely depends on multiple factors. As C. fluminea continues to expand its range around the world, questions regarding invasion success and effects on ecosystems will become important in a wide array of environmental settings.

  14. Evaluation of structural equation mixture models Parameter estimates and correct class assignment

    PubMed Central

    Tueller, Stephen; Lubke, Gitta

    2009-01-01

    Structural Equation Mixture Models(SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from one wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are investigated in a large scale simulation study. Design factors of the simulation study are (im)balanced class proportions, (im)balanced factor variances, sample size, and class separation. We compare the fit of models with correct and misspecified within-class structural relations. In addition, we investigate the potential to fit SEMMs with binary indicators. The structure of within-class distributions can be recovered under a wide variety of conditions, indicating the general potential and flexibility of SEMMs to test complex within-class models. Correct class assignment is limited. PMID:20582328

  15. Structural aging program status report

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.; Graves, H.L. III

    1994-12-31

    Research is being conducted at the Oak Ridge National Laboratory under Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of safety-related concrete structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Program accomplishments have included development of the Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, performance assessments of reinforced concrete structures in several United Kingdom nuclear power facilities, evaluation of European and North American repair practices for concrete, an evaluation of factors affecting the corrosion of metals embedded in concrete, and application of the time-dependent reliability methodology to reinforced concrete flexure and shear structural elements to investigate the role of in-service inspection and repair on their probability of failure.

  16. Structural aging program status report

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.

    1995-04-01

    Research is being conducted at the Oak Ridge National Laboratory (ORNL) under U.S. Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of safety-related concrete structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Program accomplishments have included development of the Structural Materials Information Center containing data and information of the time variation of 144 material properties under the influence of pertinent environmental stressors of aging factors, performance assessments of reinforced concrete structures in several United Kingdom nuclear power facilities, evaluation of European and North American repair practices for concrete, an evaluation of factors affecting the corrosion of metals embedded in concrete, and application of the time-dependent reliability methodology to reinforced concrete flexure and shear structural elements to investigate the role of in-service inspection and repair on their probability of failure.

  17. Aging and the statistical learning of grammatical form classes.

    PubMed

    Schwab, Jessica F; Schuler, Kathryn D; Stillman, Chelsea M; Newport, Elissa L; Howard, James H; Howard, Darlene V

    2016-08-01

    Language learners must place unfamiliar words into categories, often with few explicit indicators about when and how that word can be used grammatically. Reeder, Newport, and Aslin (2013) showed that college students can learn grammatical form classes from an artificial language by relying solely on distributional information (i.e., contextual cues in the input). Here, 2 experiments revealed that healthy older adults also show such statistical learning, though they are poorer than young at distinguishing grammatical from ungrammatical strings. This finding expands knowledge of which aspects of learning vary with aging, with potential implications for second language learning in late adulthood. (PsycINFO Database Record PMID:27294711

  18. Demographic analysis from summaries of an age-structured population

    USGS Publications Warehouse

    Link, W.A.; Royle, J. Andrew; Hatfield, J.S.

    2003-01-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  19. Neural network definitions of highly predictable protein secondary structure classes

    SciTech Connect

    Lapedes, A. |; Steeg, E.; Farber, R.

    1994-02-01

    We use two co-evolving neural networks to determine new classes of protein secondary structure which are significantly more predictable from local amino sequence than the conventional secondary structure classification. Accurate prediction of the conventional secondary structure classes: alpha helix, beta strand, and coil, from primary sequence has long been an important problem in computational molecular biology. Neural networks have been a popular method to attempt to predict these conventional secondary structure classes. Accuracy has been disappointingly low. The algorithm presented here uses neural networks to similtaneously examine both sequence and structure data, and to evolve new classes of secondary structure that can be predicted from sequence with significantly higher accuracy than the conventional classes. These new classes have both similarities to, and differences with the conventional alpha helix, beta strand and coil.

  20. Nodal Structure and the Partitioning of Equivalence Classes

    ERIC Educational Resources Information Center

    Fields, Lanny; Watanabe-Rose, Mari

    2008-01-01

    By definition, all of the stimuli in an equivalence class have to be functionally interchangeable with each other. The present experiment, however, demonstrated that this was not the case when using post-class-formation dual-option response transfer tests. With college students, two 4-node 6-member equivalence classes with nodal structures of…

  1. First in the Class? Age and the Education Production Function

    ERIC Educational Resources Information Center

    Cascio, Elizabeth U.; Schanzenbach, Diane Whitmore

    2016-01-01

    We estimate the effects of relative age in kindergarten using data from an experiment where children of the same age were randomly assigned to different kindergarten classmates. We exploit the resulting experimental variation in relative age in conjunction with variation in expected kindergarten entry age based on birth date to account for…

  2. Latent Trajectory Classes for Alcohol-Related Blackouts from Age 15 to 19 in ALSPAC

    PubMed Central

    Schuckit, Marc A.; Smith, Tom L.; Heron, Jon; Hickman, Matthew; Macleod, John; Munafo, Marcus R.; Kendler, Kenneth S.; Dick, Danielle M.; Davey-Smith, George

    2014-01-01

    Background Alcohol-related blackouts (ARBs) are reported by ~50% of drinkers. While much is known about the prevalence of ARBs in young adults and their cross-sectional correlates, there are few prospective studies regarding their trajectories over time during mid-adolescence. This paper reports latent trajectory classes of alcohol-related blackouts between ages 15 and 19, along with predictors of those patterns. Methods Latent Class Growth Analysis (LCGA) was used to evaluate the pattern of occurrence of ARBs across four time points for 1402 drinking adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC). Multinomial regression analyses evaluated age 15 demography, substance-related items, externalizing characteristics, and estimated peer substance use as predictors of latent class membership. Results ARBs were reported at age 15 in 30% and at age 19 in 74% of these subjects. Four latent trajectory classes were identified: Class 1 (5.1%) reported no blackouts; for Class 2 (29.5%) ARBs rapidly increased with age; for Class 3 (44.9%) blackouts slowly increased; and for Class 4 (20.5%) ARBs were consistently reported. Using Class 2 (rapid increasers) as the reference, predictors of class membership included female sex, higher drinking quantities, smoking, externalizing characteristics, and estimated peer substance involvement (pseudo R2 =.22). Conclusions ARBs were common and repetitive in these young subjects, and predictors of their trajectories over time involved multiple domains representing diverse characteristics. PMID:25516068

  3. Age-class separation of blue-winged ducks

    USGS Publications Warehouse

    Hohman, W.L.; Moore, J.L.; Twedt, D.J.; Mensik, John G.; Logerwell, E.

    1995-01-01

    Accurate determination of age is of fundamental importance to population and life history studies of waterfowl and their management. Therefore, we developed quantitative methods that separate adult and immature blue-winged teal (Anas discors), cinnamon teal (A. cyanoptera), and northern shovelers (A. clypeata) during spring and summer. To assess suitability of discriminant models using 9 remigial measurements, we compared model performance (% agreement between predicted age and age assigned to birds on the basis of definitive cloacal or rectral feather characteristics) in different flyways (Mississippi and Pacific) and between years (1990-91 and 1991-92). We also applied age-classification models to wings obtained from U.S. Fish and Wildlife Service harvest surveys in the Mississippi and Central-Pacific flyways (wing-bees) for which age had been determined using qualitative characteristics (i.e., remigial markings, shape, or wear). Except for male northern shovelers, models correctly aged lt 90% (range 70-86%) of blue-winged ducks. Model performance varied among species and differed between sexes and years. Proportions of individuals that were correctly aged were greater for males (range 63-86%) than females (range 39-69%). Models for northern shovelers performed better in flyway comparisons within year (1991-92, La. model applied to Calif. birds, and Calif. model applied to La. birds: 90 and 94% for M, and 89 and 76% for F, respectively) than in annual comparisons within the Mississippi Flyway (1991-92 model applied to 1990-91 data: 79% for M, 50% for F). Exclusion of measurements that varied by flyway or year did not improve model performance. Quantitative methods appear to be of limited value for age separation of female blue-winged ducks. Close agreement between predicted age and age assigned to wings from the wing-bees suggests that qualitative and quantitative methods may be equally accurate for age separation of male blue-winged ducks. We interpret annual

  4. Job Structure and Age Satisfaction

    ERIC Educational Resources Information Center

    Phillips, James S.; And Others

    1978-01-01

    From research findings on job design and redesign, the authors conclude that all individuals may not approve job enrichment programs which may actually decrease job satisfaction. Although job satisfaction may increase with age, individual differences and other variables make research results inconclusive. (MF)

  5. On the structure of valiant's complexity classes

    NASA Astrophysics Data System (ADS)

    Bürgisser, Peter

    In [25,27] Valiant developed an algebraic analogue of the theory of NP-completeness for computations with polynomials over a field. We further develop this theory in the spirit of structural complexity and obtain analogues of well-known results by Baker, Gill, and Solovay [1], Ladner [18], and Schöning [23,24].

  6. Does 3rd Age + 3rd World = 3rd Class?

    ERIC Educational Resources Information Center

    Tout, Ken

    1992-01-01

    Demographic changes, migration, and industrialization are having drastic effects on older adults in developing nations. Local programs such as Pro Vida in Colombia, supported by Help Age International, rely on the support of volunteers to improve the quality of life for elderly people. (SK)

  7. Tropical forest biomass and successional age class relationships to a vegetation index derived from Landsat TM data

    NASA Technical Reports Server (NTRS)

    Sader, Steven A.; Waide, Robert B.; Lawrence, William T.; Joyce, Armond T.

    1989-01-01

    Forest stand structure and biomass data were collected using conventional forest inventory techniques in tropical, subtropical, and warm temperate forest biomes. The feasibility of detecting tropical forest successional age class and total biomass differences using Landsat-Thematic mapper (TM) data, was evaluated. The Normalized Difference Vegetation Index (NDVI) calculated from Landsat-TM data were not significantly correlated with forest regeneration age classes in the mountain terrain of the Luquillo Experimental Forest, Puerto Rico. The low sun angle and shadows cast on steep north and west facing slopes reduced spectral reflectance values recorded by TM orbital altitude. The NDVI, calculated from low altitude aircraft scanner data, was significatly correlated with forest age classes. However, analysis of variance suggested that NDVI differences were not detectable for successional forests older than approximately 15-20 years. Also, biomass differences in young successional tropical forest were not detectable using the NDVI. The vegetation index does not appear to be a good predictor of stand structure variables (e.g., height, diameter of main stem) or total biomass in uneven age, mixed broadleaf forest. Good correlation between the vegetation index and low biomass in even age pine plantations were achieved for a warm temperate study site. The implications of the study for the use of NDVI for forest structure and biomass estimation are discussed.

  8. 33 CFR 67.30-1 - Class “C” structures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Class âCâ structures. 67.30-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âCâ Requirements § 67.30-1 Class “C” structures. Class “C” structures shall be the structures erected in an area where Class...

  9. 33 CFR 67.20-1 - Class “A” structures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Class âAâ structures. 67.20-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âAâ Requirements § 67.20-1 Class “A” structures. Class “A” structures shall be the structures erected in an area where Class...

  10. 33 CFR 67.25-1 - Class “B” structures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Class âBâ structures. 67.25-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âBâ Requirements § 67.25-1 Class “B” structures. Class “B” structures shall be the structures erected in an area where Class...

  11. 33 CFR 67.25-1 - Class “B” structures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Class âBâ structures. 67.25-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âBâ Requirements § 67.25-1 Class “B” structures. Class “B” structures shall be the structures erected in an area where Class...

  12. 33 CFR 67.20-1 - Class “A” structures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Class âAâ structures. 67.20-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âAâ Requirements § 67.20-1 Class “A” structures. Class “A” structures shall be the structures erected in an area where Class...

  13. 33 CFR 67.25-1 - Class “B” structures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Class âBâ structures. 67.25-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âBâ Requirements § 67.25-1 Class “B” structures. Class “B” structures shall be the structures erected in an area where Class...

  14. 33 CFR 67.30-1 - Class “C” structures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Class âCâ structures. 67.30-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âCâ Requirements § 67.30-1 Class “C” structures. Class “C” structures shall be the structures erected in an area where Class...

  15. 33 CFR 67.20-1 - Class “A” structures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Class âAâ structures. 67.20-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âAâ Requirements § 67.20-1 Class “A” structures. Class “A” structures shall be the structures erected in an area where Class...

  16. 33 CFR 67.30-1 - Class “C” structures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Class âCâ structures. 67.30-1... NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âCâ Requirements § 67.30-1 Class “C” structures. Class “C” structures shall be the structures erected in an area where Class...

  17. Dance Class Structure Affects Youth Physical Activity and Sedentary Behavior: A Study of Seven Dance Types

    PubMed Central

    Lopez Castillo, Maria A.; Carlson, Jordan A.; Cain, Kelli L.; Bonilla, Edith A.; Chuang, Emmeline; Elder, John P.; Sallis, James F.

    2015-01-01

    Purpose Study aims were to determine: (a) how class structure varies by dance type, (b) how moderate-to-vigorous physical activity (MVPA) and sedentary behavior (SB) vary by dance class segments, and (c) how class structure relates to total MVPA in dance classes. Methods Participants were 291 boys and girls ages 5–18 yr. enrolled in 58 dance classes at 21 dance studios in Southern California. MVPA and SB were assessed with accelerometry, with data aggregated to 15-sec epochs. Percent and minutes of MVPA and SB during dance class segments and percent of class time and minutes spent in each segment were calculated using Freedson age-specific cut points. Differences in MVPA (>3 METS) and SB (<100 counts/min) were examined using mixed effects linear regression. Results The length of each class segment was fairly consistent across dance types, with the exception that in ballet, more time was spent in technique as compared to private jazz/hip-hop classes, and Latin-flamenco and less time was spent in routine/practice as compared to Latin-salsa/ballet folklorico. Segment type accounted for 17% of the variance in the proportion of the segment spent in MVPA. The proportion of the segment in MVPA was higher for routine/practice (44.2%) than technique (34.7%). The proportion of the segment in SB was lowest for routine/practice (22.8%). Conclusion The structure of dance lessons can impact youth’s physical activity. Working with instructors to increase time in routine/practice during dance classes could contribute to physical activity promotion in youth. PMID:25775088

  18. Structural aging program status report

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.

    1994-10-01

    Reinforced concrete structures play a vital role in the safe operation of all light-water reactor plants. In general, the performance of these structures has been satisfactory. However, there have been several instances where the capability of these structures to meet future functional and performance requirements has been challenged due to problems arising from either improper material selection, construction and design deficiencies, or environmental effects. Examples of some of the potentially more serious incidents include post-tensioning anchor head failures, leaching of concrete in tendon galleries, voids under vertical tendon bearing plates, containment dome delaminations, corrosion of steel tendons and rebars, water intrusion through basement cracks, and leakage of corrosion inhibitor from tendon sheaths. Such incidents indicate that there is a need for improved surveillance, inspection and testing, and maintenance to enhance the technical bases for assurance of continued safe operation of nuclear power plants both during the initial licensing period as well as throughout any continued service period.

  19. A probabilistic multi-class classifier for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Mechbal, Nazih; Uribe, Juan Sebastian; Rébillat, Marc

    2015-08-01

    In this paper, a probabilistic multi-class pattern recognition algorithm is developed for damage monitoring of smart structures. As these structures can face damages of different severities located in various positions, multi-class classifiers are needed. We propose an original support vector machine (SVM) multi-class clustering algorithm that is based on a probabilistic decision tree (PDT) that produces a posteriori probabilities associated with damage existence, location and severity. The PDT is built by iteratively subdividing the surface and thus takes into account the structure geometry. The proposed algorithm is very appealing as it combines both the computational efficiency of tree architectures and the SVMs classification accuracy. Damage sensitive features are computed using an active approach based on the permanent emission of non-resonant Lamb waves into the structure and on the recognition of amplitude disturbed diffraction patterns. The effectiveness of this algorithm is illustrated experimentally on a composite plate instrumented with piezoelectric elements.

  20. Spatial and temporal variations in the age structure of Arctic sea ice

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.

    2005-01-01

    Spatial and temporal variations in the age structure of Arctic sea ice are investigated using a new reverse chronology algorithm that tracks ice-covered pixels to their location and date of origin based on ice motion and concentration data. The Beaufort Gyre tends to harbor the oldest (>10 years old) sea ice in the western Arctic while direct ice advection pathways toward the Transpolar Drift Stream maintain relatively young (10 years old (10+ year age class) were observed during 1989-2003. Since the mid-1990s, losses to the 10+ year age class lacked compensation by recruitment due to a prior depletion of all mature (6-10 year) age classes. Survival of the 1994 and 1996-1998 sea ice generations reestablished most mature age classes, and thereby the potential to increase extent of the 10+ year age class during the mid-2000s.

  1. Fracture toughness and structure of martensitic class steels

    SciTech Connect

    Golovinskaya, T.M.; Dmitrieva, E.A.; Kaminskii, A.A.; Rudis, T.V.

    1985-05-01

    In this paper the authors present results of a study of the influence of heat-treatment conditions of structural steels with intense decomposition of the metastable structures in tempering after hardening and with decomposition delayed by the addition of the alloy elements molybdenum and vanadium on the crack resistance, structural changes, and micromechanism of fracture. Investigation was made using the martensitic class steels 37KhN3A, 30KhGSA, and 30Kh3SNMVF.

  2. Age-Graded Themes in White American Middle-Class Slang: A Hypothesis.

    ERIC Educational Resources Information Center

    Donahue, Thomas S.

    It is proposed that middle- and upper-middle-class slang used among white young people in modern America shows age-related themes. For youngsters between the ages of eight and early adolescence, the major theme in slang use is to establish in-group and out-group membership, with standards of judgment based on clothes, manners, and physical appeal.…

  3. Class structure in a deeply divided society: class and ethnic inequality in Israel, 1974-1991.

    PubMed

    Yaish, M

    2001-09-01

    Despite the fact that in many societies ethnicity plays an important role in stratification processes, a common view held by students of stratification argues that the role of ascriptive criteria in stratification processes is diminishing, and that the main axis of the modern stratification system is rooted in the division of labour in the marketplace. Despite this, most Israeli sociologists have taken the ethnic and national cleavages to be the main axes of stratification in Israel. This paper utilizes the 1974 and 1991 mobility surveys in Israel to examine changes over time in the association between ethnicity/nationality (i.e., Ashkenazi-Jews, Sephardi-Jews and Israeli-Arabs) and class position in the Israeli stratification structure. It also examines the extent to which inequality of opportunity within the Israeli class structure is affected by ethnicity/nationality. Here it is found that the ethnic/national cleavage in Israel appears to have played a less important role over time in the allocation of Israeli men to class positions. It is shown that class crystallization processes that result from the differentiation of employment contracts in the marketplace produce a relatively common level of inequality of opportunity in Israel, across sub-populations and over time. Any difference in the level of inequality of opportunity between the various sub-populations would appear to result, in part, from different historical process of, and government policy towards, the three sub-populations. PMID:11578003

  4. Structural Imaging Measures of Brain Aging

    PubMed Central

    Lockhart, Samuel N.

    2014-01-01

    During the course of normal aging, biological changes occur in the brain that are associated with changes in cognitive ability. This review presents data from neuroimaging studies of primarily “normal” or healthy brain aging. As such, we focus on research in unimpaired or nondemented older adults, but also include findings from lifespan studies that include younger and middle aged individuals as well as from populations with prodromal or clinically symptomatic disease such as cerebrovascular or Alzheimer’s disease. This review predominantly addresses structural MRI biomarkers, such as volumetric or thickness measures from anatomical images, and measures of white matter injury and integrity respectively from FLAIR or DTI, and includes complementary data from PET and cognitive or clinical testing as appropriate. The findings reveal highly consistent age-related differences in brain structure, particularly frontal lobe and medial temporal regions that are also accompanied by age-related differences in frontal and medial temporal lobe mediated cognitive abilities. Newer findings also suggest that degeneration of specific white matter tracts such as those passing through the genu and splenium of the corpus callosum may also be related to age-related differences in cognitive performance. Interpretation of these findings, however, must be tempered by the fact that comorbid diseases such as cerebrovascular and Alzheimer’s disease also increase in prevalence with advancing age. As such, this review discusses challenges related to interpretation of current theories of cognitive aging in light of the common occurrence of these later-life diseases. Understanding the differences between “Normal” and “Healthy” brain aging and identifying potential modifiable risk factors for brain aging is critical to inform potential treatments to stall or reverse the effects of brain aging and possibly extend cognitive health for our aging society. PMID:25146995

  5. Cooperation and age structure in spatial games

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wang, Zhen; Zhu, Xiaodan; Arenzon, Jeferson J.

    2012-01-01

    We study the evolution of cooperation in evolutionary spatial games when the payoff correlates with the increasing age of players (the level of correlation is set through a single parameter, α). The demographic heterogeneous age distribution, directly affecting the outcome of the game, is thus shown to be responsible for enhancing the cooperative behavior in the population. In particular, moderate values of α allow cooperators not only to survive but to outcompete defectors, even when the temptation to defect is large and the ageless, standard α=0 model does not sustain cooperation. The interplay between age structure and noise is also considered, and we obtain the conditions for optimal levels of cooperation.

  6. Continuous Age-Structured Model for Bovine Tuberculosis in African buffalo

    NASA Astrophysics Data System (ADS)

    Anguelov, R.; Kojouharov, H.

    2009-10-01

    The paper deals with a model of the spread of bovine tuberculosis in the buffalo population in the Kruger National Park in South Africa. The model uses continuous age structure and it is formulated in terms of partial differential equations using eight epidemiological classes (compartments). More precisely, the age density for each class at time t satisfies a one way wave equation, where the age is the space variable. The continuous age model discussed here is derived from a 2006 age groups model by P. C. Cross and W. M. Getz.

  7. Normal and aging hair biology and structure 'aging and hair'.

    PubMed

    Goodier, Molly; Hordinsky, Maria

    2015-01-01

    Much like an individual's hairstyle, hair fibers along the scalp see a number of changes over the course of one's lifetime. As the decades pass, the shine and volume synonymous with youthful hair may give way to thin, dull, and brittle hair commonly associated with aging. These changes are a result of a compilation of genetic and environmental elements influencing the cells of the hair follicle, specifically the hair follicle stem cells and melanocytes. Telomere shortening, decrease in cell numbers, and particular transcription factors have all been implicated in this process. In turn, these molecular alterations lead to structural modifications of the hair fiber, decrease in melanin production, and lengthening of the telogen phase of the hair cycle. Despite this inevitable progression with aging, there exists an array of treatments such as light therapy, minoxidil, and finasteride which have been designed to mitigate the effects of aging, particularly balding and thinning hair. Although each works through a different mechanism, all aim to maintain or potentially restore the youthful quality of hair. PMID:26370639

  8. Social Skills Expression of Senior High School Age Students in Physical Education Classes

    ERIC Educational Resources Information Center

    Akelaitis, Arturas V.

    2015-01-01

    The main purpose of the present study is to reveal the peculiarities of social skills expression of senior high school age students in physical education classes. The independent random sample consisted of 244 (15-16 years old) students and 258 (17-18 years old) students, of which there were 224 boys and 278 girls. L. Bulotaite and V. Gudžinskiene…

  9. Effects of Age, Gender, School Class on Cardiopulmonary Resuscitation Skills of Nigerian Secondary School Students

    ERIC Educational Resources Information Center

    Onyeaso, Adedamola Olutoyin; Onyeaso, Chukwudi Ochi

    2016-01-01

    Background: The need for training of schoolchildren on cardiopulmonary resuscitation (CPR) as potential bystander CPR providers is growing globally but Nigeria is still behind and lacks basic necessary data. Purpose: The purpose of this study was to investigate the effects of age, gender and school class on CPR skills of Nigerian secondary school…

  10. Structural integrity of future aging airplanes

    NASA Technical Reports Server (NTRS)

    Mcguire, Jack F.; Goranson, Ulf G.

    1992-01-01

    A multitude of design considerations is involved in ensuring the structural integrity of Boeing jet transports that have common design concepts validated by extensive analyses, tests, and three decades of service. As airplanes approach their design service objectives, the incidences of fatigue and corrosion may become widespread. Continuing airworthiness of the aging jet fleet requires diligent performance from the manufacturer, the airlines, and airworthiness authorities. Aging fleet support includes timely development of supplemental structural inspection documents applicable to selected older airplanes, teardown inspections of high-time airframes retired from service, fatigue testing of older airframes, and structural surveys of more than 130 airplanes operated throughout the world. Lessons learned from these activities are incorporated in service bulletin recommendations, production line modifications, and design manual updates. An overview of traditional Boeing fleet support activities and the anticipated benefits for future generations of commercial airplanes based on the continuous design improvement process are presented.

  11. Structural integrity of future aging airplanes

    NASA Astrophysics Data System (ADS)

    McGuire, Jack F.; Goranson, Ulf G.

    1992-07-01

    A multitude of design considerations is involved in ensuring the structural integrity of Boeing jet transports that have common design concepts validated by extensive analyses, tests, and three decades of service. As airplanes approach their design service objectives, the incidences of fatigue and corrosion may become widespread. Continuing airworthiness of the aging jet fleet requires diligent performance from the manufacturer, the airlines, and airworthiness authorities. Aging fleet support includes timely development of supplemental structural inspection documents applicable to selected older airplanes, teardown inspections of high-time airframes retired from service, fatigue testing of older airframes, and structural surveys of more than 130 airplanes operated throughout the world. Lessons learned from these activities are incorporated in service bulletin recommendations, production line modifications, and design manual updates. An overview of traditional Boeing fleet support activities and the anticipated benefits for future generations of commercial airplanes based on the continuous design improvement process are presented.

  12. Distribution of HLA class I alleles differs in celiac disease patients according to age of onset.

    PubMed

    Vogelsang, Harald; Panzer, Simon; Mayr, Wolfgang R; Granditsch, Gerhard; Fischer, Gottfried F

    2003-03-01

    Celiac disease (CD) or gluten-sensitive enteropathy is strongly associated with HLA-DQ alleles; more than 95% of patients are DQB1*02. However, the uniform association with HLA-DQ alleles does not explain the clinical heterogeneity, especially the wide range in the age of onset of CD. We asked whether the age of onset of CD is also influenced by class I genes of the human MHC. We performed HLA typing in three groups of patients suffering from CD. The age of onset in the first group (N = 200) was before 15 years of age, in the second group (N = 62) between 15 and 40 years, in the third group (N = 59) after 40 years. We observed a statistically significant increase in the frequencies of HLA-B8 and Cw7 with increasing age of onset. In conclusion, we conclude that distinct alleles from the class I region of the human MHC might lead to late onset of CD. In particular, relatives of CD patients with the disease-prone HLA class I alleles HLA-B8 and Cw7 should be followed up carefully for late onset of CD. PMID:12757179

  13. Dynamic analysis of a hepatitis B model with three-age-classes

    NASA Astrophysics Data System (ADS)

    Zhang, Suxia; Zhou, Yicang

    2014-07-01

    Based on the fact that the likelihood of becoming chronically infected is dependent on age at primary infection Kane (1995) [2], Edmunds et al. (1993) [3], Medley et al. (2001) [4], and Ganem and Prince (2004) [6], we formulate a hepatitis B transmission model with three age classes. The reproduction number, R0 is defined and the dynamical behavior of the model is analyzed. It is proved that the disease-free equilibrium is globally stable if R0<1, and there exists at least one endemic equilibrium and that the disease is uniformly persistent if R0>1. The unique endemic equilibrium and its global stability is obtained in a special case. Simulations are also conducted to compare the dynamical behavior of the model with and without age classes.

  14. Functional and structural syntax networks in aging.

    PubMed

    Antonenko, Daria; Brauer, Jens; Meinzer, Marcus; Fengler, Anja; Kerti, Lucia; Friederici, Angela D; Flöel, Agnes

    2013-12-01

    Language abilities are known to deteriorate in aging, possibly related to decreased functional and structural connectivity within specialized brain networks. Here, we investigated syntactic ability in healthy young and older adults using a comprehensive assessment of behavioral performance, task-independent functional (FC) and structural brain connectivity (SC). Seed-based FC originating from left pars opercularis (part of Broca's area) known to support syntactic processes was assessed using resting-state functional magnetic resonance imaging, and SC using fractional anisotropy from diffusion weighted imaging, in the dorsally located superior longitudinal and the ventrally located uncinate fasciculi (SLF, UF) and forceps minor. Young compared to older adults exhibited superior syntactic performance and stronger FC within the mainly left-lateralized syntax network, which was beneficial for performance. In contrast, in older adults, FC within the mainly left-lateralized syntax network was reduced and did not correlate with performance; inter-hemispheric FC to right inferior frontal and angular gyri was detrimental for performance. In both groups, performance was positively correlated with inter-hemispheric SC. For intra-hemispheric SC, performance correlated with structural integrity of SLF in young adults and with integrity of UF in older adults. Our data show that reduced syntactic ability in older adults is associated with decreased FC within dedicated syntax networks. Moreover, young adults showed an association of syntactic ability with structural integrity of the dorsal tract, while older adults rely more on ventral fibers. In sum, our study provided novel insight into the relationship between connectivity and syntactic performance in young and older adults. In addition to elucidating age-related changes in syntax networks and their behavioral relevance, our results contribute to a better understanding of age-related changes in functional and structural brain

  15. Relative Age Effects in Mathematics and Reading: Investigating the Generalizability across Students, Time and Classes.

    PubMed

    Thoren, Katharina; Heinig, Elisa; Brunner, Martin

    2016-01-01

    A child's age in comparison to the age of her or his classmates (relative age) has been found to be an influential factor on academic achievement, particularly but not exclusively at the beginning of formal schooling. However, few studies have focused on the generalizability of relative age effects. To close this gap, the present study analyzes the generalizability across students with and without immigrant backgrounds, across three student cohorts that entered school under a changing law of school enrollment, and across classes. To this end, we capitalized on representative large-scale data sets from three student cohorts attending public schools in Berlin, the capital of Germany. We analyzed the data using a multilevel framework. Our results for the overall student sample indicate relative age effects for reading and mathematics in favor of the relatively older students in Grade 2 that become somewhat smaller in size in Grade 3. By Grade 8, relative age effects had vanished in reading and had even reversed in favor of the relatively young in mathematics. Furthermore, relative age effects were not found to be systematically different among students with and without immigrant backgrounds, student cohorts, or across classes. Taken together, these results empirically underscore the broad generalizability of the findings as found for the overall student population and replicate the pattern of findings on relative effects as identified by the majority of previous studies. PMID:27242593

  16. Relative Age Effects in Mathematics and Reading: Investigating the Generalizability across Students, Time and Classes

    PubMed Central

    Thoren, Katharina; Heinig, Elisa; Brunner, Martin

    2016-01-01

    A child's age in comparison to the age of her or his classmates (relative age) has been found to be an influential factor on academic achievement, particularly but not exclusively at the beginning of formal schooling. However, few studies have focused on the generalizability of relative age effects. To close this gap, the present study analyzes the generalizability across students with and without immigrant backgrounds, across three student cohorts that entered school under a changing law of school enrollment, and across classes. To this end, we capitalized on representative large-scale data sets from three student cohorts attending public schools in Berlin, the capital of Germany. We analyzed the data using a multilevel framework. Our results for the overall student sample indicate relative age effects for reading and mathematics in favor of the relatively older students in Grade 2 that become somewhat smaller in size in Grade 3. By Grade 8, relative age effects had vanished in reading and had even reversed in favor of the relatively young in mathematics. Furthermore, relative age effects were not found to be systematically different among students with and without immigrant backgrounds, student cohorts, or across classes. Taken together, these results empirically underscore the broad generalizability of the findings as found for the overall student population and replicate the pattern of findings on relative effects as identified by the majority of previous studies. PMID:27242593

  17. A protein structural class prediction method based on novel features.

    PubMed

    Zhang, Lichao; Zhao, Xiqiang; Kong, Liang

    2013-09-01

    In this study, a 12-dimensional feature vector is constructed to reflect the general contents and spatial arrangements of the secondary structural elements of a given protein sequence. Among the 12 features, 6 novel features are specially designed to improve the prediction accuracies for α/β and α + β classes based on the distributions of α-helices and β-strands and the characteristics of parallel β-sheets and anti-parallel β-sheets. To evaluate our method, the jackknife cross-validating test is employed on two widely-used datasets, 25PDB and 1189 datasets with sequence similarity lower than 40% and 25%, respectively. The performance of our method outperforms the recently reported methods in most cases, and the 6 newly-designed features have significant positive effect to the prediction accuracies, especially for α/β and α + β classes. PMID:23770446

  18. Crystal Structure of Patatin-17 in Complex with Aged and Non-Aged Organophosphorus Compounds

    PubMed Central

    Wijeyesakere, Sanjeeva J.; Richardson, Rudy J.; Stuckey, Jeanne A.

    2014-01-01

    Patatin is a non-specific plant lipase and the eponymous member of a broad class of serine hydrolases termed the patatin-like phospholipase domain containing proteins (PNPLAs). Certain PNPLA family members can be inhibited by organophosphorus (OP) compounds. Currently, no structural data are available on the modes of interaction between the PNPLAs and OP compounds or their native substrates. To this end, we present the crystal structure of patatin-17 (pat17) in its native state as well as following inhibition with methyl arachidonyl fluorophosphonate (MAFP) and inhibition/aging with diisopropylphosphorofluoridate (DFP). The native pat17 structure revealed the existence of two portals (portal1 and portal2) that lead to its active-site chamber. The DFP-inhibited enzyme underwent the aging process with the negatively charged phosphoryl oxygen, resulting from the loss of an isopropyl group, being within hydrogen-binding distance to the oxyanion hole. The MAFP-inhibited pat17 structure showed that MAFP did not age following its interaction with the nucleophilic serine residue (Ser77) of pat17 since its O-methyl group was intact. The MAFP moiety is oriented with its phosphoryl oxygen in close proximity to the oxyanion hole of pat17 and its O-methyl group located farther away from the oxyanion hole of pat17 relative to the DFP-bound state. The orientation of the alkoxy oxygens within the two OP compounds suggests a role for the oxyanion hole in stabilizing the emerging negative charge on the oxygen during the aging reaction. The arachidonic acid side chain of MAFP could be contained within portals 1 or 2. Comparisons of pat17 in the native, inhibited, and aged states showed no significant global conformational changes with respect to their Cα backbones, consistent with observations from other α/β hydrolases such as group VIIA phospholipase A2. PMID:25248161

  19. Structural hierarchy in molecular films of two class II hydrophobins.

    PubMed

    Paananen, Arja; Vuorimaa, Elina; Torkkeli, Mika; Penttilä, Merja; Kauranen, Martti; Ikkala, Olli; Lemmetyinen, Helge; Serimaa, Ritva; Linder, Markus B

    2003-05-13

    Hydrophobins are highly surface-active proteins that are specific to filamentous fungi. They function as coatings on various fungal structures, enable aerial growth of hyphae, and facilitate attachment to surfaces. Little is known about their structures and structure-function relationships. In this work we show highly organized surface layers of hydrophobins, representing the most detailed structural study of hydrophobin films so far. Langmuir-Blodgett films of class II hydrophobins HFBI and HFBII from Trichoderma reesei were prepared and analyzed by atomic force microscopy. The films showed highly ordered two-dimensional crystalline structures. By combining our recent results on small-angle X-ray scattering of hydrophobin solutions, we found that the unit cells in the films have dimensions similar to those of tetrameric aggregates found in solutions. Further analysis leads to a model in which the building blocks of the two-dimensional crystals are shape-persistent supramolecules consisting of four hydrophobin molecules. The results also indicate functional and structural differences between HFBI and HFBII that help to explain differences in their properties. The possibility that the highly organized surface assemblies of hydrophobins could allow a route for manufacturing functional surfaces is suggested. PMID:12731866

  20. Prediction of protein structural classes and subcellular locations.

    PubMed

    Chou, K C

    2000-09-01

    The structural class and subcellular location are the two important features of proteins that are closely related to their biological functions. With the rapid increase in new protein sequences entering into data banks, it is highly desirable to develop a fast and accurate method for predicting the attributes of these features for them. This can expedite the functionality determination of new proteins and the process of prioritizing genes and proteins identified by genomics efforts as potential molecular targets for drug design. Various prediction methods have been developed during the last two decades. This review is devoted to presenting a systematic introduction and comparison of the existing methods in respect to the prediction algorithm and classification scheme. The attention is focused on the state-of-the-art, which is featured by the covarient-discriminant algorithm developed very recently, as well as some new classification schemes for protein structural classes and subcellular locations. Particularly, addressed are also the physical chemistry foundation of the existing prediction methods, and the essence why the covariant-discriminant algorithm is so powerful. PMID:12369916

  1. Race, childhood insulin, childhood caloric intake, and class 3 obesity at age 24: 14-year prospective study of schoolgirls.

    PubMed

    Morrison, John A; Glueck, Charles J; Daniels, Stephen R; Wang, Ping

    2012-03-01

    The prevalence of Class 3 obesity (BMI ≥40 kg/m(2)) has more than doubled in the past 25 years. In a 14-year prospective study from age 10 to 24 of a biracial schoolgirl cohort (293 black, 256 white), we assessed childhood correlates of Class 3 BMI at age 24. Of 42 girls with Class 3 BMI at age 24, 36 (86%) were black. By logistic regression, significant explanatory variables of Class 3 BMI at age 24 included top decile waist circumference at age 11 (odds ratio (OR) 5.7, 95% confidence interval (CI) 2.3-13.9, P = 0.0002), age 10 BMI ≥ the Center for Disease Control (CDC) 2000 top 15% (OR 7.0, 95% CI 2.5-19.3, P = 0.0002), and a three-way interaction between race, childhood insulin, and average caloric intake from age 10 to age 19 (for each unit increase, OR 1.7 95% CI 1.3-2.2, P = 0.0003). Age 10 BMI, age 11 waist circumference, and interaction of race, childhood insulin, and childhood caloric intake predict Class 3 obesity in young adulthood, facilitating childhood identification of girls at high risk for developing Class 3 obesity. PMID:21593807

  2. AGE-STRUCTURAL TRANSITION IN INDONESIA

    PubMed Central

    Kreager, Philip; Schröder-Butterfill, Elisabeth

    2016-01-01

    This paper responds to recent calls for empirical study of the impact of age-structural transition. It begins by reviewing evidence of cohort oscillations in twentieth-century Indonesia, which indicates that current older generations are likely to have smaller numbers of children on whom they may rely than generations before and after them. However, to assess whether the imbalances implied by this situation are actually influencing people’s lives, attention to further factors shaping the availability and reliability of younger generations, notably differences in socio-economic status and in patterns of inter-generational support flows, is required. Community-level Indonesian data confirm that elders in the lower social strata are child-poor. Social structural and family network patterns, however, have a greater influence on the availability of inter-generational support than cohort differentials. PMID:27158254

  3. Evaluation of bursal depth as an indicator of age class of harlequin ducks

    USGS Publications Warehouse

    Mather, D.D.; Esler, Daniel

    1999-01-01

    We contrasted the estimated age class of recaptured Harlequin Ducks (Histrionicus histrionicus) (n = 255) based on bursal depth with expected age class based on bursal depth at first capture and time since first capture. Although neither estimated nor expected ages can be assumed to be correct, rates of discrepancies between the two for within-year recaptures indicate sampling error, while between-year recaptures test assumptions about rates of bursal involution. Within-year, between-year, and overall discrepancy rates were 10%, 24%, and 18%, respectively. Most (86%) between-year discrepancies occurred for birds expected to be after-third-year (ATY) but estimated to be third-year (TY). Of these ATY-TY discrepancies, 22 of 25 (88%) birds had bursal depths of 2 or 3 mm. Further, five of six between-year recaptures that were known to be ATY but estimated to be TY had 2 mm bursas. Reclassifying birds with 2 or 3 mm bursas as ATY resulted in reduction in between-year (24% to 10%) and overall (18% to 11%) discrepancy rates. We conclude that age determination of Harlequin Ducks based on bursal depth, particularly using our modified criteria, is a relatively consistent and reliable technique.

  4. A novel predictor for protein structural class based on integrated information of the secondary structure sequence.

    PubMed

    Zhang, Lichao; Zhao, Xiqiang; Kong, Liang; Liu, Shuxia

    2014-08-01

    The structural class has become one of the most important features for characterizing the overall folding type of a protein and played important roles in many aspects of protein research. At present, it is still a challenging problem to accurately predict protein structural class for low-similarity sequences. In this study, an 18-dimensional integrated feature vector is proposed by fusing the information about content and position of the predicted secondary structure elements. The consistently high accuracies of jackknife and 10-fold cross-validation tests on different low-similarity benchmark datasets show that the proposed method is reliable and stable. Comparison of our results with other methods demonstrates that our method is an effective computational tool for protein structural class prediction, especially for low-similarity sequences. PMID:24859536

  5. A protein structural classes prediction method based on predicted secondary structure and PSI-BLAST profile.

    PubMed

    Ding, Shuyan; Li, Yan; Shi, Zhuoxing; Yan, Shoujiang

    2014-02-01

    Knowledge of protein secondary structural classes plays an important role in understanding protein folding patterns. In this paper, 25 features based on position-specific scoring matrices are selected to reflect evolutionary information. In combination with other 11 rational features based on predicted protein secondary structure sequences proposed by the previous researchers, a 36-dimensional representation feature vector is presented to predict protein secondary structural classes for low-similarity sequences. ASTRALtraining dataset is used to train and design our method, other three low-similarity datasets ASTRALtest, 25PDB and 1189 are used to test the proposed method. Comparisons with other methods show that our method is effective to predict protein secondary structural classes. Stand alone version of the proposed method (PSSS-PSSM) is written in MATLAB language and it can be downloaded from http://letsgob.com/bioinfo_PSSS_PSSM/. PMID:24067326

  6. Effects of predation and oxygen deficiency on different age classes of the amphipod Monoporeia affinis

    NASA Astrophysics Data System (ADS)

    Sandberg, E.; Bonsdorff, E.

    1996-06-01

    Predation by the big brackish-water isopod Saduria entomon on two age-classes (juveniles and adults) of the small deposit-feeding amphipod Monoporeia (syn. Pontoporeia) affinis was studied at different oxygen conditions (normoxia>11 mg/l O 2, and moderate hypoxia 4 mg/l O 2). Vulnerability of juvenile and adult M. affinis was studied in single and mixed age-class treatments. The proportions of juveniles and adults were varied at one total numerical density. The predatory effects were measured as numbers of individuals consumed and of total biomass intake (mg ash-free dry weight). The highest predation rate (in numbers) was detected in the single-prey treatment with juvenile M. affinis, both in normoxia and moderate hypoxia. No preference for any of the two size classes was found in the treatment with equal numbers of adults and juveniles. In normoxia, the total number of prey consumed decreased with increasing proportions of adults, while intake increased in terms of biomass. In moderate hypoxia, high proportions of adults reduced the predation rate of S. entomon to such an extent that also the intake in terms of biomass was significantly negatively affected.

  7. A new class of optical structures: Supersymmetric mode converters

    NASA Astrophysics Data System (ADS)

    Stützer, Simon; Heinrich, Matthias; Miri, Mohammad-Ali; El-Ganainy, Ramy; Nolte, Stefan; Christodoulides, Demetrios N.; Szameit, Alexander

    2014-05-01

    Originally developed in the area of quantum field theory, the concept of supersymmetry (SUSY) can be exploited to systematically design a new class of mode converters. In our work, we show for the first time how supersymmetric optical structures can be utilized to control the flow of light for mode division multiplexing applications. Optical potentials and their superpartner configurations are experimentally realized in coupled waveguide arrays using the direct laser-writing technology. This key method allows a flexible and precise tuning of coupling and propagation constants in our optical network. Fluorescence microscopy is used for a direct observation of light dynamics in such systems. In our experiments we show that the fundamental mode of a multimode optical structure can be removed, while establishing global phase matching conditions for the remaining set of modes. SUSY may serve as a promising platform for a new generation of versatile optical components with novel properties and functionalities or even synthesize artificial optical structures that exhibit properties not found in nature.

  8. Restoration of Retarded Influenza Virus-specific Immunoglobulin Class Switch in Aged Mice

    PubMed Central

    Zhang, Yongxin; Wang, Ying; Zhang, Monica; Liu, Lin; Mbawuike, Innocent N

    2016-01-01

    Objective The declined immune response to infection causes significant higher morbidity and mortality in aging in spite of the coexisted hyperimmunoglobulinemia (HIG). This study is to reveal the cellular basis of HIG and mechanism of weakened HA-specific IgG response in aged mice and to test cell therapy in the treatment of age-related IgG antibody production deficiency with immunocyte adoptive transfer. Methods BALB/c mice was immunized with Influenza A/Taiwan vaccine and challenged with the same strain of virus. ELISA was used to assess the levels of total immunoglobulins and antigen specific antibody response. The flow cytometry and ELISPOT were used to evaluate the frequencies of total immunoglobulin- and specific antibody-producing and secreting B lymphocytes. In vitro expanded mononuclear cells, CD4+ T lymphocytes and CD20+ B lymphocytes from old and young mice were adoptively transferred into influenza virus-challenged aged mice, and HA-specific IgG responses were observed. Results It is found that old mice exhibited higher levels of total serum IgG, IgM and IgA, higher frequencies of IgG+, IgM+ and IgA+ cells, and greater antigen-specific IgM and IgA responses to influenza infection, in comparison to young mice. However, influenza antigen- specific IgG and its subclass responses in old mice were significantly lower. Conclusion The retarded specific IgG response could be attributed to an insufficiency of immunoglobulin class switch in aging. Correlation analysis indicated that HIG and deficient specific IgG production in aged mice could be independent to each other in their pathogenesis. Correction of deficient specific IgG production by adoptive transfer of in vitro expanded and unexpanded CD4+ cells from immunized young mice suggests the CD4+ cell dysfunction contributes to the insufficiency of immunoglobulin class switch in aged mice. The transfusion of in vitro expanded lymphocytes could be a potential effective therapy for the age

  9. Geophagy in chacma baboons: patterns of soil consumption by age class, sex, and reproductive state.

    PubMed

    Pebsworth, Paula A; Bardi, Massimo; Huffman, Michael A

    2012-01-01

    Despite baboons' widespread distribution across Africa, geophagy among all subspecies has been poorly documented. We used video camera traps and soil analyses to investigate geophagy in chacma baboons (Papio cynocephalus ursinus) inhabiting the Western Cape of South Africa. During an 18-month study, from August 2009 to January 2011, we continually monitored the largest and most frequently visited geophagy sites with camera traps for 545 days and captured soil consumption at one or more sites on 266 of those days (49%). In 3,500 baboon visits to geophagy sites, video camera traps captured 58.6 hr of geophagy. From these data, we evaluated site preference based on time spent consuming soil among these four geophagy sites. One hundred and seventy days of soil consumption data from the most frequently visited geophagy site allowed us to look for demographic trends in geophagy. Selected consumed soils from geophagy sites were analyzed for mineral, physical, and chemical properties. The baboons spent more time consuming white alkaline soils with high percentages of clay and fine silt, which contained higher concentrations of sodium than non-white acidic soils that contained higher concentrations of iron. Our data indicate that pregnant chacma baboons spent more time consuming soil at monitored geophagy sites than baboons of any other age class, sex, or reproductive state. Based on analytical results, the soils consumed would be effective at alleviating gastrointestinal distress and possibly supplementing minerals for all age/sex classes, but potentially for different age/sex requirements. PMID:21969111

  10. Affluence, Class Structure, and Working-Class Consciousness in Modern Spain

    ERIC Educational Resources Information Center

    Logan, John R.

    1977-01-01

    A survey of textile workers in Barcelona indicates that the growing proportion of affluent workers in Spain has become a major source of class consciousness, militancy, and politicization. A theoretical framework is presented which interprets the survey findings in terms of the relationship between affluence and class consciousness. (Author/DB)

  11. Predicting protein structural class with AdaBoost Learner.

    PubMed

    Niu, Bing; Cai, Yu-Dong; Lu, Wen-Cong; Li, Guo-Zheng; Chou, Kuo-Chen

    2006-01-01

    The structural class is an important feature in characterizing the overall topological folding type of a protein or the domains therein. Prediction of protein structural classification has attracted the attention and efforts from many investigators. In this paper a novel predictor, the AdaBoost Learner, was introduced to deal with this problem. The essence of the AdaBoost Learner is that a combination of many 'weak' learning algorithms, each performing just slightly better than a random guessing algorithm, will generate a 'strong' learning algorithm. Demonstration thru jackknife cross-validation on two working datasets constructed by previous investigators indicated that AdaBoost outperformed other predictors such as SVM (support vector machine), a powerful algorithm widely used in biological literatures. It has not escaped our notice that AdaBoost may hold a high potential for improving the quality in predicting the other protein features as well, such as subcellular location and receptor type, among many others. Or at the very least, it will play a complementary role to many of the existing algorithms in this regard. PMID:16800803

  12. Spatial and temporal variations in the age structure of Arctic sea ice

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.

    2005-01-01

    Spatial and temporal variations in the age structure of Arctic sea ice are investigated using a new reversechronology algorithm that tracks ice-covered pixels to their location and date of origin based on ice motion and concentration data. The Beaufort Gyre tends to harbor the oldest (>10 years old) sea ice in the western Arctic while direct ice advection pathways toward the Transpolar Drift Stream maintain relatively young (???5 years) ice in the eastern Arctic. Persistent net losses (-4.2% yr-1) in extent of ice >10 years old (10+ year age class) were observed during 1989-2003. Since the mid-1990s, losses to the 10+ year age class lacked compensation by recruitment due to a prior depletion of all mature (6-10 year) age classes. Survival of the 1994 and 1996-1998 sea ice generations reestablished most mature age classes, and thereby the potential to increase extent of the 10+ year age class during the mid-2000s. Copyright 2005 by the American Geophysical Union.

  13. Structural health management for aging aircraft

    NASA Astrophysics Data System (ADS)

    Ikegami, Roy; Haugse, Eric D.

    2001-06-01

    An effective structural health management (SHM) system can be a useful tool for making aircraft fleet management decisions ranging from individual aircraft maintenance scheduling and usage restrictions to fleet rotation strategies. This paper discusses the end-user requirements for the elements and architecture of an effective SHM system for application to both military and commercial aging aircraft fleets. The elements discussed include the sensor systems for monitoring and characterizing the health of the structure, data processing methods for interpreting sensor data and converting it into useable information, and automated methods for erroneous data detection, data archiving and information dissemination. Current and past SHM technology development/maturation efforts in these areas at the Boeing Company will be described. An evolutionary technology development strategy is developed in which the technologies needed will be matured, integrated into a vehicle health management system, and benefits established without requiring extensive changes to the end-user's existing operation and maintenance infrastructure. Issues regarding the end-user customer acceptance of SHM systems are discussed and summarized.

  14. Differential Range Use between Age Classes of Southern African Bearded Vultures Gypaetus barbatus

    PubMed Central

    Krüger, Sonja; Reid, Timothy; Amar, Arjun

    2014-01-01

    Bearded Vulture Gypaetus barbatus movements were investigated in southern Africa to determine whether an individual's age, sex or breeding status influenced its ranging behaviour and to provide the information required to guide conservation activities. Data from satellite transmitters fitted to 18 individuals of four age classes were used to determine range size and use. Because of the nature of the movements of marked individuals, these data could be used to determine the overall foraging range of the entire population, which was estimated to be 51 767 km2. Although juvenile, immature and sub-adult birds used different parts of the overall range, their combined foraging range was 65% (33 636 km2) of the overall range. Average adult home ranges (286 km2) were only around 1% the size of the average foraging ranges of non-adults (10 540 –25 985 km2), with those of breeding adults being even smaller (95 km2). Home ranges of breeding adults did not vary in size between seasons but adults utilized their home range more intensively whilst breeding, moving greater distances during the incubation and chick hatching period. Range size and use increased as non-adults aged. Immatures and sub-adults had larger range sizes during winter, but range use of non-adults did not vary seasonally. Range size and use did not differ between the sexes in any of the age classes. Information on home range size and use enables specific areas within the species' range to be targeted for management planning, education and conservation action. PMID:25551614

  15. Differential range use between age classes of southern African Bearded Vultures Gypaetus barbatus.

    PubMed

    Krüger, Sonja; Reid, Timothy; Amar, Arjun

    2014-01-01

    Bearded Vulture Gypaetus barbatus movements were investigated in southern Africa to determine whether an individual's age, sex or breeding status influenced its ranging behaviour and to provide the information required to guide conservation activities. Data from satellite transmitters fitted to 18 individuals of four age classes were used to determine range size and use. Because of the nature of the movements of marked individuals, these data could be used to determine the overall foraging range of the entire population, which was estimated to be 51 767 km(2). Although juvenile, immature and sub-adult birds used different parts of the overall range, their combined foraging range was 65% (33 636 km(2)) of the overall range. Average adult home ranges (286 km(2)) were only around 1% the size of the average foraging ranges of non-adults (10 540 -25 985 km(2)), with those of breeding adults being even smaller (95 km(2)). Home ranges of breeding adults did not vary in size between seasons but adults utilized their home range more intensively whilst breeding, moving greater distances during the incubation and chick hatching period. Range size and use increased as non-adults aged. Immatures and sub-adults had larger range sizes during winter, but range use of non-adults did not vary seasonally. Range size and use did not differ between the sexes in any of the age classes. Information on home range size and use enables specific areas within the species' range to be targeted for management planning, education and conservation action. PMID:25551614

  16. Age Differences Explain Social Class Differences in Students' Friendship at University: Implications for Transition and Retention

    ERIC Educational Resources Information Center

    Rubin, Mark; Wright, Chrysalis L.

    2015-01-01

    The present research tested the hypotheses that (a) working-class students have fewer friends at university than middle-class students and (b) this social class difference occurs because working-class students tend to be older than middle-class students. A sample of 376 first-year undergraduate students from an Australian university completed an…

  17. Discrete structural features among interface residue-level classes

    PubMed Central

    2015-01-01

    Background Protein-protein interaction (PPI) is essential for molecular functions in biological cells. Investigation on protein interfaces of known complexes is an important step towards deciphering the driving forces of PPIs. Each PPI complex is specific, sensitive and selective to binding. Therefore, we have estimated the relative difference in percentage of polar residues between surface and the interface for each complex in a non-redundant heterodimer dataset of 278 complexes to understand the predominant forces driving binding. Results Our analysis showed ~60% of protein complexes with surface polarity greater than interface polarity (designated as class A). However, a considerable number of complexes (~40%) have interface polarity greater than surface polarity, (designated as class B), with a significantly different p-value of 1.66E-45 from class A. Comprehensive analyses of protein complexes show that interface features such as interface area, interface polarity abundance, solvation free energy gain upon interface formation, binding energy and the percentage of interface charged residue abundance distinguish among class A and class B complexes, while electrostatic visualization maps also help differentiate interface classes among complexes. Conclusions Class A complexes are classical with abundant non-polar interactions at the interface; however class B complexes have abundant polar interactions at the interface, similar to protein surface characteristics. Five physicochemical interface features analyzed from the protein heterodimer dataset are discriminatory among the interface residue-level classes. These novel observations find application in developing residue-level models for protein-protein binding prediction, protein-protein docking studies and interface inhibitor design as drugs. PMID:26679043

  18. 49 CFR 176.172 - Structural serviceability of freight containers and vehicles carrying Class 1 (explosive...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... and vehicles carrying Class 1 (explosive) materials on ships. 176.172 Section 176.172 Transportation... Class 1 (Explosive) Materials Cargo Transport Units and Shipborne Barges § 176.172 Structural serviceability of freight containers and vehicles carrying Class 1 (explosive) materials on ships. (a) Except...

  19. Aging IQ Intervention with Older Korean Americans: A Comparison of Internet-Based and In-Class Education

    ERIC Educational Resources Information Center

    Jang, Yuri; Yoon, Hyunwoo; Marti, C. Nathan; Kim, Miyong T.

    2015-01-01

    Using the translated contents of the National Institute on Aging (NIA)'s Aging IQ, an educational intervention was delivered to older Korean Americans. The educational program was delivered via two different modalities, Internet-based education (n = 12) and in-class education (n = 11), and the overall feasibility and efficacy were evaluated by the…

  20. Structural, Functional, and Taxonomic Diversity of Three PreQ1 Riboswitch Classes

    PubMed Central

    Weinberg, Zasha; Breaker, Ronald R.

    2014-01-01

    SUMMARY Previously, two riboswitch classes have been identified that sense and respond to the hypermodified nucleobase called pre-queuosine1 (preQ1). The enormous expansion of available genomic DNA sequence data creates new opportunities to identify additional representatives of the known riboswitch classes and to discover novel classes. We conducted bioinformatics searches on microbial genomic DNA datasets to discover numerous additional examples belonging to the two previously known riboswitch classes for preQ1 (classes preQ1-I and preQ1-II), including some structural variants that further restrict ligand specificity. Additionally, we discovered a third preQ1-binding riboswitch class (preQ1-III) that is structurally distinct from previously known classes. These findings demonstrate that numerous organisms monitor the concentrations of this modified nucleobase by exploiting one or more riboswitch classes for this widespread compound. PMID:25036777

  1. Changing family structure and aging issues.

    PubMed

    Bae, H

    1987-12-01

    Rapid industrialization, adaptation of modern values, and rural-urban migration in Korea have led to the replacement of the extended family with the nuclear of conjugal family. In 1980, 13% of Korean households were 1-generational, 70% were 2-generational, 17% were 3-generational and less than 1% were 4-generational. This trend has had serious implications for the aged, who have become increasingly isolated from Korean society. Hindering the adaptation of the aged to modern society are their low educational level, rural concentration, low income, and high rate of female members. Adult children who are well educated and prosperous economically are most likely to refuse to take responsibility for aged parents. Since some 23% of the aged currently live alone, Korean society must assume some of the responsibility that has traditionally been accepted by family members. There is a need for systematic programming that takes into account the current sociodemographic circumstances of Korea's aged population. Incentives such as tax exemptions and aged care allowances should be considered to encourage children to take responsibility for their aged parents. To meet the needs of the growing number of aged who are disabled and without family support, the number of geriatric hospitals and institutions must be expanded. Also important are supplementary programs such as housekeeping services, meals on wheels, and day care. Although the expansion of social welfare programs and institutions for the aged is essential, they can not in themselves meet the emotional needs of the aged that have traditionally been served by family connectedness. PMID:12315151

  2. Rigor and academic achievement: Career academies versus traditional class structure

    NASA Astrophysics Data System (ADS)

    Kyees, Linda L.

    The purpose of this study was to determine if students who attended high school Career Academy classes, as part of Career and Technical Education, showed greater academic achievement than students who attended traditional high school classes. While all participants attended schools in the same school district, and were seeking the same goal of graduation with a standard diploma, the Career Academy students had the benefit of all classes being directed by a team of teachers who helped them connect their learning to their desired career through collaborative learning projects and assignments. The traditional high school classes taught each subject independent of other subjects and did not have specific connections to desired career goals of the students. The study used a causal-comparative research design and the participants included 1,142 students from 11th and 12th grades who attended 9 high schools in a diversely populated area of central Florida with 571 enrolled in the Career Academies and 571 enrolled in traditional classes. The 10th-grade FCAT scores served as the dependent variable. All students attended similar classes with similar content, making the primary variable the difference in academic gains between students participating in the Career Academy design and the traditional design classes. Using the Man-Whitney U Test resulted in the Career Academy group achieving the higher scores overall. This resulted in rejection of the first null-hypothesis. Further examination determined that the 10th-grade FCAT scores were greater for the average students group, which comprised the largest portion of the participant group, also resulted in rejection of the second null-hypothesis. The gifted and at-risk student group scores resulted in failure to reject the third and fourth null-hypotheses.

  3. Middle-Class Mythology in an Age of Immigration and Segmented Assimilation: Implication for Counseling Psychology

    ERIC Educational Resources Information Center

    Lee, Richard M.; Dean, Brooke L.

    2004-01-01

    W. M. Liu, S. R. Ali, et al. (2004) provide a useful framework to understand the relevance of social class to counseling psychology research, but they overlook the intersection of race and social class in their review. The authors critique the middle-class mythology that pervades social class research in psychology and introduce segmented…

  4. 33 CFR 67.20-1 - Class “A” structures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Class âAâ structures. 67.20-1 Section 67.20-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âAâ Requirements §...

  5. 33 CFR 67.20-1 - Class “A” structures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Class âAâ structures. 67.20-1 Section 67.20-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âAâ Requirements §...

  6. 33 CFR 67.25-1 - Class “B” structures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Class âBâ structures. 67.25-1 Section 67.25-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âBâ Requirements §...

  7. 33 CFR 67.30-1 - Class “C” structures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Class âCâ structures. 67.30-1 Section 67.30-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âCâ Requirements §...

  8. 33 CFR 67.30-1 - Class “C” structures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Class âCâ structures. 67.30-1 Section 67.30-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âCâ Requirements §...

  9. 33 CFR 67.25-1 - Class “B” structures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Class âBâ structures. 67.25-1 Section 67.25-1 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Class âBâ Requirements §...

  10. Ethnicity, Gender, Social Class and Achievement Gaps at Age 16: Intersectionality and "Getting It" for the White Working Class

    ERIC Educational Resources Information Center

    Strand, Steve

    2014-01-01

    Perhaps the most prevailing inequalities in educational achievement in England are those associated with socio-economic status (SES), ethnicity and gender. However, little research has sought to compare the relative size of these gaps or to explore interactions between these factors. This paper analyses the educational achievement at age 11, 14…

  11. Lipid composition of the Antarctic fish Pleuragramma antarcticum. Influence of age class

    NASA Astrophysics Data System (ADS)

    Mayzaud, P.; Chevallier, J.; Tavernier, E.; Moteki, M.; Koubbi, P.

    2011-08-01

    Larvae and juvenile stages of Pleuragramma antarcticum have been collected in the Dumont D’Urville Sea (East Antarctica) during summer 2008 on board the TRV Umitaka Maru during the CEAMARC survey. Detailed analyses of their lipid class and fatty acid compositions were carried out. P. antarcticum showed a pronounced ontogenic lipid accumulation with increasing size. Larvae displayed a dominance of polar lipids (83% of total lipids) and low percentage of triglycerides (7%). Conversely juveniles showed an increasing accumulation of triglycerides (up to 72.4%). The fatty acid composition of polar lipids remained rather stable between stages with 22:6n-3 and 20:5n-3 as dominant contributors. The relatively minor ontogenic changes, e.g. increase of monounsaturated and decrease of C18 polyunsaturated fatty acids, may reflect the influence of differences in diet. Triglycerides showed that all three age classes are well segregated in term of fatty acid composition. Larvae triglycerides are characterized by significant percentages of 16:0, 20:5n-3, 20:6n-3 and to a minor extent 18:4n-3, which suggest a prymnesiophyte based diet. Juveniles are characterized by larger percentages of C20:1 and C22:1 acids, considered as markers of Calanus type copepods. The increasing contribution of 18:1n-9 in the triglycerides of the older juveniles suggests a gradual and increasing shift from a copepod dominant diet to an euphausiid dominant diet. Fatty acid trophic markers pattern suggests a shift from a phytophagous and omnivorous diet for larvae to a carnivorous diet for juveniles.

  12. Class Anxiety in Secondary Education: Exploring Structural Relations with Perceived Control, Engagement, Disaffection, and Performance.

    PubMed

    González, Antonio; Faílde Garrido, José María; Rodríguez Castro, Yolanda; Carrera Rodríguez, María Victoria

    2015-01-01

    The aim of this study was to assess the relationships between class-related anxiety with perceived control, teacher-reported behavioral engagement, behavioral disaffection, and academic performance. Participants were 355 compulsory secondary students (9th and 10th grades; Mean age = 15.2 years; SD = 1.8 years). Structural equation models revealed performance was predicted by perceived control, anxiety, disaffection, and engagement. Perceived control predicted anxiety, disaffection, and engagement. Anxiety predicted disaffection and engagement, and partially mediated the effects from control on disaffection (β = -.277, p < .005; CI = -.378, -.197) and engagement (β = .170, p < .002; CI = .103 .258). The negative association between anxiety and performance was mediated by engagement and disaffection (β = -.295, p < .002; CI = -.439, -.182). Anxiety, engagement, and disaffection mediated the effects of control on performance (β = .352, p < .003; CI = .279, .440). The implications of these results are discussed in the light of current theory and educational interventions. PMID:26364673

  13. Crystal structure of cod liver class I alcohol dehydrogenase: substrate pocket and structurally variable segments.

    PubMed Central

    Ramaswamy, S.; el Ahmad, M.; Danielsson, O.; Jörnvall, H.; Eklund, H.

    1996-01-01

    The structural framework of cod liver alcohol dehydrogenase is similar to that of horse and human alcohol dehydrogenases. In contrast, the substrate pocket differs significantly, and main differences are located in three loops. Nevertheless, the substrate pocket is hydrophobic like that of the mammalian class I enzymes and has a similar topography in spite of many main-chain and side-chain differences. The structural framework of alcohol dehydrogenase is also present in a number of related enzymes like glucose dehydrogenase and quinone oxidoreductase. These enzymes have completely different substrate specificity, but also for these enzymes, the corresponding loops of the substrate pocket have significantly different structures. The domains of the two subunits in the crystals of the cod enzyme further differ by a rotation of the catalytic domains by about 6 degrees. In one subunit, they close around the coenzyme similarly as in coenzyme complexes of the horse enzyme, but form a more open cleft in the other subunit, similar to the situation in coenzyme-free structures of the horse enzyme. The proton relay system differs from the mammalian class I alcohol dehydrogenases. His 51, which has been implicated in mammalian enzymes to be important for proton transfer from the buried active site to the surface is not present in the cod enzyme. A tyrosine in the corresponding position is turned into the substrate pocket and a water molecule occupies the same position in space as the His side chain, forming a shorter proton relay system. PMID:8845755

  14. The effect of small class sizes on mortality through age 29 years: evidence from a multicenter randomized controlled trial.

    PubMed

    Muennig, Peter; Johnson, Gretchen; Wilde, Elizabeth Ty

    2011-06-15

    Limiting the number of students per classroom in the early years has been shown to improve educational outcomes. Improved education is, in turn, hypothesized to improve health. The authors examined whether smaller class sizes affect mortality through age 29 years and whether cognitive factors play a role. They used data from the Project Student Teacher Achievement Ratio, a 4-year multicenter randomized controlled trial of reduced class sizes in Tennessee involving 11,601 students between 1985 and 1989. Children randomized to small classes (13-17 students) experienced improved measures of cognition and academic performance relative to those assigned to regular classes (22-25 students). As expected, these cognitive measures were significantly inversely associated with mortality rates (P < 0.05). However, through age 29 years, students randomized to small class size nevertheless experienced higher mortality rates than those randomized to regular size classes (hazard ratio (HR) = 1.58, 95% confidence interval (CI): 1.07, 2.32). The groups at risk included males (HR = 1.73, 95% CI: 1.05, 2.85), whites/Asians (HR = 1.68, 95% CI: 1.04, 2.72), and higher income students (HR = 2.20, 95% CI: 1.06, 4.57). The authors speculate that small classes might produce behavior changes that increase mortality through young adulthood that are stronger than the protective effects of enhanced cognition. PMID:21540326

  15. Structural aging program -- a summary of activities, results, and conclusions

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1997-01-01

    Research has been conducted by the Oak Ridge National Laboratory to address aging management of nuclear power plant concrete structures. The purpose was to identify potential structural safety issues and acceptance criteria for use in continued service assessments. Primary program accomplishments have included formulation of a Structural Materials Information Center that contains data and information on the time variation of material properties under the influence of pertinent environmental stressors and aging factors for 144 materials, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact their performance, guidelines and evaluation criteria for use in condition assessments of reinforced concrete structures, and a reliability-based methodology for current condition assessments and estimations of future performance of reinforced concrete nuclear power plant structures. In addition, the Structural Aging Program conducted in-depth evaluations of several nondestructive evaluation and repair-related technologies to develop guidance on their applicability.

  16. Nuclear Structure Data for the Present Age

    NASA Astrophysics Data System (ADS)

    Baglin, Coral M.

    2005-05-01

    The US Nuclear Data Program maintains and provides easy and free access to several comprehensive databases that assist scientists to sift through and assess the vast quantity of published nuclear structure and decay data. These databases are an invaluable asset for nuclear-science experimentalists and theorists alike, and the recommended values provided for nuclear properties such as decay modes, level energies and lifetimes, and radiation properties can also be of great importance to specialists in other fields such as medicine, geophysics, and reactor design. The Evaluated Nuclear Structure Data File (ENSDF) contains experimental nuclear structure data for all known nuclides, evaluated by the US nuclear data program evaluators in collaboration with a number of international data groups; the Nuclear Science Reference (NSR) database provides complementary bibliographic information; the Experimental Unevaluated Nuclear Data Listing (XUNDL) exists to enable rapid access to experimental nuclear-structure data compiled from the most recent publications (primarily in high-spin physics). This paper presents an overview of the nuclear structure and decay data available through these databases, with emphasis on recent and forthcoming additions to and presentations of the available material.

  17. Age, occupational class and sickness absence during pregnancy: a retrospective analysis study of the Norwegian population registry

    PubMed Central

    Ariansen, Anja M S

    2014-01-01

    Objective Western women increasingly delay having children to advance their career, and pregnancy is considered to be riskier among older women. In Norway, this development surprisingly coincides with increased sickness absence among young pregnant women, rather than their older counterparts. This paper tests the hypothesis that young pregnant women have a higher number of sick days because this age group includes a higher proportion of working class women, who are more prone to sickness absence. Design A zero-inflated Poisson regression was conducted on the Norwegian population registry. Participants All pregnant employees giving birth in 2004–2008 were included in the study. A total number of 216 541 pregnancies were observed among 180 483 women. Outcome measure Number of sick days. Results Although the association between age and number of sick days was U-shaped, pregnant women in their early 20s had a higher number of sick days than those in their mid-40s. This was particularly the case for pregnant women with previous births. In this group, 20-year-olds had 12.6 more sick days than 45-year-olds; this age difference was reduced to 6.3 after control for class. Among women undergoing their first pregnancy, 20-year-olds initially had 1.2 more sick days than 45-year-olds, but control for class altered this age difference. After control for class, 45-year-old first-time pregnant women had 2.9 more sick days than 20-year-olds with corresponding characteristics. Conclusions The negative association between age and sickness absence was partly due to younger age groups including more working class women, who were more prone to sickness absence. Young pregnant women's needs for job adjustments should not be underestimated. PMID:24793246

  18. Evaluation of aging degradation of structural components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1992-03-01

    Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

  19. Evaluation of aging degradation of structural components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1992-03-01

    Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center_dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

  20. Communication Breakdown: The Impact of Ageing on Synapse Structure

    PubMed Central

    Petralia, Ronald S.; Mattson, Mark P.; Yao, Pamela J.

    2014-01-01

    Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences. PMID:24495392

  1. Spatial variation in age structure among colonies of a marine snake: the influence of ectothermy.

    PubMed

    Bonnet, Xavier; Brischoux, François; Pinaud, David; Michel, Catherine Louise; Clobert, Jean; Shine, Richard; Fauvel, Thomas

    2015-07-01

    Several tetrapod lineages that have evolved to exploit marine environments (e.g. seals, seabirds, sea kraits) continue to rely upon land for reproduction and, thus, form dense colonies on suitable islands. In birds and mammals (endotherms), the offspring cannot survive without their parents. Terrestrial colonies contain all age classes. In reptiles (ectotherms), this constraint is relaxed, because offspring are independent from birth. Hence, each age class has the potential to select sites with characteristics that favour them. Our studies of sea snakes (sea kraits) in the lagoon of New Caledonia reveal marked spatial heterogeneity in age structure among colonies. Sea krait colonies exhibit the endothermic 'seal-seabird' pattern (mixed-age classes within populations) only where the lagoon is narrow. Where the lagoon is wide, most snake colonies are comprised primarily of a single age cohort. Nurseries are located near the coast, adult colonies offshore and mixed colonies in-between. We suggest that ectothermy allows individuals to utilize habitats that are best suited to their own ecological requirements, a flexibility not available to endothermic marine taxa with obligate parental care. PMID:25785869

  2. The Relationship between Professional Preparation and Class Structure on Health Instruction in the Secondary Classroom

    ERIC Educational Resources Information Center

    Hammig, Bart; Ogletree, Roberta; Wycoff-Horn, Marcie R.

    2011-01-01

    Background: The aim of the present study was to examine the impact of professional preparation and class structure on health content delivery and time spent delivering content among required health education classes in the United States. Methods: Data from the classroom-level file of the 2006 School Health Policies and Programs Study were…

  3. Measurement and Structural Model Class Separation in Mixture CFA: ML/EM versus MCMC

    ERIC Educational Resources Information Center

    Depaoli, Sarah

    2012-01-01

    Parameter recovery was assessed within mixture confirmatory factor analysis across multiple estimator conditions under different simulated levels of mixture class separation. Mixture class separation was defined in the measurement model (through factor loadings) and the structural model (through factor variances). Maximum likelihood (ML) via the…

  4. Influence of Professional Preparation and Class Structure on Sexuality Topics Taught in Middle and High Schools

    ERIC Educational Resources Information Center

    Rhodes, Darson L.; Kirchofer, Gregg; Hammig, Bart J.; Ogletree, Roberta J.

    2013-01-01

    Background: This study examined the impact of professional preparation and class structure on sexuality topics taught and use of practice-based instructional strategies in US middle and high school health classes. Methods: Data from the classroom-level file of the 2006 School Health Policies and Programs were used. A series of multivariable…

  5. Age effect on subcortical structures in healthy adults

    PubMed Central

    Goodro, Matt; Sameti, Mohammad; Patenaude, Brian; Fein, George

    2012-01-01

    Cross-sectional age effects in normal control volunteers were investigated in 8 subcortical structures: lateral ventricles, thalamus, caudate, putamen, pallidum, hippocampus, amygdala and nucleus accumbens. Two hundred and twenty six control subjects, ranging in age from 19 to 85 years, were scanned on a 1.5T GE system (n = 184) or a 3.0T Siemens system (n = 42). Cranium-size adjusted subcortical structure volumes were estimated using FSL’s FIRST software, which is fully automated. Significant age effects were found for all volumes when the entire age range was analyzed, however the older subjects (60–85 years of age) showed a stronger correlation between age and structural volume for the ventricles, hippocampus, amygdala and accumbens than middle-aged (35–60 years of age) subjects. Middle-aged subjects were studied at both sites, and age effects in these groups were comparable, despite differences in magnet strength and acquisition systems. This agreement lends support to the validity of the image analysis tools and procedures used in the present study. PMID:22863654

  6. Effects of age and sex on the structural, chemical and technological characteristics of mule duck meat.

    PubMed

    Baeza, E; Salichon, M R; Marche, G; Wacrenier, N; Dominguez, B; Culioli, J

    2000-07-01

    1. The aim of the study was to analyse the effect of age and sex on the chemical, structural and technological characteristics of mule duck meat. 2. Ten males and 10 females were weighed and slaughtered at 8, 10, 11, 12 and 13 weeks of age. Weight, pH value, colour, tenderness and juice loss of breast muscle were determined. 3. The activities of 3 enzymes (citrate synthase, beta-hydroxyacyl CoA dehydrogenase, lactate dehydrogenase) which indicate muscular metabolic activity were assayed. 4. Chemical composition (moisture, lipids, proteins, minerals, lipid and phospholipid classes, fatty acid composition) of breast muscle was analysed. 5. Fibre type, fibre type percentage and cross-sectional areas were determined using histochemistry and an image analysis system. 6. For growth performance and muscular structure, the ideal slaughter age of mule ducks is 10 weeks of age. Chemical and technological analysis indicated that muscular maturity in Pectoralis major was reached at 11 weeks of age, but, at this age, breast lipid content is high. Moreover, after 10 weeks of age, food costs rapidly increased. 7. Lastly, sexual dimorphism for body weight is minor. In this study, at any given age, no significant differences between males and females were shown. Thus, it is possible to rear both sexes together and to slaughter them at the same age. PMID:11081424

  7. Undergraduates Improve upon Published Crystal Structure in Class Assignment

    ERIC Educational Resources Information Center

    Horowitz, Scott; Koldewey, Philipp; Bardwell, James C.

    2014-01-01

    Recently, 57 undergraduate students at the University of Michigan were assigned the task of solving a crystal structure, given only the electron density map of a 1.3 Å crystal structure from the electron density server, and the position of the N-terminal amino acid. To test their knowledge of amino acid chemistry, the students were not given the…

  8. Picnic in the Park--Humanizing an Aging Unit in a Personal Health Class.

    ERIC Educational Resources Information Center

    Gaeta, Michael J.

    1979-01-01

    The unit on an aging program described is designed to provide students with an accurate knowledge base of the biological, psychological, and sociological aspects of aging as well as with experiences to sensitize them to the realities of aging. (JMF)

  9. Mammalian class IV alcohol dehydrogenase (stomach alcohol dehydrogenase): structure, origin, and correlation with enzymology.

    PubMed Central

    Parés, X; Cederlund, E; Moreno, A; Hjelmqvist, L; Farrés, J; Jörnvall, H

    1994-01-01

    The structure of a mammalian class IV alcohol dehydrogenase has been determined by peptide analysis of the protein isolated from rat stomach. The structure indicates that the enzyme constitutes a separate alcohol dehydrogenase class, in agreement with the distinct enzymatic properties; the class IV enzyme is somewhat closer to class I (the "classical" liver alcohol dehydrogenase; approximately 68% residue identities) than to the other classes (II, III, and V; approximately 60% residue identities), suggesting that class IV might have originated through duplication of an early vertebrate class I gene. The activity of the class IV protein toward ethanol is even higher than that of the classical liver enzyme. Both Km and kcat values are high, the latter being the highest of any class characterized so far. Structurally, these properties are correlated with replacements at the active site, affecting both substrate and coenzyme binding. In particular, Ala-294 (instead of valine) results in increased space in the middle section of the substrate cleft, Gly-47 (instead of a basic residue) results in decreased charge interactions with the coenzyme pyrophosphate, and Tyr-363 (instead of a basic residue) may also affect coenzyme binding. In combination, these exchanges are compatible with a promotion of the off dissociation and an increased turnover rate. In contrast, residues at the inner part of the substrate cleft are bulky, accounting for low activity toward secondary alcohols and cyclohexanol. Exchanges at positions 259-261 involve minor shifts in glycine residues at a reverse turn in the coenzyme-binding fold. Clearly, class IV is distinct in structure, ethanol turnover, stomach expression, and possible emergence from class I. PMID:8127901

  10. Special class of nonlinear damping models in flexible space structures

    NASA Technical Reports Server (NTRS)

    Hu, Anren; Singh, Ramendra P.; Taylor, Lawrence W.

    1991-01-01

    A special class of nonlinear damping models is investigated in which the damping force is proportional to the product of positive integer or the fractional power of the absolute values of displacement and velocity. For a one-degree-of-freedom system, the classical Krylov-Bogoliubov 'averaging' method is used, whereas for a distributed system, both an ad hoc perturbation technique and the finite difference method are employed to study the effects of nonlinear damping. The results are compared with linear viscous damping models. The amplitude decrement of free vibration for a single mode system with nonlinear models depends not only on the damping ratio but also on the initial amplitude, the time to measure the response, the frequency of the system, and the powers of displacement and velocity. For the distributed system, the action of nonlinear damping is found to reduce the energy of the system and to pass energy to lower modes.

  11. Chromatin structure and transposable elements in organismal aging

    PubMed Central

    Wood, Jason G.; Helfand, Stephen L.

    2013-01-01

    Epigenetic regulatory mechanisms are increasingly appreciated as central to a diverse array of biological processes, including aging. An association between heterochromatic silencing and longevity has long been recognized in yeast, and in more recent years evidence has accumulated of age-related chromatin changes in Caenorhabditis elegans, Drosophila, and mouse model systems, as well as in the tissue culture-based replicative senescence model of cell aging. In addition, a number of studies have linked expression of transposable elements (TEs), as well as changes in the RNAi pathways that cells use to combat TEs, to the aging process. This review summarizes the recent evidence linking chromatin structure and function to aging, with a particular focus on the relationship of heterochromatin structure to organismal aging. PMID:24363663

  12. Biological fitness and the Price Equation in class-structured populations.

    PubMed

    Grafen, Alan

    2015-05-21

    Price׳s extended covariance selection mathematics is applied to class-structured populations with additional assumptions, to derive the 'genetic Price Equation with class structure'. Each individual belongs to a class, and there may be overlapping generations; the equation is genetic because the trait is restricted to an arbitrary weighted sum of allele frequencies. Two special cases are then considered, a demography-like case corresponding to Fisher's fundamental theorem of natural selection, and a sex-ratio-like case corresponding to Fisher's sex ratio argument: these differ in whether it is natural to assume that the per-capita or the total reproductive values of each class are maintained from the parental to the descendant population. These cases also match the two existing attempts to eliminate from the effects of natural selection those passive changes in allele frequencies that are caused by the class structure, and suggest improvements in one of them. In each case a more specialised Price Equation, and a 'fundamental theorem of natural selection', are proved, which hold out of class-structure equilibrium, showing that passive changes can be eliminated in more than one way, and hinting at the possibility of a more general formulation. Previous class-structured Price Equations and a 'fundamental theorem' are linked to these results. The power of Price's formal approach is vividly illustrated by this lucid conspectus of otherwise self-standing theories with confusing interconnections. PMID:25701635

  13. Localizing Age-Related Individual Differences in a Hierarchical Structure

    ERIC Educational Resources Information Center

    Salthouse, Timothy A.

    2004-01-01

    Data from 33 separate studies were combined to create an aggregate data set consisting of 16 cognitive variables and 6832 different individuals who ranged between 18 and 95 years of age. Analyses were conducted to determine where in a hierarchical structure of cognitive abilities individual differences associated with age, gender, education, and…

  14. Buying into the Computer Age: A Look at the Hispanic Middle Class.

    ERIC Educational Resources Information Center

    Wilhelm, Anthony G.

    The Tomas Rivera Policy Institute conducted focus groups in the summer of 1997 to gain insight into why there is a gap in computer ownership between Hispanic middle-class families and non-Hispanic families of the same middle class income bracket (between 25 and 50 thousand dollars). Results from 6 focus groups of 15 to 20 heads of household each…

  15. Leaf area and light use efficiency patterns of Norway spruce under different thinning regimes and age classes

    PubMed Central

    Gspaltl, Martin; Bauerle, William; Binkley, Dan; Sterba, Hubert

    2013-01-01

    Silviculture focuses on establishing forest stand conditions that improve the stand increment. Knowledge about the efficiency of an individual tree is essential to be able to establish stand structures that increase tree resource use efficiency and stand level production. Efficiency is often expressed as stem growth per unit leaf area (leaf area efficiency), or per unit of light absorbed (light use efficiency). We tested the hypotheses that: (1) volume increment relates more closely with crown light absorption than leaf area, since one unit of leaf area can receive different amounts of light due to competition with neighboring trees and self-shading, (2) dominant trees use light more efficiently than suppressed trees and (3) thinning increases the efficiency of light use by residual trees, partially accounting for commonly observed increases in post-thinning growth. We investigated eight even-aged Norway spruce (Picea abies (L.) Karst.) stands at Bärnkopf, Austria, spanning three age classes (mature, immature and pole-stage) and two thinning regimes (thinned and unthinned). Individual leaf area was calculated with allometric equations and absorbed photosynthetically active radiation was estimated for each tree using the three-dimensional crown model Maestra. Absorbed photosynthetically active radiation was only a slightly better predictor of volume increment than leaf area. Light use efficiency increased with increasing tree size in all stands, supporting the second hypothesis. At a given tree size, trees from the unthinned plots were more efficient, however, due to generally larger tree sizes in the thinned stands, an average tree from the thinned treatment was superior (not congruent in all plots, thus only partly supporting the third hypothesis). PMID:25540477

  16. Agency Amidst Formidable Structures: How Girls Perform Gender in Science Class

    ERIC Educational Resources Information Center

    Carlone, Heidi B.; Johnson, Angela; Scott, Catherine M.

    2015-01-01

    Larger social structures such as race, class, gender, and sexuality and classroom structures like narrowly defined participation practices constrain individuals' agency to engage in untroubled and sustained science identity work. This article explores the central dilemma of attending to structure and agency in settings where inequities are…

  17. The Structure of the Compression Front in Carrington Class CMEs

    NASA Astrophysics Data System (ADS)

    Freed, Alexander J.; Russell, Christopher T.; Luhmann, Janet G.; Galvin, Antoinette B.; Mewaldt, Richard A.; Mason, Glenn

    2015-04-01

    The canonical model of an energetic space weather event is a fast shock preceding the arrival of a large rapidly expanding magnetic rope. The shock front contributes to the high fluxes of energetic particles by further accelerating the energetic particles generated in the initial launch of the magnetic rope. The 1859 Carrington event is popularly portrayed as not simply being the first major space weather event recorded by terrestrial observers, but being the largest recorded event. However, if we quantify the Carrington event in the only parameter that was accurately determined for the event, its transit time, we find that we have modern events with the same transit time and at least one with a faster time. Hence we can probe Carrington-class events with today's fleet of space weather probes. Our best observed event occurred on August 23, 2012, at STEREO A, well away from the Earth-Sun line. We find that this event does not have the classic fast-mode shock ahead of the flux rope, but that the compression is a slow-mode wave. This discovery alters the simple model of shock acceleration proposed for producing the particles accompanying strong coronal mass ejections.

  18. Euler Teaches a Class in Structural Steel Design

    ERIC Educational Resources Information Center

    Boyajian, David M.

    2009-01-01

    Even before steel was a topic of formal study for structural engineers, the brilliant eighteenth century Swiss mathematician and physicist, Leonhard Euler (1707-1783), investigated the theory governing the elastic behaviour of columns, the results of which are incorporated into the American Institute of Steel Construction's (AISC's) Bible: the…

  19. Aging of safety class 1E transformers in safety systems of nuclear power plants

    SciTech Connect

    Roberts, E.W.; Edson, J.L.; Udy, A.C.

    1996-02-01

    This report discusses aging effects on safety-related power transformers in nuclear power plants. It also evaluates maintenance, testing, and monitoring practices with respect to their effectiveness in detecting and mitigating the effects of aging. The study follows the US Nuclear Regulatory Commission`s (NRC`s) Nuclear Plant-Aging Research approach. It investigates the materials used in transformer construction, identifies stressors and aging mechanisms, presents operating and testing experience with aging effects, analyzes transformer failure events reported in various databases, and evaluates maintenance practices. Databases maintained by the nuclear industry were analyzed to evaluate the effects of aging on the operation of nuclear power plants.

  20. Structural basis for resistance to diverse classes of NAMPT inhibitors.

    PubMed

    Wang, Weiru; Elkins, Kristi; Oh, Angela; Ho, Yen-Ching; Wu, Jiansheng; Li, Hong; Xiao, Yang; Kwong, Mandy; Coons, Mary; Brillantes, Bobby; Cheng, Eric; Crocker, Lisa; Dragovich, Peter S; Sampath, Deepak; Zheng, Xiaozhang; Bair, Kenneth W; O'Brien, Thomas; Belmont, Lisa D

    2014-01-01

    Inhibiting NAD biosynthesis by blocking the function of nicotinamide phosphoribosyl transferase (NAMPT) is an attractive therapeutic strategy for targeting tumor metabolism. However, the development of drug resistance commonly limits the efficacy of cancer therapeutics. This study identifies mutations in NAMPT that confer resistance to a novel NAMPT inhibitor, GNE-618, in cell culture and in vivo, thus demonstrating that the cytotoxicity of GNE-618 is on target. We determine the crystal structures of six NAMPT mutants in the apo form and in complex with various inhibitors and use cellular, biochemical and structural data to elucidate two resistance mechanisms. One is the surprising finding of allosteric modulation by mutation of residue Ser165, resulting in unwinding of an α-helix that binds the NAMPT substrate 5-phosphoribosyl-1-pyrophosphate (PRPP). The other mechanism is orthosteric blocking of inhibitor binding by mutations of Gly217. Furthermore, by evaluating a panel of diverse small molecule inhibitors, we unravel inhibitor structure activity relationships on the mutant enzymes. These results provide valuable insights into the design of next generation NAMPT inhibitors that offer improved therapeutic potential by evading certain mechanisms of resistance. PMID:25285661

  1. Aging and demographic plasticity in response to experimental age structures in honeybees (Apis mellifera L)

    PubMed Central

    Linford, Robyn; Gardner, Preston; Coleman, Jennifer; Fine, Kari

    2008-01-01

    Honeybee colonies are highly integrated functional units characterized by a pronounced division of labor. Division of labor among workers is mainly age-based, with younger individuals focusing on in-hive tasks and older workers performing the more hazardous foraging activities. Thus, experimental disruption of the age composition of the worker hive population is expected to have profound consequences for colony function. Adaptive demography theory predicts that the natural hive age composition represents a colony-level adaptation and thus results in optimal hive performance. Alternatively, the hive age composition may be an epiphenomenon, resulting from individual life history optimization. We addressed these predictions by comparing individual worker longevity and brood production in hives that were composed of a single age cohort, two distinct age cohorts, and hives that had a continuous, natural age distribution. Four experimental replicates showed that colonies with a natural age composition did not consistently have a higher life expectancy and/or brood production than the single cohort or double cohort hives. Instead, a complex interplay of age structure, environmental conditions, colony size, brood production, and individual mortality emerged. A general trade-off between worker life expectancy and colony productivity was apparent, and the transition from in-hive tasks to foraging was the most significant predictor of worker lifespan irrespective of the colony age structure. We conclude that the natural age structure of honeybee hives is not a colony-level adaptation. Furthermore, our results show that honeybees exhibit pronounced demographic plasticity in addition to behavioral plasticity to react to demographic disturbances of their societies. PMID:18663386

  2. Further understanding of aged composite and adhesively bonded structures

    NASA Astrophysics Data System (ADS)

    Heslehurst, Rikard B.; Baird, John P.

    1996-11-01

    As the application of advanced composite materials and adhesively bonded components becomes increasingly numerous in aircraft structures, so is the number of aircraft containing such structures that can be classified in the aging aircraft category. The effect of environmental and in- service aging of such structures is not well known or understood, neither have NDE techniques been able to satisfactorily qualify and quantify the loss of structural integrity due to the aging process. This paper will present the latest developments in the practical use of a field portable holographic interferometric testing system. The system results, known as holographic interferograms, provide a better understanding of how a structure is behaving under realistic loads in the presence of defects, damage and material property aging. The system has been applied to a variety of defects in composite and adhesive bondlines, as well as artificial environmental aging of these materials. The holographic interferograms produced form these investigations will be briefly reviewed and their impact on structural integrity of the component discussed.

  3. Solar Array Structures for 300 kW-Class Spacecraft

    NASA Technical Reports Server (NTRS)

    Pappa, Richard; Rose, Geoff; Mann, Troy O.; Warren, Jerry E.; Mikulas, Martin M., Jr.; Kerslake, Tom; Kraft, Tom; Banik, Jeremy

    2013-01-01

    State-of-the-art solar arrays for spacecraft provide on the order of 20 kW of electrical power, and they usually consist of 3J solar cells bonded to hinged rigid panels about 1 inch in thickness. This structural construction allows specific mass and packaging volumes of up to approximately 70 W/kg and 15 kW/m3 to be achieved. Significant advances in solar array structures are required for future very-high-power spacecraft (300+ kW), such as those proposed for pre-positioning heavy cargo on or near the Moon, Mars, or asteroids using solar electric propulsion. These applications will require considerable increases in both W/kg and kW/m3, and will undoubtedly require the use of flexible-substrate designs. This presentation summarizes work sponsored by NASA's Game Changing Development Program since Oct. 2011 to address the challenge of developing 300+ kW solar arrays. The work is primarily being done at NASA Langley, NASA Glenn, and two contractor teams (ATK and DSS), with technical collaboration from AFRL/Kirtland. The near-tem objective of the project is design, analysis, and testing of 30-50 kW solar array designs that are extensible to the far-term objective of 300+ kW. The work is currently focused on three designs: the MegaFlex concept by ATK, the Mega-ROSA concept by DSS, and an in-house 300-kW Government Reference Array concept. Each of these designs will be described in the presentation. Results obtained to date by the team, as well as future work plans, for the design, analysis, and testing of these large solar array structures will be summarized.

  4. Mathematical modeling of a class of multibody flexible spacecraft structures

    NASA Technical Reports Server (NTRS)

    Kelkar, Atul, G.

    1994-01-01

    A mathematical model for a general multibody flexible spacecraft is obtained. The generic spacecraft considered consists of a flexible central body to which a number of flexible multibody structures are attached. The coordinate systems used in the derivation allow effective decoupling of the translational motion of the entire spacecraft from its rotational motion about its center of mass. The derivation assumes that the deformations in the bodies are only due to elastic motions. The dynamic model derived is a closed-form vector-matrix differential equation. The model developed can be used for analysis and simulation of many realistic spacecraft configurations.

  5. Integrated controls-structures design methodology development for a class of flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Maghami, P. G.; Joshi, S. M.; Walz, J. E.; Armstrong, E. S.

    1990-01-01

    Future utilization of space will require large space structures in low-Earth and geostationary orbits. Example missions include: Earth observation systems, personal communication systems, space science missions, space processing facilities, etc., requiring large antennas, platforms, and solar arrays. The dimensions of such structures will range from a few meters to possibly hundreds of meters. For reducing the cost of construction, launching, and operating (e.g., energy required for reboosting and control), it will be necessary to make the structure as light as possible. However, reducing structural mass tends to increase the flexibility which would make it more difficult to control with the specified precision in attitude and shape. Therefore, there is a need to develop a methodology for designing space structures which are optimal with respect to both structural design and control design. In the current spacecraft design practice, it is customary to first perform the structural design and then the controller design. However, the structural design and the control design problems are substantially coupled and must be considered concurrently in order to obtain a truly optimal spacecraft design. For example, let C denote the set of the 'control' design variables (e.g., controller gains), and L the set of the 'structural' design variables (e.g., member sizes). If a structural member thickness is changed, the dynamics would change which would then change the control law and the actuator mass. That would, in turn, change the structural model. Thus, the sets C and L depend on each other. Future space structures can be roughly divided into four mission classes. Class 1 missions include flexible spacecraft with no articulated appendages which require fine attitude pointing and vibration suppression (e.g., large space antennas). Class 2 missions consist of flexible spacecraft with articulated multiple payloads, where the requirement is to fine-point the spacecraft and each

  6. Who Tweets? Deriving the Demographic Characteristics of Age, Occupation and Social Class from Twitter User Meta-Data

    PubMed Central

    Sloan, Luke; Morgan, Jeffrey; Burnap, Pete; Williams, Matthew

    2015-01-01

    This paper specifies, designs and critically evaluates two tools for the automated identification of demographic data (age, occupation and social class) from the profile descriptions of Twitter users in the United Kingdom (UK). Meta-data data routinely collected through the Collaborative Social Media Observatory (COSMOS: http://www.cosmosproject.net/) relating to UK Twitter users is matched with the occupational lookup tables between job and social class provided by the Office for National Statistics (ONS) using SOC2010. Using expert human validation, the validity and reliability of the automated matching process is critically assessed and a prospective class distribution of UK Twitter users is offered with 2011 Census baseline comparisons. The pattern matching rules for identifying age are explained and enacted following a discussion on how to minimise false positives. The age distribution of Twitter users, as identified using the tool, is presented alongside the age distribution of the UK population from the 2011 Census. The automated occupation detection tool reliably identifies certain occupational groups, such as professionals, for which job titles cannot be confused with hobbies or are used in common parlance within alternative contexts. An alternative explanation on the prevalence of hobbies is that the creative sector is overrepresented on Twitter compared to 2011 Census data. The age detection tool illustrates the youthfulness of Twitter users compared to the general UK population as of the 2011 Census according to proportions, but projections demonstrate that there is still potentially a large number of older platform users. It is possible to detect “signatures” of both occupation and age from Twitter meta-data with varying degrees of accuracy (particularly dependent on occupational groups) but further confirmatory work is needed. PMID:25729900

  7. Who tweets? Deriving the demographic characteristics of age, occupation and social class from twitter user meta-data.

    PubMed

    Sloan, Luke; Morgan, Jeffrey; Burnap, Pete; Williams, Matthew

    2015-01-01

    This paper specifies, designs and critically evaluates two tools for the automated identification of demographic data (age, occupation and social class) from the profile descriptions of Twitter users in the United Kingdom (UK). Meta-data data routinely collected through the Collaborative Social Media Observatory (COSMOS: http://www.cosmosproject.net/) relating to UK Twitter users is matched with the occupational lookup tables between job and social class provided by the Office for National Statistics (ONS) using SOC2010. Using expert human validation, the validity and reliability of the automated matching process is critically assessed and a prospective class distribution of UK Twitter users is offered with 2011 Census baseline comparisons. The pattern matching rules for identifying age are explained and enacted following a discussion on how to minimise false positives. The age distribution of Twitter users, as identified using the tool, is presented alongside the age distribution of the UK population from the 2011 Census. The automated occupation detection tool reliably identifies certain occupational groups, such as professionals, for which job titles cannot be confused with hobbies or are used in common parlance within alternative contexts. An alternative explanation on the prevalence of hobbies is that the creative sector is overrepresented on Twitter compared to 2011 Census data. The age detection tool illustrates the youthfulness of Twitter users compared to the general UK population as of the 2011 Census according to proportions, but projections demonstrate that there is still potentially a large number of older platform users. It is possible to detect "signatures" of both occupation and age from Twitter meta-data with varying degrees of accuracy (particularly dependent on occupational groups) but further confirmatory work is needed. PMID:25729900

  8. The Effect of Verb Semantic Class and Verb Frequency (Entrenchment) on Children's and Adults' Graded Judgements of Argument-Structure Overgeneralization Errors

    ERIC Educational Resources Information Center

    Ambridge, Ben; Pine, Julian M.; Rowland, Caroline F.; Young, Chris R.

    2008-01-01

    Participants (aged 5-6 yrs, 9-10 yrs and adults) rated (using a five-point scale) grammatical (intransitive) and overgeneralized (transitive causative) uses of a high frequency, low frequency and novel intransitive verb from each of three semantic classes [Pinker, S. (1989a). "Learnability and cognition: the acquisition of argument structure."…

  9. Subtypes, Severity, and Structural Stability of Peer Victimization: What Does Latent Class Analysis Say?

    ERIC Educational Resources Information Center

    Nylund, Karen; Bellmore, Amy; Nishina, Adrienne; Graham, Sandra

    2007-01-01

    This study uses latent class analysis (LCA) to empirically identify victimization groups during middle school. Approximately 2,000 urban, public middle school students (mean age in sixth grade = 11.57) reported on their peer victimization during the Fall and Spring semesters of their sixth, seventh, and eighth grades. Independent LCA analyses at…

  10. Effect of natural damping on the dynamics and control of a class of optimally designed structures

    NASA Technical Reports Server (NTRS)

    Satyanarayana, K.; Bainum, M.

    1988-01-01

    In this study the vibration control of large space structures with structural damping is investigated. Emphasis is made on the control of both a class of optimally designed (stepped) structures and also the corresponding uniform structures using a cantilever beam as an example. The open loop and closed loop dynamics are compared and the transient responses are determined to study the effect of damping on the control system design.

  11. Local structural differences in homologous proteins: specificities in different SCOP classes.

    PubMed

    Joseph, Agnel Praveen; Valadié, Hélène; Srinivasan, Narayanaswamy; de Brevern, Alexandre G

    2012-01-01

    The constant increase in the number of solved protein structures is of great help in understanding the basic principles behind protein folding and evolution. 3-D structural knowledge is valuable in designing and developing methods for comparison, modelling and prediction of protein structures. These approaches for structure analysis can be directly implicated in studying protein function and for drug design. The backbone of a protein structure favours certain local conformations which include α-helices, β-strands and turns. Libraries of limited number of local conformations (Structural Alphabets) were developed in the past to obtain a useful categorization of backbone conformation. Protein Block (PB) is one such Structural Alphabet that gave a reasonable structure approximation of 0.42 Å. In this study, we use PB description of local structures to analyse conformations that are preferred sites for structural variations and insertions, among group of related folds. This knowledge can be utilized in improving tools for structure comparison that work by analysing local structure similarities. Conformational differences between homologous proteins are known to occur often in the regions comprising turns and loops. Interestingly, these differences are found to have specific preferences depending upon the structural classes of proteins. Such class-specific preferences are mainly seen in the all-β class with changes involving short helical conformations and hairpin turns. A test carried out on a benchmark dataset also indicates that the use of knowledge on the class specific variations can improve the performance of a PB based structure comparison approach. The preference for the indel sites also seem to be confined to a few backbone conformations involving β-turns and helix C-caps. These are mainly associated with short loops joining the regular secondary structures that mediate a reversal in the chain direction. Rare β-turns of type I' and II' are also identified

  12. Local Structural Differences in Homologous Proteins: Specificities in Different SCOP Classes

    PubMed Central

    Joseph, Agnel Praveen; Valadié, Hélène; Srinivasan, Narayanaswamy; de Brevern, Alexandre G.

    2012-01-01

    The constant increase in the number of solved protein structures is of great help in understanding the basic principles behind protein folding and evolution. 3-D structural knowledge is valuable in designing and developing methods for comparison, modelling and prediction of protein structures. These approaches for structure analysis can be directly implicated in studying protein function and for drug design. The backbone of a protein structure favours certain local conformations which include α-helices, β-strands and turns. Libraries of limited number of local conformations (Structural Alphabets) were developed in the past to obtain a useful categorization of backbone conformation. Protein Block (PB) is one such Structural Alphabet that gave a reasonable structure approximation of 0.42 Å. In this study, we use PB description of local structures to analyse conformations that are preferred sites for structural variations and insertions, among group of related folds. This knowledge can be utilized in improving tools for structure comparison that work by analysing local structure similarities. Conformational differences between homologous proteins are known to occur often in the regions comprising turns and loops. Interestingly, these differences are found to have specific preferences depending upon the structural classes of proteins. Such class-specific preferences are mainly seen in the all-β class with changes involving short helical conformations and hairpin turns. A test carried out on a benchmark dataset also indicates that the use of knowledge on the class specific variations can improve the performance of a PB based structure comparison approach. The preference for the indel sites also seem to be confined to a few backbone conformations involving β-turns and helix C-caps. These are mainly associated with short loops joining the regular secondary structures that mediate a reversal in the chain direction. Rare β-turns of type I’ and II’ are also

  13. Aviation Structural Mechanic, Second Class, 2-13. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This self-paced, individualized course, adapted from military curriculum materials for use in vocational and technical education, teaches students the skills needed to become aviation structural mechanics (second class). The course materials consist of five pamphlets covering the structural maintenance and repair of aircraft. The first pamphlet…

  14. Structure and Function of Four Classes of the 4Fe-4S Protein, IspH.

    PubMed

    Rao, Guodong; Oldfield, Eric

    2016-07-26

    IspH, (E)-1-hydroxy-2-methyl-but-2-enyl 4-diphosphate reductase, is an essential enzyme in isoprenoid biosynthesis and an important drug/herbicide target. Using X-ray crystallographic, bioinformatics, mutagenesis/kinetics/stability, and electron paramagnetic resonance (EPR) results, we show that organisms from different environments ultilize one of four main IspH classes. The classes are based on the arrangement of the aromatic residues near the 4Fe-4S cluster and the presence or absence of N- and C-terminal extensions. Class A enzymes are found primarily in anaerobic and microaerophilic bacteria. Class B enzymes are found in aerobic bacteria. Class C enzymes are found in cyanobacteria and plants. Class D enzymes are found in apicomplexan parasites. Using mutagenesis, we show that the cluster-associated aromatic groups in class A and class B IspHs enhance cluster oxidative stability. Y198A, F302A, and a C-terminal truncation mutant of the class B (Escherichia coli) IspH have catalytic activity lower than that of the wild-type protein when using methyl viologen as the electron donor, but higher activity with dithionite as the electron donor, due to ready access of the small reductant to the cluster, consistent with their increased oxygen and H2O2 sensitivity. F302A has the largest effect on the reaction rates, and EPR studies indicate this residue affects Fe-S cluster structure. Similar effects on cluster stability are seen with class A (F14A and Y98A) mutants; however, effects on ET rates are smaller, and there are no differences between the EPR spectra of mutant and wild-type proteins. Overall, the results are of general interest because they show, for the first time, that there are multiple IspH classes that have evolved to allow organisms to survive in diverse oxidative-stress environments. PMID:27357244

  15. Stochastic Demography and the Neutral Substitution Rate in Class-Structured Populations

    PubMed Central

    Lehmann, Laurent

    2014-01-01

    The neutral rate of allelic substitution is analyzed for a class-structured population subject to a stationary stochastic demographic process. The substitution rate is shown to be generally equal to the effective mutation rate, and under overlapping generations it can be expressed as the effective mutation rate in newborns when measured in units of average generation time. With uniform mutation rate across classes the substitution rate reduces to the mutation rate. PMID:24594520

  16. The lumbar extradural structure changes with increasing age.

    PubMed

    Igarashi, T; Hirabayashi, Y; Shimizu, R; Saitoh, K; Fukuda, H; Mitsuhata, H

    1997-02-01

    We have examined the extradural space using a flexible extraduroscope in 74 patients undergoing extradural anaesthesia at the L2-3 interspace. Extraduroscopy showed that the extradural space becomes widely patent and the fatty tissue in the extradural space diminishes with increasing age. We postulate that these age-related structural changes may affect the spread of local anaesthetic in the extradural space. PMID:9068330

  17. Self-reported ballet classes undertaken at age 10-12 years and hip bone mineral density in later life.

    PubMed

    Khan, K M; Bennell, K L; Hopper, J L; Flicker, L; Nowson, C A; Sherwin, A J; Crichton, K J; Harcourt, P R; Wark, J D

    1998-01-01

    The major effect of weightbearing exercise on adult bone mass may be exerted during childhood. We examined the relationship between reported hours of ballet classes per week undertaken as a child and adult bone mineral density (BMD) at the hip, spine, and forearm. We performed a retrospective cohort study in 99 female retired dancers (mean age 51 years, SD 14 years) and 99 normal controls, derived from a twin study, matched hierarchically for age, height, weight and menopausal status. Starting age of ballet was recalled and weekly hours of ballet as a child was self-reported on two occasions. BMD was measured using dualenergy X-ray absorptiometry and reported as a Z-score. Self-reported hours of ballet class undertaken per week at each age between 10 and 12 years was positively associated with a difference in BMD between dancers and controls at both the femoral neck site (beta = 0.73, p = 0.001) and the total hip site (beta = 0.55, p < 0.01). These associations were unaffected by adjustment for covariates including measures of adult activity (current physical activity, years of fulltime ballet), measures of menstrual disturbance (age of menarche, history of irregular menses), dietary history (calcium intake as a child, adolescent or adult) or lifestyle factors (lifetime smoking, lifetime alcohol). Although starting age of ballet was negatively associated with weight-adjusted within-pair hip BMD difference, it was no longer associated after adjustment for weekly hours of ballet. There was no relationship between hours of ballet undertaken as a child and differences in BMD at the lumbar spine or upper limb, at any age. Our data suggest that classical ballet classes undertaken between the ages of 10 and 12 years are independently and positively associated with a difference in hip BMD between dancers and controls. The findings are consistent with the hypothesis that this age range identifies a stage of development when the proximal femur is particularly responsive to

  18. Likelihood analysis of spatial capture-recapture models for stratified or class structured populations

    USGS Publications Warehouse

    Royle, J. Andrew; Sutherland, Christopher S.; Fuller, Angela K.; Sun, Catherine C.

    2015-01-01

    We develop a likelihood analysis framework for fitting spatial capture-recapture (SCR) models to data collected on class structured or stratified populations. Our interest is motivated by the necessity of accommodating the problem of missing observations of individual class membership. This is particularly problematic in SCR data arising from DNA analysis of scat, hair or other material, which frequently yields individual identity but fails to identify the sex. Moreover, this can represent a large fraction of the data and, given the typically small sample sizes of many capture-recapture studies based on DNA information, utilization of the data with missing sex information is necessary. We develop the class structured likelihood for the case of missing covariate values, and then we address the scaling of the likelihood so that models with and without class structured parameters can be formally compared regardless of missing values. We apply our class structured model to black bear data collected in New York in which sex could be determined for only 62 of 169 uniquely identified individuals. The models containing sex-specificity of both the intercept of the SCR encounter probability model and the distance coefficient, and including a behavioral response are strongly favored by log-likelihood. Estimated population sex ratio is strongly influenced by sex structure in model parameters illustrating the importance of rigorous modeling of sex differences in capture-recapture models.

  19. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca

    While in external or high-redshift galaxies we can only measure integrated stellar properties at best, the Milky Way offers us the unique opportunity to study its individual baryonic components, including stars. We use oscillations measured in red giant stars by the Kepler satellite to derive stellar ages and explore the vertical age structure across few kpc of the Milky Way disc. We find that old stars dominate at increasing Galactic heights, whereas closer to the plane a rich zoology of ages exists. The age distribution of stars shows a smooth distribution over the last 10 Gyr, which together with a flat age-metallicity relation is consistent with a quiescent evolution for the Milky Way disc since a redshift of about two.

  20. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca; Silva Aguirre, Victor; Schlesinger, Katharine J.; Stello, Dennis; Huber, Daniel; Serenelli, Aldo; Schoenrich, Ralph; Asplund, Martin; Feltzing, Sofia

    2015-08-01

    While in external or high-redshift galaxies we can only measure integrated stellar properties at best, the Milky Way offers us the unique opportunity to study its individual baryonic components, including stars. We use oscillations measured in giant stars by the Kepler satellite to derive stellar ages and explore the vertical age structure across few kpc of the Milky Way disc. We find that old stars dominate at increasing Galactic heights, whereas closer to the plane a rich zoology of ages exists. The age distribution of stars shows a smooth decline over the last 10 Gyr, which together with a flat age-metallicity relation is consistent with a quiescent evolution for the Milky Way disc since a redshift of about two.

  1. Report on aging of nuclear power plant reinforced concrete structures

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  2. Structure, function and disease relevance of Omega-class glutathione transferases.

    PubMed

    Board, Philip G; Menon, Deepthi

    2016-05-01

    The Omega-class cytosolic glutathione transferases (GSTs) have distinct structural and functional attributes that allow them to perform novel roles unrelated to the functions of other GSTs. Mammalian GSTO1-1 has been found to play a previously unappreciated role in the glutathionylation cycle that is emerging as significant mechanism regulating protein function. GSTO1-1-catalyzed glutathionylation or deglutathionylation of a key signaling protein may explain the requirement for catalytically active GSTO1-1 in LPS-stimulated pro-inflammatory signaling through the TLR4 receptor. The observation that ML175 a specific GSTO1-1 inhibitor can block LPS-stimulated inflammatory signaling has opened a new avenue for the development of novel anti-inflammatory drugs that could be useful in the treatment of toxic shock and other inflammatory disorders. The role of GSTO2-2 remains unclear. As a dehydroascorbate reductase, it could contribute to the maintenance of cellular redox balance and it is interesting to note that the GSTO2 N142D polymorphism has been associated with multiple diseases including Alzheimer's disease, Parkinson's disease, familial amyotrophic lateral sclerosis, chronic obstructive pulmonary disease, age-related cataract and breast cancer. PMID:26993125

  3. Identity, Age, Proportion of Online Classes, and Success among Students in a Predominantly Online Degree Program

    ERIC Educational Resources Information Center

    Carlsen-Landy, Bev

    2012-01-01

    Most colleges and universities in the US offer at least some classes online, and a significant number of colleges and universities offer degree programs either all online or predominantly online. Many of the distance learning courses and programs emerge from traditional courses and programs; however, in the past decade we have seen the emergence…

  4. Mind-Reading Ability and Structural Connectivity Changes in Aging

    PubMed Central

    Cabinio, Monia; Rossetto, Federica; Blasi, Valeria; Savazzi, Federica; Castelli, Ilaria; Massaro, Davide; Valle, Annalisa; Nemni, Raffaello; Clerici, Mario; Marchetti, Antonella; Baglio, Francesca

    2015-01-01

    The Mind-Reading ability through the eyes is an important component of the affective Theory of Mind (ToM), which allows people to infer the other’s mental state from the eye gaze. The aim of the present study was to investigate to which extent age-associated structural brain changes impact this ability and to determine if this association is related to executive functions in elderly subjects. For this purpose, Magnetic Resonance Imaging was used to determine both gray matter and white matter (WM) areas associated with aging. The resulting areas have been included in a subsequent correlation analysis to detect the brain regions whose structure was associated with the Mind-Reading ability through the eyes, assessed with the Italian version of the “Reading the Mind in the Eyes” (RME) test, in a sample of 36 healthy subjects ranging from 24 to 79 years of age. The analysis resulted in three important findings: (1) the performance to the RME test is relatively stable across the decades 20–70 (despite a slight decrease of this ability with aging) and independent from executive functions; (2) structural brain imaging demonstrated the involvement of a great number of cortical ToM areas for the execution of the RME test: the bilateral precentral gyrus, the bilateral posterior insula, the left superior temporal gyrus and the left inferior frontal gyrus, which also showed a significant volume decrease with age; (3) an age and task-related decline in WM connectivity on left fronto-temporal portion of the brain. Our results confirm the age-related structural modifications of the brain and show that these changes have an influence on the Mind-Reading ability through the eyes. PMID:26635702

  5. Mind-Reading Ability and Structural Connectivity Changes in Aging.

    PubMed

    Cabinio, Monia; Rossetto, Federica; Blasi, Valeria; Savazzi, Federica; Castelli, Ilaria; Massaro, Davide; Valle, Annalisa; Nemni, Raffaello; Clerici, Mario; Marchetti, Antonella; Baglio, Francesca

    2015-01-01

    The Mind-Reading ability through the eyes is an important component of the affective Theory of Mind (ToM), which allows people to infer the other's mental state from the eye gaze. The aim of the present study was to investigate to which extent age-associated structural brain changes impact this ability and to determine if this association is related to executive functions in elderly subjects. For this purpose, Magnetic Resonance Imaging was used to determine both gray matter and white matter (WM) areas associated with aging. The resulting areas have been included in a subsequent correlation analysis to detect the brain regions whose structure was associated with the Mind-Reading ability through the eyes, assessed with the Italian version of the "Reading the Mind in the Eyes" (RME) test, in a sample of 36 healthy subjects ranging from 24 to 79 years of age. The analysis resulted in three important findings: (1) the performance to the RME test is relatively stable across the decades 20-70 (despite a slight decrease of this ability with aging) and independent from executive functions; (2) structural brain imaging demonstrated the involvement of a great number of cortical ToM areas for the execution of the RME test: the bilateral precentral gyrus, the bilateral posterior insula, the left superior temporal gyrus and the left inferior frontal gyrus, which also showed a significant volume decrease with age; (3) an age and task-related decline in WM connectivity on left fronto-temporal portion of the brain. Our results confirm the age-related structural modifications of the brain and show that these changes have an influence on the Mind-Reading ability through the eyes. PMID:26635702

  6. A protein structural classes prediction method based on PSI-BLAST profile.

    PubMed

    Ding, Shuyan; Yan, Shoujiang; Qi, Shuhua; Li, Yan; Yao, Yuhua

    2014-07-21

    Knowledge of protein structural classes plays an important role in understanding protein folding patterns. Prediction of protein structural class based solely on sequence data remains to be a challenging problem. In this study, we extract the long-range correlation information and linear correlation information from position-specific score matrix (PSSM). A total of 3600 features are extracted, then, 278 features are selected by a filter feature selection method based on 1189 dataset. To verify the performance of our method (named by LCC-PSSM), jackknife tests are performed on three widely used low similarity benchmark datasets. Comparison of our results with the existing methods shows that our method provides the favorable performance for protein structural class prediction. Stand-alone version of the proposed method (LCC-PSSM) is written in MATLAB language and it can be downloaded from http://bioinfo.zstu.edu.cn/LCC-PSSM/. PMID:24607742

  7. 1 Protein Methyltransferases: Their Distribution Among the Five Structural Classes of AdoMet-Dependent Methyltransferases.

    PubMed

    Schubert, Heidi L; Blumenthal, Robert M; Cheng, Xiaodong

    2006-01-01

    S-adenosyl-l-methionine (AdoMet) dependent methyltransferases (MTases) are involved in biosynthesis, signal transduction, protein repair, chromatin regulation, and gene silencing. Five different structural folds (designated I through V) have been described that bind AdoMet and catalyze methyltransfer to diverse substrates, although the great majority of known MTases have the Class I fold. Even within a particular MTase class the amino-acid sequence similarity can be as low as 10%. Thus, the structural and catalytic requirements for methyltransfer from AdoMet appear to be remarkably flexible. MTases that act on protein substrates have been found to date among three of the five structural classes (I, the classical fold; III, the corrin MTase fold; and V, the SET fold). "There are many paths to the top of the mountain, but the view is always the same."-Chinese proverb The Columbia World of Quotations, New York, Columbia University Press, 1996. PMID:26718035

  8. Investigation of olefinic structures in class I resinites by isolation and characterization of soluble polylabdanoids

    SciTech Connect

    Clifford, D.J.; Botto, R.E.; Anderson, K.B.

    1996-10-01

    Resinites derived from labdatriene structures (Class I) are ubiquitous throughout the geosphere. A soluble polylabdanoid material has been isolated by sequential extraction with organic solvents. Solid- and liquid-state NMR spectroscopy, and Py-GC-MS, indicate that at least for immature resinites, the extractable polymer is representative of the insoluble, polylabdanoid material, which constitutes the bulk of most Class I resinites. With increasing maturity, the dominant chemical transformation that occurs in these materials is the {open_quotes}loss{close_quotes} of exomethylene structures and depletion of olefinic character from {approximately}two to {approximately}one olefin per monomer unit. To investigate the fate of olefinic structures and to determine the nature of the residual olefin distribution in these materials, two-dimensional NMR correlation spectroscopies (COSY and HMQC) and nuclear Overhauser experiments (NOESY) have been undertaken. Results from these analyses and their implications to the maturation of Class-I resinites will be discussed.

  9. HIV Structural Database using Chem BLAST for all classes of AIDS inhibitors

    National Institute of Standards and Technology Data Gateway

    SRD 155 HIV Structural Database using Chem BLAST for all classes of AIDS inhibitors (Web, free access)   The HIV structural database (HIVSDB) is a comprehensive collection of the structures of HIV protease, both of unliganded enzyme and of its inhibitor complexes. It contains abstracts and crystallographic data such as inhibitor and protein coordinates for 248 data sets, of which only 141 are from the Protein Data Bank (PDB).

  10. Seismic-fragility tests of new and accelerated-aged Class 1E battery cells

    SciTech Connect

    Bonzon, L.L.; Janis, W.J.; Black, D.A.; Paulsen, G.A.

    1987-01-01

    The seismic-fragility response of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the potential survivability of a battery given a seismic event. Prior reports in this series discussed the seismic-fragility tests and results for three specific naturally-aged cell types: 12-year old NCX-2250, 10-year old LCU-13, and 10-year old FHC-19. This report focuses on the complementary approach, namely, the seismic-fragility response of accelerated-aged batteries. Of particular interest is the degree to which such approaches accurately reproduce the actual failure modes and thresholds. In these tests the significant aging effects observed, in terms of seismic survivability, were: embrittlement of cell cases, positive bus material and positive plate grids; and excessive sulphation of positive plate active material causing hardening and expansion of positive plates. The IEEE Standard 535 accelerated aging method successfully reproduced seismically significant aging effects in new cells but accelerated grid embrittlement an estimated five years beyond the conditional age of other components.

  11. The impact of aging on gray matter structural covariance networks.

    PubMed

    Montembeault, Maxime; Joubert, Sven; Doyon, Julien; Carrier, Julie; Gagnon, Jean-François; Monchi, Oury; Lungu, Ovidiu; Belleville, Sylvie; Brambati, Simona Maria

    2012-11-01

    Previous anatomical volumetric studies have shown that healthy aging is associated with gray matter tissue loss in specific cerebral regions. However, these studies may have potentially missed critical elements of age-related brain changes, which largely exist within interrelationships among brain regions. This magnetic resonance imaging research aims to assess the effects of aging on the organization of gray matter structural covariance networks. Here, we used voxel-based morphometry on high-definition brain scans to compare the patterns of gray matter structural covariance networks that sustain different sensorimotor and high-order cognitive functions among young (n=88, mean age=23.5±3.1 years, female/male=55/33) and older (n=88, mean age=67.3±5.9 years, female/male=55/33) participants. This approach relies on the assumption that functionally correlated brain regions show correlations in gray matter volume as a result of mutually trophic influences or common experience-related plasticity. We found reduced structural association in older adults compared with younger adults, specifically in high-order cognitive networks. Major differences were observed in the structural covariance networks that subserve the following: a) the language-related semantic network, b) the executive control network, and c) the default-mode network. Moreover, these cognitive functions are typically altered in the older population. Our results indicate that healthy aging alters the structural organization of cognitive networks, shifting from a more distributed (in young adulthood) to a more localized topological organization in older individuals. PMID:22776455

  12. The relation between overweight and subjective health according to age, social class, slimming behavior and smoking habits in Dutch adults.

    PubMed Central

    Seidell, J C; Bakx, K C; Deurenberg, P; Burema, J; Hautvast, J G; Huygen, F J

    1986-01-01

    Subjective health status was assessed in relation to overweight by administering a list of 51 health complaints to adult men and women who were either chronically overweight as defined by Body Mass Index (BMI) or not overweight, in a continuous morbidity registration in four general practices during the period 1967-83. Responses were received from 455 men (182 overweight) and 790 women (386 overweight), ages 26-66 years. Response rate (71 per cent) and age distribution (mean age 48) were similar in overweight and non-overweight groups of both sexes. BMI was correlated with the total number of complaints in women (r = 0.15) but not in men (r = 0.07). Multiple regression analysis revealed, however, that age was an effect modifier in this relation, there being a negative association between BMI and subjective health in younger men and a positive association in older men, whereas in women the association between BMI and subjective health was much more pronounced at younger ages than at older ages. In addition, current smoking habits and social class (in men and women) and reported slimming behavior (in women) had an independent relation to the total number of health complaints. BMI was also related to specific complaints and groups of complaints, particularly in women. PMID:3777287

  13. Structural brain changes in aging: courses, causes and cognitive consequences.

    PubMed

    Fjell, Anders M; Walhovd, Kristine B

    2010-01-01

    The structure of the brain is constantly changing from birth throughout the lifetime, meaning that normal aging, free from dementia, is associated with structural brain changes. This paper reviews recent evidence from magnetic resonance imaging (MRI) studies about age-related changes in the brain. The main conclusions are that (1) the brain shrinks in volume and the ventricular system expands in healthy aging. However, the pattern of changes is highly heterogeneous, with the largest changes seen in the frontal and temporal cortex, and in the putamen, thalamus, and accumbens. With modern approaches to analysis of MRI data, changes in cortical thickness and subcortical volume can be tracked over periods as short as one year, with annual reductions of between 0.5% and 1.0% in most brain areas. (2) The volumetric brain reductions in healthy aging are likely only to a minor extent related to neuronal loss. Rather, shrinkage of neurons, reductions of synaptic spines, and lower numbers of synapses probably account for the reductions in grey matter. In addition, the length of myelinated axons is greatly reduced, up to almost 50%. (3) Reductions in specific cognitive abilities--for instance processing speed, executive functions, and episodic memory--are seen in healthy aging. Such reductions are to a substantial degree mediated by neuroanatomical changes, meaning that between 25% and 100% of the differences between young and old participants in selected cognitive functions can be explained by group differences in structural brain characteristics. PMID:20879692

  14. Domain structures and molecular evolution of class I and class II major histocompatibility gene complex (MHC) products deduced from amino acid and nucleotide sequence homologies

    NASA Astrophysics Data System (ADS)

    Ohnishi, Koji

    1984-12-01

    Domain structures of class I and class II MHC products were analyzed from a viewpoint of amino acid and nucleotide sequence homologies. Alignment statistics revealed that class I (transplantation) antigen H chains consist of four mutually homologous domains, and that class II (HLA-DR) antigen β and α chains are both composed of three mutually homologous ones. The N-terminal three and two domains of class I and class II (both β and α) gene products, respectively, all of which being ˜90 residues long, were concluded to be homologous to β2-microglobulin (β2M). The membraneembedded C-terminal shorter domains of these MHC products were also found to be homologous to one another and to the third domain of class I H chains. Class I H chains were found to be more closely related to class II α chains than to class II β chains. Based on these findings, an exon duplication history from a common ancestral gene encoding a β2M-like primodial protein of one-domain-length up to the contemporary MHC products was proposed.

  15. Changes in Age Structure and Rural Community Growth.

    ERIC Educational Resources Information Center

    McGranahan, David A.

    1985-01-01

    Whatever migration patterns evolve, changes in the age structure mean that rural communities in general can expect fairly stable elementary school population, reduced high school population, slower growth in new business and employment, and continued increase in the elderly population. (JHZ)

  16. Processing of temporal fine structure as a function of age

    PubMed Central

    Grose, John H.; Mamo, Sara K.

    2010-01-01

    Objectives The purpose of this study was to determine whether the processing of temporal fine structure diminishes with age, even in the presence of relatively normal audiometric hearing. Temporal fine structure processing was assessed by measuring the discrimination of inter-aural phase differences (IPDs). The hypothesis was that IPD discrimination is more acute in middle-aged observers than in older observers but that acuity in middle-aged observers is nevertheless poorer than in young adults. Design Two experiments were undertaken. The first measured discrimination of 0-and π-radian inter-aural phases as a function of carrier frequency. The stimulus was a 5-Hz sinusoidally amplitude modulated tone where, in the signal waveform, the inter-aural phase of the carrier was inverted during alternate modulation periods. The second experiment measured IPD discrimination at fixed frequencies. The stimulus was a pair of tone pulses where, in the signal, the trailing pulse contained an IPD. A total of 39 adults with normal audiograms below 2000 Hz participated: 15 younger, 12 middle-aged, and 12 older. Results Experiment 1 showed that the highest carrier frequency at which a π-radian IPD could be discriminated from the diotic, 0-radian standard was significantly lower in middle-aged listeners than young adults, and lower still in older listeners. Experiment 2 indicated that middle-aged listeners were less sensitive to IPDs than young adults at all but the lowest frequencies tested. Older listeners, as a group, had the poorest thresholds. Conclusions These results suggest that deficits in temporal fine structure processing are evident in the pre-senescent auditory system. This adds to the accumulating evidence that deficiencies in some aspects of auditory temporal processing emerge relatively early in the aging process. It is possible that early-emerging temporal processing deficits manifest themselves in challenging speech-in-noise environments. PMID:20592614

  17. Sequence, structural and evolutionary relationships between class 2 aminoacyl-tRNA synthetases.

    PubMed Central

    Cusack, S; Härtlein, M; Leberman, R

    1991-01-01

    Class 2 aminoacyl-tRNA synthetases, which include the enzymes for alanine, aspartic acid, asparagine, glycine, histidine, lysine, phenylalanine, proline, serine and threonine, are characterised by three distinct sequence motifs 1,2 and 3 (reference 1). The structural and evolutionary relatedness of these ten enzymes are examined using alignments of primary sequences from prokaryotic and eukaryotic sources and the known three dimensional structure of seryl-tRNA synthetase from E. coli. It is shown that motif 1 forms part of the dimer interface of seryl-tRNA synthetase and motifs 2 and 3 part of the putative active site. It is further shown that the seven alpha 2 dimeric synthetases can be subdivided into class 2a (proline, threonine, histidine and serine) and class 2b (aspartic acid, asparagine and lysine), each subclass sharing several important characteristic sequence motifs in addition to those characteristic of class 2 enzymes in general. The alpha 2 beta 2 tetrameric enzymes (for glycine and phenylalanine) show certain special features in common as well as some of the class 2b motifs. In the alanyl-tRNA synthetase only motif 3 and possibly motif 2 can be identified. The sequence alignments suggest that the catalytic domain of other class 2 synthetases should resemble the antiparallel domain found in seryl-tRNA synthetase. Predictions are made about the sequence location of certain important helices and beta-strands in this domain as well as suggestions concerning which residues are important in ATP and amino acid binding. Strong homologies are found in the N-terminal extensions of class 2b synthetases and in the C-terminal extensions of class 2a synthetases suggesting that these putative tRNA binding domains have been added at a later stage in evolution to the catalytic domain. Images PMID:1852601

  18. Social Orders and Interactions among Children in Age-Mixed Classes in Primary Schools--New Perspectives from a Synthesis of Ethnographic Data

    ERIC Educational Resources Information Center

    Huf, Christina; Raggl, Andrea

    2015-01-01

    The article synthesises data from two ethnographic projects, which both explore interactions of children in age-mixed groups in primary schools. It illuminates critical perspectives on social orders and children's interactions in age-mixed classes by showing how pupils in age-mixed groups become involved in power relations and how the teacher's…

  19. Management of aging of nuclear power plant containment structures

    SciTech Connect

    Naus, D.; Oland, C.B.; Ellingwood, B.; Norris, W.E.; Graves, H.L. III

    1998-06-01

    Research addressing aging management of nuclear power plant concrete and steel containment structures is summarized. Accomplishments related to concrete containment structures include formation of a materials` property database; an aging assessment methodology to identify critical structures and degradation factors; guidelines and evaluation criteria for use in condition assessments; and a time-dependent reliability-based methodology for condition assessments and estimations of future performance. Under the steel containments and liners activity, a degradation assessment methodology has been developed, mathematical models that describe time-dependent changes in the containment due to aggressive environmental factors have been identified, and statistical data supporting the use of these models in time-dependent reliability analysis have been summarized.

  20. Social class, ethnicity and other risk factors for small for gestational age and preterm delivery in The Netherlands.

    PubMed

    Verkerk, P H; Zaadstra, B M; Reerink, J D; Herngreen, W P; Verloove-Vanhorick, S P

    1994-02-01

    Social class and ethnicity are important risk factors for small-for-gestational-age and preterm delivery in many countries. This study was performed to assess whether this is also the case in the Netherlands, a country with a high level of social security, relatively small income differences and easy access to medical care for all its inhabitants. Other risk factors that were taken into account were smoking, drinking, occupation, age and height. Information was collected by interview in the first 3 weeks of life of the mothers of 2027 (response 97%) live-born singletons born in the period from April 1988 to October 1989 in the study area. After adjustment for possible confounding factors very low social class, compared with high social class, was significantly associated with reduced birthweight (-4.0%; 95% CI, -7.4% to -0.7%), but not with preterm delivery (OR, 2.09; 95% CI, 0.67-6.48). The adjusted birthweight of Turkish infants (2.7%; 95% CI, -1.1% to 6.5%) and the adjusted birthweight of infants from Suriname or the Antilles (-1.6%; 95% CI, -5.5% to 2.1%) were not significantly different compared with infants of Dutch mothers. After adjustment, the frequency of preterm birth was lower in Turkish infants, but not significantly (OR, 0.22; 95% CI, 0.04-1.10), whereas the frequency of preterm birth in infants from Suriname or the Antilles was significantly higher (OR, 2.51; 95% CI, 1.04-6.08) compared with Dutch infants. Of the other factors the main risk factors were smoking (negatively related with birth-weight) and maternal age(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8194649

  1. Age structured dynamical model for an endangered lizard Eulamprus leuraensis

    NASA Astrophysics Data System (ADS)

    Supriatna, A. K.; Rachmadani, Q.; Ilahi, F.; Anggriani, N.; Nuraini, N.

    2014-02-01

    The Blue Mountains Water Skink, Eulamprus leuraensis, is listed as an endangered species under the IUCN Red List. This lizard species has a typical characteristic of growth with a low fecundity. It is known that the offspring quality may decline with maternal age of the parents despite they can grow rapidly from neonatal size to adult size within two to three years. It is also believed that low adult survival rates and specialization on rare and fragmented type of habitat are the main cause leading to the endangered status of the lizard. A mathematical model with age structure for Eulamprus leuraensis, taking into account the variation of survival rate in each structure and the declining of offspring quality with respect to maternal age is considered here. Stable coexistence of non-trivial equilibriumis shown. It is also shown that an endangered status is due to combination oflow reproductive output and low rates of adult survival. Further, understanding the age structure within populations can facilitate efective management of the endangered species.

  2. 49 CFR 176.172 - Structural serviceability of freight containers and vehicles carrying Class 1 (explosive...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Structural serviceability of freight containers and vehicles carrying Class 1 (explosive) materials on ships. 176.172 Section 176.172 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS...

  3. [Method of Calculating the Distance Between the Classes of the Structural Components of the Forebrain Birds].

    PubMed

    Voronov, L N; Konstantinov, V Y

    2016-01-01

    The method of calculating the distance between the classes of the structural components of the brain of birds. Compared interclass distances of glia, neurons and neuroglial complexes in the forebrain hooded crow (Corvus cornix) (a bird with a highly rational activity) and common crossbill (Loxia curvirostra) (birds with a medium level of rational activity). PMID:27263281

  4. 49 CFR 176.172 - Structural serviceability of freight containers and vehicles carrying Class 1 (explosive...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Structural serviceability of freight containers and vehicles carrying Class 1 (explosive) materials on ships. 176.172 Section 176.172 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS...

  5. A class of unsteady, three-dimensional flow structures in turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Ash, R. L.

    1981-01-01

    A restricted class of mathematically admissible, unsteady, three dimensional flows was identified which may constitute part of the structure observed in turbulent boundary layers. The development of the model and some general results are discussed. The resulting solution has characteristics which suggest how upwelling low speed flow can trigger a downward jetting of irrotational high speed fluid into the boundary layer.

  6. Measuring Quality in Kindergarten Classrooms: Structural Analysis of the Classroom Assessment Scoring System (CLASS K-3)

    ERIC Educational Resources Information Center

    Sandilos, Lia E.; DiPerna, James C.

    2014-01-01

    Research Findings: The purpose of the current study was to evaluate the structural validity of scores on a measure of global classroom quality, the Classroom Assessment Scoring System (CLASS K-3; Pianta, La Paro, & Hamre, 2008). Using observational data from a sample of 417 kindergarten classrooms from the southern and mid-Atlantic regions of…

  7. Influence of Professional Preparation and Class Structure on HIV, STD, and Pregnancy Prevention Education

    ERIC Educational Resources Information Center

    Rhodes, Darson L.; Jozkowski, Kristen N.; Hammig, Bart J.; Ogletree, Roberta J.; Fogarty, Erin C.

    2014-01-01

    Objective: The purpose of this study was to determine if education about human immunodeficiency virus (HIV)/sexually transmitted disease (STD) and pregnancy prevention is dependent on professional preparation and/or class structure. Design: A secondary data analysis of the 2006 School Health Policies and Programmes Study (SHPPS) was conducted.…

  8. Aviation Structural Mechanic, First Class, 2-12. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This self-paced, individualized course, adapted from military curriculum materials for use in vocational and technical education, teaches students the skills needed to become aviation structural mechanics (first class). The course materials consist of three pamphlets. The first pamphlet covers aircraft maintenance management, records, and reports…

  9. Age, Gender, and Class Differences in Physical Punishment and Physical Abuse of American Children.

    ERIC Educational Resources Information Center

    Wauchope, Barbara A.; Straus, Murray A.

    This study examined the relationship of the age and gender of the child, and the occupational status and gender of the parent, to the incidence and frequency of physical punishment and two levels of physical abuse of children, as measured by the minor, severe, and very severe violence indexes of the Conflict Tactics Scales. The subjects were…

  10. Sweepnet captures of Lygus hesperus (Hemiptera:Miridae) adult genders and age-classes in cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of the western tarnished plant bug, Lygus hesperus Knight, in cotton usually relies on population estimates obtained using the sweepnet. Recent studies indicated adult L. hesperus gender and physiological age influence feeding behavior, within-plant distribution, and injury to cotton. W...

  11. First in the Class? Age and the Education Production Function. NBER Working Paper No. 13663

    ERIC Educational Resources Information Center

    Cascio, Elizabeth; Schanzenbach, Diane Whitmore

    2007-01-01

    Older children outperform younger children in a school-entry cohort well into their school careers. The existing literature has provided little insight into the causes of this phenomenon, leaving open the possibility that school-entry age is zero-sum game, where relatively young students lose what relatively old students gain. In this paper, we…

  12. Stratified at Seven: In-Class Ability Grouping and the Relative Age Effect

    ERIC Educational Resources Information Center

    Campbell, Tammy

    2014-01-01

    There is an established body of evidence indicating that a pupil's relative age within their school year cohort is associated with academic attainment throughout compulsory education. In England, autumn-born pupils consistently attain at higher levels than summer-born pupils. Analysis here investigates a possible channel of this relative age…

  13. Aging of Johari-Goldstein Relaxation in Structural Glasses

    NASA Astrophysics Data System (ADS)

    Yardimci, Hasan; Leheny, Robert L.

    2006-03-01

    Using frequency-dependent dielectric susceptibility measurements we characterize the aging in two supercooled liquids, sorbitol and xylitol, below their calorimetric glass transition temperatures, Tg. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibilities of both liquids possess a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench below Tg, the susceptibility slowly approaches equilibrium behavior. For both liquids, features of the Johari-Goldstein relaxation display a dependence on the time since the quench, or aging time, that is very similar to the age dependence of the alpha peak. However, one can not assign a single fictive temperature to both the alpha and Johari-Goldstein relaxations. For example, the peak frequency of the Johari-Goldstein relaxation remains constant during aging for sorbitol while it increases with age for xylitol, inconsistent with a decreasing fictive temperature. This behavior contrasts with that of the high frequency tail of the alpha peak whose shape and position track the aging of the main part of the peak.

  14. Active-Site Structure of Class IV Adenylyl Cyclase and Transphyletic Mechanism

    SciTech Connect

    Gallagher, D.T.; Robinson, H.; Kim, S.-K.; Reddy, P. T.

    2011-01-21

    Adenylyl cyclases (ACs) belonging to three nonhomologous classes (II, III, and IV) have been structurally characterized, enabling a comparison of the mechanisms of cyclic adenosine 3',5'-monophosphate biosynthesis. We report the crystal structures of three active-site complexes for Yersinia pestis class IV AC (AC-IV)-two with substrate analogs and one with product. Mn{sup 2+} binds to all three phosphates, and to Glu12 and Glu136. Electropositive residues Lys14, Arg63, Lys76, Lys111, and Arg113 also form hydrogen bonds to phosphates. The conformation of the analogs is suitable for in-line nucleophilic attack by the ribose O3' on {alpha}-phosphate (distance {approx} 4 {angstrom}). In the product complex, a second Mn ion is observed to be coordinated to both ribose 2' oxygen and ribose 3' oxygen. Observation of both metal sites, together with kinetic measurements, provides strong support for a two-cation mechanism. Eleven active-site mutants were also made and kinetically characterized. These findings and comparisons with class II and class III enzymes enable a detailed transphyletic analysis of the AC mechanism. Consistent with its lack of coordination to purine, Y. pestis AC-IV cyclizes both ATP and GTP. As in other classes of AC, the ribose is loosely bound, and as in class III, no base appears to ionize the O3' nucleophile. Different syn/anti conformations suggest that the mechanism involves a conformational transition, and further evidence suggests a role for ribosyl pseudorotation. With resolutions of 1.6-1.7 {angstrom}, these are the most detailed active-site ligand complexes for any class of this ubiquitous signaling enzyme.

  15. Active-Site Structure of Class IV Adenylyl Cyclase and Transphyletic Mechanism

    SciTech Connect

    D Gallagher; S Kim; H Robinson; P Reddy

    2011-12-31

    Adenylyl cyclases (ACs) belonging to three nonhomologous classes (II, III, and IV) have been structurally characterized, enabling a comparison of the mechanisms of cyclic adenosine 3',5'-monophosphate biosynthesis. We report the crystal structures of three active-site complexes for Yersinia pestis class IV AC (AC-IV) - two with substrate analogs and one with product. Mn{sup 2+} binds to all three phosphates, and to Glu12 and Glu136. Electropositive residues Lys14, Arg63, Lys76, Lys111, and Arg113 also form hydrogen bonds to phosphates. The conformation of the analogs is suitable for in-line nucleophilic attack by the ribose O3' on {alpha}-phosphate (distance {approx} 4 {angstrom}). In the product complex, a second Mn ion is observed to be coordinated to both ribose 2' oxygen and ribose 3' oxygen. Observation of both metal sites, together with kinetic measurements, provides strong support for a two-cation mechanism. Eleven active-site mutants were also made and kinetically characterized. These findings and comparisons with class II and class III enzymes enable a detailed transphyletic analysis of the AC mechanism. Consistent with its lack of coordination to purine, Y. pestis AC-IV cyclizes both ATP and GTP. As in other classes of AC, the ribose is loosely bound, and as in class III, no base appears to ionize the O3' nucleophile. Different syn/anti conformations suggest that the mechanism involves a conformational transition, and further evidence suggests a role for ribosyl pseudorotation. With resolutions of 1.6-1.7 {angstrom}, these are the most detailed active-site ligand complexes for any class of this ubiquitous signaling enzyme.

  16. Ageing management of french NPP civil work structures

    NASA Astrophysics Data System (ADS)

    Gallitre, E.; Dauffer, D.

    2011-04-01

    This paper presents EDF practice about concrete structure ageing management, from the mechanisms analysis to the formal procedure which allows the French company to increase 900 MWe NPP lifetime until 40 years; it will also introduce its action plan for 60 years lifetime extension. This practice is based on a methodology which identifies every ageing mechanism; both plants feedback and state of the art are screened and conclusions are drawn up into an "ageing analysis data sheet". That leads at first to a collection of 57 data sheets which give the mechanism identification, the components that are concerned and an analysis grid which is designed to assess the safety risk. This analysis screens the reference documents describing the mechanism, the design lifetime hypotheses, the associated regulation or codification, the feedback experiences, the accessibility, the maintenance actions, the repair possibility and so one. This analysis has to lead to a conclusion about the risk taking into account monitoring and maintenance. If the data sheet conclusion is not clear enough, then a more detailed report is launched. The technical document which is needed, is a formal detailed report which summarizes every theoretical knowledge and monitoring data: its objective is to propose a solution for ageing management: this solution can include more inspections or specific research development, or additional maintenance. After a first stage on the 900 MWe units, only two generic ageing management detailed reports have been needed for the civil engineering part: one about reactor building containment, and one about other structures which focuses on concrete inflating reactions. The second stage consists on deriving this generic analysis (ageing mechanism and detailed reports) to every plant where a complete ageing report is required (one report for all equipments and structures of the plant, but specific for each reactor). This ageing management is a continuous process because the

  17. Inhibitory Control Efficiency in a Piaget-Like Class-Inclusion Task in School-Age Children and Adults: A Developmental Negative Priming Study

    ERIC Educational Resources Information Center

    Borst, G.; Poirel, N.; Pineau, A.; Cassotti, M.; Houdé, O.

    2013-01-01

    Most children under 7 years of age presented with 10 daisies and 2 roses fail to indicate that there are more flowers than daisies. Instead of the appropriate comparison of the relative numerosities of the superordinate class (flowers) to its subordinate class (daisies), they perform a direct perceptual comparison of the extensions of the 2…

  18. Novel structural class of four disulfide-bridged peptides from Tityus serrulatus venom.

    PubMed

    Pimenta, Adriano M C; Legros, Christian; Almeida, Flávia de Marco; Mansuelle, Pascal; De Lima, Maria Elena; Bougis, Pierre E; Martin-Eauclaire, Marie France

    2003-02-21

    A new structural class of short peptides folded by four disulfide-bridges was found in the venom of the Brazilian scorpion Tityus serrulatus. Peptides were put on evidence independently by means of two different approaches of structurally guided prospection. First, a cDNA sequence was obtained using a degenerate primer constructed according to the C-terminal sequence of kaliotoxin (KTx2), from the Androctonus australis venom. Second, MALDI-TOF mass spectrometry analyses of toxic fraction FIII from T. serrulatus venom revealed a family of molecules ranging approximately from 2900 to 3000 Da. Three new peptides were isolated and named TsPep1, TsPep2, and TsPep3. Biochemical characterization showed that they are 29 amino acids long, constrained by a new pattern of four disulfide-bridges. These results enable us to classify these new molecules as part of a novel structural class of short peptides from scorpion venoms. PMID:12589824

  19. Length-independent structural similarities enrich the antibody CDR canonical class model.

    PubMed

    Nowak, Jaroslaw; Baker, Terry; Georges, Guy; Kelm, Sebastian; Klostermann, Stefan; Shi, Jiye; Sridharan, Sudharsan; Deane, Charlotte M

    2016-01-01

    Complementarity-determining regions (CDRs) are antibody loops that make up the antigen binding site. Here, we show that all CDR types have structurally similar loops of different lengths. Based on these findings, we created length-independent canonical classes for the non-H3 CDRs. Our length variable structural clusters show strong sequence patterns suggesting either that they evolved from the same original structure or result from some form of convergence. We find that our length-independent method not only clusters a larger number of CDRs, but also predicts canonical class from sequence better than the standard length-dependent approach. To demonstrate the usefulness of our findings, we predicted cluster membership of CDR-L3 sequences from 3 next-generation sequencing datasets of the antibody repertoire (over 1,000,000 sequences). Using the length-independent clusters, we can structurally classify an additional 135,000 sequences, which represents a ∼20% improvement over the standard approach. This suggests that our length-independent canonical classes might be a highly prevalent feature of antibody space, and could substantially improve our ability to accurately predict the structure of novel CDRs identified by next-generation sequencing. PMID:26963563

  20. Length-independent structural similarities enrich the antibody CDR canonical class model

    PubMed Central

    Nowak, Jaroslaw; Baker, Terry; Georges, Guy; Kelm, Sebastian; Klostermann, Stefan; Shi, Jiye; Sridharan, Sudharsan; Deane, Charlotte M.

    2016-01-01

    ABSTRACT Complementarity-determining regions (CDRs) are antibody loops that make up the antigen binding site. Here, we show that all CDR types have structurally similar loops of different lengths. Based on these findings, we created length-independent canonical classes for the non-H3 CDRs. Our length variable structural clusters show strong sequence patterns suggesting either that they evolved from the same original structure or result from some form of convergence. We find that our length-independent method not only clusters a larger number of CDRs, but also predicts canonical class from sequence better than the standard length-dependent approach. To demonstrate the usefulness of our findings, we predicted cluster membership of CDR-L3 sequences from 3 next-generation sequencing datasets of the antibody repertoire (over 1,000,000 sequences). Using the length-independent clusters, we can structurally classify an additional 135,000 sequences, which represents a ∼20% improvement over the standard approach. This suggests that our length-independent canonical classes might be a highly prevalent feature of antibody space, and could substantially improve our ability to accurately predict the structure of novel CDRs identified by next-generation sequencing. PMID:26963563

  1. [Esophageal wall structure in people of elderly and senile age].

    PubMed

    aminova, G G; Grigorenko, D E; Sapin, M R; Mkhitarov, V A

    2014-01-01

    Using histological methods, the esophageal wall structure and the cytoarchitectonics of mucous membrane were studied in the individuals of elderly (n = 5) and senile (n = 10) age. The control group included the individuals of I (n = 3) and II (n = 3) periods of mature age. It was demonstrated that with advancing age in most cases the destructive processes took place in the epithelium (delamination of the layer, separation of large fragments, formation of microerosions etc.) in most of the studied cases. Lymphocytes, neutrophils and eosinophils were found between the epithelial cells; the numbers of infiltrating cells was increased 2-3 times during aging. Mucosal lamina propria and the submucosa, in particular, were characterized by the thickening of the bundles of collagen fibers. A two-fold increase in the number of the cells of the fibroblast lineage was found. The number of leukocytes in the lamina propria was increased by the eldery age in the upper and lower parts of the esophagus (3.5 and 1.75 times respectively). The changes in lamina muscularis were manifested by its thinning, delamination and myocyte dissociation. Remodeling of the muscular tunic was less pronounced. The degree of changes increased distally and varied widely depending on the individual peculiarities. PMID:25282822

  2. The Umm Al Binni Structure and Bronze Age Catastrophes

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.

    Archaeological excavations of sites dating from 2200 BCE and 1200 BCE in the Middle East, Asia Minor, and southeast Europe provide evidence that a large scale disaster affected Bronze Age civilizations. There are numerous debates as to whether this was caused by warfare, a large-scale natural disaster, or some other factor. In 2001, Sharad Master used satellite images to discover a possible Holocene impact structure in the Al 'Amarah marshes of southern Iraq, known as Umm al Binni lake. With an estimated age of < 5000 years and a diameter of ~3.4 km, this structure may help explain this disaster. Using numerical models and scaling equations for a cosmic impact, I show that although destructive forces would have damaged Sumerian cities within a few hundred km of the coast, it is unlikely that this single impact would have caused the large-scale destruction seen over the larger region. The impact origin of the structure is unconfirmed and any connection to Bronze Age catastrophes remains speculative. Errata: Table 4 provides a list of impact sites, three of which are associated with nickel-iron impactors and therefore cannot be from a "fragmented comet".

  3. Universality class of the structural phase transition in the normal phase of cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Najafi, M. N.; Tavana, A.

    2016-08-01

    The tetragonal-orthorhombic structural phase transition of oxygen atoms in the basal plane of YBa2Cu3O6 +δ high-TC cuprate superconductors is studied numerically. By mapping the system onto the asymmetric next-nearest-neighbor Ising model, we characterize this phase transition. Results indicate the degrees of critical behavior. We show that this phase transition occurs at the temperature TC≃0.148 eV in the thermodynamic limit. By analyzing the critical exponents, it is found that this universality class displays some common features, with the two-dimensional three-state Potts model universality class, although the possibility of other universality classes cannot be ruled out. Conformal invariance at T =Tc is investigated using the Schramm-Loewner evolution (SLE) technique, and it is found that the SLE diffusivity parameter for this system is 3.34 ±0.01 .

  4. Structural basis of the inhibition of class C acid phosphatases by adenosine 5;#8242;-phosphorothioate

    SciTech Connect

    Singh, Harkewal; Reilly, Thomas J.; Tanner, John J.

    2012-01-20

    The inhibition of phosphatases by adenosine 5'-phosphorothioate (AMPS) was first reported in the late 1960s; however, the structural basis for the inhibition has remained unknown. Here, it is shown that AMPS is a submicromolar inhibitor of class C acid phosphatases, a group of bacterial outer membrane enzymes belonging to the haloacid dehalogenase structural superfamily. Furthermore, the 1.35-{angstrom} resolution crystal structure of the inhibited recombinant Haemophilus influenzae class C acid phosphatase was determined; this is the first structure of a phosphatase complexed with AMPS. The conformation of AMPS is identical to that of the substrate 5'-AMP, except that steric factors force a rotation of the thiophosphoryl out of the normal phosphoryl-binding pocket. This conformation is catalytically nonproductive, because the P atom is not positioned optimally for nucleophilic attack by Asp64, and the O atom of the scissile O-P bond is too far from the Asp (Asp66) that protonates the leaving group. The structure of 5'-AMP complexed with the Asp64 {yields} Asn mutant enzyme was also determined at 1.35-{angstrom} resolution. This mutation induces the substrate to adopt the same nonproductive binding mode that is observed in the AMPS complex. In this case, electrostatic considerations, rather than steric factors, underlie the movement of the phosphoryl. The structures not only provide an explanation for the inhibition by AMPS, but also highlight the precise steric and electrostatic requirements of phosphoryl recognition by class C acid phosphatases. Moreover, the structure of the Asp64 {yields} Asn mutant illustrates how a seemingly innocuous mutation can cause an unexpected structural change.

  5. Predicting protein structural classes based on complex networks and recurrence analysis.

    PubMed

    Olyaee, Mohammad H; Yaghoubi, Ali; Yaghoobi, Mahdi

    2016-09-01

    Protein sequences are divided into four structural classes. The determination of class is a challenging and beneficial task in the bioinformatics field. Several methods have been proposed to this end, but most utilize too many features and produce unsuitable results. In the present, features are extracted based on the predicted secondary structures. At first, predicted secondary structure sequences are mapped into two time series by the chaos game representation. Then, a recurrence matrix is calculated from each of the time series. The recurrence matrix is identified with the adjacency matrix of a complex network and measures are applied for the characterization of complex networks to these recurrence matrixes. For a given protein sequence, a total of 24 characteristic features can be calculated and these are fed into Fisher's discriminated analysis algorithm for classification. To examine the proposed method, two widely used low similarity benchmark datasets design and test its performance. A comparison with the results of existing methods shows that the current study's approach provides a satisfactory performance for protein structural class prediction. PMID:27320678

  6. Paleomagnetic Age for the World-class Century Zn-Pb-Ag Deposit, Australia

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Symons, D. T.; Dawborn, T.

    2009-05-01

    Paleomagnetic results are reported for the Century Zn-Pb-Ag SEDEX deposit in northwestern Queensland, Australia. The stratiform mineralization occurs in fine parallel lamellae in ˜1595 Ma siderite-rich siltstones and black shales of the upper Lawn Hill Formation in the Proterozoic McNamara Group. Galena from the deposit has given a Pb/Pb model age of ˜1575 Ma. Paleomagnetic analysis of 333 specimens from ore zones (15 sites), and hanging wall (4 sites) and footwall (5 sites) siltstones using mostly thermal and then alternating field step demagnetization, isolates a stable characteristic remanent magnetization (ChRM) for the ore sites only. Step demagnetization, rock magnetic tests and thermomagnetic analyses of ore, Zn and Pb concentrates and tailings show that the main remanence carriers are single- or pseudosingle-domain inclusions of titanomagnetite in sphalerite and gangue, and pyrrhotite in galena with modern goethite and/or hematite from the weathering of siderite. A paleomagnetic fold test using the ore sites is positive, showing that the ore ChRM predates D2 deformation in the ˜1595 to ˜1500 Ma Isan orogeny. The orogeny folded the main-stage mineralization, indicating that the ore retains a primary magnetization. The optimum 80% tilt-corrected unit mean ChRM direction for the ore gives a Mesoproterozoic paleopole at ˜1560 Ma on the northern Australian apparent polar wander path. Thus this result both constrains the timing of mineralization and provides an upper age limit for D2 deformation in the orogeny.

  7. Structure of the Class IV Adenylyl Cyclase Reveals a Novel Fold

    SciTech Connect

    Gallagher,D.; Smith, N.; Kim, S.; Heroux, A.; Robinson, H.; Reddy, P.

    2006-01-01

    The crystal structure of the class IV adenylyl cyclase (AC) from Yersinia pestis (Yp) is reported at 1.9 {angstrom} resolution. The class IV AC fold is distinct from the previously described folds for class II and class III ACs. The dimeric AC-IV folds into an antiparallel eight-stranded barrel whose connectivity has been seen in only three previous structures: yeast RNA triphosphatase and two proteins of unknown function from Pyrococcus furiosus and Vibrio parahaemolyticus. Eight highly conserved ionic residues E10, E12, K14, R63, K76, K111, D126, and E136 lie in the barrel core and form the likely binding sites for substrate and divalent cations. A phosphate ion is observed bound to R63, K76, K111, and R113 near the center of the conserved cluster. Unlike the AC-II and AC-III active sites that utilize two-Asp motifs for cation binding, the AC-IV active site is relatively enriched in glutamate and features an ExE motif as its most conserved element. Homologs of Y. pestis AC-IV, including human thiamine triphosphatase, span the three kingdoms of life and delineate an ancient family of phosphonucleotide processing enzymes.

  8. Multiple plumage traits convey information about age and within-age-class qualities of a canopy-dwelling songbird, the Cerulean Warbler

    USGS Publications Warehouse

    Boves, Than J.; Buehler, David A.; Wood, Petra Bohall; Rodewald, Amanda D.; Larkin, Jeffrey L.; Keyser, Patrick D.; Wigley, T. Ben

    2014-01-01

    Colorful plumage traits in birds may convey multiple, redundant, or unreliable messages about an individual. Plumage may reliably convey information about disparate qualities such as age, condition, and parental ability because discrete tracts of feathers may cause individuals to incur different intrinsic or extrinsic costs. Few studies have examined the information content of plumage in a species that inhabits forest canopies, a habitat with unique light environments and selective pressures. We investigated the information content of four plumage patches (blue-green crown and rump, tail white, and black breast band) in a canopy-dwelling species, the Cerulean Warbler (Setophaga cerulea), in relation to age, condition, provisioning, and reproduction. We found that older males displayed wider breast bands, greater tail white, and crown and rump feathers with greater blue-green (435–534 nm) chroma and hue than males in their first potential breeding season. In turn, older birds were in better condition (short and long term) and were reproductively superior to younger birds. We propose that these age-related plumage differences (i.e. delayed plumage maturation) were not a consequence of a life history strategy but instead resulted from constraints during early feather molts. Within age classes, we found evidence to support the multiple messages hypothesis. Birds with greater tail white molted tails in faster, those with more exaggerated rump plumage (lower hue, greater blue-green chroma) provisioned more, and those with lower rump blue-green chroma were in better condition. Despite evidence of reliable signaling in this species, we found no strong relationships between plumage and reproductive performance, potentially because factors other than individual differences more strongly influenced fecundity.

  9. Complex structure of a bacterial class 2 histone deacetylase homologue with a trifluoromethylketone inhibitor

    SciTech Connect

    Nielsen, Tine Kragh; Hildmann, Christian; Riester, Daniel; Wegener, Dennis; Schwienhorst, Andreas; Ficner, Ralf

    2007-04-01

    The crystal structure of HDAH FB188 in complex with a trifluoromethylketone at 2.2 Å resolution is reported and compared to a previously determined inhibitor complex. Histone deacetylases (HDACs) have emerged as attractive targets in anticancer drug development. To date, a number of HDAC inhibitors have been developed and most of them are hydroxamic acid derivatives, typified by suberoylanilide hydroxamic acid (SAHA). Not surprisingly, structural information that can greatly enhance the design of novel HDAC inhibitors is so far only available for hydroxamic acids in complex with HDAC or HDAC-like enzymes. Here, the first structure of an enzyme complex with a nonhydroxamate HDAC inhibitor is presented. The structure of the trifluoromethyl ketone inhibitor 9,9,9-trifluoro-8-oxo-N-phenylnonanamide in complex with bacterial FB188 HDAH (histone deacetylase-like amidohydrolase from Bordetella/Alcaligenes strain FB188) has been determined. HDAH reveals high sequential and functional homology to human class 2 HDACs and a high structural homology to human class 1 HDACs. Comparison with the structure of HDAH in complex with SAHA reveals that the two inhibitors superimpose well. However, significant differences in binding to the active site of HDAH were observed. In the presented structure the O atom of the trifluoromethyl ketone moiety is within binding distance of the Zn atom of the enzyme and the F atoms participate in interactions with the enzyme, thereby involving more amino acids in enzyme–inhibitor binding.

  10. Estimating survival of precocial chicks during the prefledging period using a catch-curve analysis and count-based age-class data

    USGS Publications Warehouse

    McGowan, C.P.; Millspaugh, J.J.; Ryan, M.R.; Kruse, C.D.; Pavelka, G.

    2009-01-01

    Estimating reproductive success for birds with precocial young can be difficult because chicks leave nests soon after hatching and individuals or broods can be difficult to track. Researchers often turn to estimating survival during the prefledging period and, though effective, mark-recapture based approaches are not always feasible due to cost, time, and animal welfare concerns. Using a threatened population of Piping Plovers (Charadrius melodus) that breeds along the Missouri River, we present an approach for estimating chick survival during the prefledging period using long-term (1993-2005), count-based, age-class data. We used a modified catch-curve analysis, and data collected during three 5-day sampling periods near the middle of the breeding season. The approach has several ecological and statistical assumptions and our analyses were designed to minimize the probability of violating those assumptions. For example, limiting the sampling periods to only 5 days gave reasonable assurance that population size was stable during the sampling period. Annual daily survival estimates ranged from 0.825 (SD = 0.03) to 0.931 (0.02) depending on year and sampling period, with these estimates assuming constant survival during the prefledging period and no change in the age structure of the population. The average probability of survival to fledging ranged from 0.126 to 0.188. Our results are similar to other published estimates for this species in similar habitats. This method of estimating chick survival may be useful for a variety of precocial bird species when mark-recapture methods are not feasible and only count-based age class data are available. ?? 2009 Association of Field Ornithologists.

  11. Towards universal structure-based prediction of class II MHC epitopes for diverse allotypes.

    PubMed

    Bordner, Andrew J

    2010-01-01

    The binding of peptide fragments of antigens to class II MHC proteins is a crucial step in initiating a helper T cell immune response. The discovery of these peptide epitopes is important for understanding the normal immune response and its misregulation in autoimmunity and allergies and also for vaccine design. In spite of their biomedical importance, the high diversity of class II MHC proteins combined with the large number of possible peptide sequences make comprehensive experimental determination of epitopes for all MHC allotypes infeasible. Computational methods can address this need by predicting epitopes for a particular MHC allotype. We present a structure-based method for predicting class II epitopes that combines molecular mechanics docking of a fully flexible peptide into the MHC binding cleft followed by binding affinity prediction using a machine learning classifier trained on interaction energy components calculated from the docking solution. Although the primary advantage of structure-based prediction methods over the commonly employed sequence-based methods is their applicability to essentially any MHC allotype, this has not yet been convincingly demonstrated. In order to test the transferability of the prediction method to different MHC proteins, we trained the scoring method on binding data for DRB1*0101 and used it to make predictions for multiple MHC allotypes with distinct peptide binding specificities including representatives from the other human class II MHC loci, HLA-DP and HLA-DQ, as well as for two murine allotypes. The results showed that the prediction method was able to achieve significant discrimination between epitope and non-epitope peptides for all MHC allotypes examined, based on AUC values in the range 0.632-0.821. We also discuss how accounting for peptide binding in multiple registers to class II MHC largely explains the systematically worse performance of prediction methods for class II MHC compared with those for class I MHC

  12. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-03-08

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (NM) impedance technique are sighted and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency EIM impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acoustic-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  13. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-02-29

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  14. Active sensors for health monitoring of aging aerospace structures

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Redmond, James M.; Roach, Dennis P.; Rackow, Kirk

    2000-06-01

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto- ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  15. Structural class prediction of protein using novel feature extraction method from chaos game representation of predicted secondary structure.

    PubMed

    Zhang, Lichao; Kong, Liang; Han, Xiaodong; Lv, Jinfeng

    2016-07-01

    Protein structural class prediction plays an important role in protein structure and function analysis, drug design and many other biological applications. Extracting good representation from protein sequence is fundamental for this prediction task. In recent years, although several secondary structure based feature extraction strategies have been specially proposed for low-similarity protein sequences, the prediction accuracy still remains limited. To explore the potential of secondary structure information, this study proposed a novel feature extraction method from the chaos game representation of predicted secondary structure to mainly capture sequence order information and secondary structure segments distribution information in a given protein sequence. Several kinds of prediction accuracies obtained by the jackknife test are reported on three widely used low-similarity benchmark datasets (25PDB, 1189 and 640). Compared with the state-of-the-art prediction methods, the proposed method achieves the highest overall accuracies on all the three datasets. The experimental results confirm that the proposed feature extraction method is effective for accurate prediction of protein structural class. Moreover, it is anticipated that the proposed method could be extended to other graphical representations of protein sequence and be helpful in future research. PMID:27084358

  16. Two Classes of Bacterial IMPDHs according to Their Quaternary Structures and Catalytic Properties

    PubMed Central

    Alexandre, Thomas; Rayna, Bertrand; Munier-Lehmann, Hélène

    2015-01-01

    Inosine-5′-monophosphate dehydrogenase (IMPDH) occupies a key position in purine nucleotide metabolism. In this study, we have performed the biochemical and physico-chemical characterization of eight bacterial IMPDHs, among which six were totally unexplored. This study led to a classification of bacterial IMPDHs according to the regulation of their catalytic properties and their quaternary structures. Class I IMPDHs are cooperative enzymes for IMP, which are activated by MgATP and are octameric in all tested conditions. On the other hand, class II IMPDHs behave as Michaelis-Menten enzymes for both substrates and are tetramers in their apo state or in the presence of IMP, which are shifted to octamers in the presence of NAD or MgATP. Our work provides new insights into the IMPDH functional regulation and a model for the quaternary structure modulation is proposed. PMID:25706619

  17. Harnessing heredity in Gilded Age America: middle class mores and industrial breeding in a cultural context.

    PubMed

    Thurtle, Phillip

    2002-01-01

    By investigating the practices and beliefs of Gilded Age trotting horse breeders, this article demonstrates the relationship between industrial economic development and the growth of genetic reasoning in the United States. As most historians of biology already know, E. H. Harriman, Leland Stanford, and John D. Rockefeller not only transformed American business practice, they donated heavily to institutions that promoted eugenic research programs. What is not widely known, however, is that these same industrialists were accomplished trotting horse breeders with well-developed theories of inheritance. The article that follows uses these theories to place the rise of eugenic and genetic research into the context of the rapid development of industry in post Civil War America. Specifically, the study identifies how functional utility as defined through the narrow concerns of industrial practices were privileged over form and pedigree in American horse breeding. Even more importantly, this article suggests that the continuity established between the practices of the industrial philanthropists and the scientific research institutions that they established occurred at two levels: through the values privileged by the development of the dynamics of a mass society and through the tools used to process the large amounts of information necessary to understand breeding patterns in slow breeding organisms. PMID:12068894

  18. Implications of a class of grand unified theories for large scale structure in the universe

    NASA Technical Reports Server (NTRS)

    Shafi, Q.; Stecker, F. W.

    1983-01-01

    A class of grand unified theories in which cosmologicaly significant axion and neutrino energy densities arise naturally is discussed. To obtain large scale structure three scenarios are considered: (1) an inflationary scenario; (2) inflation followed by string production; and (3) a non-inflationary scenario with density fluctuations caused solely by strings. Inflation may be compatible with the recent observational indications that mega 1 on the scale of superclusters, particularly if strings are present.

  19. Improving protein fold recognition and structural class prediction accuracies using physicochemical properties of amino acids.

    PubMed

    Raicar, Gaurav; Saini, Harsh; Dehzangi, Abdollah; Lal, Sunil; Sharma, Alok

    2016-08-01

    Predicting the three-dimensional (3-D) structure of a protein is an important task in the field of bioinformatics and biological sciences. However, directly predicting the 3-D structure from the primary structure is hard to achieve. Therefore, predicting the fold or structural class of a protein sequence is generally used as an intermediate step in determining the protein's 3-D structure. For protein fold recognition (PFR) and structural class prediction (SCP), two steps are required - feature extraction step and classification step. Feature extraction techniques generally utilize syntactical-based information, evolutionary-based information and physicochemical-based information to extract features. In this study, we explore the importance of utilizing the physicochemical properties of amino acids for improving PFR and SCP accuracies. For this, we propose a Forward Consecutive Search (FCS) scheme which aims to strategically select physicochemical attributes that will supplement the existing feature extraction techniques for PFR and SCP. An exhaustive search is conducted on all the existing 544 physicochemical attributes using the proposed FCS scheme and a subset of physicochemical attributes is identified. Features extracted from these selected attributes are then combined with existing syntactical-based and evolutionary-based features, to show an improvement in the recognition and prediction performance on benchmark datasets. PMID:27164998

  20. Verb production in agrammatic aphasia: The influence of semantic class and argument structure properties on generalisation

    PubMed Central

    Schneider, Sandra L.; Thompson, Cynthia K.

    2011-01-01

    Background Some individuals with agrammatic aphasia have difficulty producing verbs when naming and generating sentences (Miceli, Silveri, Villa, & Caramazza, 1984; Saffran, Schwartz, & Marin, 1980; Zingeser & Berndt, 1990). And when verbs are produced there is an over-reliance on verbs requiring simple argument structure arrangements (Thompson, Lange, Schneider, & Shapiro, 1997; Thompson, Shapiro, Schneider, & Tait, 1994). Verbs, as argument-taking elements, show especially complex semantic and argument structure properties. This study investigated the role these properties have on verb production in individuals with agrammatic aphasia. Aim This treatment study examined the extent to which semantic class and argument structure properties of verbs influenced the ability of seven individuals with agrammatic Broca’s aphasia to retrieve verbs and then use them in correct sentence production. Verbs from two semantic classes and two argument structure categories were trained using either a semantic or an argument structure verb retrieval treatment. Specifically, acquisition and generalisation to trained and untrained verbs within and across semantic and argument structure categories was examined. In addition, the influence of verb production on each participant’s sentence production was also examined. Methods & Procedures Utilising a single-subject crossover design in combination with a multiple baseline design across subjects and behaviours, seven individuals with agrammatic aphasia were trained to retrieve verbs with specific argument structures from two semantic classes under two treatment conditions—semantic verb retrieval treatment and verb argument structure retrieval treatment. Treatment was provided on two-place and three-place motion or change of state verbs, counterbalanced across subjects and behaviours. A total of 102 verbs, depicted in black and white drawings, were utilised in the study, divided equally into motion and change of state verbs (semantic

  1. Age structure and cooperation in coevolutionary games on dynamic network

    NASA Astrophysics Data System (ADS)

    Qin, Zilong; Hu, Zhenhua; Zhou, Xiaoping; Yi, Jingzhang

    2015-04-01

    Our proposed model imitates the growth of a population and describes the age structure and the level of cooperation in games on dynamic network with continuous changes of structure and topology. The removal of nodes and links caused by age-dependent attack, together with the nodes addition standing for the newborns of population, badly ruins Matthew effect in this coevolutionary process. Though the network is generated by growth and preferential attachment, it degenerates into random network and it is no longer heterogeneous. When the removal of nodes and links is equal to the addition of nodes and links, the size of dynamic network is maintained in steady-state, so is the low level of cooperation. Severe structure variation, homogeneous topology and continuous invasion of new defection jointly make dynamic network unsuitable for the survival of cooperator even when the probability with which the newborn players initially adopt the strategy cooperation is high, while things change slightly when the connections of newborn players are restricted. Fortunately, moderate interactions in a generation trigger an optimal recovering process to encourage cooperation. The model developed in this paper outlines an explanation of the cohesion changes in the development process of an organization. Some suggestions for cooperative behavior improvement are given in the end.

  2. Structures of the Class D Carbapenemase OXA-24 from Acinetobacter baumannii in Complex with Doripenem

    SciTech Connect

    Schneider, Kyle D.; Ortega, Caleb J.; Renck, Nicholas A.; Bonomo, Robert A.; Powers, Rachel A.; Leonard, David A.

    2012-02-08

    The emergence of class D {beta}-lactamases with carbapenemase activity presents an enormous challenge to health practitioners, particularly with regard to the treatment of infections caused by Gram-negative pathogens such as Acinetobacter baumannii. Unfortunately, class D {beta}-lactamases with carbapenemase activity are resistant to {beta}-lactamase inhibitors. To better understand the details of the how these enzymes bind and hydrolyze carbapenems, we have determined the structures of two deacylation-deficient variants (K84D and V130D) of the class D carbapenemase OXA-24 with doripenem bound as a covalent acyl-enzyme intermediate. Doripenem adopts essentially the same configuration in both OXA-24 variant structures, but varies significantly when compared to the non-carbapenemase class D member OXA-1/doripenem complex. The alcohol of the 6a hydroxyethyl moiety is directed away from the general base carboxy-K84, with implications for activation of the deacylating water. The tunnel formed by the Y112/M223 bridge in the apo form of OXA-24 is largely unchanged by the binding of doripenem. The presence of this bridge, however, causes the distal pyrrolidine/sulfonamide group to bind in a drastically different conformation compared to doripenem bound to OXA-1. The resulting difference in the position of the side-chain bridge sulfur of doripenem is consistent with the hypothesis that the tautomeric state of the pyrroline ring contributes to the different carbapenem hydrolysis rates of OXA-1 and OXA-24. These findings represent a snapshot of a key step in the catalytic mechanism of an important class D enzyme, and might be useful for the design of novel inhibitors.

  3. Concurrent effects of age class and food distribution on immigration success and population dynamics in a small mammal.

    PubMed

    Rémy, Alice; Le Galliard, Jean-François; Odden, Morten; Andreassen, Harry P

    2014-07-01

    During the settlement stage of dispersal, the outcome of conflicts between residents and immigrants should depend on the social organization of resident populations as well as on individual traits of immigrants, such as their age class, body mass and/or behaviour. We have previously shown that spatial distribution of food influences the social organization of female bank voles (Myodes glareolus). Here, we aimed to determine the relative impact of food distribution and immigrant age class on the success and demographic consequences of female bank vole immigration. We manipulated the spatial distribution of food within populations having either clumped or dispersed food. After a pre-experimental period, we released either adult immigrants or juvenile immigrants, for which we scored sociability and aggressiveness prior to introduction. We found that immigrant females survived less well and moved more between populations than resident females, which suggest settlement costs. However, settled juvenile immigrants had a higher probability to reproduce than field-born juveniles. Food distribution had little effects on the settlement success of immigrant females. Survival and settlement probabilities of immigrants were influenced by adult female density in opposite ways for adult and juvenile immigrants, suggesting a strong adult-adult competition. Moreover, females of higher body mass at release had a lower probability to survive, and the breeding probability of settled immigrants increased with their aggressiveness and decreased with their sociability. Prior to the introduction of immigrants, resident females were more aggregated in the clumped food treatment than in the dispersed food treatment, but immigration reversed this relationship. In addition, differences in growth trajectories were seen during the breeding season, with populations reaching higher densities when adult immigrants were introduced in a plot with dispersed food, or when juvenile immigrants were

  4. Apparent inferiority of first-time breeders in the kittiwake: The role of heterogeneity among age classes

    USGS Publications Warehouse

    Cam, E.; Monnat, J.-Y.

    2000-01-01

    1. Many studies have provided evidence that first-time breeders have a lower survival, a lower probability of success, or of breeding, in the following year. Hypotheses based on reproductive costs have often been proposed to explain this. However, because of the intrinsic relationship between age and experience, the apparent inferiority of first-time breeders at the population level may result from selection, and experience may not influence performance within each individual. In this paper we address the question of phenotypic correlations between fitness components. This addresses differences in individual quality, a prerequisite for a selection process to occur. We also test the hypothesis of an influence of experience on these components while taking age and reproductive success into account: two factors likely to play a key role in a selection process. 2. Using data from a long-term study on the kittiwake, we found that first-time breeders have a lower probability of success, a lower survival and a lower probability of breeding in the next year than experienced breeders. However, neither experienced nor inexperienced breeders have a lower survival or a lower probability of breeding in the following year than birds that skipped a breeding opportunity. This suggests heterogeneity in quality among individuals. 3. Failed birds have a lower survival and a lower probability of breeding in the following year regardless of experience. This can be interpreted in the light of the selection hypothesis. The inferiority of inexperienced breeders may be linked to a higher proportion of lower-quality individuals in younger age classes. When age and breeding success are controlled for, there is no evidence of an influence of experience on survival or future breeding probability. 4. Using data from individuals whose reproductive life lasted the same number of years, we investigated the influence of experience on reproductive performance within individuals. There is no strong

  5. Aging effects on the structure underlying balance abilities tests.

    PubMed

    Urushihata, Toshiya; Kinugasa, Takashi; Soma, Yuki; Miyoshi, Hirokazu

    2010-01-01

    Balance impairment is one of the biggest risk factors for falls reducing inactivity, resulting in nursing care. Therefore, balance ability is crucial to maintain the activities of independent daily living of older adults. Many tests to assess balance ability have been developed. However, few reports reveal the structure underlying results of balance performance tests comparing young and older adults. Covariance structure analysis is a tool that is used to test statistically whether factorial structure fits data. This study examined aging effects on the factorial structure underlying balance performance tests. Participants comprised 60 healthy young women aged 22 ± 3 years (young group) and 60 community-dwelling older women aged 69 ± 5 years (older group). Six balance tests: postural sway, one-leg standing, functional reach, timed up and go (TUG), gait, and the EquiTest were employed. Exploratory factor analysis revealed that three clearly interpretable factors were extracted in the young group. The first factor had high loadings on the EquiTest, and was interpreted as 'Reactive'. The second factor had high loadings on the postural sway test, and was interpreted as 'Static'. The third factor had high loadings on TUG and gait test, and was interpreted as 'Dynamic'. Similarly, three interpretable factors were extracted in the older group. The first factor had high loadings on the postural sway test and the EquiTest and therefore was interpreted as 'Static and Reactive'. The second factor, which had high loadings on the EquiTest, was interpreted as 'Reactive'. The third factor, which had high loadings on TUG and the gait test, was interpreted as 'Dynamic'. A covariance structure model was applied to the test data: the second-order factor was balance ability, and the first-order factors were static, dynamic and reactive factors which were assumed to be measured based on the six balance tests. Goodness-of-fit index (GFI) of the models were acceptable (young group, GFI

  6. Aging Effects on the Structure Underlying Balance Abilities Tests

    PubMed Central

    Kinugasa, Takashi; Soma, Yuki; Miyoshi, Hirokazu

    2010-01-01

    Balance impairment is one of the biggest risk factors for falls reducing inactivity, resulting in nursing care. Therefore, balance ability is crucial to maintain the activities of independent daily living of older adults. Many tests to assess balance ability have been developed. However, few reports reveal the structure underlying results of balance performance tests comparing young and older adults. Covariance structure analysis is a tool that is used to test statistically whether factorial structure fits data. This study examined aging effects on the factorial structure underlying balance performance tests. Participants comprised 60 healthy young women aged 22 ± 3 years (young group) and 60 community-dwelling older women aged 69 ± 5 years (older group). Six balance tests: postural sway, one-leg standing, functional reach, timed up and go (TUG), gait, and the EquiTest were employed. Exploratory factor analysis revealed that three clearly interpretable factors were extracted in the young group. The first factor had high loadings on the EquiTest, and was interpreted as ‘Reactive’. The second factor had high loadings on the postural sway test, and was interpreted as ‘Static’. The third factor had high loadings on TUG and gait test, and was interpreted as ‘Dynamic’. Similarly, three interpretable factors were extracted in the older group. The first factor had high loadings on the postural sway test and the EquiTest and therefore was interpreted as ‘Static and Reactive’. The second factor, which had high loadings on the EquiTest, was interpreted as ‘Reactive’. The third factor, which had high loadings on TUG and the gait test, was interpreted as ‘Dynamic’. A covariance structure model was applied to the test data: the second-order factor was balance ability, and the first-order factors were static, dynamic and reactive factors which were assumed to be measured based on the six balance tests. Goodness-of-fit index (GFI) of the models were

  7. Shock spectra applications to a class of multiple degree-of-freedom structures system

    NASA Technical Reports Server (NTRS)

    Hwang, Shoi Y.

    1988-01-01

    The demand on safety performance of launching structure and equipment system from impulsive excitations necessitates a study which predicts the maximum response of the system as well as the maximum stresses in the system. A method to extract higher modes and frequencies for a class of multiple degree-of-freedom (MDOF) Structure system is proposed. And, along with the shock spectra derived from a linear oscillator model, a procedure to obtain upper bound solutions for maximum displacement and maximum stresses in the MDOF system is presented.

  8. ``Thermal'' and ``superthermal'' two-class structure of the personal income distribution

    NASA Astrophysics Data System (ADS)

    Yakovenko, Victor

    2005-03-01

    In Ref. [1] we proposed an analogy between the thermal Boltzmann-Gibbs probability distribution of energy in physics and the probability distribution of money in economics in statistical equilibrium. In Ref. [2] we find that the probability distribution of personal income in the USA has a well-defined two-class structure. The majority of population (97-99%) belongs to the lower class characterized by the exponential Boltzmann-Gibbs (``thermal'') distribution, whereas the upper class (1-3% of population) has a Pareto power-law (``superthermal'') distribution. By analyzing the income data for 1983--2001 from IRS, we show that the ``thermal'' part is stationary in time, save for a gradual increase of the effective temperature, whereas the nonequilibrium ``superthermal'' tail swells and shrinks following the stock market. We discuss the concept of equilibrium inequality in a society, based on the principle of maximal entropy, and quantitatively show that it applies to the majority of the US population. [] [1] A. Dragulescu and V. M. Yakovenko, ``Statistical mechanics of money'', Eur. Phys. J. B 17, 723--729 (2000). [cond-mat/0001432] [] [2] A. C. Silva and V. M. Yakovenko, ``Temporal evolution of the `thermal' and `superthermal' income classes in the USA during 1983--2001'', accepted to Europhysics Letters. [cond- mat/0406385

  9. Accuracy of a structural homology model for a class II histocompatibility protein, HLA-DR1: comparison to the crystal structure.

    PubMed

    Nauss, J L; Reid, R H; Sadegh-Nasseri, S

    1995-06-01

    Structural homology modeling is used to test the accuracy by which a Class I major histocompatibility complex (MHC) could be used to model a Class II MHC. The crystal structure of HLA-aw68 served as a reference molecule to model HLA-DR1. The resulting model was compared to the recently released crystal structure by Brown et al. (Nature, Vol. 364, p. 33-39 (1993)). The overall tertiary structure motif (two alpha-helices and a beta-sheet forming a peptide binding cleft) was maintained. However, significant deviations in the secondary structure elements were found between the model and the DR1 crystal structure. These deviations were consistent with the differences between Class I and Class II crystal structures. In regions where the model and DR1 crystals structures are most similar, side chain orientations are also similar. Specific peptide-MHC interactions are discussed and compared with the crystal structure results. PMID:7669268

  10. The Structural Basis for Class II Cytokine Receptor Recognition by JAK1.

    PubMed

    Ferrao, Ryan; Wallweber, Heidi J A; Ho, Hoangdung; Tam, Christine; Franke, Yvonne; Quinn, John; Lupardus, Patrick J

    2016-06-01

    JAK1 is a member of the Janus kinase (JAK) family of non-receptor tyrosine kinases that are activated in response to cytokines and interferons. Here, we present two crystal structures of the human JAK1 FERM and SH2 domains bound to peptides derived from the class II cytokine receptors IFN-λ receptor 1 and IL-10 receptor 1 (IFNLR1 and IL10RA). These structures reveal an interaction site in the JAK1 FERM that accommodates the so-called "box1" membrane-proximal receptor peptide motif. Biophysical analysis of the JAK1-IFNLR1 interaction indicates that the receptor box1 is the primary driver of the JAK1 interaction, and identifies residues conserved among class II receptors as important for binding. In addition, we demonstrate that a second "box2" receptor motif further stabilizes the JAK1-IFNLR1 complex. Together, these data identify a conserved JAK binding site for receptor peptides and elucidate the mechanism by which class II cytokine receptors interact with JAK1. PMID:27133025

  11. The leader peptide of mutacin 1140 has distinct structural components compared to related class I lantibiotics

    PubMed Central

    Escano, Jerome; Stauffer, Byron; Brennan, Jacob; Bullock, Monica; Smith, Leif

    2014-01-01

    Lantibiotics are ribosomally synthesized peptide antibiotics composed of an N-terminal leader peptide that promotes the core peptide's interaction with the post translational modification (PTM) enzymes. Following PTMs, mutacin 1140 is transported out of the cell and the leader peptide is cleaved to yield the antibacterial peptide. Mutacin 1140 leader peptide is structurally unique compared to other class I lantibiotic leader peptides. Herein, we further our understanding of the structural differences of mutacin 1140 leader peptide with regard to other class I leader peptides. We have determined that the length of the leader peptide is important for the biosynthesis of mutacin 1140. We have also determined that mutacin 1140 leader peptide contains a novel four amino acid motif compared to related lantibiotics. PTM enzyme recognition of the leader peptide appears to be evolutionarily distinct from related class I lantibiotics. Our study on mutacin 1140 leader peptide provides a basis for future studies aimed at understanding its interaction with the PTM enzymes. PMID:25400246

  12. Site and age class variation of hematologic parameters for female Greater Sage Grouse (Centrocercus urophasianus) of Northern Nevada.

    PubMed

    Dyer, Kathryn J; Perryman, Barry L; Holcombe, Dale W

    2010-01-01

    Decreases in Greater Sage Grouse (Centrocercus urophasianus) numbers throughout the western United States have been attributed to declining habitat quantity and quality. Improving our understanding of how interannual ecologic site variability affects nutritional status and fitness of different bird age classes will lead to improved land management and conservation strategies. Greater Sage Grouse were sampled from two Population Management Units located in northern Nevada, United States: Tuscarora (TU) and Lone Willow (LW) during 15 March-11 April 2004 and 14-20 March 2005. Twenty (16 yearlings, four adults) and 17 (7 yearlings, 10 adults) female Sage Grouse were captured and bled during 2004, and 12 (four yearlings, eight adults) and 14 (10 yearlings, four adults) were sampled during 2005 in TU and LW, respectively. Samples were evaluated to examine the effect of site, age, and year on specific hematologic and serum chemistry parameters. Several differences between age classes, sites, and years were detected for a number of fitness indicators; however, actual values fell within normal ranges of variation for Sage Grouse or other avian species. Differences were also detected for several parameters more closely related to reproductive fitness, including total plasma and serum proteins, and serum calcium and phosphorus. Yearlings had lower plasma protein (P<0.0001) and lower serum protein than did adults (P=0.0003). In 2004, TU yearlings had lower serum calcium levels than the adults, and in 2005, LW yearlings had lower levels than adults (P=0.008). Females on the TU site had lower serum phosphorus than the LW females (P<0.0001). Overall, adult females weighed more than yearlings (P=0.0004). Lower values found in yearlings, and on the TU management unit, indicate a lower production potential, particularly in unfavorable years. A lower intrinsic ability of yearlings to reproduce, combined with lower nutrition potentials and associated annual variations on certain types

  13. Form Follows Function: Structural and Catalytic Variation in the Class A Flavoprotein Monooxygenases

    PubMed Central

    Crozier-Reabe, Karen; Moran, Graham R.

    2012-01-01

    Flavoprotein monooxygenases (FPMOs) exhibit an array of mechanistic solutions to a common chemical objective; the monooxygenation of a target substrate. Each FPMO efficiently couples reduction of a flavin cofactor by NAD(P)H to oxygenation of the target substrate via a (hydro)peroxyflavin intermediate. This purpose of this review is to describe in detail the Class A flavoprotein hydroxylases (FPMO) in the context of the other FPMO classes (B–F). Both one and two component FPMOs are found in nature. Two-component enzymes require, in addition to the monooxygenase, the involvement of a reductase that first catalyzes the reduction of the flavin by NAD(P)H. The Class A and B FPMOs are single-component and manage to orchestrate the same net reaction within a single peptide. The Class A enzymes have, by some considerable margin, the most complete research record. These enzymes use choreographed movements of the flavin ring that facilitate access of the organic substrates to the active site, provide a means for interaction of NADPH with the flavin, offer a mechanism to sequester the dioxygen reduction chemistry from solvent and a means to release the product. The majority of the discrete catalytic events of the catalytic cycle can be observed directly in exquisite detail using spectrophotometric kinetic methods and many of the key mechanistic conclusions are further supported by structural data. This review attempts to compile each of the key observations made for both paradigm and newly discovered examples of Class A FPMOs into a complete catalytic description of one enzymatic turnover. PMID:23443084

  14. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    SciTech Connect

    Ellingwood, B.; Song, J.

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  15. Inhibitory control efficiency in a Piaget-like class-inclusion task in school-age children and adults: a developmental negative priming study.

    PubMed

    Borst, G; Poirel, N; Pineau, A; Cassotti, M; Houdé, O

    2013-07-01

    Most children under 7 years of age presented with 10 daisies and 2 roses fail to indicate that there are more flowers than daisies. Instead of the appropriate comparison of the relative numerosities of the superordinate class (flowers) to its subordinate class (daisies), they perform a direct perceptual comparison of the extensions of the 2 subordinate classes (daisies vs. roses). In our experiment, we investigated whether increasing efficiency in solving the Piagetian class-inclusion task is related to increasing efficiency in the ability to resist (inhibit) this direct comparison of the subordinate classes' extensions. Ten-year-old and young adult participants performed a computerized priming version of a Piaget-like class-inclusion task. The experimental design was such that the misleading perceptual strategy to inhibit on the prime (in which a superordinate class had to be compared with a subordinate class) became a congruent strategy to activate on the probe (in which the two subordinate classes' extensions were directly compared). We found a negative priming effect of 291 ms in children and 129 ms in adults. These results provide evidence for the first time (a) that adults still need to inhibit the comparison of the subordinate classes' extensions in class-inclusion tasks and (b) that the ability to inhibit this heuristic increases with age (resulting in a lower executive cost). Taken together, these findings provide additional support for the neo-Piagetian approach of cognitive development that suggests that the acquisition of increasingly complex knowledge is based on the ability to resist (inhibit) heuristics and previously acquired knowledge. PMID:22889392

  16. Distribution, stocks, and age structure of the invader Mya arenaria before and after mass mortalities in the Black Sea

    NASA Astrophysics Data System (ADS)

    Ivanov, D. A.

    2013-05-01

    The distribution, stocks, and age structure of the invader soft-shell clam Mya arenaria populations before and after the mass mortalities in the northwestern Black Sea have been studied from 1967 to 1987. At the prolonged influence of mortalities from 1973 to 1985, the number of age classes decreased from six in the period before the mortalities to three in 1985. The restoration of the stocks of Mya arenaria and the possibility of fishing these mollusks after the improvement of the ecological state in this part of the sea are predicted.

  17. Structural and phylogenetic analysis of the MHC class I-like Fc receptor gene

    SciTech Connect

    Kandil, Eman; Ishibashi, Teruo; Kasahara, Masanori

    1995-06-01

    The intestinal epithelium of neonatal mice and rats expresses an Fc receptor that mediates selective uptake of IgG in mothers`milk. This receptor (FcRn), which helps newborn animals to acquire passive immunity, is an MHC class I-like heterodimer made up of a heavy chain and {beta}{sub 2}-microglobulin. In the present study, we determined the genomic structure of a mouse gene (FcRn) encoding the heavy of FcRn. The overall exon-intron organization of the Fcrn gene was similar to that of the Fcrn gene, thus providing structural evidence that Fcrn os a bona fide class I gene. The 5{prime}-flanking region of the Fcrn gene contained the binding motifs for two cytokine-inducible transcription factors, NF-IL6 and NF1. However, regulatory elements found in MHC class I genes (enhancer A, enhancer B, and the IFN response element) were absent. Phylogenetic tree analysis suggested that, like the MICA, AZGP1, and CD1 genes, the Fcrn gene diverged form MHC class I genes after the emergence of amphibians but before the split of placental and marsupial mammals. Consistent with this result, Southern blot analysis with a mouse Fcrn cDNA probe detected cross-hybridizing bands in various mammalian species and chickens. Sequence analysis of the Fcrn gene isolated from eight mouse strains showed that the membrane-distal domain of FcRn has at least three amino acid variants. The fact that Fcrn is a single copy gene indicates that it is expressed in both the neonatal intestine and the fetal yolk sac. 74 refs., 7 figs., 2 tabs.

  18. Experimental validation of an integrated controls-structures design methodology for a class of flexible space structures

    NASA Technical Reports Server (NTRS)

    Maghami, Peiman G.; Gupta, Sandeep; Elliott, Kenny B.; Joshi, Suresh M.; Walz, Joseph E.

    1994-01-01

    This paper describes the first experimental validation of an optimization-based integrated controls-structures design methodology for a class of flexible space structures. The Controls-Structures-Interaction (CSI) Evolutionary Model, a laboratory test bed at Langley, is redesigned based on the integrated design methodology with two different dissipative control strategies. The redesigned structure is fabricated, assembled in the laboratory, and experimentally compared with the original test structure. Design guides are proposed and used in the integrated design process to ensure that the resulting structure can be fabricated. Experimental results indicate that the integrated design requires greater than 60 percent less average control power (by thruster actuators) than the conventional control-optimized design while maintaining the required line-of-sight performance, thereby confirming the analytical findings about the superiority of the integrated design methodology. Amenability of the integrated design structure to other control strategies is considered and evaluated analytically and experimentally. This work also demonstrates the capabilities of the Langley-developed design tool CSI DESIGN which provides a unified environment for structural and control design.

  19. The Atiyah class and complex structure stabilization in heterotic Calabi-Yau compactifications

    NASA Astrophysics Data System (ADS)

    Anderson, Lara B.; Gray, James; Lukas, Andre; Ovrut, Burt

    2011-10-01

    Holomorphic gauge fields in N = 1 supersymmetri cheterotic compactifications can constrain the complex structure moduli of a Calabi-Yau manifold. In this paper, the tools necessary to use holomorphic bundles as a mechanism for moduli stabilization are systematically developed. We review the requisite deformation theory — including the Atiyah class, which determines the deformations of the complex structure for which the gauge bundle becomes non-holomorphic and, hence, non-supersymmetric. In addition, two equivalent approaches to this mechanism of moduli stabilization are presented. The first isan efficient computational algorithm for determining the supersymmetric moduli space, while the second is an F-term potential in the four-dimensional theory associated with vector bundle holomorphy. These three methods are proven to be rigorously equivalent. We present explicit examples in which large numbers of complex structure moduli are stabilized. Finally, higher-order corrections to the moduli space are discussed.

  20. Self-Learning Variable Structure Control for a Class of Sensor-Actuator Systems

    PubMed Central

    Chen, Sanfeng; Li, Shuai; Liu, Bo; Lou, Yuesheng; Liang, Yongsheng

    2012-01-01

    Variable structure strategy is widely used for the control of sensor-actuator systems modeled by Euler-Lagrange equations. However, accurate knowledge on the model structure and model parameters are often required for the control design. In this paper, we consider model-free variable structure control of a class of sensor-actuator systems, where only the online input and output of the system are available while the mathematic model of the system is unknown. The problem is formulated from an optimal control perspective and the implicit form of the control law are analytically obtained by using the principle of optimality. The control law and the optimal cost function are explicitly solved iteratively. Simulations demonstrate the effectiveness and the efficiency of the proposed method. PMID:22778633

  1. Discovery of a new class of coronal structures in white light eclipse images

    SciTech Connect

    Druckmüller, Miloslav; Habbal, Shadia Rifai; Morgan, Huw

    2014-04-10

    White light images of the solar corona, taken during total solar eclipses, capture the complex dynamic relationship between the coronal plasma and the magnetic field. This relationship can be recorded on timescales of seconds to minutes, within a few solar radii above the solar surface. Rays, large-scale loops, and streamers, which are the brightest structures in these images, have shaped current models of the coronal magnetic field and solar wind flow. We show in this work how the application of novel image processing techniques to unique high-resolution white light eclipse images reveals the presence of a new class of structures, reminiscent of smoke rings, faint nested expanding loops, expanding bubbles, and twisted helical structures. These features are interpreted as snapshots of the dynamical evolution of instabilities developing at prominence-corona interfaces and propagating outward with the solar wind.

  2. Structure-Based Consensus Scoring Scheme for Selecting Class A Aminergic GPCR Fragments.

    PubMed

    Kelemen, Ádám A; Kiss, Róbert; Ferenczy, György G; Kovács, László; Flachner, Beáta; Lőrincz, Zsolt; Keserű, György M

    2016-02-22

    Aminergic G-protein coupled receptors (GPRCs) represent well-known targets of central nervous-system related diseases. In this study a structure-based consensus virtual screening scheme was developed for designing targeted fragment libraries against class A aminergic GPCRs. Nine representative aminergic GPCR structures were selected by first clustering available X-ray structures and then choosing the one in each cluster that performs best in self-docking calculations. A consensus scoring protocol was developed using known promiscuous aminergic ligands and decoys as a training set. The consensus score (FrACS-fragment aminergic consensus score) calculated for the optimized protein ensemble showed improved enrichments in most cases as compared to stand-alone structures. Retrospective validation was carried out on public screening data for aminergic targets (5-HT1 serotonin receptor, TA1 trace-amine receptor) showing 8-17-fold enrichments using an ensemble of aminergic receptor structures. The performance of the structure based FrACS in combination with our ligand-based prefilter (FrAGS) was investigated both in a retrospective validation on the ChEMBL database and in a prospective validation on an in-house fragment library. In prospective validation virtual fragment hits were tested on 5-HT6 serotonin receptors not involved in the development of FrACS. Six out of the 36 experimentally tested fragments exhibited remarkable antagonist efficacies, and 4 showed IC50 values in the low micromolar or submicromolar range in a cell-based assay. Both retrospective and prospective validations revealed that the methodology is suitable for designing focused class A GPCR fragment libraries from large screening decks, commercial compound collections, or virtual databases. PMID:26760056

  3. Development of a new class of satellites: a composite lightweight affordable spacecraft structure

    SciTech Connect

    Thompson, T.C.; Parietti, L.

    1996-06-01

    The Los Alamos National Laboratory (LANL) in partnership with Composite Optics Incorporated (COI) has successfully designed and tested a Composite Lightweight Affordable Structure (CLASS). The use of advanced composites in space applications is well developed, but the application of an all-composite satellite structure has not been achieved until now. The development of this low-cost, lightweight, composite technology for use in small satellite structures, in this case, for the Fast On-Orbit Recording of Transient Events (FORT{acute E}) satellite mission will make a considerable contribution to the advanced spacecraft community. A common practice for constructing small spacecraft structures is to use an all-aluminum spacecraft bus. Compared to a composite structure, this reduces the payload capacity significantly; however, the cost of the aluminum structure has historically been lower than one of that uses lightweight components. LANL mission requirements dictate the need for a long term solution that substantially increased the ratio of payload to structural mass while maintaining a low-risk low-cost approach. LANL intends to use the concept developed for FORT{acute E} on future missions requiring similar enhanced payload capacities. 1 fig.

  4. Tectonic structures on Mercury: kinematics and age dating

    NASA Astrophysics Data System (ADS)

    Giacomini, Lorenza; Massironi, Matteo; Rothery, David; Di Achille, Gaetano; Marchi, Simone; Galluzzi, Valentina; Ferrari, Sabrina; Fassett, Caleb; Cremonese, Gabriele

    2015-04-01

    At a global scale, Mercury is dominated by contractional features manifested as lobate scarps, wrinkle ridges and high-relief ridges. Here, we show that some of these features are associated with strike-slip kinematic indicators, which we identified using flyby and orbital Mercury Dual Imaging System (MDIS) data and digital terrain models. We recognize oblique-shear kinematics along lobate scarps and high-relief ridges by means of (1) map geometries of fault patterns (frontal thrusts bordered by lateral ramps, strike-slip duplexes, restraining bends); (2) structural morphologies indicating lateral shearing (en echelon folding, pop-ups, pull-aparts); and (3) estimates of offsets based on displaced crater rims and differences in elevation between pop-up structures and pull-apart basins and their surroundings. Transpressional faults, documented across a wide range of latitudes, are found associated with reactivated rims of ancient buried basins and, in most cases, linked to frontal thrusts as lateral ramps hundreds of kilometres long. This latter observation suggests stable directions of tectonic transport over wide regions of Mercury's surface. In contrast, global cooling would imply an overall isotropic contraction with limited processes of lateral shearing induced by pre-existent lithospheric heterogeneities. Mantle convection therefore may have played an important role during the early tectonic evolution of Mercury. Estimating absolute model ages for compressional features and comparing it from what it is envisaged with thermal modeling based on cooling alone can be useful in determining if other processes could have been responsible for lobate scarps nucleation. In particular, ages more ancient that the one predicted by the models would imply other kind of tectonic processes ongoing during the early evolution of Mercury . For this reason, we date an extended thrust system, which we term the Blossom Thrust System, located between 80°E and 100°E, and 30°N and 15

  5. Contextual Land Use Classification: how Detailed can the Class Structure Be?

    NASA Astrophysics Data System (ADS)

    Albert, L.; Rottensteiner, F.; Heipke, C.

    2016-06-01

    The goal of this paper is to investigate the maximum level of semantic resolution that can be achieved in an automated land use change detection process based on mono-temporal, multi-spectral, high-resolution aerial image data. For this purpose, we perform a step-wise refinement of the land use classes that follows the hierarchical structure of most object catalogues for land use databases. The investigation is based on our previous work for the simultaneous contextual classification of aerial imagery to determine land cover and land use. Land cover is determined at the level of small image segments. Land use classification is applied to objects from the geospatial database. Experiments are carried out on two test areas with different characteristics and are intended to evaluate the step-wise refinement of the land use classes empirically. The experiments show that a semantic resolution of ten classes still delivers acceptable results, where the accuracy of the results depends on the characteristics of the test areas used. Furthermore, we confirm that the incorporation of contextual knowledge, especially in the form of contextual features, is beneficial for land use classification.

  6. Molecular cloning, nucleotide sequence and fine-structural analysis of the Corynebacterium glutamicum fda gene: structural comparison of C. glutamicum fructose-1,6-biphosphate aldolase to class I and class II aldolases.

    PubMed

    von der Osten, C H; Barbas, C F; Wong, C H; Sinskey, A J

    1989-11-01

    The Corynebacterium glutamicum fda gene encoding fructose-1,6-biphosphate (FBP) aldolase has been isolated by complementation of an Escherichia coli mutant. The nucleotide sequence of a 3371 bp chromosomal fragment containing the C. glutamicum fda gene was determined. The N-terminal amino acid sequence of C. glutamicum FBP aldolase identified the correct initiation site for the fda gene, and a molecular weight of 37,092 was predicted for the fda polypeptide. S1 nuclease mapping identified the transcriptional start site, and Northern hybridization analysis indicated that the fda gene encodes a single 1.3 kb transcript. The primary structure of C. glutamicum FBP aldolase shows strong homology to class II FBP aldolases. Conservation of primary structure was observed between class I and class II aldolases, but several residues essential for catalytic activity in class I aldolases were absent from class II aldolases. PMID:2615658

  7. Inferring Selection Intensity and Allele Age from Multilocus Haplotype Structure

    PubMed Central

    Chen, Hua; Slatkin, Montgomery

    2013-01-01

    It is a challenging task to infer selection intensity and allele age from population genetic data. Here we present a method that can efficiently estimate selection intensity and allele age from the multilocus haplotype structure in the vicinity of a segregating mutant under positive selection. We use a structured-coalescent approach to model the effect of directional selection on the gene genealogies of neutral markers linked to the selected mutant. The frequency trajectory of the selected allele follows the Wright-Fisher model. Given the position of the selected mutant, we propose a simplified multilocus haplotype model that can efficiently model the dynamics of the ancestral haplotypes under the joint influence of selection and recombination. This model approximates the ancestral genealogies of the sample, which reduces the number of states from an exponential function of the number of single-nucleotide polymorphism loci to a quadratic function. That allows parameter inference from data covering DNA regions as large as several hundred kilo-bases. Importance sampling algorithms are adopted to evaluate the probability of a sample by exploring the space of both allele frequency trajectories of the selected mutation and gene genealogies of the linked sites. We demonstrate by simulation that the method can accurately estimate selection intensity for moderate and strong positive selection. We apply the method to a data set of the G6PD gene in an African population and obtain an estimate of 0.0456 (95% confidence interval 0.0144−0.0769) for the selection intensity. The proposed method is novel in jointly modeling the multilocus haplotype pattern caused by recombination and mutation, allowing the analysis of haplotype data in recombining regions. Moreover, the method is applicable to data from populations under exponential growth and a variety of other demographic histories. PMID:23797107

  8. The Work of Power and the Power of Work: Teaching for Class Consciousness in the Neo-Liberal Age

    ERIC Educational Resources Information Center

    Weiner, Eric J.

    2004-01-01

    As workers throughout the globe struggle to gain control over the conditions in which they labor as well as the means by which capital is produced, the importance of understanding class struggle, class formation and class consciousness as they relate to education and schooling takes on a new urgency. In the early part of the twenty-first century,…

  9. Age- and sex-specific mortality and population structure in sea otters

    USGS Publications Warehouse

    Bodkin, J.L.; Burdin, A.M.; Ryazanov, D.A.

    2000-01-01

    We used 742 beach-cast carcasses to characterize age- and sex-specific sea otter mortality during the winter of 1990-1991 at Bering Island, Russia. We also examined 363 carcasses recovered after the 1989 grounding of the T/V Exxon Valdez, to characterize age and sex composition in the living western Prince William Sound (WPWS) sea otter population. At Bering Island, mortality was male-biased (81%), and 75% were adults. The WPWS population was female-biased (59%) and most animals were subadult (79% of the males and 45% of the females). In the decade prior to 1990-1991 we found increasing sea otter densities (particularly among males), declining prey resources, and declining weights in adult male sea otters at Bering Island. Our findings suggest the increased mortality at Bering Island in 1990-1991 was a density-dependent population response. We propose male-maintained breeding territories and exclusion of juvenile females by adult females, providing a mechanism for potentially moderating the effects of prey reductions on the female population. Increased adult male mortality at Bearing Island in 1990-1991 likely modified the sex and age class structure there toward that observed in Prince William Sound.

  10. Understanding social reproduction: The recursive nature of structure and agency within a science class

    NASA Astrophysics Data System (ADS)

    Seiler, Gale A.

    Schools and science classrooms within schools continue to contribute to social reproduction and to the disenfranchisement of inner city African American students though attempts have been made to remedy the situation through standards, high-stakes testing, and compensatory programs. Such reforms ignore the sociocultural, political, and economic contexts of the individual students in the schools they are impacting. They do not take into account the uniqueness and diversity of the learners in these settings and have not included the voices of the students. Another possibility was studied here; that of starting with the cultural capital of the learner rather than with external standards. In a non-required science course at a local high school two coteachers endeavored to enact a student-emergent curriculum as a way to foster student agency and to counteract the reproductive nature of schools. The class was examined as a field within multiple other fields. The dialectical relationship between structure and agency in the class was used to frame the analysis and the tension between them was examined at several levels through video and audio analysis. Structural and rational choice views of action were abandoned in favor of an understanding hinged upon strategies of action that actors construct from cultural toolkits in and through practice. In this setting the students and teachers co-constructed a class that can be described and characterized in certain ways yet contained many counter-examples and alternative characterizations. A continuum of successes and failures, agency and subjectivity can be found in the trends and counter-trends in the course. The contradictions were examined to portray the complexity of the interactions and the possibilities for agency within them.

  11. Structure of a Class I Tagatose-1,6-bisphosphate Aldolase

    PubMed Central

    LowKam, Clotilde; Liotard, Brigitte; Sygusch, Jurgen

    2010-01-01

    Tagatose-1,6-bisphosphate aldolase from Streptococcus pyogenes is a class I aldolase that exhibits a remarkable lack of chiral discrimination with respect to the configuration of hydroxyl groups at both C3 and C4 positions. The enzyme catalyzes the reversible cleavage of four diastereoisomers (fructose 1,6-bisphosphate (FBP), psicose 1,6-bisphosphate, sorbose 1,6-bisphosphate, and tagatose 1,6-bisphosphate) to dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate with high catalytic efficiency. To investigate its enzymatic mechanism, high resolution crystal structures were determined of both native enzyme and native enzyme in complex with dihydroxyacetone-P. The electron density map revealed a (α/β)8 fold in each dimeric subunit. Flash-cooled crystals of native enzyme soaked with dihydroxyacetone phosphate trapped a covalent intermediate with carbanionic character at Lys205, different from the enamine mesomer bound in stereospecific class I FBP aldolase. Structural analysis indicates extensive active site conservation with respect to class I FBP aldolases, including conserved conformational responses to DHAP binding and conserved stereospecific proton transfer at the DHAP C3 carbon mediated by a proximal water molecule. Exchange reactions with tritiated water and tritium-labeled DHAP at C3 hydrogen were carried out in both solution and crystalline state to assess stereochemical control at C3. The kinetic studies show labeling at both pro-R and pro-S C3 positions of DHAP yet detritiation only at the C3 pro-S-labeled position. Detritiation of the C3 pro-R label was not detected and is consistent with preferential cis-trans isomerism about the C2–C3 bond in the carbanion as the mechanism responsible for C3 epimerization in tagatose-1,6-bisphosphate aldolase. PMID:20427286

  12. How good strong union men line it out: explorations of the structure and dynamics of coal-miners' class consciousness

    SciTech Connect

    Yarrow, M.N.

    1982-01-01

    This study explores how working-class people apprehend and analyze the class dynamics of their social world. As an exploratory empirical study of the structure and dynamics of working-class consciousness, it seeks to develop the theory of actual class consciousness by bringing previous theories into dialogue with the articulated analyses of coal miners in central Appalachia. Although changing conditions are shown to have a powerful effect on class consciousness, the respondents were found to respond differently to the changing context and to remain loyal to important elements of their earlier perspectives. Suggestions are made for how the theory could be developed further. The data for the study are flexibly structured interviews which were conducted with active, retired, and disabled miners in southern West Virginia and western Virginia. A dozen miners were interviewed during the 1978 strike and again the following summer; during the summer of 1978, nineteen additional miners were interviewed.

  13. Structural and thermodynamic properties of kappa class glutathione transferase from Camelus dromedarius.

    PubMed

    Malik, Ajamaluddin; Fouad, Dalia; Labrou, Nikolaos E; Al-Senaidy, Abdulrahman M; Ismael, Mohamed A; Saeed, Hesham M; Ataya, Farid S

    2016-07-01

    The Arabian camel, Camelus dromedarius is naturally adapted to extreme desert climate and has evolved protective mechanisms to limit oxidative stress. The mitochondrial kappa class glutathione transferase enzyme is a member of GST supergene family that represents an important enzyme group in cellular Phase II detoxification machinery and is involved in the protection against oxidative stress and xenobiotics. In the present study, C. dromedarius kappa class glutathione transferase (CdGSTK1-1) was cloned, expressed in E. coli BL21, purified and its structural, thermodynamic and unfolding pathway was investigated. The results showed that CdGSTK1-1 has unique trimeric structure, exhibits low thermostability and a complex equilibrium unfolding profile. It unfolds through three folding states with formation of thinly populated intermediate species. The melting points (Tm) of the first unfolding transition was 40.3±0.2°C and Tm of the second unfolding transition was 49.1±0.1°C. The van't Hoff enthalpy of the first and second transition were 298.7±13.2 and 616.5±2.4kJ/mol, respectively. Moreover, intrinsic fluorescence and near-UV CD studies indicates that substrate binding does not leads to major conformational changes in CdGSTK1-1. PMID:27044344

  14. Self-optimising control for a class of continuous bioreactor via variable-structure feedback

    NASA Astrophysics Data System (ADS)

    Lara-Cisneros, Gerardo; Alvarez-Ramírez, José; Femat, Ricardo

    2016-04-01

    A self-optimising controller is designed for stabilisation of a class of bioreactor exploiting sliding-mode techniques. The stability analysis for the class of bioreactor, in open-loop configuration, suggests that the optimal behaviour, respect to maximal biomass production, occurs in an unstable region (structurally unstable). In this contribution, a variable-structure controller is designed, exploiting the inhibitory effect of substrate concentration under the biomass growth rate, such that the closed-loop system reaches the optimal manifold where the effect induced by the growth rate gradient is compensated (favouring the maximum growth rate). The self-optimising comprises an uncertainty estimator which computes the unknown terms for increasing the robustness issues of the sliding-mode scheme. Numerical experiments illustrate the performance and execution of the control strategy considering different parameter values for biomass growth rate. The robustness and fragility of the proposed controller are also discussed with respect to the modelling uncertainty and small changes in the controller gains, respectively.

  15. Structural basis for a class of nanomolar influenza A neuraminidase inhibitors

    NASA Astrophysics Data System (ADS)

    Kerry, Philip S.; Mohan, Sankar; Russell, Rupert J. M.; Bance, Nicole; Niikura, Masahiro; Pinto, B. Mario

    2013-10-01

    The influenza virus neuraminidase (NA) is essential for the virus life cycle. The rise of resistance mutations against current antiviral therapies has increased the need for the development of novel inhibitors. Recent efforts have targeted a cavity adjacent to the catalytic site (the 150-cavity) in addition to the primary catalytic subsite in order to increase specificity and reduce the likelihood of resistance. This study details structural and in vitro analyses of a class of inhibitors that bind uniquely in both subsites. Crystal structures of three inhibitors show occupation of the 150-cavity in two distinct and novel binding modes. We believe these are the first nanomolar inhibitors of NA to be characterized in this way. Furthermore, we show that one inhibitor, binding within the catalytic site, offers reduced susceptibility to known resistance mutations via increased flexibility of a pendant pentyloxy group and the ability to pivot about a strong hydrogen-bonding network.

  16. Structural Properties and Complexity of a New Network Class: Collatz Step Graphs

    PubMed Central

    Emmert-Streib, Frank

    2013-01-01

    In this paper, we introduce a biologically inspired model to generate complex networks. In contrast to many other construction procedures for growing networks introduced so far, our method generates networks from one-dimensional symbol sequences that are related to the so called Collatz problem from number theory. The major purpose of the present paper is, first, to derive a symbol sequence from the Collatz problem, we call the step sequence, and investigate its structural properties. Second, we introduce a construction procedure for growing networks that is based on these step sequences. Third, we investigate the structural properties of this new network class including their finite scaling and asymptotic behavior of their complexity, average shortest path lengths and clustering coefficients. Interestingly, in contrast to many other network models including the small-world network from Watts & Strogatz, we find that CS graphs become ‘smaller’ with an increasing size. PMID:23431377

  17. Urban groundwater age modeling under unconfined condition - Impact of underground structures on groundwater age: Evidence of a piston effect

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Rossier, Yvan; Eisenlohr, Laurent

    2016-04-01

    In this paper, underground structures are shown to have a major influence on the groundwater mean age distribution described as a dispersive piston effect. Urban underground development does not occur without impacts on subsoil resources. In particular, groundwater resources can be vulnerable and generate disturbances when this space is exploited. Groundwater age spatial distribution data are fundamental for resource management as it can provide operational sustainability indicators. However, the application of groundwater age modeling is neglected regarding the potential effect of underground structures in urban areas. A three dimensional modeling approach was conducted to quantify the impact of two underground structures: (1) an impervious structure and (2) a draining structure. Both structures are shown to cause significant mixing processes occurring between shallow and deeper aquifers. The design technique used for draining structures is shown to have the greatest impact, generating a decrease in mean age of more than 80% under the structure. Groundwater age modeling is shown to be relevant for highlighting the role played by underground structures in advective-dispersive flows in urban areas.

  18. Structures of Staphylococcus aureus peptide deformylase in complex with two classes of new inhibitors.

    PubMed

    Lee, Sang Jae; Lee, Seung-Jae; Lee, Seung Kyu; Yoon, Hye-Jin; Lee, Hyung Ho; Kim, Kyeong Kyu; Lee, Bong Jin; Lee, Byung Il; Suh, Se Won

    2012-07-01

    Peptide deformylase (PDF) catalyzes the removal of the formyl group from the N-terminal methionine residue in newly synthesized polypeptides, which is an essential process in bacteria. Four new inhibitors of PDF that belong to two different classes, hydroxamate/pseudopeptide compounds [PMT387 (7a) and PMT497] and reverse-hydroxamate/nonpeptide compounds [PMT1039 (15e) and PMT1067], have been developed. These compounds inhibited the growth of several pathogens involved in respiratory-tract infections, such as Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae, and leading nosocomial pathogens such as Staphylococcus aureus and Klebsiella pneumoniae with a minimum inhibitory concentration (MIC) in the range 0.1-0.8 mg ml(-1). Interestingly, the reverse-hydroxamate/nonpeptide compounds showed a 250-fold higher antimicrobial activity towards S. aureus, although the four compounds showed similar K(i) values against S. aureus PDF enzymes, with K(i) values in the 11-85 nM range. To provide a structural basis for the discovery of additional PDF inhibitors, the crystal structures of S. aureus PDF in complex with the four inhibitors were determined at resolutions of 1.90-2.30 Å. The inhibitor-bound structures displayed distinct deviations depending on the inhibitor class. The distance between the Zn(2+) ion and the carbonyl O atom of the hydroxamate inhibitors (or the hydroxyl O atom of the reverse-hydroxamate inhibitors) appears to be correlated to S. aureus inhibition activity. The structural information reported in this study should aid in the discovery of new PDF inhibitors that can be used as novel antibacterial drugs. PMID:22751663

  19. The effect of verb semantic class and verb frequency (entrenchment) on children's and adults' graded judgements of argument-structure overgeneralization errors.

    PubMed

    Ambridge, Ben; Pine, Julian M; Rowland, Caroline F; Young, Chris R

    2008-01-01

    Participants (aged 5-6 yrs, 9-10 yrs and adults) rated (using a five-point scale) grammatical (intransitive) and overgeneralized (transitive causative)(1) uses of a high frequency, low frequency and novel intransitive verb from each of three semantic classes [Pinker, S. (1989a). Learnability and cognition: The acquisition of argument structure. Cambridge, MA: MIT Press]: "directed motion" (fall, tumble), "going out of existence" (disappear, vanish) and "semivoluntary expression of emotion" (laugh, giggle). In support of Pinker's semantic verb class hypothesis, participants' preference for grammatical over overgeneralized uses of novel (and English) verbs increased between 5-6 yrs and 9-10 yrs, and was greatest for the latter class, which is associated with the lowest degree of direct external causation (the prototypical meaning of the transitive causative construction). In support of Braine and Brooks's [Braine, M.D.S., & Brooks, P.J. (1995). Verb argument strucure and the problem of avoiding an overgeneral grammar. In M. Tomasello & W. E. Merriman (Eds.), Beyond names for things: Young children's acquisition of verbs (pp. 352-376). Hillsdale, NJ: Erlbaum] entrenchment hypothesis, all participants showed the greatest preference for grammatical over ungrammatical uses of high frequency verbs, with this preference smaller for low frequency verbs, and smaller again for novel verbs. We conclude that both the formation of semantic verb classes and entrenchment play a role in children's retreat from argument-structure overgeneralization errors. PMID:17316595

  20. Structural analysis of an epsilon-class glutathione transferase from housefly, Musca domestica.

    PubMed

    Nakamura, Chihiro; Yajima, Shunsuke; Miyamoto, Toru; Sue, Masayuki

    2013-01-25

    Glutathione transferases (GSTs) play an important role in the detoxification of insecticides, and as such, they are a key contributor to enhanced resistance to insecticides. In the housefly (Musca domestica), two epsilon-class GSTs (MdGST6A and MdGST6B) that share high sequence homology have been identified, which are believed to be involved in resistance against insecticides. The structural determinants controlling the substrate specificity and enzyme activity of MdGST6s are unknown. The aim of this study was to crystallize and perform structural analysis of the GST isozyme, MdGST6B. The crystal structure of MdGST6B complexed with reduced glutathione (GSH) was determined at a resolution of 1.8 Å. MdGST6B was found to have a typical GST folding comprised of N-terminal and C-terminal domains. Arg113 and Phe121 on helix 4 were shown to protrude into the substrate binding pocket, and as a result, the entrance of the substrate binding pocket was narrower compared to delta- and epsilon-class GSTs from Africa malaria vector Anopheles gambiae, agGSTd1-6 and agGSTe2, respectively. This substrate pocket narrowing is partly due to the presence of a π-helix in the middle of helix 4. Among the six residues that donate hydrogen bonds to GSH, only Arg113 was located in the C-terminal domain. Ala substitution of Arg113 did not have a significant effect on enzyme activity, suggesting that the Arg113 hydrogen bond does not play a crucial role in catalysis. On the other hand, mutation at Phe108, located just below Arg113 in the binding pocket, reduced the affinity and catalytic activity to both GSH and the electrophilic co-substrate, 1-chloro-2,4-dinitrobenzene. PMID:23268341

  1. Structural determinants for ligand capture by a class II preQ1 riboswitch.

    PubMed

    Kang, Mijeong; Eichhorn, Catherine D; Feigon, Juli

    2014-02-11

    Prequeuosine (preQ1) riboswitches are RNA regulatory elements located in the 5' UTR of genes involved in the biosynthesis and transport of preQ1, a precursor of the modified base queuosine universally found in four tRNAs. The preQ1 class II (preQ1-II) riboswitch regulates preQ1 biosynthesis at the translational level. We present the solution NMR structure and conformational dynamics of the 59 nucleotide Streptococcus pneumoniae preQ1-II riboswitch bound to preQ1. Unlike in the preQ1 class I (preQ1-I) riboswitch, divalent cations are required for high-affinity binding. The solution structure is an unusual H-type pseudoknot featuring a P4 hairpin embedded in loop 3, which forms a three-way junction with the other two stems. (13)C relaxation and residual dipolar coupling experiments revealed interhelical flexibility of P4. We found that the P4 helix and flanking adenine residues play crucial and unexpected roles in controlling pseudoknot formation and, in turn, sequestering the Shine-Dalgarno sequence. Aided by divalent cations, P4 is poised to act as a "screw cap" on preQ1 recognition to block ligand exit and stabilize the binding pocket. Comparison of preQ1-I and preQ1-II riboswitch structures reveals that whereas both form H-type pseudoknots and recognize preQ1 using one A, C, or U nucleotide from each of three loops, these nucleotides interact with preQ1 differently, with preQ1 inserting into different grooves. Our studies show that the preQ1-II riboswitch uses an unusual mechanism to harness exquisite control over queuosine metabolism. PMID:24469808

  2. Structural diversity and transcription of class III peroxidases from Arabidopsis thaliana.

    PubMed

    Welinder, Karen G; Justesen, Annemarie F; Kjaersgård, Inger V H; Jensen, Rikke B; Rasmussen, Søren K; Jespersen, Hans M; Duroux, Laurent

    2002-12-01

    Understanding peroxidase function in plants is complicated by the lack of substrate specificity, the high number of genes, their diversity in structure and our limited knowledge of peroxidase gene transcription and translation. In the present study we sequenced expressed sequence tags (ESTs) encoding novel heme-containing class III peroxidases from Arabidopsis thaliana and annotated 73 full-length genes identified in the genome. In total, transcripts of 58 of these genes have now been observed. The expression of individual peroxidase genes was assessed in organ-specific EST libraries and compared to the expression of 33 peroxidase genes which we analyzed in whole plants 3, 6, 15, 35 and 59 days after sowing. Expression was assessed in root, rosette leaf, stem, cauline leaf, flower bud and cell culture tissues using the gene-specific and highly sensitive reverse transcriptase-polymerase chain reaction (RT-PCR). We predicted that 71 genes could yield stable proteins folded similarly to horseradish peroxidase (HRP). The putative mature peroxidases derived from these genes showed 28-94% amino acid sequence identity and were all targeted to the endoplasmic reticulum by N-terminal signal peptides. In 20 peroxidases these signal peptides were followed by various N-terminal extensions of unknown function which are not present in HRP. Ten peroxidases showed a C-terminal extension indicating vacuolar targeting. We found that the majority of peroxidase genes were expressed in root. In total, class III peroxidases accounted for an impressive 2.2% of root ESTs. Rather few peroxidases showed organ specificity. Most importantly, genes expressed constitutively in all organs and genes with a preference for root represented structurally diverse peroxidases (< 70% sequence identity). Furthermore, genes appearing in tandem showed distinct expression profiles. The alignment of 73 Arabidopsis peroxidase sequences provides an easy access to the identification of orthologous peroxidases

  3. Structural Insights into a Novel Class of Aspartate Aminotransferase from Corynebacterium glutamicum.

    PubMed

    Son, Hyeoncheol Francis; Kim, Kyung-Jin

    2016-01-01

    Aspartate aminotransferase from Corynebacterium glutamicum (CgAspAT) is a PLP-dependent enzyme that catalyzes the production of L-aspartate and α-ketoglutarate from L-glutamate and oxaloacetate in L-lysine biosynthesis. In order to understand the molecular mechanism of CgAspAT and compare it with those of other aspartate aminotransferases (AspATs) from the aminotransferase class I, we determined the crystal structure of CgAspAT. CgAspAT functions as a dimer, and the CgAspAT monomer consists of two domains, the core domain and the auxiliary domain. The PLP cofactor is found to be bound to CgAspAT and stabilized through unique residues. In our current structure, a citrate molecule is bound at the active site of one molecule and mimics binding of the glutamate substrate. The residues involved in binding of the PLP cofactor and the glutamate substrate were confirmed by site-directed mutagenesis. Interestingly, compared with other AspATs from aminotransferase subgroup Ia and Ib, CgAspAT exhibited unique binding sites for both cofactor and substrate; moreover, it was found to have unusual structural features in the auxiliary domain. Based on these structural differences, we propose that CgAspAT does not belong to either subgroup Ia or Ib, and can be categorized into a subgroup Ic. The phylogenetic tree and RMSD analysis also indicates that CgAspAT is located in an independent AspAT subgroup. PMID:27355211

  4. The Structure of Genealogies in the Presence of Purifying Selection: A Fitness-Class Coalescent

    PubMed Central

    Walczak, Aleksandra M.; Nicolaisen, Lauren E.; Plotkin, Joshua B.; Desai, Michael M.

    2012-01-01

    Compared to a neutral model, purifying selection distorts the structure of genealogies and hence alters the patterns of sampled genetic variation. Although these distortions may be common in nature, our understanding of how we expect purifying selection to affect patterns of molecular variation remains incomplete. Genealogical approaches such as coalescent theory have proven difficult to generalize to situations involving selection at many linked sites, unless selection pressures are extremely strong. Here, we introduce an effective coalescent theory (a “fitness-class coalescent”) to describe the structure of genealogies in the presence of purifying selection at many linked sites. We use this effective theory to calculate several simple statistics describing the expected patterns of variation in sequence data, both at the sites under selection and at linked neutral sites. Our analysis combines a description of the allele frequency spectrum in the presence of purifying selection with the structured coalescent approach of Kaplan et al. (1988), to trace the ancestry of individuals through the distribution of fitnesses within the population. We also derive our results using a more direct extension of the structured coalescent approach of Hudson and Kaplan (1994). We find that purifying selection leads to patterns of genetic variation that are related but not identical to a neutrally evolving population in which population size has varied in a specific way in the past. PMID:22135349

  5. Structural Insights into a Novel Class of Aspartate Aminotransferase from Corynebacterium glutamicum

    PubMed Central

    Son, Hyeoncheol Francis; Kim, Kyung-Jin

    2016-01-01

    Aspartate aminotransferase from Corynebacterium glutamicum (CgAspAT) is a PLP-dependent enzyme that catalyzes the production of L-aspartate and α-ketoglutarate from L-glutamate and oxaloacetate in L-lysine biosynthesis. In order to understand the molecular mechanism of CgAspAT and compare it with those of other aspartate aminotransferases (AspATs) from the aminotransferase class I, we determined the crystal structure of CgAspAT. CgAspAT functions as a dimer, and the CgAspAT monomer consists of two domains, the core domain and the auxiliary domain. The PLP cofactor is found to be bound to CgAspAT and stabilized through unique residues. In our current structure, a citrate molecule is bound at the active site of one molecule and mimics binding of the glutamate substrate. The residues involved in binding of the PLP cofactor and the glutamate substrate were confirmed by site-directed mutagenesis. Interestingly, compared with other AspATs from aminotransferase subgroup Ia and Ib, CgAspAT exhibited unique binding sites for both cofactor and substrate; moreover, it was found to have unusual structural features in the auxiliary domain. Based on these structural differences, we propose that CgAspAT does not belong to either subgroup Ia or Ib, and can be categorized into a subgroup Ic. The phylogenetic tree and RMSD analysis also indicates that CgAspAT is located in an independent AspAT subgroup. PMID:27355211

  6. The Indris Have Got Rhythm! Timing and Pitch Variation of a Primate Song Examined between Sexes and Age Classes

    PubMed Central

    Gamba, Marco; Torti, Valeria; Estienne, Vittoria; Randrianarison, Rose M.; Valente, Daria; Rovara, Paolo; Bonadonna, Giovanna; Friard, Olivier; Giacoma, Cristina

    2016-01-01

    A crucial, common feature of speech and music is that they show non-random structures over time. It is an open question which of the other species share rhythmic abilities with humans, but in most cases the lack of knowledge about their behavioral displays prevents further studies. Indris are the only lemurs who sing. They produce loud howling cries that can be heard at several kilometers, in which all members of a group usually sing. We tested whether overlapping and turn-taking during the songs followed a precise pattern by analysing the temporal structure of the individuals' contribution to the song. We found that both dominants (males and females) and non-dominants influenced the onset timing one another. We have found that the dominant male and the dominant female in a group overlapped each other more frequently than they did with the non-dominants. We then focused on the temporal and frequency structure of particular phrases occurring during the song. Our results show that males and females have dimorphic inter-onset intervals during the phrases. Moreover, median frequencies of the unit emitted in the phrases also differ between the sexes, with males showing higher frequencies when compared to females. We have not found an effect of age on the temporal and spectral structure of the phrases. These results indicate that singing in indris has a high behavioral flexibility and varies according to social and individual factors. The flexible spectral structure of the phrases given during the song may underlie perceptual abilities that are relatively unknown in other non-human primates, such as the ability to recognize particular pitch patterns. PMID:27378834

  7. Sequence-structure based phylogeny of GPCR Class A Rhodopsin receptors.

    PubMed

    Kakarala, Kavita Kumari; Jamil, Kaiser

    2014-05-01

    Current methods of G protein coupled receptors (GPCRs) phylogenetic classification are sequence based and therefore inappropriate for highly divergent sequences, sharing low sequence identity. In this study, sequence structure profile based alignment generated by PROMALS3D was used to understand the GPCR Class A Rhodopsin superfamily evolution using the MEGA 5 software. Phylogenetic analysis included a combination of Neighbor-Joining method and Maximum Likelihood method, with 1000 bootstrap replicates. Our study was able to identify potential ligand association for Class A Orphans and putative/unclassified Class A receptors with no cognate ligand information: GPR21 and GPR52 with fatty acids; GPR75 with Neuropeptide Y; GPR82, GPR18, GPR141 with N-arachidonylglycine; GPR176 with Free fatty acids, GPR10 with Tachykinin & Neuropeptide Y; GPR85 with ATP, ADP & UDP glucose; GPR151 with Galanin; GPR153 and GPR162 with Adrenalin, Noradrenalin; GPR146, GPR139, GPR142 with Neuromedin, Ghrelin, Neuromedin U-25 & Thyrotropin-releasing hormone; GPR171 with ATP, ADP & UDP Glucose; GPR88, GPR135, GPR161, GPR101with 11-cis-retinal; GPR83 with Tackykinin; GPR148 with Prostanoids, GPR109b, GPR81, GPR31with ATP & UTP and GPR150 with GnRH I & GnRHII. Furthermore, we suggest that this study would prove useful in re-classification of receptors, selecting templates for homology modeling and identifying ligands which may show cross reactivity with other GPCRs as signaling via multiple ligands play a significant role in disease modulation. PMID:24503482

  8. MAGNETIC STRUCTURE PRODUCING X- AND M-CLASS SOLAR FLARES IN SOLAR ACTIVE REGION 11158

    SciTech Connect

    Inoue, S.; Magara, T.; Choe, G. S.; Hayashi, K.; Shiota, D.

    2013-06-10

    We study the three-dimensional magnetic structure of the solar active region 11158, which produced one X-class and several M-class flares on 2011 February 13-16. We focus on the magnetic twist in four flare events, M6.6, X2.2, M1.0, and M1.1. The magnetic twist is estimated from the nonlinear force-free field extrapolated from the vector fields obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory using the magnetohydrodynamic relaxation method developed by Inoue et al. We found that strongly twisted lines ranging from half-turn to one-turn twists were built up just before the M6.6 and X2.2 flares and disappeared after that. Because most of the twists remaining after these flares were less than a half-turn twist, this result suggests that the buildup of magnetic twist over the half-turn twist is a key process in the production of large flares. On the other hand, even though these strong twists were also built up just before the M1.0 and M1.1 flares, most of them remained afterward. Careful topological analysis before the M1.0 and M1.1 flares shows that the strongly twisted lines were surrounded mostly by the weakly twisted lines formed in accordance with the clockwise motion of the positive sunspot, whose footpoints are rooted in strong magnetic flux regions. These results imply that these weakly twisted lines might suppress the activity of the strongly twisted lines in the last two M-class flares.

  9. Sensitivity analysis of the age-structured malaria transmission model

    NASA Astrophysics Data System (ADS)

    Addawe, Joel M.; Lope, Jose Ernie C.

    2012-09-01

    We propose an age-structured malaria transmission model and perform sensitivity analyses to determine the relative importance of model parameters to disease transmission. We subdivide the human population into two: preschool humans (below 5 years) and the rest of the human population (above 5 years). We then consider two sets of baseline parameters, one for areas of high transmission and the other for areas of low transmission. We compute the sensitivity indices of the reproductive number and the endemic equilibrium point with respect to the two sets of baseline parameters. Our simulations reveal that in areas of either high or low transmission, the reproductive number is most sensitive to the number of bites by a female mosquito on the rest of the human population. For areas of low transmission, we find that the equilibrium proportion of infectious pre-school humans is most sensitive to the number of bites by a female mosquito. For the rest of the human population it is most sensitive to the rate of acquiring temporary immunity. In areas of high transmission, the equilibrium proportion of infectious pre-school humans and the rest of the human population are both most sensitive to the birth rate of humans. This suggests that strategies that target the mosquito biting rate on pre-school humans and those that shortens the time in acquiring immunity can be successful in preventing the spread of malaria.

  10. Cooperation-controlled learning for explicit class structure in self-organizing maps.

    PubMed

    Kamimura, Ryotaro

    2014-01-01

    We attempt to demonstrate the effectiveness of multiple points of view toward neural networks. By restricting ourselves to two points of view of a neuron, we propose a new type of information-theoretic method called "cooperation-controlled learning." In this method, individual and collective neurons are distinguished from one another, and we suppose that the characteristics of individual and collective neurons are different. To implement individual and collective neurons, we prepare two networks, namely, cooperative and uncooperative networks. The roles of these networks and the roles of individual and collective neurons are controlled by the cooperation parameter. As the parameter is increased, the role of cooperative networks becomes more important in learning, and the characteristics of collective neurons become more dominant. On the other hand, when the parameter is small, individual neurons play a more important role. We applied the method to the automobile and housing data from the machine learning database and examined whether explicit class boundaries could be obtained. Experimental results showed that cooperation-controlled learning, in particular taking into account information on input units, could be used to produce clearer class structure than conventional self-organizing maps. PMID:25309950

  11. Structural homology between lymphocyte receptors for high endothelium and class III extracellular matrix receptor.

    PubMed Central

    Gallatin, W M; Wayner, E A; Hoffman, P A; St John, T; Butcher, E C; Carter, W G

    1989-01-01

    We have identified extensive structural homology between one type of heterotypic adhesion receptor (HAR) involved in lymphocyte interactions with high endothelium in lymphoid organs and a collagen-binding protein, termed class III extracellular matrix receptor (ECMRIII), expressed on most nucleated cell types. Both receptors have been described as heterogeneous 90-kDa transmembrane glycoproteins, referred to here as gp90. Monoclonal anti-HAR antibodies, Hermes-1 and Hutch-1, and monoclonal anti-ECMRIII antibodies, P1G12 and P3H9, were utilized to compare the two receptors. (i) All these monoclonal antibodies immunoprecipitated major gp90 components as well as uncharacterized additional higher molecular mass antigens of 120-200 kDa in human and macaque fibroblasts and peripheral blood mononuclear cells. (ii) Competitive binding analyses with the antibodies identified distinct epitopes present on gp90. (iii) Enzymatic and chemical digestions generated identical peptide fragments from all the antigens in human and macaque fibroblasts and peripheral blood mononuclear cells. (iv) Sequential immunoprecipitation with P1G12 followed by the other monoclonal antibodies indicated that all gp90 species reactive with Hermes-1 and Hutch-1 also expressed the P1G12 defined epitope. In reciprocal experiments, Hermes-1 and Hutch-1 immunoprecipitation did not completely remove all P1G12-reactive gp90 from cellular extracts. One inference from these data would be that gp90 is serologically heterogeneous, encompassing HARs as a major subset of this broadly expressed class of molecules. Images PMID:2471973

  12. A Class of Rigid Linker-bearing Glucosides for Membrane Protein Structural Study

    PubMed Central

    Sadaf, Aiman; Mortensen, Jonas S.; Capaldi, Stefano; Tikhonova, Elena; Hariharan, Parameswaran; de Castro Ribeiro, Orquidea; Loland, Claus J; Guan, Lan; Byrne, Bernadette

    2015-01-01

    Membrane proteins are amphipathic bio-macromolecules incompatible with the polar environments of aqueous media. Conventional detergents encapsulate the hydrophobic surfaces of membrane proteins allowing them to exist in aqueous solution. Membrane proteins stabilized by detergent micelles are used for structural and functional analysis. Despite the availability of a large number of detergents, only a few agents are sufficiently effective at maintaining the integrity of membrane proteins to allow successful crystallization. In the present study, we describe a novel class of synthetic amphiphiles with a branched tail group and a triglucoside head group. These head and tail groups were connected via an amide or ether linkage by using a tris(hydroxylmethyl)aminomethane (TRIS) or neopentyl glycol (NPG) linker to produce TRIS-derived triglucosides (TDTs) and NPG-derived triglucosides (NDTs), respectively. Members of this class conferred enhanced stability on target membrane proteins compared to conventional detergents. Because of straightforward synthesis of the novel agents and their favourable effects on a range of membrane proteins, these agents should be of wide applicability to membrane protein science. PMID:27110345

  13. Cooperation-Controlled Learning for Explicit Class Structure in Self-Organizing Maps

    PubMed Central

    Kamimura, Ryotaro

    2014-01-01

    We attempt to demonstrate the effectiveness of multiple points of view toward neural networks. By restricting ourselves to two points of view of a neuron, we propose a new type of information-theoretic method called “cooperation-controlled learning.” In this method, individual and collective neurons are distinguished from one another, and we suppose that the characteristics of individual and collective neurons are different. To implement individual and collective neurons, we prepare two networks, namely, cooperative and uncooperative networks. The roles of these networks and the roles of individual and collective neurons are controlled by the cooperation parameter. As the parameter is increased, the role of cooperative networks becomes more important in learning, and the characteristics of collective neurons become more dominant. On the other hand, when the parameter is small, individual neurons play a more important role. We applied the method to the automobile and housing data from the machine learning database and examined whether explicit class boundaries could be obtained. Experimental results showed that cooperation-controlled learning, in particular taking into account information on input units, could be used to produce clearer class structure than conventional self-organizing maps. PMID:25309950

  14. Differential predation by age and sex classes in blue wildebeest in Serengeti: study of a modern carnivore den in Olduvai Gorge (Tanzania).

    PubMed

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Martínez-Maza, Cayetana; Mabulla, Audax; Baquedano, Enrique

    2015-01-01

    Age and sex selection of prey is an aspect of predator ecology which has been extensively studied in both temperate and African ecosystems. This dimension, along with fecundity, survival rates of prey and mortality factors other than predation are important in laying down the population dynamics of prey and have important implications in the management of species. A carnivore den located in the short-grassland ecological unit of the Serengeti was studied. Sex- and age- class (using five age categories) of the wildebeest remains recovered were analyzed through horn morphology, biometrics of the bones and tooth wear patterns. We compared our results with previous studies from lion and hyaena kills through multivariate analyses. Seasonality of the accumulation was analyzed through tooth histology. PCA and CVA results show that age class selection by predators depends on season, habitat-type, and growth rate of the wildebeest population. Female-biased predation was found to contradict classical hypotheses based on territorial male behaviour. The lion and spotted hyaena showed strong selection on age classes, contrary to previous studies. Migratory wildebeest sex ratio is regulated through differential predation by seasons and female deaths in the wet season are a trade-off for population stability. These data are crucial for an effective management of the species and the new method created may be useful for different carnivore species and their prey. PMID:26017363

  15. Differential Predation by Age and Sex Classes in Blue Wildebeest in Serengeti: Study of a Modern Carnivore Den in Olduvai Gorge (Tanzania)

    PubMed Central

    Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel; Martínez-Maza, Cayetana; Mabulla, Audax; Baquedano, Enrique

    2015-01-01

    Age and sex selection of prey is an aspect of predator ecology which has been extensively studied in both temperate and African ecosystems. This dimension, along with fecundity, survival rates of prey and mortality factors other than predation are important in laying down the population dynamics of prey and have important implications in the management of species. A carnivore den located in the short-grassland ecological unit of the Serengeti was studied. Sex- and age- class (using five age categories) of the wildebeest remains recovered were analyzed through horn morphology, biometrics of the bones and tooth wear patterns. We compared our results with previous studies from lion and hyaena kills through multivariate analyses. Seasonality of the accumulation was analyzed through tooth histology. PCA and CVA results show that age class selection by predators depends on season, habitat-type, and growth rate of the wildebeest population. Female-biased predation was found to contradict classical hypotheses based on territorial male behaviour. The lion and spotted hyaena showed strong selection on age classes, contrary to previous studies. Migratory wildebeest sex ratio is regulated through differential predation by seasons and female deaths in the wet season are a trade-off for population stability. These data are crucial for an effective management of the species and the new method created may be useful for different carnivore species and their prey. PMID:26017363

  16. Family Structure and the Timing of Transitions from 70 to 103 Years of Age.

    ERIC Educational Resources Information Center

    Johnson, Colleen L.; Troll, Lillian

    1996-01-01

    Using a cross-sectional analysis of 250 white individuals, 70-103 years of age, this article questions whether a vertical family structure is found with increasing age. Findings indicate, among other things, that at least until age 90 the proportion of individuals with a vertical family structure with four generations never exceeds the numbers of…

  17. Ectopic Lymphoid Structures Support Ongoing Production of Class-Switched Autoantibodies in Rheumatoid Synovium

    PubMed Central

    Manzo, Antonio; Kelly, Stephen; Blades, Mark C; Kirkham, Bruce; Spencer, Jo; Pitzalis, Costantino

    2009-01-01

    Background Follicular structures resembling germinal centres (GCs) that are characterized by follicular dendritic cell (FDC) networks have long been recognized in chronically inflamed tissues in autoimmune diseases, including the synovium of rheumatoid arthritis (RA). However, it is debated whether these ectopic structures promote autoimmunity and chronic inflammation driving the production of pathogenic autoantibodies. Anti-citrullinated protein/peptide antibodies (ACPA) are highly specific markers of RA, predict a poor prognosis, and have been suggested to be pathogenic. Therefore, the main study objectives were to determine whether ectopic lymphoid structures in RA synovium: (i) express activation-induced cytidine deaminase (AID), the enzyme required for somatic hypermutation and class-switch recombination (CSR) of Ig genes; (ii) support ongoing CSR and ACPA production; and (iii) remain functional in a RA/severe combined immunodeficiency (SCID) chimera model devoid of new immune cell influx into the synovium. Methods and Findings Using immunohistochemistry (IHC) and quantitative Taqman real-time PCR (QT-PCR) in synovial tissue from 55 patients with RA, we demonstrated that FDC+ structures invariably expressed AID with a distribution resembling secondary lymphoid organs. Further, AID+/CD21+ follicular structures were surrounded by ACPA+/CD138+ plasma cells, as demonstrated by immune reactivity to citrullinated fibrinogen. Moreover, we identified a novel subset of synovial AID+/CD20+ B cells outside GCs resembling interfollicular large B cells. In order to gain direct functional evidence that AID+ structures support CSR and in situ manufacturing of class-switched ACPA, 34 SCID mice were transplanted with RA synovium and humanely killed at 4 wk for harvesting of transplants and sera. Persistent expression of AID and Iγ-Cμ circular transcripts (identifying ongoing IgM-IgG class-switching) was observed in synovial grafts expressing FDCs/CD21L. Furthermore, synovial

  18. Role of post-translational modifications on structure, function and pharmacology of class C G protein-coupled receptors.

    PubMed

    Nørskov-Lauritsen, Lenea; Bräuner-Osborne, Hans

    2015-09-15

    G protein-coupled receptors are divided into three classes (A, B and C) based on homology of their seven transmembrane domains. Class C is the smallest class with 22 human receptor subtypes including eight metabotropic glutamate (mGlu1-8) receptors, two GABAB receptors (GABAB1 and GABAB2), three taste receptors (T1R1-3), one calcium-sensing (CaS) receptor, one GPCR, class C, group 6, subtype A (GPRC6) receptor, and seven orphan receptors. G protein-coupled receptors undergo a number of post-translational modifications, which regulate their structure, function and/or pharmacology. Here, we review the existence of post-translational modifications in class C G protein-coupled receptors and their regulatory roles, with particular focus on glycosylation, phosphorylation, ubiquitination, SUMOylation, disulphide bonding and lipidation. PMID:25981296

  19. Quaternary structure defines a large class of amyloid-β oligomers neutralized by sequestration

    PubMed Central

    Liu, Peng; Reed, Miranda N.; Kotilinek, Linda A.; Grant, Marianne K.O.; Forster, Colleen L.; Qiang, Wei; Shapiro, Samantha L.; Reichl, John H.; Chiang, Angie C.A.; Jankowsky, Joanna L.; Wilmot, Carrie M.; Cleary, James P.; Zahs, Kathleen R.; Ashe, Karen H.

    2015-01-01

    Summary The accumulation of amyloid-β (Aβ) as amyloid fibrils and toxic oligomers is an important step in the development of Alzheimer's disease (AD). However, there are numerous potentially toxic oligomers and little is known about their neurological effects when generated in the living brain. Here, we show that Aβ oligomers can be assigned to one of at least two classes (Type 1 and Type 2) based on their temporal, spatial and structural relationships to amyloid fibrils. The Type 2 oligomers are related to amyloid fibrils and represent the majority of oligomers generated in vivo, but remain confined to the vicinity of amyloid plaques and do not impair cognition at levels relevant to AD. Type 1 oligomers are unrelated to amyloid fibrils and may have greater potential to cause global neural dysfunction in AD because they are dispersed. These results refine our understanding of the pathogenicity of Aβ oligomers in vivo. PMID:26051935

  20. Discovery and refinement of a new structural class of potent peptide deformylase inhibitors.

    PubMed

    Boularot, Adrien; Giglione, Carmela; Petit, Sylvain; Duroc, Yann; Alves de Sousa, Rodolphe; Larue, Valéry; Cresteil, Thierry; Dardel, Frédéric; Artaud, Isabelle; Meinnel, Thierry

    2007-01-11

    New classes of antibiotics are urgently needed to counter increasing levels of pathogen resistance. Peptide deformylase (PDF) was originally selected as a specific bacterial target, but a human homologue, the inhibition of which causes cell death, was recently discovered. We developed a dual-screening strategy for selecting highly effective compounds with low inhibition effect against human PDF. We selected a new scaffold in vitro that discriminated between human and bacterial PDFs. Analyses of structure-activity relationships identified potent antibiotics such as 2-(5-bromo-1H-indol-3-yl)-N-hydroxyacetamide (6b) with the same mode of action in vivo as previously identified PDF inhibitors but without the apoptotic effects of these inhibitors in human cells. PMID:17201406

  1. The Two-Peptide (Class-IIb) Bacteriocins: Genetics, Biosynthesis, Structure, and Mode of Action

    NASA Astrophysics Data System (ADS)

    Nissen-Meyer, Jon; Oppegård, Camilla; Rogne, Per; Haugen, Helen Sophie; Kristiansen, Per Eugen

    The two-peptide (class-IIb) bacteriocins consist of two different peptides, both of which are required to obtain high antimicrobial activity. These bacteriocins kill target-cells by inducing membrane-leakage and they seem to display some specificity with respect to the molecules they transfer across membranes. The genes encoding the two peptides of two-peptide bacteriocins are next to each other on the same operon. In the same or a nearby operon are genes encoding (i) the immunity protein that protects the bacteriocin-producer from its own bacteriocin, (ii) a dedicated ABC-transporter that exports the bacteriocin from cells and cleaves off the N-terminal bacteriocin leader sequence, and (iii) an accessory protein whose exact function has not been fully clarified. Some two-peptide bacteriocins appear to be produced constitutively, whereas the production of other two-peptide bacteriocins is regulated through a three-component regulatory system that consists of a peptide pheromone, a membrane-associated histidine protein kinase, and response regulators. It has recently been proposed that the two peptides of (some) two-peptide bacteriocins may form a membrane-penetrating helix-helix structure involving helix-helix interacting GxxxG-motifs present in all currently characterized two-peptide bacteriocins. It has also been suggested that the helix-helix structure interacts with an integrated membrane (transport) protein, thus inducing a conformational change in the protein, which in turn causes membrane-leakage. This proposed mode-of-action is similar to that of the pediocin-like (class-IIa) bacteriocins and lactococcin A, which bind to a part of the mannose phosphotransferase permease that is embedded in the cell membrane, thereby altering the conformation of the ­permease in a manner that causes membrane-leakage and cell death.

  2. The poplar Phi class glutathione transferase: expression, activity and structure of GSTF1

    PubMed Central

    Pégeot, Henri; Koh, Cha San; Petre, Benjamin; Mathiot, Sandrine; Duplessis, Sébastien; Hecker, Arnaud; Didierjean, Claude; Rouhier, Nicolas

    2014-01-01

    Glutathione transferases (GSTs) constitute a superfamily of enzymes with essential roles in cellular detoxification and secondary metabolism in plants as in other organisms. Several plant GSTs, including those of the Phi class (GSTFs), require a conserved catalytic serine residue to perform glutathione (GSH)-conjugation reactions. Genomic analyses revealed that terrestrial plants have around ten GSTFs, eight in the Populus trichocarpa genome, but their physiological functions and substrates are mostly unknown. Transcript expression analyses showed a predominant expression of all genes both in reproductive (female flowers, fruits, floral buds) and vegetative organs (leaves, petioles). Here, we show that the recombinant poplar GSTF1 (PttGSTF1) possesses peroxidase activity toward cumene hydroperoxide and GSH-conjugation activity toward model substrates such as 2,4-dinitrochlorobenzene, benzyl and phenetyl isothiocyanate, 4-nitrophenyl butyrate and 4-hydroxy-2-nonenal but interestingly not on previously identified GSTF-class substrates. In accordance with analytical gel filtration data, crystal structure of PttGSTF1 showed a canonical dimeric organization with bound GSH or 2-(N-morpholino)ethanesulfonic acid molecules. The structure of these protein-substrate complexes allowed delineating the residues contributing to both the G and H sites that form the active site cavity. In sum, the presence of GSTF1 transcripts and proteins in most poplar organs especially those rich in secondary metabolites such as flowers and fruits, together with its GSH-conjugation activity and its documented stress-responsive expression suggest that its function is associated with the catalytic transformation of metabolites and/or peroxide removal rather than with ligandin properties as previously reported for other GSTFs. PMID:25566286

  3. The poplar Phi class glutathione transferase: expression, activity and structure of GSTF1.

    PubMed

    Pégeot, Henri; Koh, Cha San; Petre, Benjamin; Mathiot, Sandrine; Duplessis, Sébastien; Hecker, Arnaud; Didierjean, Claude; Rouhier, Nicolas

    2014-01-01

    Glutathione transferases (GSTs) constitute a superfamily of enzymes with essential roles in cellular detoxification and secondary metabolism in plants as in other organisms. Several plant GSTs, including those of the Phi class (GSTFs), require a conserved catalytic serine residue to perform glutathione (GSH)-conjugation reactions. Genomic analyses revealed that terrestrial plants have around ten GSTFs, eight in the Populus trichocarpa genome, but their physiological functions and substrates are mostly unknown. Transcript expression analyses showed a predominant expression of all genes both in reproductive (female flowers, fruits, floral buds) and vegetative organs (leaves, petioles). Here, we show that the recombinant poplar GSTF1 (PttGSTF1) possesses peroxidase activity toward cumene hydroperoxide and GSH-conjugation activity toward model substrates such as 2,4-dinitrochlorobenzene, benzyl and phenetyl isothiocyanate, 4-nitrophenyl butyrate and 4-hydroxy-2-nonenal but interestingly not on previously identified GSTF-class substrates. In accordance with analytical gel filtration data, crystal structure of PttGSTF1 showed a canonical dimeric organization with bound GSH or 2-(N-morpholino)ethanesulfonic acid molecules. The structure of these protein-substrate complexes allowed delineating the residues contributing to both the G and H sites that form the active site cavity. In sum, the presence of GSTF1 transcripts and proteins in most poplar organs especially those rich in secondary metabolites such as flowers and fruits, together with its GSH-conjugation activity and its documented stress-responsive expression suggest that its function is associated with the catalytic transformation of metabolites and/or peroxide removal rather than with ligandin properties as previously reported for other GSTFs. PMID:25566286

  4. Novel 3D bio-macromolecular bilinear descriptors for protein science: Predicting protein structural classes.

    PubMed

    Marrero-Ponce, Yovani; Contreras-Torres, Ernesto; García-Jacas, César R; Barigye, Stephen J; Cubillán, Néstor; Alvarado, Ysaías J

    2015-06-01

    In the present study, we introduce novel 3D protein descriptors based on the bilinear algebraic form in the ℝ(n) space on the coulombic matrix. For the calculation of these descriptors, macromolecular vectors belonging to ℝ(n) space, whose components represent certain amino acid side-chain properties, were used as weighting schemes. Generalization approaches for the calculation of inter-amino acidic residue spatial distances based on Minkowski metrics are proposed. The simple- and double-stochastic schemes were defined as approaches to normalize the coulombic matrix. The local-fragment indices for both amino acid-types and amino acid-groups are presented in order to permit characterizing fragments of interest in proteins. On the other hand, with the objective of taking into account specific interactions among amino acids in global or local indices, geometric and topological cut-offs are defined. To assess the utility of global and local indices a classification model for the prediction of the major four protein structural classes, was built with the Linear Discriminant Analysis (LDA) technique. The developed LDA-model correctly classifies the 92.6% and 92.7% of the proteins on the training and test sets, respectively. The obtained model showed high values of the generalized square correlation coefficient (GC(2)) on both the training and test series. The statistical parameters derived from the internal and external validation procedures demonstrate the robustness, stability and the high predictive power of the proposed model. The performance of the LDA-model demonstrates the capability of the proposed indices not only to codify relevant biochemical information related to the structural classes of proteins, but also to yield suitable interpretability. It is anticipated that the current method will benefit the prediction of other protein attributes or functions. PMID:25843214

  5. Structural and compositional characterization of ``covetics'' a new class of materials containing high C concentration

    NASA Astrophysics Data System (ADS)

    Isaacs, R. A.; Herzing, A.; Forrest, D. R.; Mansour, A. N.; Lemieux, M. C.; Shugart, J.; Salamanca-Riba, L.

    2013-03-01

    ``Covetics'' are a new class of materials formed by the incorporation of high concentrations (> 6 wt %) of nanoscale carbon in a metal matrix. The carbon incorporates into the crystal structure of the host metal and remains dispersed after subsequent melting and re-solidification. The carbon is highly stable in these materials despite the absence of a predicted solid solution at such concentrations in the binary phase diagrams. Covetics have been shown to exhibit enhanced electrical, mechanical and thermal properties when compared with non-covetic metals. We have performed energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), SEM, TEM, STEM/electron energy loss spectroscopy (EELS), AFM, and Raman spectroscopy to investigate the structure of Al, Cu, and Ag covetics. Both bulk samples and thin films are investigated. Carbon was detected in the form of nanoparticles 5 nm - 200 nm in diameter with an interconnecting carbon matrix. The carbon is detectable by EDS and XPS, but not by analytical methods such as LECO and GDMS. Raman indicates a similar signal to that of CNTs in covetics. A detailed investigation of the morphology of the nanocarbon and the structure of several covetics will be presented. Supported in part by NSF MRSEC DMR 0520471.

  6. Tangled Up in Knots: Structures of Inactivated Forms of E. coli Class Ia Ribonucleotide Reductase

    SciTech Connect

    Zimanyi, Christina M.; Ando, Nozomi; Brignole, Edward J.; Asturias, Francisco J.; Stubbe, JoAnne; Drennan, Catherine L.

    2012-10-23

    Ribonucleotide reductases (RNRs) provide the precursors for DNA biosynthesis and repair and are successful targets for anticancer drugs such as clofarabine and gemcitabine. Recently, we reported that dATP inhibits E. coli class Ia RNR by driving formation of RNR subunits into {alpha}{sub 4}{beta}{sub 4} rings. Here, we present the first X-ray structure of a gemcitabine-inhibited E. coli RNR and show that the previously described {alpha}{sub 4}{beta}{sub 4} rings can interlock to form an unprecedented ({alpha}{sub 4}{beta}{sub 4}){sub 2} megacomplex. This complex is also seen in a higher-resolution dATP-inhibited RNR structure presented here, which employs a distinct crystal lattice from that observed in the gemcitabine-inhibited case. With few reported examples of protein catenanes, we use data from small-angle X-ray scattering and electron microscopy to both understand the solution conditions that contribute to concatenation in RNRs as well as present a mechanism for the formation of these unusual structures.

  7. Tangled up in knots – Structures of inactivated forms of E. coli class Ia Ribonucleotide Reductase

    PubMed Central

    Zimanyi, Christina M.; Ando, Nozomi; Brignole, Edward J.; Asturias, Francisco J.; Stubbe, JoAnne; Drennan, Catherine L.

    2012-01-01

    Summary Successful targets for anti-cancer drugs such as clofarabine and gemcitabine, ribonucleotide reductases (RNRs) provide the precursors for DNA biosynthesis and repair. Recently, we reported that dATP inhibits E. coli class Ia RNR by driving formation of RNR subunits into α4β4 rings. Here, we present the first X-ray structure of gemcitabine-inhibited E. coli RNR and show that the previously described α4β4 rings can interlock to form an unprecedented (α4β4)2 megacomplex. This complex is also seen in a higher-resolution dATP-inhibited RNR structure presented here, which employs a distinct crystal lattice from that observed in the gemcitabine-inhibited case. With few reported examples of protein catenanes, we use data from small-angle X-ray scattering and electron microscopy to both understand the solution conditions that contribute to concatenation in RNR as well as present a mechanism for the formation of these unusual structures. PMID:22727814

  8. Decorin expression is important for age-related changes in tendon structure and mechanical properties.

    PubMed

    Dunkman, Andrew A; Buckley, Mark R; Mienaltowski, Michael J; Adams, Sheila M; Thomas, Stephen J; Satchell, Lauren; Kumar, Akash; Pathmanathan, Lydia; Beason, David P; Iozzo, Renato V; Birk, David E; Soslowsky, Louis J

    2013-01-01

    The aging population is at an increased risk of tendon injury and tendinopathy. Elucidating the molecular basis of tendon aging is crucial to understanding the age-related changes in structure and function in this vulnerable tissue. In this study, the structural and functional features of tendon aging are investigated. In addition, the roles of decorin and biglycan in the aging process were analyzed using transgenic mice at both mature and aged time points. Our hypothesis is that the increase in tendon injuries in the aging population is the result of altered structural properties that reduce the biomechanical function of the tendon and consequently increase susceptibility to injury. Decorin and biglycan are important regulators of tendon structure and therefore, we further hypothesized that decreased function in aged tendons is partly the result of altered decorin and biglycan expression. Biomechanical analyses of mature (day 150) and aged (day 570) patellar tendons revealed deteriorating viscoelastic properties with age. Histology and polarized light microscopy demonstrated decreased cellularity, alterations in tenocyte shape, and reduced collagen fiber alignment in the aged tendons. Ultrastructural analysis of fibril diameter distributions indicated an altered distribution in aged tendons with an increase of large diameter fibrils. Aged wild type tendons maintained expression of decorin which was associated with the structural and functional changes seen in aged tendons. Aged patellar tendons exhibited altered and generally inferior properties across multiple assays. However, decorin-null tendons exhibited significantly decreased effects of aging compared to the other genotypes. The amelioration of the functional deficits seen in the absence of decorin in aged tendons was associated with altered tendon fibril structure. Fibril diameter distributions in the decorin-null aged tendons were comparable to those observed in the mature wild type tendon with the absence

  9. Decorin expression is important for age-related changes in tendon structure and mechanical properties

    PubMed Central

    Dunkman, Andrew A.; Buckley, Mark R.; Mienaltowski, Michael J.; Adams, Sheila M.; Thomas, Stephen J.; Satchell, Lauren; Kumar, Akash; Pathmanathan, Lydia; Beason, David P.; Iozzo, Renato V.; Birk, David E.; Soslowsky, Louis J.

    2013-01-01

    The aging population is at an increased risk of tendon injury and tendinopathy. Elucidating the molecular basis of tendon aging is crucial to understanding the age-related changes in structure and function in this vulnerable tissue. In this study, the structural and functional features of tendon aging are investigated. In addition, the roles of decorin and biglycan in the aging process were analyzed using transgenic mice at both mature and aged time points. Our hypothesis is that the increase in tendon injuries in the aging population is the result of altered structural properties that reduce the biomechanical function of the tendon and consequently increase susceptibility to injury. Decorin and biglycan are important regulators of tendon structure and therefore, we further hypothesized that decreased function in aged tendons is partly the result of altered decorin and biglycan expression. Biomechanical analyses of mature (day 150) and aged (day 570) patellar tendons revealed deteriorating viscoelastic properties with age. Histology and polarized light microscopy demonstrated decreased cellularity, alterations in tenocyte shape, and reduced collagen fiber alignment in the aged tendons. Ultrastructural analysis of fibril diameter distributions indicated an altered distribution in aged tendons with an increase of large diameter fibrils. Aged wild type tendons maintained expression of decorin which was associated with the structural and functional changes seen in aged tendons. Aged patellar tendons exhibited altered and generally inferior properties across multiple assays. However, decorin-null tendons exhibited significantly decreased effects of aging compared to the other genotypes. The amelioration of the functional deficits seen in the absence of decorin in aged tendons was associated with altered tendon fibril structure. Fibril diameter distributions in the decorin-null aged tendons were comparable to those observed in the mature wild type tendon with the absence

  10. Accurate prediction of protein structural classes by incorporating predicted secondary structure information into the general form of Chou's pseudo amino acid composition.

    PubMed

    Kong, Liang; Zhang, Lichao; Lv, Jinfeng

    2014-03-01

    Extracting good representation from protein sequence is fundamental for protein structural classes prediction tasks. In this paper, we propose a novel and powerful method to predict protein structural classes based on the predicted secondary structure information. At the feature extraction stage, a 13-dimensional feature vector is extracted to characterize general contents and spatial arrangements of the secondary structural elements of a given protein sequence. Specially, four segment-level features are designed to elevate discriminative ability for proteins from the α/β and α+β classes. After the features are extracted, a multi-class non-linear support vector machine classifier is used to implement protein structural classes prediction. We report extensive experiments comparing the proposed method to the state-of-the-art in protein structural classes prediction on three widely used low-similarity benchmark datasets: FC699, 1189 and 640. Our method achieves competitive performance on prediction accuracies, especially for the overall prediction accuracies which have exceeded the best reported results on all of the three datasets. PMID:24316044

  11. Spatio-temporal variations in age structures of a partially re-established population of northern river otters (Lontra canadensis)

    USGS Publications Warehouse

    Barrett, Dominic A.; Leslie, David M., Jr.

    2012-01-01

    Examination of age structures and sex ratios is useful in the management of northern river otters (Lontra canadensis) and other furbearers. Reintroductions and subsequent recolonizations of river otters have been well documented, but changes in demographics between expanding and established populations have not been observed. As a result of reintroduction efforts, immigration from Arkansas and northeastern Texas, and other efforts, river otters have become partially reestablished throughout eastern and central Oklahoma. Our objective was to examine age structures of river otters in Oklahoma and identify trends that relate to space (watersheds, county) and time (USDA Animal and Plant Health Inspection Service county trapping records). We predicted that river otters in western areas of the state were younger than river otters occurring farther east. From 2005–2007, we obtained salvaged river otter carcasses from federal and state agencies, and we live-captured other river otters using leg hold traps. Seventy-two river otters were sampled. Overall, sex ratios were skewed toward females (1F∶0.8M), but they did not differ among spatiotemporal scales examined. Teeth were removed from salvaged and live-captured river otters (n  =  63) for aging. One-year old river otters represented the largest age class (30.2%). Proportion of juveniles (<1 y old) in Oklahoma (19.0%) was less than other states. Mean age of river otters decreased from east-to-west in the Arkansas River and its tributaries. Mean age of river otters differed between the Canadian River Watershed (0.8 y) and the Arkansas River Watershed (2.9 y) and the Canadian River Watershed and the Red River Watershed (2.4 y). Proportion of juveniles did not differ among spatiotemporal scales examined. Similar to age structure variations in other mammalian carnivores, colonizing or growing western populations of river otters in Oklahoma contained younger ages than more established eastern populations.

  12. Middle and upper cretaceous amber from the Taimyr Peninsula, Siberia: Evidence for a new structural sub-class of resinite

    SciTech Connect

    Anderson, K.B.

    1994-08-01

    Analysis of three amber (resinite) samples collected from Middle and Upper Cretaceous sediments in the Taimyr Peninsula, Siberia, indicates that these materials are based on copolymers of biformene (I) and communol (II). No resinites of similar structural character have previously been described and hence, these samples represent a previously unknown structural sub-class of resinite.

  13. Race/Ethnicity and Social Capital among Middle- and Upper-Middle-Class Elementary School Families: A Structural Equation Model

    ERIC Educational Resources Information Center

    Caldas, Stephen J.; Cornigans, Linda

    2015-01-01

    This study used structural equation modeling to conduct a first and second order confirmatory factor analysis (CFA) of a scale developed by McDonald and Moberg (2002) to measure three dimensions of social capital among a diverse group of middle- and upper-middle-class elementary school parents in suburban New York. A structural path model was…

  14. RSL Class I Genes Controlled the Development of Epidermal Structures in the Common Ancestor of Land Plants.

    PubMed

    Proust, Hélène; Honkanen, Suvi; Jones, Victor A S; Morieri, Giulia; Prescott, Helen; Kelly, Steve; Ishizaki, Kimitsune; Kohchi, Takayuki; Dolan, Liam

    2016-01-11

    The colonization of the land by plants, sometime before 470 million years ago, was accompanied by the evolution tissue systems [1-3]. Specialized structures with diverse functions-from nutrient acquisition to reproduction-derived from single cells in the outermost layer (epidermis) were important sources of morphological innovation at this time [2, 4, 5]. In extant plants, these structures may be unicellular extensions, such as root hairs or rhizoids [6-9], or multicellular structures, such as asexual propagules or secretory hairs (papillae) [10-12]. Here, we show that a ROOTHAIR DEFECTIVE SIX-LIKE (RSL) class I basic helix-loop-helix transcription factor positively regulates the development of the unicellular and multicellular structures that develop from individual cells that expand out of the epidermal plane of the liverwort Marchantia polymorpha; mutants that lack MpRSL1 function do not develop rhizoids, slime papillae, mucilage papillae, or gemmae. Furthermore, we discovered that RSL class I genes are also required for the development of multicellular axillary hairs on the gametophyte of the moss Physcomitrella patens. Because class I RSL proteins also control the development of rhizoids in mosses and root hairs in angiosperms [13, 14], these data demonstrate that the function of RSL class I genes was to control the development of structures derived from single epidermal cells in the common ancestor of the land plants. Class I RSL genes therefore controlled the generation of adaptive morphological diversity as plants colonized the land from the water. PMID:26725198

  15. RSL Class I Genes Controlled the Development of Epidermal Structures in the Common Ancestor of Land Plants

    PubMed Central

    Proust, Hélène; Honkanen, Suvi; Jones, Victor A.S.; Morieri, Giulia; Prescott, Helen; Kelly, Steve; Ishizaki, Kimitsune; Kohchi, Takayuki; Dolan, Liam

    2016-01-01

    Summary The colonization of the land by plants, sometime before 470 million years ago, was accompanied by the evolution tissue systems [1, 2, 3]. Specialized structures with diverse functions—from nutrient acquisition to reproduction—derived from single cells in the outermost layer (epidermis) were important sources of morphological innovation at this time [2, 4, 5]. In extant plants, these structures may be unicellular extensions, such as root hairs or rhizoids [6, 7, 8, 9], or multicellular structures, such as asexual propagules or secretory hairs (papillae) [10, 11, 12]. Here, we show that a ROOTHAIR DEFECTIVE SIX-LIKE (RSL) class I basic helix-loop-helix transcription factor positively regulates the development of the unicellular and multicellular structures that develop from individual cells that expand out of the epidermal plane of the liverwort Marchantia polymorpha; mutants that lack MpRSL1 function do not develop rhizoids, slime papillae, mucilage papillae, or gemmae. Furthermore, we discovered that RSL class I genes are also required for the development of multicellular axillary hairs on the gametophyte of the moss Physcomitrella patens. Because class I RSL proteins also control the development of rhizoids in mosses and root hairs in angiosperms [13, 14], these data demonstrate that the function of RSL class I genes was to control the development of structures derived from single epidermal cells in the common ancestor of the land plants. Class I RSL genes therefore controlled the generation of adaptive morphological diversity as plants colonized the land from the water. PMID:26725198

  16. Age Differences in Personality Structure: A Cluster Analytic Approach

    ERIC Educational Resources Information Center

    Costa, Paul T., Jr.; McCrae, Robert R.

    1976-01-01

    Presented at the 81st APA Convention, Montreal, 1973, this study showed how a cluster analytic approach was used to determine age differences in personality measured by the Sixteen Personality Factor Questionnaire (16PF). Subjects were 969 adult male volunteers, 25 to 34, 35 to 54, and 55 to 82. Openness to experience showed age-related…

  17. Effects of Aging Structures and Humidity on Fatigue Properties of Maraging Steel

    NASA Astrophysics Data System (ADS)

    Hayashi, Kousuke; Nagano, Takanori; Moriyama, Michihiko; Wang, Xishu; Kawagoishi, Norio

    Effects of aging structures and humidity on fatigue properties of 350 grade 18% Ni maraging steel were investigated under rotating bending in relative humidity of 25% and 85%. Aging conditions tested were a conventional single aging and a double one which was aged at low temperature after the conventional aging. In each aging, under and peak aged steels were prepared. Tensile strength was increased by the double aging without reduction of the ductility. Proportional relation between fatigue limit and Vickers hardness held until 750HV in low humidity. However fatigue strength was largely decreased by high humidity, especially in the peak aged steel at the single aging. The decrease in fatigue strength by high humidity was mainly caused by the acceleration of a crack initiation due to the anodic dissolution. The acceleration of a crack initiation was larger in the steel peak aged at the single aging with larger precipitated particles.

  18. Geometric and Electronic Structure of the Mn(IV)Fe(III) Cofactor in Class Ic Ribonucleotide Reductase: Correlation to the Class Ia Binuclear Non-Heme Iron Enzyme

    PubMed Central

    Kwak, Yeonju; Jiang, Wei; Dassama, Laura M.K.; Park, Kiyoung; Bell, Caleb B.; Liu, Lei V.; Wong, Shaun D.; Saito, Makina; Kobayashi, Yasuhiro; Kitao, Shinji; Seto, Makoto; Yoda, Yoshitaka; Alp, E. Ercan; Zhao, Jiyong; Bollinger, J Martin; Krebs, Carsten; Solomon, Edward I.

    2013-01-01

    The class Ic ribonucleotide reductase (RNR) from Chlamydia trachomatis (Ct) utilizes a Mn/Fe hetero-binuclear cofactor, rather than the Fe/Fe cofactor found in the β (R2) subunit of the class Ia enzymes, to react with O2. This reaction produces a stable MnIVFeIII cofactor that initiates a radical, which transfers to the adjacent α (R1) subunit and reacts with the substrate. We have studied the MnIVFeIII cofactor using nuclear resonance vibrational spectroscopy (NRVS) and absorption (Abs) / circular dichroism (CD) / magnetic CD (MCD) / variable temperature, variable field (VTVH) MCD spectroscopies to obtain detailed insight into its geometric/electronic structure and to correlate structure with reactivity; NRVS focuses on the FeIII, whereas MCD reflects the spin-allowed transitions mostly on the MnIV. We have evaluated 18 systematically varied structures. Comparison of the simulated NRVS spectra to the experimental data shows that the cofactor has one carboxylate bridge, with MnIV at the site proximal to Phe127. Abs/CD/MCD/VTVH MCD data exhibit 12 transitions that are assigned as d-d, and oxo and OH− to metal charge transfer (CT) transitions. Assignments are based on MCD/Abs intensity ratios, transition energies, polarizations, and derivative-shaped pseudo-A term CT transitions. Correlating these results with TD-DFT calculations defines the MnIVFeIII cofactor as having a µ-oxo, µ-hydroxo core and a terminal hydroxo ligand on the MnIV. From DFT calculations, the MnIV at site 1 is necessary to tune the redox potential to a value similar to that of the tyrosine radical in class Ia RNR, and the OH− terminal ligand on this MnIV provides a high proton affinity that could gate radical translocation to the α (R1) subunit. PMID:24131208

  19. Structure and Correlates of Cognitive Aging in a Narrow Age Cohort

    PubMed Central

    2014-01-01

    Aging-related changes occur for multiple domains of cognitive functioning. An accumulating body of research indicates that, rather than representing statistically independent phenomena, aging-related cognitive changes are moderately to strongly correlated across domains. However, previous studies have typically been conducted in age-heterogeneous samples over longitudinal time lags of 6 or more years, and have failed to consider whether results are robust to a comprehensive set of controls. Capitalizing on 3-year longitudinal data from the Lothian Birth Cohort of 1936, we took a longitudinal narrow age cohort approach to examine cross-domain cognitive change interrelations from ages 70 to 73 years. We fit multivariate latent difference score models to factors representing visuospatial ability, processing speed, memory, and crystallized ability. Changes were moderately interrelated, with a general factor of change accounting for 47% of the variance in changes across domains. Change interrelations persisted at close to full strength after controlling for a comprehensive set of demographic, physical, and medical factors including educational attainment, childhood intelligence, physical function, APOE genotype, smoking status, diagnosis of hypertension, diagnosis of cardiovascular disease, and diagnosis of diabetes. Thus, the positive manifold of aging-related cognitive changes is highly robust in that it can be detected in a narrow age cohort followed over a relatively brief longitudinal period, and persists even after controlling for many potential confounders. PMID:24955992

  20. Structure determination and interception of biosynthetic intermediates for the plantazolicin class of highly discriminating antibiotics.

    PubMed

    Molohon, Katie J; Melby, Joel O; Lee, Jaeheon; Evans, Bradley S; Dunbar, Kyle L; Bumpus, Stefanie B; Kelleher, Neil L; Mitchell, Douglas A

    2011-12-16

    The soil-dwelling, plant growth-promoting bacterium Bacillus amyloliquefaciens FZB42 is a prolific producer of complex natural products. Recently, a new FZB42 metabolite, plantazolicin (PZN), has been described as a member of the growing thiazole/oxazole-modified microcin (TOMM) family. TOMMs are biosynthesized from inactive, ribosomal peptides and undergo a series of cyclodehydrations, dehydrogenations, and other modifications to become bioactive natural products. Using high-resolution mass spectrometry, chemoselective modification, genetic interruptions, and other spectroscopic tools, we have determined the molecular structure of PZN. In addition to two conjugated polyazole moieties, the amino-terminus of PZN has been modified to N(α),N(α)-dimethylarginine. PZN exhibited a highly selective antibiotic activity toward Bacillus anthracis, but no other tested human pathogen. By altering oxygenation levels during fermentation, PZN analogues were produced that bear variability in their heterocycle content, which yielded insight into the order of biosynthetic events. Lastly, genome-mining has revealed the existence of four additional PZN-like biosynthetic gene clusters. Given their structural uniqueness and intriguing antimicrobial specificity, the PZN class of antibiotics may hold pharmacological value. PMID:21950656

  1. Structure Determination and Interception of Biosynthetic Intermediates for the Plantazolicin Class of Highly Discriminating Antibiotics

    PubMed Central

    Molohon, Katie J.; Melby, Joel O.; Lee, Jaeheon; Evans, Bradley S.; Dunbar, Kyle L.; Bumpus, Stefanie B.; Kelleher, Neil L.; Mitchell, Douglas A.

    2011-01-01

    The soil dwelling, plant-growth promoting bacterium, Bacillus amyloliquefaciens FZB42, is a prolific producer of complex natural products. Recently, a new FZB42 metabolite, plantazolicin (PZN), has been described as a member of the growing thiazole/oxazole-modified microcin (TOMM) family. TOMMs are biosynthesized from inactive, ribosomal peptides and undergo a series of cyclodehydrations, dehydrogenations, and other modifications to become bioactive natural products. Using high-resolution mass spectrometry, chemoselective modification, genetic interruptions, and other spectroscopic tools, we have determined the molecular structure of PZN. In addition to two conjugated polyazole moieties, the amino-terminus of PZN has been modified to Nα,Nα-dimethylarginine. PZN exhibited a highly selective antibiotic activity towards Bacillus anthracis, but no other tested human pathogen. By altering oxygenation levels during fermentation, PZN analogs were produced that bear variability in their heterocycle content, which yielded insight into the order of biosynthetic events. Lastly, genome-mining has revealed the existence of four additional PZN-like biosynthetic gene clusters. Given their structural uniqueness and intriguing antimicrobial specificity, the PZN class of antibiotics may hold pharmacological value. PMID:21950656

  2. Significance of microhabitat heterogeneity in the spatial pattern and size-class structure of Anastatica hierochuntica L.

    NASA Astrophysics Data System (ADS)

    Hegazy, Ahmad K.; Kabiel, Hanan F.

    2007-05-01

    Anastatica hierochuntica L. (Brassicaceae) is a desert monocarpic annual species characterized by a topochory/ombrohydrochory type of seed dispersal. The hygrochastic nature of the dry skeletons (dead individuals) permits controlling seed dispersal by rain events. The amount of dispersed seeds is proportional to the intensity of rainfall. When light showers occur, seeds are released and remain in the site. Seeds dispersed in the vicinity of the mother or source plant (primary type of seed dispersal) resulted in clumped pattern and complicated interrelationships among size-classes of the population. Following heavy rainfall, most seeds are released and transported into small patches and shallow depressions which collect runoff water. The dead A. hierochuntica skeletons demonstrate site-dependent size-class structure, spatial pattern and spatial interrelationships in different microhabitats. Four microhabitat types have been sampled: runnels, patches and simple and compound depressions in two sites (gravel and sand). Ripley's K-function was used to analyze the spatial pattern in populations of A. hierochuntica skeletons in the study microhabitats. Clumped patterns were observed in nearly all of the study microhabitats. Populations of A. hierochuntica in the sand site were more productive than in the gravel site and usually had more individuals in the larger size-classes. In the compound-depression microhabitat, the degree of clumping decreased from the core zone to the intermediate zone then shifted into overdispersed pattern in the outer zone. At the within size-class level, the clumped pattern dominated in small size classes but shifted into random and overdispersed patterns in the larger size classes. Aggregation between small and large size-classes was not well-defined but large individuals were found closer to the smaller individuals than to those of their own class. In relation to the phytomass and the size-class structure, the outer zone of the simple

  3. The distribution of Fst and other genetic statistics for a class of population structure models.

    PubMed

    Leviyang, Sivan

    2011-02-01

    We examine genetic statistics used in the study of structured populations. In a 1999 paper, Wakeley observed that the coalescent process associated with the finite island model can be decomposed into a scattering phase and a collecting phase. This decomposition becomes exact in the large population limit with the coalescent at the end of the scattering phase converging to the Ewens sampling formula and the coalescent during the collecting phase converging to the Kingman coalescent. In this paper we introduce a class of limiting models, which we refer to as G/KC models, that generalize Wakeley's decomposition. G in G/KC represents a completely general limit for the scattering phase, while KC represents a Kingman coalescent limit for the collecting phase. We show that both the island and two-dimensional stepping stone models converge to G/KC models in the large population limit. We then derive the distribution of the statistic F(st) for all G/KC models under a large sample limit for the cases of strong or weak mutation, thereby deriving the large population, large sample limiting distribution of F(st) for the island and two-dimensional stepping stone models as a special case of a general formula. Our methods allow us to take the large population and large sample limits simultaneously. In the context of large population, large sample limits, we show that the variance of F(st) in the presence of weak mutation collapses as O(1/log d) where d is the number of demes sampled. Further, we show that this O(1/log d) is caused by a heavy tail in the distribution of F(st). Our analysis of F(st) can be extended to an entire class of genetic statistics, and we use our approach to examine homozygosity measures. Our analysis uses coalescent based methods. PMID:20186418

  4. Improving the prediction accuracy of protein structural class: approached with alternating word frequency and normalized Lempel-Ziv complexity.

    PubMed

    Zhang, Shengli; Liang, Yunyun; Yuan, Xiguo

    2014-01-21

    Prediction of protein structural class for low-similarity sequences remains a challenging problem. In this study, the new computational method has been developed to predict protein structural class by incorporating alternating word frequency and normalized Lempel-Ziv complexity. To evaluate the performance of the proposed method, jackknife cross-validation tests are performed on three widely used benchmark datasets, 25PDB, 1189 and 640, respectively. We report 83.6%, 81.8% and 83.6% prediction accuracies for 25PDB, 1189 and 640 benchmarks, respectively. Comparison of our results with other methods shows that the proposed method is very promising and may provide a cost-effective alternative to predict protein structural class in particular for low-similarity datasets and may at least play an important complementary role to existing methods. PMID:24140787

  5. Age of Onset of Schizophrenia: Perspectives From Structural Neuroimaging Studies

    PubMed Central

    Gogtay, Nitin; Vyas, Nora S.; Testa, Renee; Wood, Stephen J.; Pantelis, Christos

    2011-01-01

    Many of the major neuropsychiatric illnesses, including schizophrenia, have a typical age of onset in late adolescence. Late adolescence may reflect a critical period in brain development making it particularly vulnerable for the onset of psychopathology. Neuroimaging studies that focus on this age range may provide unique insights into the onset and course of psychosis. In this review, we examine the evidence from 2 unique longitudinal cohorts that span the ages from early childhood through young adulthood; a study of childhood-onset schizophrenia where patients and siblings are followed from ages 6 through to their early twenties, and an ultra-high risk study where subjects (mean age of 19 years) are studied before and after the onset of psychosis. From the available evidence, we make an argument that subtle, regionally specific, and genetically influenced alterations during developmental age windows influence the course of psychosis and the resultant brain phenotype. The importance of examining trajectories of development and the need for future combined approaches, using multimodal imaging together with molecular studies is discussed. PMID:21505117

  6. Age of onset of schizophrenia: perspectives from structural neuroimaging studies.

    PubMed

    Gogtay, Nitin; Vyas, Nora S; Testa, Renee; Wood, Stephen J; Pantelis, Christos

    2011-05-01

    Many of the major neuropsychiatric illnesses, including schizophrenia, have a typical age of onset in late adolescence. Late adolescence may reflect a critical period in brain development making it particularly vulnerable for the onset of psychopathology. Neuroimaging studies that focus on this age range may provide unique insights into the onset and course of psychosis. In this review, we examine the evidence from 2 unique longitudinal cohorts that span the ages from early childhood through young adulthood; a study of childhood-onset schizophrenia where patients and siblings are followed from ages 6 through to their early twenties, and an ultra-high risk study where subjects (mean age of 19 years) are studied before and after the onset of psychosis. From the available evidence, we make an argument that subtle, regionally specific, and genetically influenced alterations during developmental age windows influence the course of psychosis and the resultant brain phenotype. The importance of examining trajectories of development and the need for future combined approaches, using multimodal imaging together with molecular studies is discussed. PMID:21505117

  7. Lake Erie Yellow perch age estimation based on three structures: Precision, processing times, and management implications

    USGS Publications Warehouse

    Vandergoot, C.S.; Bur, M.T.; Powell, K.A.

    2008-01-01

    Yellow perch Perca flavescens support economically important recreational and commercial fisheries in Lake Erie and are intensively managed. Age estimation represents an integral component in the management of Lake Erie yellow perch stocks, as age-structured population models are used to set safe harvest levels on an annual basis. We compared the precision associated with yellow perch (N = 251) age estimates from scales, sagittal otoliths, and anal spine sections and evaluated the time required to process and estimate age from each structure. Three readers of varying experience estimated ages. The precision (mean coefficient of variation) of estimates among readers was 1% for sagittal otoliths, 5-6% for anal spines, and 11-13% for scales. Agreement rates among readers were 94-95% for otoliths, 71-76% for anal spines, and 45-50% for scales. Systematic age estimation differences were evident among scale and anal spine readers; less-experienced readers tended to underestimate ages of yellow perch older than age 4 relative to estimates made by an experienced reader. Mean scale age tended to underestimate ages of age-6 and older fish relative to otolith ages estimated by an experienced reader. Total annual mortality estimates based on scale ages were 20% higher than those based on otolith ages; mortality estimates based on anal spine ages were 4% higher than those based on otolith ages. Otoliths required more removal and preparation time than scales and anal spines, but age estimation time was substantially lower for otoliths than for the other two structures. We suggest the use of otoliths or anal spines for age estimation in yellow perch (regardless of length) from Lake Erie and other systems where precise age estimates are necessary, because age estimation errors resulting from the use of scales could generate incorrect management decisions. ?? Copyright by the American Fisheries Society 2008.

  8. The evolution of labile traits in sex- and age-structured populations.

    PubMed

    Childs, Dylan Z; Sheldon, Ben C; Rees, Mark

    2016-03-01

    Many quantitative traits are labile (e.g. somatic growth rate, reproductive timing and investment), varying over the life cycle as a result of behavioural adaptation, developmental processes and plastic responses to the environment. At the population level, selection can alter the distribution of such traits across age classes and among generations. Despite a growing body of theoretical research exploring the evolutionary dynamics of labile traits, a data-driven framework for incorporating such traits into demographic models has not yet been developed. Integral projection models (IPMs) are increasingly being used to understand the interplay between changes in labile characters, life histories and population dynamics. One limitation of the IPM approach is that it relies on phenotypic associations between parents and offspring traits to capture inheritance. However, it is well-established that many different processes may drive these associations, and currently, no clear consensus has emerged on how to model micro-evolutionary dynamics in an IPM framework. We show how to embed quantitative genetic models of inheritance of labile traits into age-structured, two-sex models that resemble standard IPMs. Commonly used statistical tools such as GLMs and their mixed model counterparts can then be used for model parameterization. We illustrate the methodology through development of a simple model of egg-laying date evolution, parameterized using data from a population of Great tits (Parus major). We demonstrate how our framework can be used to project the joint dynamics of species' traits and population density. We then develop a simple extension of the age-structured Price equation (ASPE) for two-sex populations, and apply this to examine the age-specific contributions of different processes to change in the mean phenotype and breeding value. The data-driven framework we outline here has the potential to facilitate greater insight into the nature of selection and its

  9. Motor Control and Aging: Links to Age-Related Brain Structural, Functional, and Biochemical Effects

    PubMed Central

    Seidler, Rachael D.; Bernard, Jessica A.; Burutolu, Taritonye B.; Fling, Brett W.; Gordon, Mark T.; Gwin, Joseph T.; Kwak, Youngbin; Lipps, David B.

    2009-01-01

    Although connections between cognitive deficits and age-associated brain differences have been elucidated, relationships with motor performance are less well understood. Here, we broadly review age-related brain differences and motor deficits in older adults in addition to cognition-action theories. Age-related atrophy of the motor cortical regions and corpus callosum may precipitate or coincide with motor declines such as balance and gait deficits, coordination deficits, and movement slowing. Correspondingly, degeneration of neurotransmitter systems—primarily the dopaminergic system—may contribute to age-related gross and fine motor declines, as well as to higher cognitive deficits. In general, older adults exhibit involvement of more widespread brain regions for motor control than young adults, particularly the prefrontal cortex and basal ganglia networks. Unfortunately these same regions are the most vulnerable to age-related effects, resulting in an imbalance of “supply and demand”. Existing exercise, pharmaceutical, and motor training interventions may ameliorate motor deficits in older adults. PMID:19850077

  10. Aortic Aging in ESRD: Structural, Hemodynamic, and Mortality Implications.

    PubMed

    London, Gérard M; Safar, Michel E; Pannier, Bruno

    2016-06-01

    Aging incurs aortic stiffening and dilation, but these changes are less pronounced in peripheral arteries, resulting in stiffness and geometry gradients influencing progression of the forward and reflected pressure waves. Because premature arterial aging is observed in ESRD, we determined the respective roles of stiffness and aortic geometry gradients in 73 controls and 156 patients on hemodialysis. We measured aortic pulse wave velocity (PWV) and brachial PWV to evaluate the stiffness gradient [(brachial PWV/aortic PWV)(0.5)] and ascending aortic and aortic bifurcation diameters to assess aortic taper (ascending aortic diameter/aortic bifurcation diameter). The global reflection coefficient was estimated from characteristic impedance and vascular resistance. Cox proportional hazard models were used to determine mortality risk. The age-associated increase in aortic PWV was higher in patients (P<0.001). In controls, aortic ascending and bifurcation diameters increased with age, with an unchanged aortic taper. In patients on hemodialysis, age did not associate with increased ascending aortic diameter but did associate with increased aortic bifurcation diameter and decreased aortic taper, both of which also associated with abdominal aortic calcifications and smaller global reflection coefficient (P<0.001). In patients, multivariate models revealed all-cause and cardiovascular mortality associated with age, aortic PWV, and aortic bifurcation diameter with high specificity and sensitivity. Using stiffness gradient, aortic taper, or global reflection coefficient in the model produced similar results. Thus, whereas aortic stiffness is a known independent predictor of mortality, these results indicate the importance of also evaluating the aortic geometry in patients on hemodialysis. PMID:26475595

  11. On the dynamics of the age structure, dependency, and consumption

    PubMed Central

    Hock, Heinrich

    2013-01-01

    We examine the effects of population aging due to declining fertility and rising elderly life expectancy on consumption possibilities in the presence of intergenerational transfers. Our analysis is based on a highly tractable continuous-time overlapping generations model in which the population is divided into three groups (youth dependents, workers, and elderly dependents) and lifecourse transitions take place in a probabilistic fashion. We show that the consumption-maximizing response to greater longevity in highly developed countries is an increase in fertility. However, with larger transfer payments, the actual fertility response will likely be the opposite, leading to further population aging. PMID:24353374

  12. Structural and Functional Characterization of Methicillin-Resistant Staphylococcus aureus’s Class IIb Fructose 1,6-Bisphosphate Aldolase

    PubMed Central

    2015-01-01

    Staphylococcus aureus is one of the most common nosocomial sources of soft-tissue and skin infections and has more recently become prevalent in the community setting as well. Since the use of penicillins to combat S. aureus infections in the 1940s, the bacterium has been notorious for developing resistances to antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA). With the persistence of MRSA as well as many other drug resistant bacteria and parasites, there is a growing need to focus on new pharmacological targets. Recently, class II fructose 1,6-bisphosphate aldolases (FBAs) have garnered attention to fill this role. Regrettably, scarce biochemical data and no structural data are currently available for the class II FBA found in MRSA (SaFBA). With the recent finding of a flexible active site zinc-binding loop (Z-Loop) in class IIa FBAs and its potential for broad spectrum class II FBA inhibition, the lack of information regarding this feature of class IIb FBAs, such as SaFBA, has been limiting for further Z-loop inhibitor development. Therefore, we elucidated the crystal structure of SaFBA to 2.1 Å allowing for a more direct structural analysis of SaFBA. Furthermore, we determined the KM for one of SaFBA’s substrates, fructose 1,6-bisphosphate, as well as performed mode of inhibition studies for an inhibitor that takes advantage of the Z-loop’s flexibility. Together the data offers insight into a class IIb FBA from a pervasively drug resistant bacterium and a comparison of Z-loops and other features between the different subtypes of class II FBAs. PMID:25390935

  13. Composite Structural Analysis of Flat-Back Shaped Blade for Multi-MW Class Wind Turbine

    NASA Astrophysics Data System (ADS)

    Kim, Soo-Hyun; Bang, Hyung-Joon; Shin, Hyung-Ki; Jang, Moon-Seok

    2014-06-01

    This paper provides an overview of failure mode estimation based on 3D structural finite element (FE) analysis of the flat-back shaped wind turbine blade. Buckling stability, fiber failure (FF), and inter-fiber failure (IFF) analyses were performed to account for delamination or matrix failure of composite materials and to predict the realistic behavior of the entire blade region. Puck's fracture criteria were used for IFF evaluation. Blade design loads applicable to multi-megawatt (MW) wind turbine systems were calculated according to the Germanischer Lloyd (GL) guideline and the International Electrotechnical Commission (IEC) 61400-1 standard, under Class IIA wind conditions. After the post-processing of final load results, a number of principal load cases were selected and converted into applied forces at the each section along the blade's radius of the FE model. Nonlinear static analyses were performed for laminate failure, FF, and IFF check. For buckling stability, linear eigenvalue analysis was performed. As a result, we were able to estimate the failure mode and locate the major weak point.

  14. Structural synthesis of a class of 2R2T hybrid mechanisms

    NASA Astrophysics Data System (ADS)

    Tian, Chunxu; Fang, Yuefa; Guo, Sheng

    2016-01-01

    Conventional overconstrained parallel manipulators have been widely studied both in industry and academia, however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied, especially for the four degrees of freedom(DOF) hybrid mechanisms. In order to develop a manipulator with additional constraints, a class of important spatial mechanisms with coupling chains(CCs) whose motion type is two rotations and two translations(2R2T) is presented. Based on screw theory, the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed. The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method. Moreover, the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains(SKCs) of the corresponding parallel mechanisms are presented. According to the constraint analysis of the mechanisms, the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains. At last, fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented. The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.

  15. The Frontal Hypothesis of Cognitive Aging: Factor Structure and Age Effects on Four "Frontal Tests" among Healthy Individuals

    ERIC Educational Resources Information Center

    Rodriguez-Aranda, Claudia; Sundet, Kjetil

    2006-01-01

    With 101 healthy aging adult participants, the authors investigated whether executive functions are a unitary concept. The authors established the factor structure of the Wisconsin Card Sorting Test (WCST; E. A. Berg, 1948), the Stroop color and word test (C. J. Golden, 1978), verbal fluency using the Controlled Oral Word Association Test (COWAT;…

  16. The recognition of multi-class protein folds by adding average chemical shifts of secondary structure elements

    PubMed Central

    Feng, Zhenxing; Hu, Xiuzhen; Jiang, Zhuo; Song, Hangyu; Ashraf, Muhammad Aqeel

    2015-01-01

    The recognition of protein folds is an important step in the prediction of protein structure and function. Recently, an increasing number of researchers have sought to improve the methods for protein fold recognition. Following the construction of a dataset consisting of 27 protein fold classes by Ding and Dubchak in 2001, prediction algorithms, parameters and the construction of new datasets have improved for the prediction of protein folds. In this study, we reorganized a dataset consisting of 76-fold classes constructed by Liu et al. and used the values of the increment of diversity, average chemical shifts of secondary structure elements and secondary structure motifs as feature parameters in the recognition of multi-class protein folds. With the combined feature vector as the input parameter for the Random Forests algorithm and ensemble classification strategy, we propose a novel method to identify the 76 protein fold classes. The overall accuracy of the test dataset using an independent test was 66.69%; when the training and test sets were combined, with 5-fold cross-validation, the overall accuracy was 73.43%. This method was further used to predict the test dataset and the corresponding structural classification of the first 27-protein fold class dataset, resulting in overall accuracies of 79.66% and 93.40%, respectively. Moreover, when the training set and test sets were combined, the accuracy using 5-fold cross-validation was 81.21%. Additionally, this approach resulted in improved prediction results using the 27-protein fold class dataset constructed by Ding and Dubchak. PMID:26980999

  17. 76 FR 69292 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    .... ML100920158), for which a notice of availability was published in the Federal Register on June 22, 2010 (75 FR... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY... Staff Guidance (LR-ISG), LR- ISG-2011-01, ``Aging Management of Stainless Steel Structures...

  18. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Fee structure for age search and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee Searches of one census for one person and one transcript $65.00 Each additional copy of census transcript...

  19. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Fee structure for age search and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee Searches of one census for one person and one transcript $65.00 Each additional copy of census transcript...

  20. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Fee structure for age search and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee Searches of one census for one person and one transcript $65.00 Each additional copy of census transcript...

  1. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Fee structure for age search and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee Searches of one census for one person and one transcript $65.00 Each additional copy of census transcript...

  2. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce...

  3. Educating Other People's Children: Race, Class, Ethnicity, Aging, and the Politics of School Funding in Long Island, New York.

    ERIC Educational Resources Information Center

    Singer, Alan

    Long Island, New York, including Nassau and Suffolk Counties, is a patchwork of small ethnically, racially, and economically segregated towns organized into 126 school districts. School funding patterns and problems conform to racial, ethnic, and class lines. Predominantly minority school districts generally have higher property tax rates, fewer…

  4. School Finance Systems: Aging Structures in Need of Renovation.

    ERIC Educational Resources Information Center

    Odden, Allan; Clune, William H.

    1998-01-01

    Traditional school-finance systems need dramatic change to make them more supportive of the goals and strategies of standards. The shortcomings of current structures are reviewed, and suggestions are provided for changing finance structures, including a shift from fiscal equity toward educational adequacy. Elements to enhance a new system are…

  5. Structure and disulfide bonding pattern of the hevein-like peptide domains from plant class IV chitinases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn (Zea mays) and Arabidopsis (Arabidopsis thaliana) produce GH family 19 plant class IV chitinases. These chitinases contain two domains: a small N-terminal hevein region, and a C-terminal chitinase. Numerous structures of GH19 chitinase domains have been reported, including the chitinase domain ...

  6. A Latent Class Analysis of Teacher Candidates' Goal Orientation, Perception of Classroom Structure, Motivation, and Self-Regulation

    ERIC Educational Resources Information Center

    Bembenutty, Hefer

    2010-01-01

    The purpose of this study was to examine whether teacher candidates with mastery- and performance-approach orientations would perceived their education courses as depicting a goal structure consistent with their personal orientations, use of self-regulatory strategies, and motivation for learning. A latent class analysis procedure was used to…

  7. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    NASA Astrophysics Data System (ADS)

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-08-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100‑xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections.

  8. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    PubMed Central

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100−xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  9. Crystal structures of an archaeal class II DNA photolyase and its complex with UV-damaged duplex DNA.

    PubMed

    Kiontke, Stephan; Geisselbrecht, Yann; Pokorny, Richard; Carell, Thomas; Batschauer, Alfred; Essen, Lars-Oliver

    2011-11-01

    Class II photolyases ubiquitously occur in plants, animals, prokaryotes and some viruses. Like the distantly related microbial class I photolyases, these enzymes repair UV-induced cyclobutane pyrimidine dimer (CPD) lesions within duplex DNA using blue/near-UV light. Methanosarcina mazei Mm0852 is a class II photolyase of the archaeal order of Methanosarcinales, and is closely related to plant and metazoan counterparts. Mm0852 catalyses light-driven DNA repair and photoreduction, but in contrast to class I enzymes lacks a high degree of binding discrimination between UV-damaged and intact duplex DNA. We solved crystal structures of Mm0852, the first one for a class II photolyase, alone and in complex with CPD lesion-containing duplex DNA. The lesion-binding mode differs from other photolyases by a larger DNA-binding site, and an unrepaired CPD lesion is found flipped into the active site and recognized by a cluster of five water molecules next to the bound 3'-thymine base. Different from other members of the photolyase-cryptochrome family, class II photolyases appear to utilize an unusual, conserved tryptophane dyad as electron transfer pathway to the catalytic FAD cofactor. PMID:21892138

  10. The MARK-AGE phenotypic database: Structure and strategy.

    PubMed

    Moreno-Villanueva, María; Kötter, Tobias; Sindlinger, Thilo; Baur, Jennifer; Oehlke, Sebastian; Bürkle, Alexander; Berthold, Michael R

    2015-11-01

    In the context of the MARK-AGE study, anthropometric, clinical and social data as well as samples of venous blood, buccal mucosal cells and urine were systematically collected from 3337 volunteers. Information from about 500 standardised questions and about 500 analysed biomarkers needed to be documented per individual. On the one hand handling with such a vast amount of data necessitates the use of appropriate informatics tools and the establishment of a database. On the other hand personal information on subjects obtained as a result of such studies has, of course, to be kept confidential, and therefore the investigators must ensure that the subjects' anonymity will be maintained. Such secrecy obligation implies a well-designed and secure system for data storage. In order to fulfil the demands of the MARK-AGE study we established a phenotypic database for storing information on the study subjects by using a doubly coded system. PMID:25817205

  11. Structural Basis for Catalysis of a Tetrameric Class IIa Fructose 1,6-Bisphosphate Aldolase from Mycobacterium tuberculosis

    SciTech Connect

    Pegan, Scott D.; Ruskseree, Kamolchanok; Franzblau, Scott G.; Mesecar, Andrew D. ); )

    2009-03-04

    Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), currently infects one-third of the world's population in its latent form. The emergence of multidrug-resistant and extensive drug-resistant strains has highlighted the need for new pharmacological targets within M. tuberculosis. The class IIa fructose 1,6-bisphosphate aldolase (FBA) enzyme from M. tuberculosis (MtFBA) has been proposed as one such target since it is upregulated in latent TB. Since the structure of MtFBA has not been determined and there is little information available on its reaction mechanism, we sought to determine the X-ray structure of MtFBA in complex with its substrates. By lowering the pH of the enzyme in the crystalline state, we were able to determine a series of high-resolution X-ray structures of MtFBA bound to dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, and fructose 1,6-bisphosphate at 1.5, 2.1, and 1.3 {angstrom}, respectively. Through these structures, it was discovered that MtFBA belongs to a novel tetrameric class of type IIa FBAs. The molecular details at the interface of the tetramer revealed important information for better predictability of the quaternary structures among the FBAs based on their primary sequences. These X-ray structures also provide interesting and new details on the reaction mechanism of class II FBAs. Substrates and products were observed in geometries poised for catalysis; in addition, unexpectedly, the hydroxyl-enolate intermediate of dihydroxyacetone phosphate was also captured and resolved structurally. These concise new details offer a better understanding of the reaction mechanisms for FBAs in general and provide a structural basis for inhibitor design efforts aimed at this class of enzymes.

  12. Structural basis for catalysis of a tetrameric, class IIa fructose 1,6-bisphosphate aldolase from M. tuberculosis

    PubMed Central

    Pegan, Scott D.; Rukseree, Kamolchanok; Franzblau, Scott G.; Mesecar, Andrew D.

    2009-01-01

    Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), currently infects one third of the world’s population in its latent form. The emergence of multidrug resistant strains, MDR-TB and XDR-TB has highlighted the need for new pharmacological targets within M. tuberculosis. The Class IIa fructose 1,6-bisphosphate aldolase (FBA) enzyme from M. tuberculosis (MtFBA) has been proposed as one such target since its upregulated in latent TB. Since the structure of MtFBA had not been determined and since there was little information available on its reaction mechanism, we sought to determine the X-ray structure of MtFBA in complex with its substrates. By lowering the pH of the enzyme in the crystalline state, we were able to determine a series of high-resolution X-ray structures of MtFBA bound to dihydroxyacetonephosphate (DHAP), glyceraldehyde-3-phosphate (G3P), and fructose 1,6-bisphosphate (FBP) at 1.5 Å, 2.1 Å, and 1.3 Å respectively. Through these structures it was discovered that MtFBA belongs to a novel tetrameric class of the type IIa FBAs. The molecular details at the interface of the tetramer revealed important information for being able to better predict the quaternary structures among the FBAs based on their primary sequences. These X-ray structures also provide interesting and new details on the reaction mechanism of class II FBAs. Not only were the substrates and products observed in geometries poised for catalysis, but unexpectedly the hydroxyl enolate intermediate of DHAP was also captured and resolved structurally. These concise new details provide a better understanding of the reaction mechanisms for FBAs in general and provide a structural basis for inhibitor design efforts aimed at this class of enzymes. PMID:19167403

  13. Mixing in age-structured population models of infectious diseases.

    PubMed

    Glasser, John; Feng, Zhilan; Moylan, Andrew; Del Valle, Sara; Castillo-Chavez, Carlos

    2012-01-01

    Infectious diseases are controlled by reducing pathogen replication within or transmission between hosts. Models can reliably evaluate alternative strategies for curtailing transmission, but only if interpersonal mixing is represented realistically. Compartmental modelers commonly use convex combinations of contacts within and among groups of similarly aged individuals, respectively termed preferential and proportionate mixing. Recently published face-to-face conversation and time-use studies suggest that parents and children and co-workers also mix preferentially. As indirect effects arise from the off-diagonal elements of mixing matrices, these observations are exceedingly important. Accordingly, we refined the formula published by Jacquez et al. [19] to account for these newly-observed patterns and estimated age-specific fractions of contacts with each preferred group. As the ages of contemporaries need not be identical nor those of parents and children to differ by exactly the generation time, we also estimated the variances of the Gaussian distributions with which we replaced the Kronecker delta commonly used in theoretical studies. Our formulae reproduce observed patterns and can be used, given contacts, to estimate probabilities of infection on contact, infection rates, and reproduction numbers. As examples, we illustrate these calculations for influenza based on "attack rates" from a prospective household study during the 1957 pandemic and for varicella based on cumulative incidence estimated from a cross-sectional serological survey conducted from 1988-94, together with contact rates from the several face-to-face conversation and time-use studies. Susceptibility to infection on contact generally declines with age, but may be elevated among adolescents and adults with young children. PMID:22037144

  14. Age structure of refractory interstellar dust and isotopic consequences

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.; Scowen, Paul; Liffman, Kurt

    1989-01-01

    A sputtering and recycling Monte Carlo model, developed by Liffman and Clayton (1988) is used to calculate the distribution of existence times of the matter in interstellar dust composed of refractory metals. The mean age of each dust particle is defined not as the time it has existed but rather as the mass-weighted existence times of its parts at t = 6 Gyr of the modeled solar system formation. It is shown that Galactic evolution generates a mean correlation, applying to large numbers of particles binned according to size rather than according to individual particles, whose mean ages fluctuate statistically. The cosmochemical consequence is that if interstellar particles can be dynamically sorted into separate size populations during the aggregation history of solar system bodies, the collections of larger grains will constitute matter that is chemically older than collections of smaller grains. The macroscopic age difference generates isotopic anomalies by virtue of the time dependence of the secondary/primary nucleosynthesis yields. Results are compared with three different prescriptions for the sputtering of interstellar dust.

  15. Aging.

    PubMed

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  16. Aging

    PubMed Central

    Park, Dong Choon

    2013-01-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  17. Structure and Polymorphism of the Major Histocompatibility Complex Class II Region in the Japanese Crested Ibis, Nipponia nippon

    PubMed Central

    Taniguchi, Yukio; Matsumoto, Keisuke; Matsuda, Hirokazu; Yamada, Takahisa; Sugiyama, Toshie; Homma, Kosuke; Kaneko, Yoshinori; Yamagishi, Satoshi; Iwaisaki, Hiroaki

    2014-01-01

    The major histocompatibility complex (MHC) is a highly polymorphic genomic region that plays a central role in the immune system. Despite its functional consistency, the genomic structure of the MHC differs substantially among organisms. In birds, the MHC-B structures of Galliformes, including chickens, have been well characterized, but information about other avian MHCs remains sparse. The Japanese Crested Ibis (Nipponia nippon, Pelecaniformes) is an internationally conserved, critically threatened species. The current Japanese population of N. nippon originates from only five founders; thus, understanding the genetic diversity among these founders is critical for effective population management. Because of its high polymorphism and importance for disease resistance and other functions, the MHC has been an important focus in the conservation of endangered species. Here, we report the structure and polymorphism of the Japanese Crested Ibis MHC class II region. Screening of genomic libraries allowed the construction of three contigs representing different haplotypes of MHC class II regions. Characterization of genomic clones revealed that the MHC class II genomic structure of N. nippon was largely different from that of chicken. A pair of MHC-IIA and -IIB genes was arranged head-to-head between the COL11A2 and BRD2 genes. Gene order in N. nippon was more similar to that in humans than to that in chicken. The three haplotypes contained one to three copies of MHC-IIA/IIB gene pairs. Genotyping of the MHC class II region detected only three haplotypes among the five founders, suggesting that the genetic diversity of the current Japanese Crested Ibis population is extremely low. The structure of the MHC class II region presented here provides valuable insight for future studies on the evolution of the avian MHC and for conservation of the Japanese Crested Ibis. PMID:25247679

  18. Toward a class-independent quantitative structure--activity relationship model for uncouplers of oxidative phosphorylation.

    PubMed

    Spycher, Simon; Smejtek, Pavel; Netzeva, Tatiana I; Escher, Beate I

    2008-04-01

    A mechanistically based quantitative structure-activity relationship (QSAR) for the uncoupling activity of weak organic acids has been derived. The analysis of earlier experimental studies suggested that the limiting step in the uncoupling process is the rate with which anions can cross the membrane and that this rate is determined by the height of the energy barrier encountered in the hydrophobic membrane core. We use this mechanistic understanding to develop a predictive model for uncoupling. The translocation rate constants of anions correlate well with the free energy difference between the energy well and the energy barrier, Delta G well-barrier,A (-) , in the membrane calculated by a novel approach to describe internal partitioning in the membrane. An existing data set of 21 phenols measured in an in vitro test system specific for uncouplers was extended by 14 highly diverse compounds. A simple regression model based on the experimental membrane-water partition coefficient and Delta G well-barrier,A (-) showed good predictive power and had meaningful regression coefficients. To establish uncoupler QSARs independent of chemical class, it is necessary to calculate the descriptors for the charged species, as the analogous descriptors of the neutral species showed almost no correlation with the translocation rate constants of anions. The substitution of experimental with calculated partition coefficients resulted in a decrease of the model fit. A particular strength of the current model is the accurate calculation of excess toxicity, which makes it a suitable tool for database screening. The applicability domain, limitations of the model, and ideas for future research are critically discussed. PMID:18358007

  19. REACH coarse-grained biomolecular simulation: transferability between different protein structural classes.

    PubMed

    Moritsugu, Kei; Smith, Jeremy C

    2008-08-01

    Coarse graining of protein interactions provides a means of simulating large biological systems. The REACH (Realistic Extension Algorithm via Covariance Hessian) coarse-graining method, in which the force constants of a residue-scale elastic network model are calculated from the variance-covariance matrix obtained from atomistic molecular dynamics (MD) simulation, involves direct mapping between scales without the need for iterative optimization. Here, the transferability of the REACH force field is examined between protein molecules of different structural classes. As test cases, myoglobin (all alpha), plastocyanin (all beta), and dihydrofolate reductase (alpha/beta) are taken. The force constants derived are found to be closely similar in all three proteins. An MD version of REACH is presented, and low-temperature coarse-grained (CG) REACH MD simulations of the three proteins are compared with atomistic MD results. The mean-square fluctuations of the atomistic MD are well reproduced by the CGMD. Model functions for the CG interactions, derived by averaging over the three proteins, are also shown to produce fluctuations in good agreement with the atomistic MD. The results indicate that, similarly to the use of atomistic force fields, it is now possible to use a single, generic REACH force field for all protein studies, without having first to derive parameters from atomistic MD simulation for each individual system studied. The REACH method is thus likely to be a reliable way of determining spatiotemporal motion of a variety of proteins without the need for expensive computation of long atomistic MD simulations. PMID:18469078

  20. Radiostratigraphy and age structure of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    MacGregor, Joseph A.; Fahnestock, Mark A.; Catania, Ginny A.; Paden, John D.; Prasad Gogineni, S.; Young, S. Keith; Rybarski, Susan C.; Mabrey, Alexandria N.; Wagman, Benjamin M.; Morlighem, Mathieu

    2015-02-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet.

  1. Radiostratigraphy and age structure of the Greenland Ice Sheet

    PubMed Central

    MacGregor, Joseph A; Fahnestock, Mark A; Catania, Ginny A; Paden, John D; Prasad Gogineni, S; Young, S Keith; Rybarski, Susan C; Mabrey, Alexandria N; Wagman, Benjamin M; Morlighem, Mathieu

    2015-01-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet. Key Points Phase information predicts reflection slope and simplifies reflection tracing Reflections can be dated away from ice cores using a simple ice flow model Radiostratigraphy is often disrupted near the onset of fast ice flow PMID:26213664

  2. Effects of United States Department of Agriculture carcass maturity on sensory attributes of steaks produced by cattle representing two dental age classes.

    PubMed

    Semler, M L; Woerner, D R; Belk, K E; Enns, K J; Tatum, J D

    2016-05-01

    This study examined the effects of USDA carcass maturity on sensory properties of LM steaks produced by cattle representing 2 dental age classes. Carcasses identified for use in the experiment were produced by steers and heifers classified as either <30 mo of age (MOA) or ≥30 MOA at the time of slaughter using dentition. Within each dental age class, carcasses were selected to represent 2 maturity groups and 3 marbling categories, resulting in 12 dental age × maturity × marbling subclasses, each consisting of 50 carcasses. Maturity groups consisted of carcasses classified by USDA graders as either A to A (A) overall maturity or B to D (B-D) overall maturity; marbling categories consisted of carcasses with instrument marbling scores of Slight to Slight (SL), Small to Small (SM), or Modest to Moderate (MT-MD). Carcasses were selected in pairs so that each carcass chosen to represent the B-D-maturity group was paired with an A-maturity carcass of the same sex and marbling score (±50 marbling units). Strip loin (LM) steaks were obtained from both sides of each carcass. After a 14-d aging period, 1 LM steak was measured for Warner-Bratzler shear force (WBSF) and slice shear force (SSF), whereas the other LM steak was used for sensory analysis by a trained descriptive attribute panel. No differences ( > 0.05) in LM tenderness, juiciness, or flavor were detected between carcass maturity groups in either dental age class. Advanced dental age (≥30 MOA), however, was associated with more intense ( < 0.05) grassy and bloody/serumy flavors and decreased ( < 0.05) tenderness within the SL marbling group. Marbling score effectively stratified carcasses (MT-MD > SM > SL) according to differences ( < 0.0001) in LM tenderness, juiciness, beefy/brothy flavor, and buttery/beef fat flavor. In addition, increased marbling was associated with lesser ( < 0.01) intensities of bloody/serumy, livery/organy, and grassy flavors as well as smaller ( < 0.0001) values for WBSF and SSF

  3. Basic Pharmacological and Structural Evidence for Class A G-Protein-Coupled Receptor Heteromerization

    PubMed Central

    Franco, Rafael; Martínez-Pinilla, Eva; Lanciego, José L.; Navarro, Gemma

    2016-01-01

    Cell membrane receptors rarely work on isolation, often they form oligomeric complexes with other receptor molecules and they may directly interact with different proteins of the signal transduction machinery. For a variety of reasons, rhodopsin-like class A G-protein-coupled receptors (GPCRs) seem an exception to the general rule of receptor–receptor direct interaction. In fact, controversy surrounds their potential to form homo- hetero-dimers/oligomers with other class A GPCRs; in a sense, the field is going backward instead of forward. This review focuses on the convergent, complementary and telling evidence showing that homo- and heteromers of class A GPCRs exist in transfected cells and, more importantly, in natural sources. It is time to decide between questioning the occurrence of heteromers or, alternatively, facing the vast scientific and technical challenges that class A receptor-dimer/oligomer existence pose to Pharmacology and to Drug Discovery. PMID:27065866

  4. AGE-RELATED DEGRADATION OF NUCLEAR POWER PLANT STRUCTURES AND COMPONENTS.

    SciTech Connect

    BRAVERMAN,J.

    1999-03-29

    This paper summarizes and highlights the results of the initial phase of a research project on the assessment of aged and degraded structures and components important to the safe operation of nuclear power plants (NPPs). A review of age-related degradation of structures and passive components at NPPs was performed. Instances of age-related degradation have been collected and reviewed. Data were collected from plant generated documents such as Licensing Event Reports, NRC generic communications, NUREGs and industry reports. Applicable cases of degradation occurrences were reviewed and then entered into a computerized database. The results obtained from the review of degradation occurrences are summarized and discussed. Various trending analyses were performed to identify which structures and components are most affected, whether degradation occurrences are worsening, and what are the most common aging mechanisms. The paper also discusses potential aging issues and degradation-susceptible structures and passive components which would have the greatest impact on plant risk.

  5. Age-Related Degradation of Nuclear Power Plant Structures and Components

    SciTech Connect

    Braverman, J.; Chang, T.-Y.; Chokshi, N.; Hofmayer, C.; Morante, R.; Shteyngart, S.

    1999-03-29

    This paper summarizes and highlights the results of the initial phase of a research project on the assessment of aged and degraded structures and components important to the safe operation of nuclear power plants (NPPs). A review of age-related degradation of structures and passive components at NPPs was performed. Instances of age-related degradation have been collected and reviewed. Data were collected from plant generated documents such as Licensing Event Reports, NRC generic communications, NUREGs and industry reports. Applicable cases of degradation occurrences were reviewed and then entered into a computerized database. The results obtained from the review of degradation occurrences are summarized and discussed. Various trending analyses were performed to identify which structures and components are most affected, whether degradation occurrences are worsening, and what was the most common aging mechanisms. The paper also discusses potential aging issues and degradation-susceptible structures and passive components which would have the greatest impact on plant risk.

  6. A class 2 weight assessment for the implementation of commonality and preliminary structural designs for the family of commuter airplanes

    NASA Technical Reports Server (NTRS)

    Creighton, Tom; Dragush, George; Hendrich, Louis; Hensley, Doug; Morgan, Louise; Oxendine, Charles; Remen, John; Robinson, Terry; Russell, Mark; Swift, Jerry

    1987-01-01

    The feasibility of commonality objectives are determined. Commonality is discussed in terms of weight penalties that increase the take-off weight of several members of the family of airplanes. Preliminary designs of fuselage structural members and a discussion of weight penalties due to implementation of common fuselage structure throughout the family is examined. Wing torque box designs are discussed along with structural weight penalties incurred. A landing gear design study is contained along with the weight penalties that a common gear system will impose. Implementation of common power plants throughout the family and the weight penalties that occur are discussed. The weight penalties imposed by commonality on all the airplanes in the family are summarized. Class 2 breakdowns are also presented. The feasibility of commonality based on a percentage of take-off weight increase over the Class 2 baseline weights is then assessed.

  7. The 1991 International Conference on Aging Aircraft and Structural Airworthiness

    NASA Technical Reports Server (NTRS)

    Harris, Charles E. (Editor)

    1992-01-01

    Technical sessions of the conference included structural performance, nondestructive evaluation, maintenance and repair, international activities, and commuter airlines. Each session was organized to provide a well-rounded view of the subject from the industry, regulatory, and research perspective. Thirty-four presentations were given by the international technical community.

  8. Two-Class Structure of Income Distribution in the Usa:. Exponential Bulk and Power-Law Tail

    NASA Astrophysics Data System (ADS)

    Yakovenko, V. M.; Silva, A. Christian

    2007-07-01

    Personal income distribution in the USA has a well-defined two-class structure. The majority of population (97-99 %) belongs to the lower class characterized by the exponential Boltzmann-Gibbs ("thermal") distribution, whereas the upper class (1-3 % of population) has a Pareto power-law ("superthermal") distribution. By analyzing income data for 1983-2001, we show that the "thermal" part is stationary in time, save for a gradual increase of the effective temperature, whereas the "superthermal" tail swells and shrinks following the stock market. We discuss the concept of equilibrium inequality in a society, based on the principle of maximal entropy, and quantitatively show that it applies to the majority of population.

  9. Socio-occupational class, region of birth and maternal age: influence on time to detection of cryptorchidism (undescended testes): a Danish nationwide register study

    PubMed Central

    2014-01-01

    Background Cryptorchidism (undescended testes) is associated with poor male fertility, but can be alleviated and fertility preserved to some degree by early detection and treatment. Here we assess the influence of socio-occupational class, geographical region, maternal age and birth cohort on time to detection and correction of cryptorchidism. Methods All boys born in Denmark, 1981 to 1987 or 1988 to 1994, with a diagnosis of cryptorchidism were identified in nationwide registers. The boys were followed for a diagnosis until their 16th birthday. The age at first diagnosis was noted and used as proxy for time to detection of cryptorchidism. Parental employment in the calendar year preceding birth was grouped into one of five socio-occupational classes. Geographical region was defined by place of birth in one of 15 Danish counties. Detection rate ratios of cryptorchidism were analyzed as a function of parental socio-occupational group, county, maternal age and birth cohort by use of Poisson regression. Results Some 6,059 boys in the early and 5,947 boys in the late cohort received a diagnosis of cryptorchidism. Time to detection was independent of parental socio-occupational group and maternal age but differed slightly between geographical regions. A similar pattern was obtained for surgical correction after a diagnosis. Age at diagnosis decreased by 2.7 years from the early to the late cohort. Conclusions These results indicate that childhood socio-occupational inequality in detection and correction of cryptorchidism would play a negligible role in male infertility in a life course perspective. Geographical region may have exerted some influence, especially for the oldest cohort. PMID:24581337

  10. The Left Hand Second to Fourth Digit Ratio (2D:4D) Does Not Discriminate World-Class Female Gymnasts from Age Matched Sedentary Girls

    PubMed Central

    Peeters, Maarten W.; Claessens, Albrecht L.

    2012-01-01

    Introduction The second to fourth-digit-ratio (2D:4D), a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with sports performance, although results are not univocal. If this relation exists, it is most likely to be detected by comparing extreme groups on the continuum of sports performance. Methods In this study the 2D:4D ratio of world-class elite female artistic gymnasts (n = 129), competing at the 1987 Rotterdam World-Championships was compared to the 2D:4D ratio of sedentary age-matched sedentary girls (n = 129), alongside with other anthropometric characteristics including other sexually dimorphic traits such as an androgyny index (Bayer & Bayley) and Heath-Carter somatotype components (endomorphy, mesomorphy, ectomorphy) using AN(C)OVA. 2D:4D was measured on X-rays of the left hand. Results Left hand 2D:4D digit ratio in world class elite female gymnasts (0.921±0.020) did not differ significantly from 2D:4D in age-matched sedentary girls (0.924±0.018), either with or without inclusion of potentially confounding covariates such as skeletal age, height, weight, somatotype components or androgyny index. Height (161.9±6.4 cm vs 155.4±6.6 cm p<0.01), weight (53.9±7.6 kg vs 46.2 6.3 kg p<0.01), BMI (20.51±2.41 kg/m2 vs 19.05±1.56 kg/m2), skeletal age (15.2±1.1 y vs 14.5±1.2 y p>0.01), somatotype components (4.0/3.0/2.9 vs 1.7/3.7/3.2 for endomorphy (p<0.01), mesomorphy (p<0.01) and ectomorphy (p<0.05) respectively) all differed significantly between sedentary girls and elite gymnasts. As expressed by the androgyny index, gymnasts have, on average, broader shoulders relative to their hips, compared to the reference sample. Correlations between the 2D:4D ratio and chronological age, skeletal age, and the anthropometric characteristics are low and not significant. Conclusion Although other anthropometric characteristics of sexual dimorphism were significantly different between the two samples

  11. Interplay between Shear Loading and Structural Aging in a Physical Gelatin Gel

    SciTech Connect

    Ronsin, O.; Caroli, C.; Baumberger, T.

    2009-09-25

    We show that the aging of the mechanical relaxation of a gelatin gel exhibits the same scaling phenomenology as polymer and colloidal glasses. In addition, gelatin is known to exhibit logarithmic structural aging (stiffening). We find that stress accelerates this process. However, this effect is definitely irreducible to a mere age shift with respect to natural aging. We suggest that it is interpretable in terms of elastically aided elementary (coil->helix) local events whose dynamics gradually slows down as aging increases geometric frustration.

  12. Demography of deep-dwelling red coral populations: Age and reproductive structure of a highly valued marine species

    NASA Astrophysics Data System (ADS)

    Priori, Cristina; Mastascusa, Vincenza; Erra, Fabrizio; Angiolillo, Michela; Canese, Simonpietro; Santangelo, Giovanni

    2013-02-01

    The valuable Mediterranean red coral Corallium rubrum (Octocorallia Gorgonacea) has been harvested for more than 2 thousand years. Although our knowledge on the demographic features of red coral populations living between 10 and 50 m depth has increased considerably in recent years, the main life-history traits of deeper populations (the main target of current harvesting) are still largely unknown. To increase the demographic knowledge of the latter populations, sampling was carried out during early Summer 2010 in the North-Western Mediterranean (Tyrrhenian Sea - Italy), between 50 and 130 m depth. This paper quantifies the main demographic descriptors of this coral population in terms of size/age and sexual structure. Colony age was estimated by counting annual growth rings on thin sections of 69 colonies. A 2-way ANOVA showed no significant difference between the age estimated by three independent observers. The average annual colony growth rate (basal diameter), showing some decrease with colony age increase, was 0.26 mm/yr. The relationship between age and basal diameter derived from a subsample of colonies was then applied to assess the age of a larger sample of the population and showed 38% of the sampled colonies reached the commercial size (≥7 mm of basal diameter), corresponding to about 30 years in this population and a maximum life span of 93 years; about half of them (51.1%) were in the 21-25 and 26-30 age classes. The analysis of the sexual features revealed a balanced sex ratio, a colony fertility of 90.3% and an average fecundity of 0.83 oocytes or planulae per polyp. The knowledge of these life-history descriptors is needed for our understanding of deep dwelling red coral population dynamics and for matching of harvesting to population growth rate.

  13. Comparison of Class A and D G Protein-Coupled Receptors: Common Features in Structure and Activation†

    PubMed Central

    Eilers, Markus; Hornak, Viktor; Smith, Steven O.; Konopka, James B.

    2005-01-01

    All G protein-coupled receptors (GPCRs) share a common seven TM helix architecture and the ability to activate heterotrimeric G proteins. Nevertheless, these receptors have widely divergent sequences with no significant homology. We present a detailed structure–function comparison of the very divergent Class A and D receptors to address whether there is a common activation mechanism across the GPCR superfamily. The Class A and D receptors are represented by the vertebrate visual pigment rhodopsin and the yeast α-factor pheromone receptor Ste2, respectively. Conserved amino acids within each specific receptor class and amino acids where mutation alters receptor function were located in the structures of rhodopsin and Ste2 to assess whether there are functionally equivalent positions or regions within these receptors. We find several general similarities that are quite striking. First, strongly polar amino acids mediate helix interactions. Their mutation generally leads to loss of function or constitutive activity. Second, small and weakly polar amino acids facilitate tight helix packing. Third, proline is essential at similar positions in transmembrane helices 6 and 7 of both receptors. Mapping the specific location of the conserved amino acids and sites of constitutively active mutations identified conserved microdomains on transmembrane helices H3, H6, and H7, suggesting that there are underlying similarities in the mechanism of the widely divergent Class A and Class D receptors. PMID:15966721

  14. Occupational Class Inequalities in All-Cause and Cause-Specific Mortality among Middle-Aged Men in 14 European Populations during the Early 2000s

    PubMed Central

    Toch-Marquardt, Marlen; Menvielle, Gwenn; Eikemo, Terje A.; Kulhánová, Ivana; Kulik, Margarete C.; Bopp, Matthias; Esnaola, Santiago; Jasilionis, Domantas; Mäki, Netta; Martikainen, Pekka; Regidor, Enrique; Lundberg, Olle; Mackenbach, Johan P.

    2014-01-01

    This study analyses occupational class inequalities in all-cause mortality and four specific causes of death among men, in Europe in the early 2000s, and is the most extensive comparative analysis of occupational class inequalities in mortality in Europe so far. Longitudinal data, obtained from population censuses and mortality registries in 14 European populations, from around the period 2000–2005, were used. Analyses concerned men aged 30–59 years and included all-cause mortality and mortality from all cancers, all cardiovascular diseases (CVD), all external, and all other causes. Occupational class was analysed according to five categories: upper and lower non-manual workers, skilled and unskilled manual workers, and farmers and self-employed combined. Inequalities were quantified with mortality rate ratios, rate differences, and population attributable fractions (PAF). Relative and absolute inequalities in all-cause mortality were more pronounced in Finland, Denmark, France, and Lithuania than in other populations, and the same countries (except France) also had the highest PAF values for all-cause mortality. The main contributing causes to these larger inequalities differed strongly between countries (e.g., cancer in France, all other causes in Denmark). Relative and absolute inequalities in CVD mortality were markedly lower in Southern European populations. We conclude that relative and absolute occupational class differences in all-cause and cause specific mortality have persisted into the early 2000's, although the magnitude differs strongly between populations. Comparisons with previous studies suggest that the relative gap in mortality between occupational classes has further widened in some Northern and Western European populations. PMID:25268702

  15. Structural damages of maxillofacial biopolymers under solar aging.

    PubMed

    Eleni, P N; Krokida, M K; Frangou, M J; Polyzois, G L; Maroulis, Z B; Marinos-Kouris, D

    2007-09-01

    Additional types of silicone biopolymers are widely used in maxillofacial prosthetics. Therefore, the knowledge of the solar radiation's effect on their structural stability is highly important. Four different industrially synthesized biomaterials were examined, called Episil Europe 1, Europe 2, Europe 3 and Africa 3, which were exposed to solar radiation (UVA, UVB) for eight different time periods (from 8 to 168 h). Structural damages due to irradiation exposure were investigated by mechanical tests (compression) and differential scanning calorimetry (DSC) methods. Simple mathematical models were developed, containing parameters with physical meaning such as maximum stress (sigma(max)), maximum strain (epsilon), elasticity parameter (E), and viscoelastic parameter (p), for the compression test, and melting temperature (T (m)) and Enthalpy in melting point (Heat) for DSC. With increasing irradiation time their maximum stress and strain decreased significantly, and the materials lost their elasticity and molecular stability. A decrement in their melting points and heats was observed as irradiation time was increasing. Finally, experimental results demonstrated that solar radiation has a severe effect on the structural stability of the examined biomaterials. PMID:17483904

  16. Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease

    PubMed Central

    Moskalev, Alexey; Chernyagina, Elizaveta; de Magalhães, João Pedro; Barardo, Diogo; Thoppil, Harikrishnan; Shaposhnikov, Mikhail; Budovsky, Arie; Fraifeld, Vadim E.; Garazha, Andrew; Tsvetkov, Vasily; Bronovitsky, Evgeny; Bogomolov, Vladislav; Scerbacov, Alexei; Kuryan, Oleg; Gurinovich, Roman; Jellen, Leslie C.; Kennedy, Brian; Mamoshina, Polina; Dobrovolskaya, Evgeniya; Aliper, Alex; Kaminsky, Dmitry; Zhavoronkov, Alex

    2015-01-01

    As the level of interest in aging research increases, there is a growing number of geroprotectors, or therapeutic interventions that aim to extend the healthy lifespan and repair or reduce aging-related damage in model organisms and, eventually, in humans. There is a clear need for a manually-curated database of geroprotectors to compile and index their effects on aging and age-related diseases and link these effects to relevant studies and multiple biochemical and drug databases. Here, we introduce the first such resource, Geroprotectors (http://geroprotectors.org). Geroprotectors is a public, rapidly explorable database that catalogs over 250 experiments involving over 200 known or candidate geroprotectors that extend lifespan in model organisms. Each compound has a comprehensive profile complete with biochemistry, mechanisms, and lifespan effects in various model organisms, along with information ranging from chemical structure, side effects, and toxicity to FDA drug status. These are presented in a visually intuitive, efficient framework fit for casual browsing or in-depth research alike. Data are linked to the source studies or databases, providing quick and convenient access to original data. The Geroprotectors database facilitates cross-study, cross-organism, and cross-discipline analysis and saves countless hours of inefficient literature and web searching. Geroprotectors is a one-stop, knowledge-sharing, time-saving resource for researchers seeking healthy aging solutions. PMID:26342919

  17. Characterizing structural association alterations within brain networks in normal aging using Gaussian Bayesian networks

    PubMed Central

    Guo, Xiaojuan; Wang, Yan; Chen, Kewei; Wu, Xia; Zhang, Jiacai; Li, Ke; Jin, Zhen; Yao, Li

    2014-01-01

    Recent multivariate neuroimaging studies have revealed aging-related alterations in brain structural networks. However, the sensory/motor networks such as the auditory, visual and motor networks, have obtained much less attention in normal aging research. In this study, we used Gaussian Bayesian networks (BN), an approach investigating possible inter-regional directed relationship, to characterize aging effects on structural associations between core brain regions within each of these structural sensory/motor networks using volumetric MRI data. We then further examined the discriminability of BN models for the young (N = 109; mean age =22.73 years, range 20–28) and old (N = 82; mean age =74.37 years, range 60–90) groups. The results of the BN modeling demonstrated that structural associations exist between two homotopic brain regions from the left and right hemispheres in each of the three networks. In particular, compared with the young group, the old group had significant connection reductions in each of the three networks and lesser connection numbers in the visual network. Moreover, it was found that the aging-related BN models could distinguish the young and old individuals with 90.05, 73.82, and 88.48% accuracy for the auditory, visual, and motor networks, respectively. Our findings suggest that BN models can be used to investigate the normal aging process with reliable statistical power. Moreover, these differences in structural inter-regional interactions may help elucidate the neuronal mechanism of anatomical changes in normal aging. PMID:25324771

  18. Crystal structure of the N-myristoylated lipopeptide-bound MHC class I complex

    PubMed Central

    Morita, Daisuke; Yamamoto, Yukie; Mizutani, Tatsuaki; Ishikawa, Takeshi; Suzuki, Juri; Igarashi, Tatsuhiko; Mori, Naoki; Shiina, Takashi; Inoko, Hidetoshi; Fujita, Hiroaki; Iwai, Kazuhiro; Tanaka, Yoshimasa; Mikami, Bunzo; Sugita, Masahiko

    2016-01-01

    The covalent conjugation of a 14-carbon saturated fatty acid (myristic acid) to the amino-terminal glycine residue is critical for some viral proteins to function. This protein lipidation modification, termed N-myristoylation, is targeted by host cytotoxic T lymphocytes (CTLs) that specifically recognize N-myristoylated short peptides; however, the molecular mechanisms underlying lipopeptide antigen (Ag) presentation remain elusive. Here we show that a primate major histocompatibility complex (MHC) class I-encoded protein is capable of binding N-myristoylated 5-mer peptides and presenting them to specific CTLs. A high-resolution X-ray crystallographic analysis of the MHC class I:lipopeptide complex reveals an Ag-binding groove that is elaborately constructed to bind N-myristoylated short peptides rather than prototypic 9-mer peptides. The identification of lipopeptide-specific, MHC class I-restricted CTLs indicates that the widely accepted concept of MHC class I-mediated presentation of long peptides to CTLs may need some modifications to incorporate a novel MHC class I function of lipopeptide Ag presentation. PMID:26758274

  19. Crystal structure of the N-myristoylated lipopeptide-bound MHC class I complex.

    PubMed

    Morita, Daisuke; Yamamoto, Yukie; Mizutani, Tatsuaki; Ishikawa, Takeshi; Suzuki, Juri; Igarashi, Tatsuhiko; Mori, Naoki; Shiina, Takashi; Inoko, Hidetoshi; Fujita, Hiroaki; Iwai, Kazuhiro; Tanaka, Yoshimasa; Mikami, Bunzo; Sugita, Masahiko

    2016-01-01

    The covalent conjugation of a 14-carbon saturated fatty acid (myristic acid) to the amino-terminal glycine residue is critical for some viral proteins to function. This protein lipidation modification, termed N-myristoylation, is targeted by host cytotoxic T lymphocytes (CTLs) that specifically recognize N-myristoylated short peptides; however, the molecular mechanisms underlying lipopeptide antigen (Ag) presentation remain elusive. Here we show that a primate major histocompatibility complex (MHC) class I-encoded protein is capable of binding N-myristoylated 5-mer peptides and presenting them to specific CTLs. A high-resolution X-ray crystallographic analysis of the MHC class I:lipopeptide complex reveals an Ag-binding groove that is elaborately constructed to bind N-myristoylated short peptides rather than prototypic 9-mer peptides. The identification of lipopeptide-specific, MHC class I-restricted CTLs indicates that the widely accepted concept of MHC class I-mediated presentation of long peptides to CTLs may need some modifications to incorporate a novel MHC class I function of lipopeptide Ag presentation. PMID:26758274

  20. Prediction of Protein Structural Classes for Low-Similarity Sequences Based on Consensus Sequence and Segmented PSSM

    PubMed Central

    Liang, Yunyun; Liu, Sanyang; Zhang, Shengli

    2015-01-01

    Prediction of protein structural classes for low-similarity sequences is useful for understanding fold patterns, regulation, functions, and interactions of proteins. It is well known that feature extraction is significant to prediction of protein structural class and it mainly uses protein primary sequence, predicted secondary structure sequence, and position-specific scoring matrix (PSSM). Currently, prediction solely based on the PSSM has played a key role in improving the prediction accuracy. In this paper, we propose a novel method called CSP-SegPseP-SegACP by fusing consensus sequence (CS), segmented PsePSSM, and segmented autocovariance transformation (ACT) based on PSSM. Three widely used low-similarity datasets (1189, 25PDB, and 640) are adopted in this paper. Then a 700-dimensional (700D) feature vector is constructed and the dimension is decreased to 224D by using principal component analysis (PCA). To verify the performance of our method, rigorous jackknife cross-validation tests are performed on 1189, 25PDB, and 640 datasets. Comparison of our results with the existing PSSM-based methods demonstrates that our method achieves the favorable and competitive performance. This will offer an important complementary to other PSSM-based methods for prediction of protein structural classes for low-similarity sequences. PMID:26788119

  1. Prediction of Protein Structural Classes for Low-Similarity Sequences Based on Consensus Sequence and Segmented PSSM.

    PubMed

    Liang, Yunyun; Liu, Sanyang; Zhang, Shengli

    2015-01-01

    Prediction of protein structural classes for low-similarity sequences is useful for understanding fold patterns, regulation, functions, and interactions of proteins. It is well known that feature extraction is significant to prediction of protein structural class and it mainly uses protein primary sequence, predicted secondary structure sequence, and position-specific scoring matrix (PSSM). Currently, prediction solely based on the PSSM has played a key role in improving the prediction accuracy. In this paper, we propose a novel method called CSP-SegPseP-SegACP by fusing consensus sequence (CS), segmented PsePSSM, and segmented autocovariance transformation (ACT) based on PSSM. Three widely used low-similarity datasets (1189, 25PDB, and 640) are adopted in this paper. Then a 700-dimensional (700D) feature vector is constructed and the dimension is decreased to 224D by using principal component analysis (PCA). To verify the performance of our method, rigorous jackknife cross-validation tests are performed on 1189, 25PDB, and 640 datasets. Comparison of our results with the existing PSSM-based methods demonstrates that our method achieves the favorable and competitive performance. This will offer an important complementary to other PSSM-based methods for prediction of protein structural classes for low-similarity sequences. PMID:26788119

  2. The 1.4 Å Crystal Structure of the Class D [beta]-Lactamase OXA-1 Complexed with Doripenem

    SciTech Connect

    Schneider, Kyle D.; Karpen, Mary E.; Bonomo, Robert A.; Leonard, David A.; Powers, Rachel A.

    2010-01-12

    The clinical efficacy of carbapenem antibiotics depends on their resistance to the hydrolytic action of {beta}-lactamase enzymes. The structure of the class D {beta}-lactamase OXA-1 as an acyl complex with the carbapenem doripenem was determined to 1.4 {angstrom} resolution. Unlike most class A and class C carbapenem complexes, the acyl carbonyl oxygen in the OXA-1-doripenem complex is bound in the oxyanion hole. Interestingly, no water molecules were observed in the vicinity of the acyl linkage, providing an explanation for why carbapenems inhibit OXA-1. The side chain amine of K70 remains fully carboxylated in the acyl structure, and the resulting carbamate group forms a hydrogen bond to the alcohol of the 6{alpha}-hydroxyethyl moiety of doripenem. The carboxylate attached to the {beta}-lactam ring of doripenem is stabilized by a salt bridge to K212 and a hydrogen bond with T213, in lieu of the interaction with an arginine side chain found in most other {beta}-lactamase-{beta}-lactam complexes (e.g., R244 in the class A member TEM-1). This novel set of interactions with the carboxylate results in a major shift of the carbapenem's pyrroline ring compared to the structure of the same ring in meropenem bound to OXA-13. Additionally, bond angles of the pyrroline ring suggest that after acylation, doripenem adopts the {Delta}{sup 1} tautomer. These findings provide important insights into the role that carbapenems may have in the inactivation process of class D {beta}-lactamases.

  3. miR-Explore: Predicting MicroRNA Precursors by Class Grouping and Secondary Structure Positional Alignment

    PubMed Central

    Sebastian, Bram; Aggrey, Samuel E.

    2013-01-01

    MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expressions by targeting the mRNAs especially in the 3′UTR regions. The identification of miRNAs has been done by biological experiment and computational prediction. The computational prediction approach has been done using two major methods: comparative and noncomparative. The comparative method is dependent on the conservation of the miRNA sequences and secondary structure. The noncomparative method, on the other hand, does not rely on conservation. We hypothesized that each miRNA class has its own unique set of features; therefore, grouping miRNA by classes before using them as training data will improve sensitivity and specificity. The average sensitivity was 88.62% for miR-Explore, which relies on within miRNA class alignment, and 70.82% for miR-abela, which relies on global alignment. Compared with global alignment, grouping miRNA by classes yields a better sensitivity with very high specificity for pre-miRNA prediction even when a simple positional based secondary and primary structure alignment are used. PMID:23645986

  4. The Evolution of an Undergraduate Service Course--How To Cope with Success of an Age of Dinosaurs Class.

    ERIC Educational Resources Information Center

    Montgomery, Homer

    2003-01-01

    Discusses how to address the issue of a course becoming too popular. Uses as an example the Age of Dinosaurs course at the University of Texas at Dallas. Describes some issues that can arise such as classroom overflow, overwhelmed labs, cheating, testing methods, and asynchronous instruction. Recommends looking to web-based course management…

  5. [Dento-facial structural characteristics in Angle Class II malocclusion associated with abnormal facial divergency].

    PubMed

    Wu, K M; Chen, Y J; Cheng, M C; Chang, H F; Chen, K C

    1992-06-01

    Lateral cephalometric radiographs of 60 adult patients with Angle class 11 malocclusion associated with abnormal facial divergency were collected from the Orthodontic Department of the National Taiwan University Hospital. They were divided into a hyperdivergent group (35 cases) and a hypodivergent group (25 case), according to mandibular plane angle (SN-MP). The 19 landmarks on each cephalometric tracing were digitized into a computer, then computer-aided cephalometric analysis was performed to calculate the 17 skeletal measurements and 13 dentoalveolar measurements. The dento-facial structural characteristics of the hyperdivergent and hypodivergent groups were compared. It was found that the subjects of the hyperdivergent group revealed a greater tendency of divergency in the anterior cranial base plane, Frank-fort horizontal plane, palatal plane, occlusal plane, and mandibular plane. Hyperdivergent facial type, supposedly indicating an open bite or a tendency toward an open bite, has a longer lower anterior facial height, shorter posterior facial height, longer upper anterior and posterior dental height. While, the majority of dentofacial characteristics of the hypodivergent facial type observed in is study were directly opposite to those of the hyperdivergent facial type. The relationships of incisor overbite depth and other skeletal and dentoalveolar parameters were illustrated by Pearson's correlation coefficient and stepwise multiple regression analysis by means of the SPSS/PC statistic program. With the incisor overbite depth as the dependent variable, the independent variables included on the regression analysis were the 10 items of skeletal and dentoalveolar parameters. The compared parameters showed a statistically significant correlation with the incisor overbite depth (P < 0.001). By the stepwise method, the variables included on the regression equation were (1) N-Go-Gn, (2) A-Gn-Ar, (3) N-Ans/ans-Me, and (4) U1L1. The value of R square (R2) in the

  6. Direct measurement of riverine particulate organic carbon age structure

    NASA Astrophysics Data System (ADS)

    Rosenheim, Brad E.; Galy, Valier

    2012-10-01

    Carbon cycling studies focusing on transport and transformation of terrigenous carbon sources toward marine sedimentary sinks necessitate separation of particulate organic carbon (OC) derived from many different sources and integrated by river systems. Much progress has been made on isolating and characterizing young biologically-formed OC that is still chemically intact, however quantification and characterization of old, refractory rock-bound OC has remained troublesome. Quantification of both endmembers of riverine OC is important to constrain exchanges linking biologic and geologic carbon cycles and regulating atmospheric CO2 and O2. Here, we constrain petrogenic OC proportions in suspended sediment from the headwaters of the Ganges River in Nepal through direct measurement using ramped pyrolysis radiocarbon analysis. The unique results apportion the biospheric and petrogenic fractions of bulk particulate OC and characterize biospheric OC residence time. Compared to the same treatment of POC from the lower Mississippi-Atchafalaya River system, contrast in age spectra of the Ganges tributary samples illustrates the difference between small mountainous river systems and large integrative ones in terms of the global carbon cycle.

  7. Structure formation and the end of the cosmic dark ages

    NASA Astrophysics Data System (ADS)

    Alvarez, Marcelo Alonso

    We present results on the evolution of dark matter halos and reionization. Dark matter halos enshroud galaxies, quasars and stars. As such, they are fundamentally important to structure formation. In studying reionization, we focus on photoionization by the first stars, the 21-cm and cosmic microwave backgrounds, and its large-scale structure. Several new and important results are presented. First, we analyze the evolution of dark matter haloes that result from collapse within cosmological pancakes. Their mass accretion history and concentration are very similar to those reported simulations of CDM. Thus, fundamental properties of virialized halo formation and evolution are generic and not limited to hierarchical clustering or Gaussian-random-noise initial conditions. We also find that a simple one dimensional fluid model can explain this universal behaviour, implying that the evolving structure of CDM halos can be well understood as the effect of a universal, time-varying rate of smooth and continuous mass infall on an isotropic, collisionless fluid. We discuss cosmological reionization, from small scales and early times, to large scales and late times. We have simulated ionization fronts (I-fronts) created by the first stars forming in "minihalos". We find that nearby minihalos trap the I-front, so their centers remain neutral, contrary to the suggestion that these stars would trigger a second generation by ionizing neighboring minihalos cores. We then turn to the cross-correlation of cosmic microwave background (CMB) and 21-cm maps. We find that its measurement can be used to reconstruct the reionization history of the universe. Afterwards, we discuss the three versus first-year data from the Wilkinson Microwave Anisotropy Probe (WMAP). Surprisingly, the delay of reionization from three-year data is matched by a similar delay in structure formation. These effects cancel to leave the source halo efficiency constraints unchanged. We conclude by analyzing the

  8. Quantum singularity structure of a class of continuously self-similar spacetimes

    NASA Astrophysics Data System (ADS)

    Konkowski, Deborah; Helliwell, Thomas; Wiliams, Jon

    2016-03-01

    The dynamical, classical timelike singularity in a class of continuously self-similar, conformally-static, spherically-symmetric, power-law spacetimes is probed using massless scalar test fields. Ranges of metric parameters for which these classical singularities may be resolved quantum mechanically are determined; however, the wave operator is shown to be not essentially self-adjoint using Weyl's limit point-limit circle criterion. Thus, unfortunately, in this class of spacetimes the wave packet evolution still has the usual ambiguity associated with scattering off singularities. These spacetimes are not healed quantum mechanically.

  9. The aging of elite male athletes: age-related changes in performance and skeletal muscle structure and function

    PubMed Central

    Faulkner, John A.; Davis, Carol S.; Mendias, Christopher L.; Brooks, Susan V.

    2009-01-01

    Objective The paper addresses the degree to which the attainment of the status as an elite athlete in different sports ameliorates the known age-related losses in skeletal muscle structure and function. Design The retrospective design, based on comparisons of published data on former elite and masters athletes and data on control subjects, assessed the degree to which the attainment of ‘elite and masters athlete status’ ameliorated the known age-related changes in skeletal muscle structure and function. Setting Institutional. Participants Elite male athletes. Interventions Participation in selected individual and team sports. Main Outcome Measurements Strength, power, VO2 max and performance. Results For elite athletes in all sports, as for the general population, age-related muscle atrophy begins at about 50 years of age. Despite the loss of muscle mass, elite athletes who maintain an active life style age gracefully with few health problems. Conversely, those who lapse into inactivity regress toward general population norms for fitness, weight control, and health problems. Elite athletes in the dual and team sports have careers that rarely extend into the thirties. Conclusions Life long physical activity does not appear to have any impact on the loss in fiber number. The loss of fibers can be buffered to some degree by hypertrophy of fibers that remain. Surprisingly, the performance of elite athletes in all sports appears to be impaired before the onset of the fiber loss. Even with major losses in physical capacity and muscle mass, the performance of elite and masters athletes is remarkable. PMID:19001883

  10. NMR solution structure and function of the C-terminal domain of eukaryotic class 1 polypeptide chain release factor.

    PubMed

    Mantsyzov, Alexey B; Ivanova, Elena V; Birdsall, Berry; Alkalaeva, Elena Z; Kryuchkova, Polina N; Kelly, Geoff; Frolova, Ludmila Y; Polshakov, Vladimir I

    2010-06-01

    Termination of translation in eukaryotes is triggered by two polypeptide chain release factors, eukaryotic class 1 polypeptide chain release factor (eRF1) and eukaryotic class 2 polypeptide chain release factor 3. eRF1 is a three-domain protein that interacts with eukaryotic class 2 polypeptide chain release factor 3 via its C-terminal domain (C-domain). The high-resolution NMR structure of the human C-domain (residues 277-437) has been determined in solution. The overall fold and the structure of the beta-strand core of the protein in solution are similar to those found in the crystal structure. The structure of the minidomain (residues 329-372), which was ill-defined in the crystal structure, has been determined in solution. The protein backbone dynamics, studied using (15)N-relaxation experiments, showed that the C-terminal tail 414-437 and the minidomain are the most flexible parts of the human C-domain. The minidomain exists in solution in two conformational states, slowly interconverting on the NMR timescale. Superposition of this NMR solution structure of the human C-domain onto the available crystal structure of full-length human eRF1 shows that the minidomain is close to the stop codon-recognizing N-terminal domain. Mutations in the tip of the minidomain were found to affect the stop codon specificity of the factor. The results provide new insights into the possible role of the C-domain in the process of translation termination. PMID:20553496

  11. One-Class Support Vector Machines Identify the Language and Default Mode Regions As Common Patterns of Structural Alterations in Young Children with Autism Spectrum Disorders.

    PubMed

    Retico, Alessandra; Gori, Ilaria; Giuliano, Alessia; Muratori, Filippo; Calderoni, Sara

    2016-01-01

    The identification of reliable brain endophenotypes of autism spectrum disorders (ASD) has been hampered to date by the heterogeneity in the neuroanatomical abnormalities detected in this condition. To handle the complexity of neuroimaging data and to convert brain images in informative biomarkers of pathology, multivariate analysis techniques based on Support Vector Machines (SVM) have been widely used in several disease conditions. They are usually trained to distinguish patients from healthy control subjects by making a binary classification. Here, we propose the use of the One-Class Classification (OCC) or Data Description method that, in contrast to two-class classification, is based on a description of one class of objects only. This approach, by defining a multivariate normative rule on one class of subjects, allows recognizing examples from a different category as outliers. We applied the OCC to 314 regional features extracted from brain structural Magnetic Resonance Imaging (MRI) scans of young children with ASD (21 males and 20 females) and control subjects (20 males and 20 females), matched on age [range: 22-72 months of age; mean = 49 months] and non-verbal intelligence quotient (NVIQ) [range: 31-123; mean = 73]. We demonstrated that a common pattern of features characterize the ASD population. The OCC SVM trained on the group of ASD subjects showed the following performances in the ASD vs. controls separation: the area under the receiver operating characteristic curve (AUC) was 0.74 for the male and 0.68 for the female population, respectively. Notably, the ASD vs. controls discrimination results were maximized when evaluated on the subsamples of subjects with NVIQ ≥ 70, leading to AUC = 0.81 for the male and AUC = 0.72 for the female populations, respectively. Language regions and regions from the default mode network-posterior cingulate cortex, pars opercularis and pars triangularis of the inferior frontal gyrus, and transverse temporal gyrus

  12. One-Class Support Vector Machines Identify the Language and Default Mode Regions As Common Patterns of Structural Alterations in Young Children with Autism Spectrum Disorders

    PubMed Central

    Retico, Alessandra; Gori, Ilaria; Giuliano, Alessia; Muratori, Filippo; Calderoni, Sara

    2016-01-01

    The identification of reliable brain endophenotypes of autism spectrum disorders (ASD) has been hampered to date by the heterogeneity in the neuroanatomical abnormalities detected in this condition. To handle the complexity of neuroimaging data and to convert brain images in informative biomarkers of pathology, multivariate analysis techniques based on Support Vector Machines (SVM) have been widely used in several disease conditions. They are usually trained to distinguish patients from healthy control subjects by making a binary classification. Here, we propose the use of the One-Class Classification (OCC) or Data Description method that, in contrast to two-class classification, is based on a description of one class of objects only. This approach, by defining a multivariate normative rule on one class of subjects, allows recognizing examples from a different category as outliers. We applied the OCC to 314 regional features extracted from brain structural Magnetic Resonance Imaging (MRI) scans of young children with ASD (21 males and 20 females) and control subjects (20 males and 20 females), matched on age [range: 22–72 months of age; mean = 49 months] and non-verbal intelligence quotient (NVIQ) [range: 31–123; mean = 73]. We demonstrated that a common pattern of features characterize the ASD population. The OCC SVM trained on the group of ASD subjects showed the following performances in the ASD vs. controls separation: the area under the receiver operating characteristic curve (AUC) was 0.74 for the male and 0.68 for the female population, respectively. Notably, the ASD vs. controls discrimination results were maximized when evaluated on the subsamples of subjects with NVIQ ≥ 70, leading to AUC = 0.81 for the male and AUC = 0.72 for the female populations, respectively. Language regions and regions from the default mode network—posterior cingulate cortex, pars opercularis and pars triangularis of the inferior frontal gyrus, and transverse temporal

  13. Some Effects of Sex, Age, and Household Structure on Family Drawings of Barbadian Children.

    ERIC Educational Resources Information Center

    Payne, Monica A.

    1996-01-01

    Reports on an analysis of the family drawings of a nonclinical sample of 502 Barbadian children ages 7-11. Reveals a correlation among sex, age, and household structure and the inclusion or omission of figures, as well as the size and positioning of the figures of parent and self. (MJP)

  14. Estimating survival rates with time series of standing age-structure data

    USGS Publications Warehouse

    Udevitz, Mark S.; Gogan, Peter J.

    2014-01-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  15. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H. W.; Farahmand, B.; Rioja, R.

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  16. Factor Structure of Attention Deficit Hyperactivity Disorder Symptoms for Children Age 3 to 5 Years

    ERIC Educational Resources Information Center

    McGoey, Kara E.; Schreiber, James; Venesky, Lindsey; Westwood, Wendy; McGuirk, Lindsay; Schaffner, Kristen

    2015-01-01

    The diagnosis of attention deficit hyperactivity disorder (ADHD) distinguishes two dimensions of symptoms, inattention and hyperactivity-impulsivity for ages 3 to adulthood. Currently, no separate classification for preschool-age children exists, whereas preliminary research suggests that the two-factor structure of ADHD may not match the…

  17. The Coming of age of Low-cost Nanosatellites as Enablers for Constellation-class Space Weather Networks

    NASA Astrophysics Data System (ADS)

    Klumpar, D. M.

    2006-12-01

    Recent progress in the development of satellite-borne space science instrumentation has focused on increased sophistication resulting in a tremendous increase in understanding of microphysical processes in space. These tremendous advancements, however, have been made without sufficient concomitant experimental characterization of the dynamic behavior of the large-scale geospace system. Global theoretical models of the geospace system need distributed measurements for authentication. Thus there is a need to acquire in-situ space weather data at higher spatio-temporal density than currently planned. Nanosatellites (i.e. 1-10 kg spacecraft) have emerged as technically capable carriers for a variety of on-orbit missions. Advances in electronic miniaturization, reductions in power consumption, increased communications capabilities and miniaturized propulsion systems for station-keeping have enabled development of highly capable miniature satellite buses. Led primarily by universities, kg-class satellites have been developed and launched for a variety of purposes. As recently as July 2006, 18 satellites were lost in a launch booster failure in what was billed as the single largest cluster launch of satellites to date. Thirteen of the 14 one kg-class satellites in this cluster launch were designed, developed, and built in university laboratories. They were built at a fraction of the cost of typical satellites. While, in this instance, these 14 satellites had, for the most part, unrelated mission goals it is perfectly reasonable to envision that a launch of several dozen related satellites is technically feasible at a cost much lower than studies based on traditional methods have shown. This paper will review current nanosatellite capabilities and explore the application of constellations of nanosatellies as carriers of relatively unsophisticated space weather instruments where the value lies in the ability to make a network of measurements that provide unprecedented

  18. Implications of a class of grand-unified theories for large-scale structure in the universe

    NASA Technical Reports Server (NTRS)

    Shafi, Q.; Stecker, F. W.

    1984-01-01

    A class of grand-unified theories in which cosmologically significant axion and neutrino energy densities arise naturally is considered. To obtain large-scale structure, attention is given to (1) an inflationary scenario, (2) inflation followed by string production, and (3) a noninflationary scenario with density fluctuations caused solely by strings. It is shown that inflation may be compatible with the recent observational indications that Omega less than 1 on the scale of superclusters, particularly if strings are present.

  19. Does white matter structure or hippocampal volume mediate associations between cortisol and cognitive ageing?

    PubMed Central

    Cox, Simon R.; MacPherson, Sarah E.; Ferguson, Karen J.; Royle, Natalie A.; Maniega, Susana Muñoz; Hernández, Maria del C. Valdés; Bastin, Mark E.; MacLullich, Alasdair M.J.; Wardlaw, Joanna M.; Deary, Ian J.

    2015-01-01

    Elevated glucocorticoid (GC) levels putatively damage specific brain regions, which in turn may accelerate cognitive ageing. However, many studies are cross-sectional or have relatively short follow-up periods, making it difficult to relate GCs directly to changes in cognitive ability with increasing age. Moreover, studies combining endocrine, MRI and cognitive variables are scarce, measurement methods vary considerably, and formal tests of the underlying causal hypothesis (cortisol → brain → cognition) are absent. In this study, 90 men, aged 73 years, provided measures of fluid intelligence, processing speed and memory, diurnal and reactive salivary cortisol and two measures of white matter (WM) structure (WM hyperintensity volume from structural MRI and mean diffusivity averaged across 12 major tracts from diffusion tensor MRI), hippocampal volume, and also cognitive ability at age 11. We tested whether negative relationships between cognitive ageing differences (over more than 60 years) and salivary cortisol were significantly mediated by WM and hippocampal volume. Significant associations between reactive cortisol at 73 and cognitive ageing differences between 11 and 73 (r = −.28 to −.36, p < .05) were partially mediated by both WM structural measures, but not hippocampal volume. Cortisol-WM relationships were modest, as was the degree to which WM structure attenuated cortisol–cognition associations (<15%). These data support the hypothesis that GCs contribute to cognitive ageing differences from childhood to the early 70s, partly via brain WM structure. PMID:26298692

  20. Structural Revisions of a Class of Natural Products: Scaffolds of Aglycon Analogues of Fusicoccins and Cotylenins Isolated from Fungi.

    PubMed

    Tang, Ying; Xue, Yongbo; Du, Guang; Wang, Jianping; Liu, Junjun; Sun, Bin; Li, Xiao-Nian; Yao, Guangmin; Luo, Zengwei; Zhang, Yonghui

    2016-03-14

    The reisolation and structural revision of brassicicene D is described, and inspired us to reassign the core skeletons of brassicicenes C-H, J and K, ranging from dicyclopenta[a,d]cyclooctane to tricyclo[9.2.1.0(3,7)]tetradecane using quantum-chemical predictions and experimental validation strategies. Three novel, highly modified fusicoccanes, brassicicenes L-N, were also isolated from the fungus Alternaria brassicicola, and their structures were unequivocally established by spectroscopic data, ECD calculations, and crystallography. The reassigned structures represent the first class of bridgehead double-bond-containing natural products with a bicyclo[6.2.1]undecane carbon skeleton. Furthermore, their stabilities were first predicted with olefin strain energy calculations. Collectively, these findings extend our view of the application of computational predictions and biosynthetic logic-based structure elucidation to address problems related to the structure and stability of natural products. PMID:26916098

  1. A Structural Model of Task Values, Goal Orientations, and Learning Strategies in Elementary School Mathematics Class.

    ERIC Educational Resources Information Center

    Seo, Daeryong; Park, Yong Hui

    A goal mediational model to conceptualize the effects of students' motivational beliefs on their learning strategies was modified with the three goal orientations: task, performance-approach, and performance-avoidance goals. Questionnaires were administered to 161 Korean fifth graders (boys = 88; girls = 73) in an elementary school math class.…

  2. The Motivational Construct in Mathematics Learning Using Structural Equation Modeling: The Korean Elementary School Math Class.

    ERIC Educational Resources Information Center

    Seo, Daeryong

    This study was undertaken to understand a motivation model in the context of the Korean elementary school mathematics class. The sample consisted of 178 fourth graders (boys=95; girls=83) from 2 Korean elementary schools. This study showed that a goal mediational model could be modified and successfully applied to the context of the Korean…

  3. A Conflicting View in the Use of Journals for Composition and Literature Classes: Structure versus Freedom.

    ERIC Educational Resources Information Center

    Townsend, Julie E.

    The most powerful and profound thoughts known to humankind are the result of freedom to write whatever it is that the soul must purge; whatever a person is thinking that troubles him or her; anything that hinders his or her ability to be in that particular moment of living. On the first day of class, one writing instructor tells her students that…

  4. The Structure of Student Satisfaction with College Services: A Latent Class Model

    ERIC Educational Resources Information Center

    Adwere-Boamah, Joseph

    2011-01-01

    Latent Class Analysis (LCA) was used to identify distinct groups of Community college students based on their self-ratings of satisfaction with student service programs. The programs were counseling, financial aid, health center, student programs and student government. The best fitting model to describe the data was a two Discrete-Factor model…

  5. Confirming the Structural Validity of the My Class Inventory -- Short Form Revised

    ERIC Educational Resources Information Center

    Mariani, Melissa; Villares, Elizabeth; Sink, Christopher A.; Colvin, Kimberly; Kuba, Summer Perhay

    2015-01-01

    Researchers analyzed data collected from elementary school students (N = 893) to further establish the psychometric soundness of the My Class Inventory--Short Form Revised (MCI-SFR). A confirmatory factor analysis was conducted resulting in a good fit for a four-factor model, which corresponds to the instrument's four scales (Cohesion,…

  6. Visualizing Communication Structures in Science Classrooms: Tracing Cumulativity in Teacher-Led Whole Class Discussions

    ERIC Educational Resources Information Center

    Lehesvuori, Sami; Viiri, Jouni; Rasku-Puttonen, Helena; Moate, Josephine; Helaakoski, Jussi

    2013-01-01

    Teacher-led whole class discussions are essential when it comes to guiding students' construction of knowledge, and recent studies on teaching and learning emphasize the need for more student-centered teaching methods. In previous studies, the extent to which different types of communication take place in the classroom have been extensively…

  7. Aging management of safety-related concrete structures in nuclear power plants

    SciTech Connect

    Naus, D.J.; Oland, C.B. ); Arndt, E.G. )

    1990-01-01

    The Structural Aging Program has the overall objective of providing the US Nuclear Regulatory Commission with an improved basis for evaluating nuclear power plants for continued service. In meeting this objective, a materials property data base is being developed as well as an aging assessment methodology for concrete structures in nuclear power plants. Furthermore, studies are well under way to review and assess inservice inspection techniques for concrete structures and to develop a methodology which can be used for performing current as well as reliability-based future conditions assessments of these structures. 16 refs., 2 tabs.

  8. Structural Aging Program to evaluate continued performance of safety-related concrete structures in nuclear power plants

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1994-03-01

    This report discusses the Structural Aging (SAG) Program which is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory commission (USNRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into three technical tasks: Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented.

  9. A highly accurate protein structural class prediction approach using auto cross covariance transformation and recursive feature elimination.

    PubMed

    Li, Xiaowei; Liu, Taigang; Tao, Peiying; Wang, Chunhua; Chen, Lanming

    2015-12-01

    Structural class characterizes the overall folding type of a protein or its domain. Many methods have been proposed to improve the prediction accuracy of protein structural class in recent years, but it is still a challenge for the low-similarity sequences. In this study, we introduce a feature extraction technique based on auto cross covariance (ACC) transformation of position-specific score matrix (PSSM) to represent a protein sequence. Then support vector machine-recursive feature elimination (SVM-RFE) is adopted to select top K features according to their importance and these features are input to a support vector machine (SVM) to conduct the prediction. Performance evaluation of the proposed method is performed using the jackknife test on three low-similarity datasets, i.e., D640, 1189 and 25PDB. By means of this method, the overall accuracies of 97.2%, 96.2%, and 93.3% are achieved on these three datasets, which are higher than those of most existing methods. This suggests that the proposed method could serve as a very cost-effective tool for predicting protein structural class especially for low-similarity datasets. PMID:26460680

  10. Insights into MHC class I peptide loading from the structure of the Tapasin-ERp57 thiol oxidoreductase heterodimer

    SciTech Connect

    Dong, G.; Wearsch, P.A.; Peaper, D.R.; Cresswell, P.; Reinisch, K.M.

    2009-03-02

    Tapasin is a glycoprotein critical for loading major histocompatibility complex (MHC) class I molecules with high-affinity peptides. It functions within the multimeric peptide-loading complex (PLC) as a disulfide-linked, stable heterodimer with the thiol oxidoreductase ERp57, and this covalent interaction is required to support optimal PLC activity. Here, we present the 2.6 {angstrom} resolution structure of the tapasin-ERp57 core of the PLC. The structure revealed that tapasin interacts with both ERp57 catalytic domains, accounting for the stability of the heterodimer, and provided an example of a protein disulfide isomerase family member interacting with substrate. Mutational analysis identified a conserved surface on tapasin that interacted with MHC class I molecules and was critical for peptide loading and editing functions of the tapasin-ERp57 heterodimer. By combining the tapasin-ERp57 structure with those of other defined PLC components, we present a molecular model that illuminates the processes involved in MHC class I peptide loading.

  11. Test series 1: seismic-fragility tests of naturally-aged Class 1E Gould NCX-2250 battery cells

    SciTech Connect

    Bonzon, L. L.; Hente, D. B.; Kukreti, B. M.; Schendel, J. S.; Tulk, J. D.; Janis, W. J.; Black, D A; Paulsen, G. D.; Aucoin, B. D.

    1984-09-01

    The seismic-fragility response of naturally-aged, nuclear station, safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and thresholds; and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the end-of-life of a battery, given a seismic event. This report covers the first test series of an extensive program using 12-year old, lead-calcium, Gould NCX-2250 cells, from the James A. Fitzpatrick Nuclear Power Station operated by the New York Power Authority. Seismic tests with three cell configurations were performed using a triaxial shake table: single-cell tests, rigidly mounted; multi-cell (three) tests, mounted in a typical battery rack; and single-cell tests specifically aimed towards examining propagation of pre-existing case cracks. In general the test philosophy was to monitor the electrical properties including discharge capacity of cells through a graduated series of g-level step increases until either the shake-table limits were reached or until electrical failure of the cells occurred. Of nine electrically active cells, six failed during seismic testing over a range of imposed g-level loads in excess of a 1-g ZPA. Post-test examination revealed a common failure mode, the cracking at the abnormally brittle, positive lead bus-bar/post interface; further examination showed that the failure zone was extremely coarse grained and extensively corroded. Presently accepted accelerated-aging methods for qualifying batteries, per IEEE Std. 535-1979, are based on plate growth, but these naturally-aged 12-year old cells showed no significant plate growth.

  12. An agent-based computational model for tuberculosis spreading on age-structured populations

    NASA Astrophysics Data System (ADS)

    Graciani Rodrigues, C. C.; Espíndola, Aquino L.; Penna, T. J. P.

    2015-06-01

    In this work we present an agent-based computational model to study the spreading of the tuberculosis (TB) disease on age-structured populations. The model proposed is a merge of two previous models: an agent-based computational model for the spreading of tuberculosis and a bit-string model for biological aging. The combination of TB with the population aging, reproduces the coexistence of health states, as seen in real populations. In addition, the universal exponential behavior of mortalities curves is still preserved. Finally, the population distribution as function of age shows the prevalence of TB mostly in elders, for high efficacy treatments.

  13. Mathematical Model of Three Age-Structured Transmission Dynamics of Chikungunya Virus

    PubMed Central

    Agusto, Folashade B.; Easley, Shamise; Freeman, Kenneth; Thomas, Madison

    2016-01-01

    We developed a new age-structured deterministic model for the transmission dynamics of chikungunya virus. The model is analyzed to gain insights into the qualitative features of its associated equilibria. Some of the theoretical and epidemiological findings indicate that the stable disease-free equilibrium is globally asymptotically stable when the associated reproduction number is less than unity. Furthermore, the model undergoes, in the presence of disease induced mortality, the phenomenon of backward bifurcation, where the stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the associated reproduction number is less than unity. Further analysis of the model indicates that the qualitative dynamics of the model are not altered by the inclusion of age structure. This is further emphasized by the sensitivity analysis results, which shows that the dominant parameters of the model are not altered by the inclusion of age structure. However, the numerical simulations show the flaw of the exclusion of age in the transmission dynamics of chikungunya with regard to control implementations. The exclusion of age structure fails to show the age distribution needed for an effective age based control strategy, leading to a one size fits all blanket control for the entire population. PMID:27190548

  14. Comparing Class A GPCRs to bitter taste receptors: Structural motifs, ligand interactions and agonist-to-antagonist ratios.

    PubMed

    Di Pizio, Antonella; Levit, Anat; Slutzki, Michal; Behrens, Maik; Karaman, Rafik; Niv, Masha Y

    2016-01-01

    G protein-coupled receptors (GPCRs) are seven transmembrane (TM) proteins that play a key role in human physiology. The GPCR superfamily comprises about 800 members, classified into several classes, with rhodopsin-like Class A being the largest and most studied thus far. A huge component of the human repertoire consists of the chemosensory GPCRs, including ∼400 odorant receptors, 25 bitter taste receptors (TAS2Rs), which are thought to guard the organism from consuming poisons, and sweet and umami TAS1R heteromers, which indicate the nutritive value of food. The location of the binding site of TAS2Rs is similar to that of Class A GPCRs. However, most of the known bitter ligands are agonists, with only a few antagonists documented thus far. The agonist-to-antagonist ratios of Class A GPCRs vary, but in general are much lower than for TAS2Rs. For a set of well-studied GPCRs, a gradual change in agonists-to-antagonists ratios is observed when comparing low (10 μM)- and high (10 nM)-affinity ligand sets from ChEMBL and the DrugBank set of drugs. This shift reflects pharmaceutical bias toward the therapeutically desirable pharmacology for each of these GPCRs, while the 10 μM sets possibly represent the native tendency of the receptors toward either agonists or antagonists. Analyzing ligand-GPCR interactions in 56 X-ray structures representative of currently available structural data, we find that the N-terminus, TM1 and TM2 are more involved in binding of antagonists than of agonists. On the other hand, ECL2 tends to be more involved in binding of agonists. This is of interest, since TAS2Rs harbor variations on the typical Class A sequence motifs, including the absence of the ECL2-TM3 disulfide bridge. This suggests an alternative mode of regulation of conformational states for TAS2Rs, with potentially less stabilized inactive state. The comparison of TAS2Rs and Class A GPCRs structural features and the pharmacology of the their ligands highlights the intricacies of

  15. Neuroanatomical correlates of cognitive aging: evidence from structural magnetic resonance imaging.

    PubMed

    Raz, N; Gunning-Dixon, F M; Head, D; Dupuis, J H; Acker, J D

    1998-01-01

    To examine putative brain substrates of cognitive functions differentially affected by age the authors measured the volume of cortical regions and performance on tests of executive functions, working memory, explicit memory, and priming in healthy adults (18-77 years old). The results indicate that shrinkage of the prefrontal cortex mediates age-related increases in perseveration. The volume of visual processing areas predicted performance on nonverbal working memory tasks. Contrary to the hypotheses, in the examined age range, the volume of limbic structures was unrelated to any of the cognitive functions; verbal working memory, verbal explicit memory, and verbal priming were independent of cortical volumes. Nevertheless, among the participants aged above 60, reduction in the volume of limbic structures predicted declines in explicit memory. Chronological age adversely influenced all cognitive indices, although its effects on priming were only indirect, mediated by declines in verbal working memory. PMID:9460738

  16. Quota implementation of the maximum sustainable yield for age-structured fisheries.

    PubMed

    Kanik, Zafer; Kucuksenel, Serkan

    2016-06-01

    One of the main goals stated in the proposals for the Common Fisheries Policy (CFP) reform was achieving maximum sustainable yield (MSY) for all European fisheries. In this paper, we propose a fishing rights allocation mechanism or management system, which specifies catch limits for individual fishing fleets to implement MSY harvesting conditions in an age-structured bioeconomic model. An age-structured model in a single species fishery with two fleets having perfect or imperfect fishing selectivity is studied. If fishing technology or gear selectivity depends on the relative age composition of the mature fish stock, fixed harvest proportions, derived from catchability and bycatch coefficients, is not valid anymore. As a result, not only the age-structure and fishing technology but also the estimated level of MSY is steering the allocation of quota shares. The results also show that allocation of quota shares based on historical catches or auctioning may not provide viable solutions to achieve MSY. PMID:27018447

  17. Intrinsic Nanoscience of δ Pu-Ga Alloys: Local Structure and Speciation, Collective Behavior, Nanoscale Heterogeneity, and Aging Mechanisms

    SciTech Connect

    Conradson, Steven D.; Bock, Nicolas; Castro, Julio M.; Conradson, Dylan R.; Cox, Lawrence E.; Dmowski, Wojtek; Dooley, David E.; Egami, Takeshi; Espinosa-Faller, Francisco J.; Freibert, Franz J.; Garcia-Adeva, Angel J.; Hess, Nancy J.; Holmstrom, Erik; Howell, Rafael C.; Katz, Barbara A.; Lashley, Jason C.; Martinez, Raymond J.; Moore, David P.; Morales, Luis A.; Olivas, J David; Pereyra, Ramiro A.; Ramos, Michael; Terry, Jeff H.; Villella, Phillip M.

    2014-04-24

    Because diffraction measurements are sensitive only to the long range average arrangement of the atoms in the coherent portion of a crystal, complementary local structure measurements are required for a complete understanding of the structure of a complex material. This is particularly an issue in solid solutions where even random distributions of a solute will result in nanometer-scale fluctuations in the local composition. The structure will be further complicated if collective and cooperative phenomena organize the solute distribution via longer range interactions between non-bonded solute sites. If the solute affects the phase stability then the question is raised of whether the atoms in domains with local compositions outside the limits of the bulk phase will rearrange into the structure stable for that composition and temperature or if the resulting stress would prevent such a local phase transition. If the former, then phase separated, heterogeneous structures at or below the diffraction limit will form. This nanometerscale competition between the phase transition and the epitaxial mismatch – exacerbated by the added strain if the transition involves a volume change – raises the potential for the formation of novel structures that do not occur in bulk material, e.g., fcc Fe. This coupling over multiple scales between inhomogeneity ordering, elastic forces, phase competition, and texture in the form of coexisting structures is a hallmark of martensites, a class of complex materials that includes δ-stabilized PuGa and that often exhibit correlated atomic and electronic properties. The enigmatic and extreme nature of Pu is consistent with its exhibiting unusual structural behavior of this type, including nanoscale heterogeneity in δ-stabilized PuGa and its enhanced homogeneity on aging that has been suggested based on earlier X-ray Absorption Fine Structure (XAFS) spectroscopy and x-ray pair distribution function (pdf) measurements. Measurements on a

  18. A novel Multi-Agent Ada-Boost algorithm for predicting protein structural class with the information of protein secondary structure.

    PubMed

    Fan, Ming; Zheng, Bin; Li, Lihua

    2015-10-01

    Knowledge of the structural class of a given protein is important for understanding its folding patterns. Although a lot of efforts have been made, it still remains a challenging problem for prediction of protein structural class solely from protein sequences. The feature extraction and classification of proteins are the main problems in prediction. In this research, we extended our earlier work regarding these two aspects. In protein feature extraction, we proposed a scheme by calculating the word frequency and word position from sequences of amino acid, reduced amino acid, and secondary structure. For an accurate classification of the structural class of protein, we developed a novel Multi-Agent Ada-Boost (MA-Ada) method by integrating the features of Multi-Agent system into Ada-Boost algorithm. Extensive experiments were taken to test and compare the proposed method using four benchmark datasets in low homology. The results showed classification accuracies of 88.5%, 96.0%, 88.4%, and 85.5%, respectively, which are much better compared with the existing methods. The source code and dataset are available on request. PMID:26350693

  19. Age-structured mark-recapture analysis: A virtual-population-analysis-based model for analyzing age-structured capture-recapture data

    USGS Publications Warehouse

    Coggins, L.G., Jr.; Pine, William E., III; Walters, C.J.; Martell, S.J.D.

    2006-01-01

    We present a new model to estimate capture probabilities, survival, abundance, and recruitment using traditional Jolly-Seber capture-recapture methods within a standard fisheries virtual population analysis framework. This approach compares the numbers of marked and unmarked fish at age captured in each year of sampling with predictions based on estimated vulnerabilities and abundance in a likelihood function. Recruitment to the earliest age at which fish can be tagged is estimated by using a virtual population analysis method to back-calculate the expected numbers of unmarked fish at risk of capture. By using information from both marked and unmarked animals in a standard fisheries age structure framework, this approach is well suited to the sparse data situations common in long-term capture-recapture programs with variable sampling effort. ?? Copyright by the American Fisheries Society 2006.

  20. Sex differences in the latent class structure of alcohol use disorder: Does (dis)aggregation of indicators matter?

    PubMed

    Shireman, Emilie M; Steinley, Douglas; Sher, Kenneth

    2015-08-01

    Many researchers have argued for a differential presentation of alcohol use disorder (AUD) between men and women. Latent class analysis is the most commonly used analytic technique for modeling AUD subcategories, and latent class analyses have supported a variety of class structures of AUD. This article examines whether these differential results are, in part, an artifact of whether researchers have (a) analyzed men and women in the same analysis and (b) aggregated item-level symptoms into AUD diagnostic criteria prior to analysis. These related methodological issues are examined using Wave 2 data from the National Epidemiologic Survey of Alcohol and Related Conditions (N = 22,177). Direct comparison of results when the sexes are modeled separately or together shows that women are classified differently depending on whether men are included in the analysis. A comparison of disaggregated item-level symptoms and aggregated AUD criteria suggests that aggregating data remove a subgroup, individuals who exhibit tolerance but are normative on all other AUD symptoms, which is of theoretical and clinical interest. Consequently, basic methodological issues that are rarely systematically studied appear to be important determinants of studies seeking to determine whether male and female alcoholism are structurally isomorphic. PMID:26237327

  1. Structure of macrophage colony stimulating factor bound to FMS: Diverse signaling assemblies of class III receptor tyrosine kinases

    SciTech Connect

    Chen, Xiaoyan; Liu, Heli; Focia, Pamela J.; Shim, Ann Hye-Ryong; He, Xiaolin

    2009-06-12

    Macrophage colony stimulating factor (M-CSF), through binding to its receptor FMS, a class III receptor tyrosine kinase (RTK), regulates the development and function of mononuclear phagocytes, and plays important roles in innate immunity, cancer and inflammation. We report a 2.4 {angstrom} crystal structure of M-CSF bound to the first 3 domains (D1-D3) of FMS. The ligand binding mode of FMS is surprisingly different from KIT, another class III RTK, in which the major ligand-binding domain of FMS, D2, uses the CD and EF loops, but not the {beta}-sheet on the opposite side of the Ig domain as in KIT, to bind ligand. Calorimetric data indicate that M-CSF cannot dimerize FMS without receptor-receptor interactions mediated by FMS domains D4 and D5. Consistently, the structure contains only 1 FMS-D1-D3 molecule bound to a M-CSF dimer, due to a weak, hydrophilic M-CSF:FMS interface, and probably a conformational change of the M-CSF dimer in which binding to the second site is rendered unfavorable by FMS binding at the first site. The partial, intermediate complex suggests that FMS may be activated in two steps, with the initial engagement step distinct from the subsequent dimerization/activation step. Hence, the formation of signaling class III RTK complexes can be diverse, engaging various modes of ligand recognition and various mechanistic steps for dimerizing and activating receptors.

  2. Seismic fragility testing of naturally-aged, safety-related, class 1E battery cells. [PWR; BWR

    SciTech Connect

    Bonzon, L.L.; Hente, D.B.; Kukreti, B.M.; Schendel, J.S.; Black, D.A.; Paulsen, G.D.; Tulk, J.D.; Janis, W.J.; Aucoin, B.D.

    1984-01-01

    The concern over seismic susceptibility of naturally-aged lead-acid batteries used for safety-related emergency power in nuclear power stations was brought about by battery problems that periodically had been reported in Licensee Event Reports (LERs). The Turkey Point Station had reported cracked and buckled plates in several cells in October 1974 (LER 75-5). The Fitzpatrick Station had reported cracked battery cell cases in October 1977 (LER 77-55) and again in September 1979 (LER 79-59). The Browns Ferry Station had reported a cracked cell leaking a small quantity of electrolyte in July 1981 (LER 81-42). The Indian Point Station had reported cracked and leaking cells in both February (LER 82-7) and April 1982 (LER 82-16); both of these LERs indicated the cracked cells were due to expansion (i.e., growth) of the positive plates.

  3. Test Series 2: seismic-fragility tests of naturally-aged Class 1E Exide FHC-19 battery cells

    SciTech Connect

    Bonzon, L. L.; Hente, D. B.; Kukreti, B. M.; Schendel, J.; Tulk, J. D.; Janis, W. J.; Black, D. A.; Paulsen, G. D.; Aucoin, B. D.

    1985-03-01

    The seismic-fragility of naturally-aged nuclear station safety-related batteries is of interest for two reasons: (1) to determine actual failure modes and their thresholds and (2) to determine the validity of using the electrical capacity of individual cells as an indicator of the ''end-of-life'' of a battery if subjected to a seismic event. This report, the second in a test series of an extensive seismic research program, covers the testing of 10-year old lead-calcium Exide FHC-19 cells from the Calvert Cliffs Nuclear Power Station operated by the Baltimore Gas and Electric Company. The Exide cells were tested in two configurations using a triaxial shake table: single-cell tests, both rigidly and loosely mounted; and multicell (three-cell) tests, mounted in a typical battery rack. A total of six electrically active cells was used in the two different cell configurations.

  4. Protection of rubbers against aging with the use of structural, diffusion and kinetic effects

    SciTech Connect

    Kablov, V. F.; Zaikov, G. E.

    2014-05-15

    Processes of rubber aging in the different kinetic modes and mathematical models of the processes including aging and destruction processes under extreme conditions have been studied. The aging process for rubbers as thermodynamically open nonlinear systems has also been considered in the paper. It has been revealed that the aging process can be controlled by the internal physical-chemical processes organization and by creation of external influences (by organization of thermodynamic forces and flows). According to the Onsager principle, in certain conditions of aging the conjugation of thermodynamic forces and flows is possible. The diffusion and structural aspects of aging in elastomeric rubbers and articles thereof have been considered. The composite antiaging systems of prolonged action based on the use of microparticles with a saturated solution of the antiagers migrating into an elastomeric matrix at the exploitation have been proposed.

  5. Protection of rubbers against aging with the use of structural, diffusion and kinetic effects

    NASA Astrophysics Data System (ADS)

    Kablov, V. F.; Zaikov, G. E.

    2014-05-01

    Processes of rubber aging in the different kinetic modes and mathematical models of the processes including aging and destruction processes under extreme conditions have been studied. The aging process for rubbers as thermodynamically open nonlinear systems has also been considered in the paper. It has been revealed that the aging process can be controlled by the internal physical-chemical processes organization and by creation of external influences (by organization of thermodynamic forces and flows). According to the Onsager principle, in certain conditions of aging the conjugation of thermodynamic forces and flows is possible. The diffusion and structural aspects of aging in elastomeric rubbers and articles thereof have been considered. The composite antiaging systems of prolonged action based on the use of microparticles with a saturated solution of the antiagers migrating into an elastomeric matrix at the exploitation have been proposed.

  6. Structural Validity of the Professional Development Profile of the LoTi Digital-Age Survey

    ERIC Educational Resources Information Center

    Mehta, Vandhana; Hull, Darrell M.

    2013-01-01

    The present study was used to examine the structural construct validity of the Professional Development Profile of the LoTi Digital-Age Survey, a measure of teacher instructional practices with technology in the classroom. Teacher responses ("N" = 2,840) from across the United States were used to assess factor structure of the instrument using…

  7. Structural Validity of the Movement ABC-2 Test: Factor Structure Comparisons across Three Age Groups

    ERIC Educational Resources Information Center

    Schulz, Joerg; Henderson, Sheila E.; Sugden, David A.; Barnett, Anna L.

    2011-01-01

    Background: The Movement ABC test is one of the most widely used assessments in the field of Developmental Coordination Disorder (DCD). Improvements to the 2nd edition of the test (M-ABC-2) include an extension of the age range and reduction in the number of age bands as well as revision of tasks. The total test score provides a measure of motor…

  8. The effect of aging temperature on structure characteristics of ordered mesoporous silicas

    NASA Astrophysics Data System (ADS)

    Deryło-Marczewska, A.; Marczewski, A. W.; Skrzypek, I.; Pikus, S.; Kozak, M.

    2005-10-01

    A series of mesoporous silica materials were synthesized by applying Pluronic type polymers as pore creating agents. In order to differentiate the characteristics of porous structure of the obtained sorbents the temperature of aging process was changed in the synthesis. The parameters characterizing the pore structure were estimated from nitrogen adsorption/desorption isotherms. The changes of pore arrangement of the obtained materials being a result of different synthesis conditions were investigated by using a small angle X-ray scattering method. Correlations between the values of structure parameters and aging temperature were found.

  9. Structure-Based Design of a Novel Series of Potent, Selective Inhibitors of the Class I Phosphatidylinositol 3-Kinases

    SciTech Connect

    Smith, Adrian L.; D’Angelo, Noel D.; Bo, Yunxin Y.; Booker, Shon K.; Cee, Victor J.; Herberich, Brad; Hong, Fang-Tsao; Jackson, Claire L.M.; Lanman, Brian A.; Liu, Longbin; Nishimura, Nobuko; Pettus, Liping H.; Reed, Anthony B.; Tadesse, Seifu; Tamayo, Nuria A.; Wurz, Ryan P.; Yang, Kevin; Andrews, Kristin L.; Whittington, Douglas A.; McCarter, John D.; Miguel, Tisha San; Zalameda, Leeanne; Jiang, Jian; Subramanian, Raju; Mullady, Erin L.; Caenepeel, Sean; Freeman, Daniel J.; Wang, Ling; Zhang, Nancy; Wu, Tian; Hughes, Paul E.; Norman, Mark H.

    2012-09-17

    A highly selective series of inhibitors of the class I phosphatidylinositol 3-kinases (PI3Ks) has been designed and synthesized. Starting from the dual PI3K/mTOR inhibitor 5, a structure-based approach was used to improve potency and selectivity, resulting in the identification of 54 as a potent inhibitor of the class I PI3Ks with excellent selectivity over mTOR, related phosphatidylinositol kinases, and a broad panel of protein kinases. Compound 54 demonstrated a robust PD-PK relationship inhibiting the PI3K/Akt pathway in vivo in a mouse model, and it potently inhibited tumor growth in a U-87 MG xenograft model with an activated PI3K/Akt pathway.

  10. The Class III Cyclobutane Pyrimidine Dimer Photolyase Structure Reveals a New Antenna Chromophore Binding Site and Alternative Photoreduction Pathways*

    PubMed Central

    Scheerer, Patrick; Zhang, Fan; Kalms, Jacqueline; von Stetten, David; Krauß, Norbert; Oberpichler, Inga; Lamparter, Tilman

    2015-01-01

    Photolyases are proteins with an FAD chromophore that repair UV-induced pyrimidine dimers on the DNA in a light-dependent manner. The cyclobutane pyrimidine dimer class III photolyases are structurally unknown but closely related to plant cryptochromes, which serve as blue-light photoreceptors. Here we present the crystal structure of a class III photolyase termed photolyase-related protein A (PhrA) of Agrobacterium tumefaciens at 1.67-Å resolution. PhrA contains 5,10-methenyltetrahydrofolate (MTHF) as an antenna chromophore with a unique binding site and mode. Two Trp residues play pivotal roles for stabilizing MTHF by a double π-stacking sandwich. Plant cryptochrome I forms a pocket at the same site that could accommodate MTHF or a similar molecule. The PhrA structure and mutant studies showed that electrons flow during FAD photoreduction proceeds via two Trp triads. The structural studies on PhrA give a clearer picture on the evolutionary transition from photolyase to photoreceptor. PMID:25784552

  11. Extended Aging Theories for Predictions of Safe Operational Life of Critical Airborne Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Chen, Tony

    2006-01-01

    The previously developed Ko closed-form aging theory has been reformulated into a more compact mathematical form for easier application. A new equivalent loading theory and empirical loading theories have also been developed and incorporated into the revised Ko aging theory for the prediction of a safe operational life of airborne failure-critical structural components. The new set of aging and loading theories were applied to predict the safe number of flights for the B-52B aircraft to carry a launch vehicle, the structural life of critical components consumed by load excursion to proof load value, and the ground-sitting life of B-52B pylon failure-critical structural components. A special life prediction method was developed for the preflight predictions of operational life of failure-critical structural components of the B-52H pylon system, for which no flight data are available.

  12. Effects of the age class distributions of the temperate and boreal forests on the global CO2 source-sink function

    NASA Astrophysics Data System (ADS)

    Kohlmaier, G. H.; Häger, Ch.; Würth, G.; Lüdeke, M. K. B.; Ramge, P.; Badeck, F.-W.; Kindermann, J.; Lang, T.

    1995-02-01

    The rôle of the temperate and boreal forests as a global CO2 source or sink is examined, both for the present time and for the next hundred years. The results of the Forest Resource Assessment for 1990 of the Economic Comission for Europe and the Food and Agricultural Organisation of the United Nations (1992) serve as the main database in this study. Out of the estimated total area of approximately 20106 km2 of forests and wooded lands in the temperate and boreal zone only approximately fifty percent is documented within the category of exploitable forests, which are examined in detail here. In this study, a general formalism of the time evolution of an ensemble of forests within an ecological province is developed using the formalism of the Leslie matrix. This matrix can be formulated if the age class dependent mortalities which arise from the disturbances are known. A distinction is made between the natural disturbances by fire, wind throw and insect infestations and disturbances introduced through harvesting of timber. Through the use of Richards growth function each age class of a given biome is related to the corresponding biomass and annual increment. The data reported on the mean net annual increment and on the mean biomass serve to calibrate the model. The difference of the reported net annual increment and annual fellings of approximately 550 106 m3 roundwood correspond to a sink of 210-330 Mt of carbon per year excluding any changes in the soil balance. It could be shown that the present distribution of forest age classes for the United States, Canada, Europe, or the former Soviet Union does not correspond to a quasi-stationary state, in which biomass is accumulated only due to a stimulated growth under enhanced atmospheric CO2 levels. The present CO2 sink function will not persist in the next century, if harvesting rates increase with 0.5% annually or even less. The future state will also be influenced by the effect of the greenhouse climate, the impact

  13. Sleep Duration and Age-Related Changes in Brain Structure and Cognitive Performance

    PubMed Central

    Lo, June C.; Loh, Kep Kee; Zheng, Hui; Sim, Sam K.Y.; Chee, Michael W.L.

    2014-01-01

    Study Objectives: To investigate the contribution of sleep duration and quality to age-related changes in brain structure and cognitive performance in relatively healthy older adults. Design: Community-based longitudinal brain and cognitive aging study using a convenience sample. Setting: Participants were studied in a research laboratory. Participants: Relatively healthy adults aged 55 y and older at study commencement. Interventions: N/A. Measurements and Results: Participants underwent magnetic resonance imaging and neuropsychological assessment every 2 y. Subjective assessments of sleep duration and quality and blood samples were obtained. Each hour of reduced sleep duration at baseline augmented the annual expansion rate of the ventricles by 0.59% (P = 0.007) and the annual decline rate in global cognitive performance by 0.67% (P = 0.050) in the subsequent 2 y after controlling for the effects of age, sex, education, and body mass index. In contrast, global sleep quality at baseline did not modulate either brain or cognitive aging. High-sensitivity C-reactive protein, a marker of systemic inflammation, showed no correlation with baseline sleep duration, brain structure, or cognitive performance. Conclusions: In healthy older adults, short sleep duration is associated with greater age-related brain atrophy and cognitive decline. These associations are not associated with elevated inflammatory responses among short sleepers. Citation: Lo JC, Loh KK, Zheng H, Sim SK, Chee MW. Sleep duration and age-related changes in brain structure and cognitive performance. SLEEP 2014;37(7):1171-1178. PMID:25061245

  14. Contaminant effects on growth, age-structure, and reproduction, of Mytilus edulis from Puget Sound, Washington

    SciTech Connect

    Casillas, E.; Kardong, K.; Kagley, A.; Snider, R.G.; Stein, J.E.

    1994-12-31

    Age-length relationships, age structure, and reproductive status (fecundity, egg size) of Mytilus edulis from six sites in central Puget Sound and one site in the relatively pristine area of northern Puget Sound were measured. Mussels from urban-associated sites (areas with elevated sediment concentrations of PAHs, PCBs, and toxic and essential metals) exhibited high tissue burdens of these contaminants. Age length relationships, fitted to the von Bertalanffy equation, showed that the growth of mussels from urban-associated areas was similar, but was lower than in mussels from minimally-contaminated environments. Comparison of mussel population age-structure showed that at urban sites, mussels of comparable size were consistently older than mussels from minimally contaminated areas and the mean age of urban populations was higher than that of rural populations. In mussels from urban sites, gonad mass was lower while number of oocytes/g gonad was similar compared to mussels from minimally-contaminated areas of Puget Sound. Thus, in mussels from urban sites fecundity was reduced compared to mussels of comparable age from reference sites. The findings support the hypothesis that mussels from the urban areas exhibit impaired growth, altered population age-structure, and reproductive impairment as a result of accumulation of chemical contaminants.

  15. A longitudinal study of structural brain network changes with normal aging

    PubMed Central

    Wu, Kai; Taki, Yasuyuki; Sato, Kazunori; Qi, Haochen; Kawashima, Ryuta; Fukuda, Hiroshi

    2013-01-01

    The aim of this study was to investigate age-related changes in the topological organization of structural brain networks by applying a longitudinal design over 6 years. Structural brain networks were derived from measurements of regional gray matter volume and were constructed in age-specific groups from baseline and follow-up scans. The structural brain networks showed economical small-world properties, providing high global and local efficiency for parallel information processing at low connection costs. In the analysis of the global network properties, the local and global efficiency of the baseline scan were significantly lower compared to the follow-up scan. Moreover, the annual rate of change in local and global efficiency showed a positive and negative quadratic correlation with the baseline age, respectively; both curvilinear correlations peaked at approximately the age of 50. In the analysis of the regional nodal properties, significant negative correlations between the annual rate of change in nodal strength and the baseline age were found in the brain regions primarily involved in the visual and motor/control systems, whereas significant positive quadratic correlations were found in the brain regions predominately associated with the default-mode, attention, and memory systems. The results of the longitudinal study are consistent with the findings of our previous cross-sectional study: the structural brain networks develop into a fast distribution from young to middle age (approximately 50 years old) and eventually became a fast localization in the old age. Our findings elucidate the network topology of structural brain networks and its longitudinal changes, thus enhancing the understanding of the underlying physiology of normal aging in the human brain. PMID:23565087

  16. Structure and Evolution of Kuiper Belt Objects: The Case for Compositional Classes

    NASA Astrophysics Data System (ADS)

    McKinnon, William B.; Prialnik, D.; Stern, S. A.

    2007-10-01

    Kuiper belt objects (KBOs) accreted from a mélange of ices, carbonaceous matter, and rock of mixed interstellar and solar nebular provenance. The transneptunian region, where this accretion took place, was likely more radially compact than today. This and the influence of gas drag during the solar nebula epoch argue for more rapid KBO accretion than usually considered. Early evolution of KBOs was largely the result of radiogenic heating, with both short-term and long-term contributions being potentially important. Depending on rock content and porous conductivity, KBO interiors may have reached relatively high temperatures. Models suggest that KBOs likely lost very volatile ices during early evolution, whereas less volatile ices should be retained in cold, less altered subsurface layers; initially amorphous ice may have crystallized in the interior as well, releasing trapped volatiles. Generally, KBOs should be stratified in terms of composition and porosity, albeit subject to impact disruption and collisional stripping. KBOs are thus unlikely to be "the most pristine objects in the Solar System.” Large (dwarf planet) KBOs may be fully differentiated. KBO surface color and compositional classes are usually discussed in terms of "nature vs. nurture,” i.e., a generic primordial composition vs. surface processing, but the true nature of KBOs also depends on how they have evolved. The broad range of albedos now found in the Kuiper belt, deep water-ice absorptions on some objects, evidence for differentiation of Pluto and 2003 EL61, and a range of densities incompatible with a single, primordial composition and variable porosity strongly imply significant, intrinsic compositional differences among KBOs. The interplay of formation zone (accretion rate), body size, and dynamical (collisional) history may yield KBO compositional classes (and their spectral correlates) that recall the different classes of asteroids in the inner Solar System, but whose members are

  17. Brain white matter structure and information processing speed in healthy older age.

    PubMed

    Kuznetsova, Ksenia A; Maniega, Susana Muñoz; Ritchie, Stuart J; Cox, Simon R; Storkey, Amos J; Starr, John M; Wardlaw, Joanna M; Deary, Ian J; Bastin, Mark E

    2016-07-01

    Cognitive decline, especially the slowing of information processing speed, is associated with normal ageing. This decline may be due to brain cortico-cortical disconnection caused by age-related white matter deterioration. We present results from a large, narrow age range cohort of generally healthy, community-dwelling subjects in their seventies who also had their cognitive ability tested in youth (age 11 years). We investigate associations between older age brain white matter structure, several measures of information processing speed and childhood cognitive ability in 581 subjects. Analysis of diffusion tensor MRI data using Tract-based Spatial Statistics (TBSS) showed that all measures of information processing speed, as well as a general speed factor composed from these tests (g speed), were significantly associated with fractional anisotropy (FA) across the white matter skeleton rather than in specific tracts. Cognitive ability measured at age 11 years was not associated with older age white matter FA, except for the g speed-independent components of several individual processing speed tests. These results indicate that quicker and more efficient information processing requires global connectivity in older age, and that associations between white matter FA and information processing speed (both individual test scores and g speed), unlike some other aspects of later life brain structure, are generally not accounted for by cognitive ability measured in youth. PMID:26254904

  18. Relations between Classroom Goal Structures and Students' Goal Orientations in Mathematics Classes: When Is a Mastery Goal Structure Adaptive?

    ERIC Educational Resources Information Center

    Skaalvik, Einar M.; Federici, Roger A.

    2016-01-01

    The purpose of this study was to test possible interactions between mastery and performance goal structures in mathematics classrooms when predicting students' goal orientations. More specifically, we tested if the degree of performance goal structure moderated the associations between mastery goal structure and students' goal orientations.…

  19. Supersymmetric gauge theory on a class of cocalibrated G2-structures

    NASA Astrophysics Data System (ADS)

    Lischewski, Andree

    2015-06-01

    Given a seven-dimensional cocalibrated G2-structure that satisfies an additional trace condition, we construct a supersymmetric Yang-Mills-Lagrangian on it, with the supersymmetry parameters being a distinguished generalized Killing spinor of the G2-structure. The construction is based on a reinterpretation of certain generalized Killing spinors as parallel spinors in an ambient space. The results generalize previous attempts for flat G2-structures and those admitting geometric Killing spinors.

  20. The age-sex structure of the slave population in Harris County, Texas: 1850 and 1860.

    PubMed

    Hutchinson, J

    1987-10-01

    The effect of the slave system on demography can be revealed by examining the age-sex structure of slave populations. The age-sex structure of slaves in Harris County, Texas is investigated using the 1850 and 1860 slave schedules. Median ages for black and mulatto slaves suggest that the population was young. Population pyramids exhibit a narrow base and top with a broad middle. The high proportion of slaves between 10 and 30 years of age and the increase in population size between 1850 and 1860 were mainly related to the importation of slaves and only partly due to natural increase. The data also show that black slaves were older on small plantations while mulattoes were older on larger farms. It is suggested that differential treatment in terms of purchase practices, assignment of tasks, food allocation, and/or differential susceptibility to infectious diseases may account for this pattern. PMID:3322029

  1. The effect of collagen ageing on its structure and cellular behaviour

    NASA Astrophysics Data System (ADS)

    Wilson, Samantha L.; Guilbert, Marie; Sulé-Suso, Josep; Torbet, James; Jeannesson, Pierre; Sockalingum, Ganesh D.; Yang, Ying

    2012-03-01

    Collagen is the most important component in extracellular matrix (ECM) and plays a pivotal role in individual tissue function in mammals. During ageing, collagen structure changes, which can detrimentally affect its biophysical and biomechanical properties due to an accumulation of advanced glycation end-products (AGEs). AGEs have been linked to non-enzymatic cross-linking of proteins resulting in the alteration of mechanical properties of the tissue. In this study we investigate the influence of different aged collagens on the mechanical and contractile properties of reconstituted hydrogel constructs seeded with corneal stromal fibroblasts. A non-destructive indentation technique and optical coherence tomography (OCT) are used to determine the elastic modulus and dimensional changes respectively. It is revealed that the youngest collagen constructs have a higher elastic modulus and increased contraction compared to the older collagen. These results provide new insights into the relationship between collagen molecular structures and their biomechanical properties.

  2. A new class of HIV-1 protease inhibitor: the crystallographic structure, inhibition and chemical synthesis of an aminimide peptide isostere.

    PubMed

    Rutenber, E E; McPhee, F; Kaplan, A P; Gallion, S L; Hogan, J C; Craik, C S; Stroud, R M

    1996-09-01

    The essential role of HIV-1 protease (HIV-1 PR) in the viral life cycle makes it an attractive target for the development of substrate-based inhibitors that may find efficacy as anti-AIDS drugs. However, resistance has arisen to potent peptidomimetic drugs necessitating the further development of novel chemical backbones for diversity based chemistry focused on probing the active site for inhibitor interactions and binding modes that evade protease resistance. AQ148 is a potent inhibitor of HIV-1 PR and represents a new class of transition state analogues incorporating an aminimide peptide isostere. A 3-D crystallographic structure of AQ148, a tetrapeptide isostere, has been determined in complex with its target HIV-1 PR to a resolution of 2.5 A and used to evaluate the specific structural determinants of AQ148 potency and to correlate structure-activity relationships within the class of related compounds. AQ148 is a competitive inhibitor of HIV-1 PR with a Ki value of 137 nM. Twenty-nine derivatives have been synthesized and chemical modifications have been made at the P1, P2, P1', and P2' sites. The atomic resolution structure of AQ148 bound to HIV-1 PR reveals both an inhibitor binding mode that closely resembles that of other peptidomimetic inhibitors and specific protein/inhibitor interactions that correlate with structure-activity relationships. The structure provides the basis for the design, synthesis and evaluation of the next generation of hydroxyethyl aminimide inhibitors. The aminimide peptide isostere is a scaffold with favorable biological properties well suited to both the combinatorial methods of peptidomimesis and the rational design of potent and specific substrate-based analogues. PMID:8894111

  3. Aging Theories for Establishing Safe Life Spans of Airborne Critical Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2003-01-01

    New aging theories have been developed to establish the safe life span of airborne critical structural components such as B-52B aircraft pylon hooks for carrying air-launch drop-test vehicles. The new aging theories use the equivalent-constant-amplitude loading spectrum to represent the actual random loading spectrum with the same damaging effect. The crack growth due to random loading cycling of the first flight is calculated using the half-cycle theory, and then extrapolated to all the crack growths of the subsequent flights. The predictions of the new aging theories (finite difference aging theory and closed-form aging theory) are compared with the classical flight-test life theory and the previously developed Ko first- and Ko second-order aging theories. The new aging theories predict the number of safe flights as considerably lower than that predicted by the classical aging theory, and slightly lower than those predicted by the Ko first- and Ko second-order aging theories due to the inclusion of all the higher order terms.

  4. Structure-Based Design of Potent and Ligand-Efficient Inhibitors of CTX-M Class A [beta]-Lactamase

    SciTech Connect

    Nichols, Derek A.; Jaishankar, Priyadarshini; Larson, Wayne; Smith, Emmanuel; Liu, Guoqing; Beyrouthy, Racha; Bonnet, Richard; Renslo, Adam R.; Chen, Yu

    2012-07-11

    The emergence of CTX-M class A extended-spectrum {beta}-lactamases poses a serious health threat to the public. We have applied structure-based design to improve the potency of a novel noncovalent tetrazole-containing CTX-M inhibitor (K{sub i} = 21 {mu}M) more than 200-fold via structural modifications targeting two binding hot spots, a hydrophobic shelf formed by Pro167 and a polar site anchored by Asp240. Functional groups contacting each binding hot spot independently in initial designs were later combined to produce analogues with submicromolar potencies, including 6-trifluoromethyl-3H-benzoimidazole-4-carboxylic acid [3-(1H-tetrazol-5-yl)-phenyl]-amide, which had a K{sub i} value of 89 nM and reduced the MIC of cefotaxime by 64-fold in CTX-M-9 expressing Escherichia coli. The in vitro potency gains were accompanied by improvements in ligand efficiency (from 0.30 to 0.39) and LipE (from 1.37 to 3.86). These new analogues represent the first nM-affinity noncovalent inhibitors of a class A {beta}-lactamase. Their complex crystal structures provide valuable information about ligand binding for future inhibitor design.

  5. Three-dimensional structure of a peptide extending from one end of a class I MHC binding site.

    PubMed

    Collins, E J; Garboczi, D N; Wiley, D C

    1994-10-13

    Class I major histocompatibility complex (MHC) molecules present peptides to CD8+ T cells for immunological surveillance (reviewed in ref. 1). The structures of complexes of class I MHC molecules with octamer, nonamer and decamer peptides determined until now show a common binding mode, with both peptide termini bound in conserved pockets at the ends of the peptide binding site. Length variations were accommodated by the peptide bulging or zig-zagging in the middle. Here we describe the structure of a decamer peptide which binds with the carboxy-terminal residue positioned outside the peptide binding site. Several protein side chains have rearranged to allow the peptide to exit. The structure suggests that even longer peptides could bind. The energetic effect of the altered mode of binding has been assessed by measuring the stability of the complex to thermal denaturation. Peptides bound in this novel manner are stable at physiological temperature, raising questions about their role in T-cell recognition and their production by proteolytic processing. PMID:7935798

  6. Beyond the Schoolyard: The Role of Parenting Logics, Financial Resources, and Social Institutions in the Social Class Gap in Structured Activity Participation

    ERIC Educational Resources Information Center

    Bennett, Pamela R.; Lutz, Amy C.; Jayaram, Lakshmi

    2012-01-01

    We investigate class differences in youth activity participation with interview, survey, and archival data from a diverse sample of parents (n = 51) in two schools. Findings point toward structural rather than cultural explanations. Working- and middle-class parents overlap in parenting logics about participation, though differ in one respect:…

  7. Arterial structure and function in vascular ageing: are you as old as your arteries?

    PubMed

    Thijssen, Dick H J; Carter, Sophie E; Green, Daniel J

    2016-04-15

    Advancing age may be the most potent independent predictor of future cardiovascular events, a relationship that is not fully explained by time-related changes in traditional cardiovascular risk factors. Since some arteries exhibit differential susceptibility to atherosclerosis, generalisations regarding the impact of ageing in humans may be overly simplistic, whereas in vivo assessment of arterial function and health provide direct insight. Coronary and peripheral (conduit, resistance and skin) arteries demonstrate a gradual, age-related impairment in vascular function that is likely to be related to a reduction in endothelium-derived nitric oxide bioavailability and/or increased production of vasoconstrictors (e.g. endothelin-1). Increased exposure and impaired ability for defence mechanisms to resist oxidative stress and inflammation, but also cellular senescence processes, may contribute to age-related changes in vascular function and health. Arteries also undergo structural changes as they age. Gradual thickening of the arterial wall, changes in wall content (i.e. less elastin, advanced glycation end-products) and increase in conduit artery diameter are observed with older age and occur similarly in central and peripheral arteries. These changes in structure have important interactive effects on artery function, with increases in small and large arterial stiffness representing a characteristic change with older age. Importantly, direct measures of arterial function and structure predict future cardiovascular events, independent of age or other cardiovascular risk factors. Taken together, and given the differential susceptibility of arteries to atherosclerosis in humans, direct measurement of arterial function and health may help to distinguish between biological and chronological age-related change in arterial health in humans. PMID:26140618

  8. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    PubMed Central

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-01-01

    The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H2O2 generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle- and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc and VIII, indicated that the abundance these polypeptides decreased, ranging from 11 to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology. PMID:20833144

  9. A class of circular waveguiding structures containing cylindrically anisotropic metamaterials: Applications from radio frequency/microwave to optical frequencies

    NASA Astrophysics Data System (ADS)

    Pollock, Justin G.; Iyer, Ashwin K.; Pratap, Dheeraj; Anantha Ramakrishna, S.

    2016-02-01

    This paper investigates a class of circular waveguiding structures containing anisotropic metamaterials and explores their potential benefits in applications from RF to optical frequencies. The introduction of anisotropy in these waveguides is shown to provide substantial control of the dispersion and field distributions of several supported modes. For exotic material parameters such as permittivity and permeability that are typically associated with metamaterials, intriguing propagation phenomena such as backward-wave behavior, frequency-reduced modes, monomodal propagation, and field confinement are observed and provide enabling functionalities for a wide range of RF/microwave and optical applications.

  10. A kinetic theory for age-structured stochastic birth-death processes

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Greenman, Chris

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but they are structurally unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Conversely, current theories that include size-dependent population dynamics (e.g., carrying capacity) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a BBGKY-like hierarchy. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution. NSF.

  11. Structural architecture supports functional organization in the human aging brain at a regionwise and network level.

    PubMed

    Zimmermann, Joelle; Ritter, Petra; Shen, Kelly; Rothmeier, Simon; Schirner, Michael; McIntosh, Anthony R

    2016-07-01

    Functional interactions in the brain are constrained by the underlying anatomical architecture, and structural and functional networks share network features such as modularity. Accordingly, age-related changes of structural connectivity (SC) may be paralleled by changes in functional connectivity (FC). We provide a detailed qualitative and quantitative characterization of the SC-FC coupling in human aging as inferred from resting-state blood oxygen-level dependent functional magnetic resonance imaging and diffusion-weighted imaging in a sample of 47 adults with an age range of 18-82. We revealed that SC and FC decrease with age across most parts of the brain and there is a distinct age-dependency of regionwise SC-FC coupling and network-level SC-FC relations. A specific pattern of SC-FC coupling predicts age more reliably than does regionwise SC or FC alone (r = 0.73, 95% CI = [0.7093, 0.8522]). Hence, our data propose that regionwise SC-FC coupling can be used to characterize brain changes in aging. Hum Brain Mapp 37:2645-2661, 2016. © 2016 Wiley Periodicals, Inc. PMID:27041212

  12. Structural transition in sputter-deposited amorphous germanium films by aging at ambient temperature

    NASA Astrophysics Data System (ADS)

    Okugawa, M.; Nakamura, R.; Ishimaru, M.; Watanabe, K.; Yasuda, H.; Numakura, H.

    2016-06-01

    The structure of amorphous Ge (a-Ge) films prepared by sputter-deposition and the effects of aging at ambient temperature and pressure were studied by pair-distribution-function (PDF) analysis from electron scattering and molecular dynamics simulations. The PDFs of the as-deposited and aged samples for 3-13 months showed that the major peaks for Ge-Ge bonds decrease in intensity and broaden with aging for up to 7 months. In the PDFs of a-Ge of molecular dynamics simulation obtained by quenching liquid at different rates, the major peak intensities of a slowly cooled model are higher than those of a rapidly cooled model. Analyses on short- and medium-range configurations show that the slowly cooled model includes a certain amount of medium-range ordered (MRO) clusters, while the rapidly cooled model includes liquid-like configurations rather than MRO clusters. The similarity between experimental and computational PDFs implies that as-deposited films are similar in structure to the slowly cooled model, whereas the fully aged films are similar to the rapidly cooled model. It is assumed that as they undergo room-temperature aging, the MRO clusters disintegrate and transform into liquid-like regions in the same matrix. This transition in local configurations is discussed in terms of instability and the non-equilibrium of nanoclusters produced by a vapor-deposition process.

  13. Size class structure, growth rates, and orientation of the central Andean cushion Azorella compacta

    PubMed Central

    Trenary, Tim; Graham, Eric A.; Stenzel, William; Rundel, Philip W.

    2015-01-01

    Azorella compacta (llareta; Apiaceae) forms dense, woody, cushions and characterizes the high elevation rocky slopes of the central Andean Altiplano. Field studies of an elevational gradient of A. compacta within Lauca National Park in northern Chile found a reverse J-shape distribution of size classes of individuals with abundant small plants at all elevations. A new elevational limit for A. compacta was established at 5,250 m. A series of cushions marked 14 years earlier showed either slight shrinkage or small degrees of growth up to 2.2 cm yr−1. Despite their irregularity in growth, cushions of A. compacta show a strong orientation, centered on a north-facing aspect and angle of about 20° from horizontal. This exposure to maximize solar irradiance closely matches previous observations of a population favoring north-facing slopes at a similar angle. Populations of A. compacta appear to be stable, or even expanding, with young plants abundant. PMID:25802811

  14. Class I HDACs Affect DNA Replication, Repair, and Chromatin Structure: Implications for Cancer Therapy

    PubMed Central

    Stengel, Kristy R.

    2015-01-01

    Abstract Significance: The contribution of epigenetic alterations to cancer development and progression is becoming increasingly clear, prompting the development of epigenetic therapies. Histone deacetylase inhibitors (HDIs) represent one of the first classes of such therapy. Two HDIs, Vorinostat and Romidepsin, are broad-spectrum inhibitors that target multiple histone deacetylases (HDACs) and are FDA approved for the treatment of cutaneous T-cell lymphoma. However, the mechanism of action and the basis for the cancer-selective effects of these inhibitors are still unclear. Recent Advances: While the anti-tumor effects of HDIs have traditionally been attributed to their ability to modify gene expression after the accumulation of histone acetylation, recent studies have identified the effects of HDACs on DNA replication, DNA repair, and genome stability. In addition, the HDIs available in the clinic target multiple HDACs, making it difficult to assign either their anti-tumor effects or their associated toxicities to the inhibition of a single protein. However, recent studies in mouse models provide insights into the tissue-specific functions of individual HDACs and their involvement in mediating the effects of HDI therapy. Critical Issues: Here, we describe how altered replication contributes to the efficacy of HDAC-targeted therapies as well as discuss what knowledge mouse models have provided to our understanding of the specific functions of class I HDACs, their potential involvement in tumorigenesis, and how their disruption may contribute to toxicities associated with HDI treatment. Future Directions: Impairment of DNA replication by HDIs has important therapeutic implications. Future studies should assess how best to exploit these findings for therapeutic gain. Antioxid. Redox Signal. 23, 51–65. PMID:24730655

  15. Digital sleep logs reveal potential impacts of modern temporal structure on class performance in different chronotypes.

    PubMed

    Smarr, Benjamin Lee

    2015-02-01

    Stability of sleep and circadian rhythms are important for healthy learning and memory. While experimental manipulations of lifestyle and learning outcomes present major obstacles, the ongoing increase in data sources allows retrospective data mining of people's sleep timing variation. Here I use digital sleep-log data generated by 1109 students in a biology lab course at the University of Washington to test the hypothesis that higher variance in time asleep and later sleep-onset times negatively correlate with class performance, used here as a real-world proxy for learning and memory. I find that sleep duration variance and mean sleep-onset times both significantly correlate with class performance. These correlations are powerful on weeknights but undetectable on Friday and Saturday nights ("free nights"). Finally, although these data come with no demographic information beyond sex, the constructed demographic groups of "larks" and "owls" within the sexes reveal a significant decrease in performance of owls relative to larks in male students, whereas the correlation of performance with sleep-onset time for all male students was only a near-significant trend. This provides a proof of concept that deeper demographic mining of digital logs in the future may identify subgroups for which certain sleep phenotypes have greater predictive value for performance outcomes. The data analyzed are consistent with known patterns, including sleep-timing delays from weeknights to free nights and sleep-timing delays in men relative to women. These findings support the hypothesis that modern schedule impositions on sleep and circadian timing have consequences for real-world learning and memory. This study also highlights the low-cost, large-scale benefits of personal, daily, digital records as an augmentation of sleep and circadian studies. PMID:25564433

  16. Structure and Function of a New Class of Human Prolactin Antagonists

    PubMed Central

    DePalatis, Laura; Almgren, Colleen M.; Patmastan, Jypji; Troyer, Mark; Woodrich, Todd; Brooks, Charles L.

    2009-01-01

    Summary Δ41-52 hPRL (human prolactin with residues 41-52 removed) is a lead compound for a new class of hPRL antagonists. The deleted sequence contains residues that functionally couple sites 1 and 2, the two hormone surfaces that each bind receptors. Δ41-52 hPRL retains 0.03% agonist activity in FDC-1 cell bioassays, a 3,054-fold reduction in activity, and displays approximately 100-fold less agonist activity than G129R hPRL, an antagonist that reduces the binding of hPRL receptor at site 2 during the formation of the heterotrimeric hormone/receptor complex. Replacement of various numbers and types of residues into the gap created by the deletion of residues 41 through 52 created hPRLs with varying agonist activities, suggested that manipulation of the sequence connecting the C-terminal of helix 1 with the disulfide bond (cysteines 58 with 174) linking helices 1 and 4 modulates articulation of these helices and influences agonist activity. We have compared the antagonist activities of G129R and Δ41-52 hPRLs to induce apoptosis in Jurkat cells, a human lymphoid cell line displaying an autocrine/paracrine hPRL/receptor system. Δ41-52 hPRL induces apoptosis in a time and dose-dependent fashion. Under these same conditions G129R hPRL fails to induce apoptosis. We conclude Δ41-52 hPRL is a lead compound of a new class of hPRL antagonists capable at low concentrations of inducing apoptosis in human cells expressing an autocrine/paracrine hPRL/receptor system. PMID:19236917

  17. Functional and structural aging of the speech sensorimotor neural system: fMRI evidence

    PubMed Central

    Tremblay, Pascale; Dick, Anthony Steven; Small, Steven L.

    2013-01-01

    The ability to perceive and produce speech undergoes important changes in late adulthood. The goal of the present study was to characterize functional and structural age-related differences in the cortical network supporting speech perception and production using magnetic resonance imaging, as well as the relationship between functional and structural age-related changes occurring in this network. We asked young and older adults to (1) observe videos of a speaker producing single words (perception), and (B) observe and repeat the words produced (production). Results show a widespread bilateral network of brain activation for Perception and Production that was uncorrelated with age. In addition, several regions did show age-related change (auditory cortex, planum temporale, superior temporal sulcus, premotor cortices, SMA-proper). Examination of the relationship between brain signal and regional and global gray matter volume and cortical thickness revealed a complex set of relationships between structure and function, with some regions showing a relationship between structure and function and not. The present results provide novel findings about the neurobiology of aging and verbal communication. PMID:23523270

  18. Effects of Stand age Structure on Regional Carbon Budgets of Forest Ecosystems

    NASA Astrophysics Data System (ADS)

    Song, C.; Woodcock, C. E.

    2002-12-01

    This study has developed a two-stage modeling scheme to investigate the importance of age structure on regional carbon fluxes for the forests in the Pacific Northwest of the United States. In the first stage, an individual-based forest ecosystem carbon flux model (IntCarb) at stand scale is developed. IntCarb combines components from the ZELIG and CENTURY models to simulate forest growth and development, and heterotrophic respiration, respectively. Stand scale carbon fluxes simulated by IntCarb strongly depend on stand age. Due to its high variablity over large areas, forest age structure has to be taken into account for realistic estimation of carbon budgets. The RegCarb model is developed to estimate regional scale carbon fluxes based on forest age structure and adjusting for the nonrespiratory carbon losses, such as harvesting. Our initial estimate with RegCarb for the Pacific Northwest of the United States found that this region was a tremendous carbon source to the atmosphere from 1890 to 1990 due to intensive logging of old-growth forest, and is becoming a carbon sink since the last decade. Projections for the role of forests in this region in the global carbon cycle in the future strongly depend on the amount of timber to be harvested, i.e. how the age structure of forests in this region is to be altered.

  19. Developing a Computerized Aging Management System for Concrete Structures in Finnish Nuclear Power Plants

    NASA Astrophysics Data System (ADS)

    Al-Neshawy, F.; Piironen, J.; Sistonen, E.; Vesikari, E.; Tuomisto, M.; Hradil, P.; Ferreira, M.

    2013-07-01

    Finland has four nuclear reactors units in two power plants. The first unit started operation in 1977 and in the early 1980's all four units were in use. During the last few years the aging management of the Nuclear Power Plant's (NPP) concrete structures has grown an important issue because the existing structures are reaching the end of their licensed operating lifetime (about 40 years). Therefore the nuclear power companies are developing aging management systems to avoid premature degradation of NPP facilities and to be able to extend their operating lifetime. This paper is about the development of a computerized ageing management system for the nuclear power plants concrete structures. The computerized ageing management system is built upon central database and implementation applications. It will assist the personnel of power companies to implement the aging management activities at different phases of the lifetime of a power plant. It will provide systematic methods for planning, surveillance, inspection, monitoring, condition assessment, maintenance and repair of structures.

  20. Pi-class glutathione-S-transferase-positive hepatocytes in aging B6C3F1 mice undergo apoptosis induced by dietary restriction.

    PubMed Central

    Muskhelishvili, L.; Turturro, A.; Hart, R. W.; James, S. J.

    1996-01-01

    Liver sections from aging ad libitum-fed and diet-restricted B6C3F1 male mice were evaluated immunohistochemically for pi-class glutathione S-transferase (GST-II). GST-II immunostaining of hepatocytes was diffuse and occurred in periportal regions of hepatic acinus, whereas perivenous areas were weakly stained or were stain-free. Expression of GST-II was significantly diminished in diet-restricted mice in all age groups and was associated with a marked decrease in liver tumor development. As most spontaneous liver tumors were GST-II positive, it can be speculated that they developed from GST-II positive initiated hepatocytes. To determine whether dietary restriction induces apoptosis in GST-II-positive hepatocytes, 24-month-old ad libitum-fed mice were introduced to 40% diet restriction. After 1 week of diet restriction, a decrease in GST-II expression was associated with a threefold increase in the frequency of apoptotic bodies as detected by terminal deoxynucleotidyl transferase-mediated d-UTP nick end labeling of DNA fragments. A two-step immunohistochemical procedure revealed that approximately 70% of apoptotic bodies were GST-II positive. These results suggest that spontaneous, potentially preneoplastic hepatocytes in tumor-prone B6C3F1 mice are eliminated by apoptosis with dietary restriction. Images Figure 1 PMID:8909248

  1. Chromophoric spin-labeled beta-lactam antibiotics for ENDOR structural characterization of reaction intermediates of class A and class C beta-lactamases.

    PubMed

    Mustafi, Devkumar; Hofer, Jennifer E; Huang, Wanzhi; Palzkill, Timothy; Makinen, Marvin W

    2004-05-01

    The chromophoric spin-label substrate 6-N-[3-(2,2,5,5-tetramethyl-1-oxypyrrolin-3-yl)-propen-2-oyl]penicillanic acid (SLPPEN) was synthesized by acylation of 6-aminopenicillanic acid with the acid chloride of 3-(2,2,5,5-tetramethyl-1-oxypyrrolinyl)-2-propenoic acid and characterized by physical methods. By application of angle-selected electron nuclear double resonance (ENDOR), we have determined the molecular structure of SLPPEN in solution. SLPPEN exhibited UV absorption properties that allowed accurate monitoring of the kinetics of its enzyme-catalyzed hydrolysis. The maximum value of the (substrate-product) difference extinction coefficient was 2824 M(-1) cm(-1) at 275 nm compared to 670 M(-1) cm(-1) at 232 nm for SLPEN [J. Am. Chem. Soc. 117 (1995) 6739]. For SLPPEN, the steady-state kinetic parameters kcat and kcat/KM, determined under initial velocity conditions, were 637 +/- 36 s(-1) and 13.8 +/- 1.4 x 10(6) M(-1) s(-1), respectively, for hydrolysis catalyzed by TEM-1 beta-lactamase of E. coli, and 0.5 +/- 0.04 s(-1) and 3.9 +/- 0.4 x 10(4) M(-1) s(-1) for hydrolysis catalyzed by the beta-lactamase of Enterobacter cloacae P99. We have also observed "burst kinetics" for the hydrolysis of SLPPEN with P99 beta-lactamase, indicative of formation of an acylenzyme reaction intermediate. In DMSO:H2O (30:70, v:v) cryosolvent mixtures buffered to pH* 7.0, the half-life of the acylenzyme intermediate formed with the P99 enzyme at -5 degrees C was > or = 3 min, suitable for optical characterization. The observation of burst kinetics in the hydrolysis of SLPPEN catalyzed by P99 beta-lactamase suggests that this chromophoric spin-labeled substrate is differentially sensitive to active site interactions underlying the cephalosporinase and penicillinase reactivity of this class C enzyme. PMID:15134725

  2. Aging Optimization of Aluminum-Lithium Alloy L277 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Cho, A.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties and improved damage tolerance. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. A design of experiments aging study was conducted for plate and a limited study on extrusions. To achieve the T8 temper, Alloy L277 is typically aged at 290 F for 40 hours. In the study for plate, a two-step aging treatment was developed through a design of experiments study and the one step aging used as a control. Based on the earlier NASA studies on 2195, the first step aging temperature was varied between 220 F and 260 F. The second step aging temperatures was varied between 290 F and 310 F, which is in the range of the single-step aging temperature. For extrusions, two, single-step, and one two-step aging condition were evaluated. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper for plate and the results for extrusions will be presented.

  3. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    SciTech Connect

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-10-08

    Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  4. Structure and composition of arytenoid cartilage of the bullfrog (Lithobates catesbeianus) during maturation and aging.

    PubMed

    Laureano, Priscila Eliane dos Santos; Oliveira, Kris Daiana Silva; de Aro, Andrea Aparecida; Gomes, Laurecir; Pimentel, Edson Rosa; Esquisatto, Marcelo Augusto Marretto

    2015-10-01

    The aging process induces progressive and irreversible changes in the structural and functional organization of animals. The objective of this study was to evaluate the effects of aging on the structure and composition of the extracellular matrix of the arytenoid cartilage found in the larynx of male bullfrogs (Lithobates catesbeianus) kept in captivity for commercial purposes. Animals at 7, 180 and 1080 days post-metamorphosis (n=10/age) were euthanized and the cartilage was removed and processed for structural and biochemical analysis. For the structural analyses, cartilage sections were stained with picrosirius, toluidine blue, Weigert's resorcin-fuchsin and Von Kossa stain. The sections were also submitted to immunohistochemistry for detection of collagen types I and II. Other samples were processed for the ultrastructural and cytochemical analysis of proteoglycans. Histological sections were used to chondrocyte count. The number of positive stainings for proteoglycans was quantified by ultrastructural analysis. For quantification and analysis of glycosaminoglycans were used the dimethyl methylene blue and agarose gel electrophoresis methods. The chloramine T method was used for hydroxyproline quantification. At 7 days, basophilia was observed in the pericellular and territorial matrix, which decreased in the latter over the period studied. Collagen fibers were arranged perpendicular to the major axis of the cartilaginous plate and were thicker in older animals. Few calcification areas were observed at the periphery of the cartilage specimens in 1080-day-old animals. Type II collagen was present throughout the stroma at the different ages. Elastic fibers were found in the stroma and perichondrium and increased with age in the two regions. Proteoglycan staining significantly increased from 7 to 180 days and reduced at 1080 days. The amount of total glycosaminoglycans was higher in 180-day-old animals compared to the other ages, with marked presence of

  5. Kinetic theory of age-structured stochastic birth-death processes.

    PubMed

    Greenman, Chris D; Chou, Tom

    2016-01-01

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov--Born--Green--Kirkwood--Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution. PMID:26871029

  6. Kinetic theory of age-structured stochastic birth-death processes

    NASA Astrophysics Data System (ADS)

    Greenman, Chris D.; Chou, Tom

    2016-01-01

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov--Born--Green--Kirkwood--Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution.

  7. Structure of a Class I Tagatose-1,6-bisphosphate Aldolase - Investigation into an Apparent Loss of Stereospecificity

    SciTech Connect

    LowKam, C.; Liotard, B; Sygusch, J

    2010-01-01

    Tagatose-1,6-bisphosphate aldolase from Streptococcus pyogenes is a class I aldolase that exhibits a remarkable lack of chiral discrimination with respect to the configuration of hydroxyl groups at both C3 and C4 positions. The enzyme catalyzes the reversible cleavage of four diastereoisomers (fructose 1,6-bisphosphate (FBP), psicose 1,6-bisphosphate, sorbose 1,6-bisphosphate, and tagatose 1,6-bisphosphate) to dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate with high catalytic efficiency. To investigate its enzymatic mechanism, high resolution crystal structures were determined of both native enzyme and native enzyme in complex with dihydroxyacetone-P. The electron density map revealed a ({alpha}/{beta}){sub 8} fold in each dimeric subunit. Flash-cooled crystals of native enzyme soaked with dihydroxyacetone phosphate trapped a covalent intermediate with carbanionic character at Lys{sup 205}, different from the enamine mesomer bound in stereospecific class I FBP aldolase. Structural analysis indicates extensive active site conservation with respect to class I FBP aldolases, including conserved conformational responses to DHAP binding and conserved stereospecific proton transfer at the DHAP C3 carbon mediated by a proximal water molecule. Exchange reactions with tritiated water and tritium-labeled DHAP at C3 hydrogen were carried out in both solution and crystalline state to assess stereochemical control at C3. The kinetic studies show labeling at both pro-R and pro-S C3 positions of DHAP yet detritiation only at the C3 pro-S-labeled position. Detritiation of the C3 pro-R label was not detected and is consistent with preferential cis-trans isomerism about the C2-C3 bond in the carbanion as the mechanism responsible for C3 epimerization in tagatose-1,6-bisphosphate aldolase.

  8. Structure of a class I tagatose-1,6-bisphosphate aldolase: investigation into an apparent loss of stereospecificity.

    PubMed

    LowKam, Clotilde; Liotard, Brigitte; Sygusch, Jurgen

    2010-07-01

    Tagatose-1,6-bisphosphate aldolase from Streptococcus pyogenes is a class I aldolase that exhibits a remarkable lack of chiral discrimination with respect to the configuration of hydroxyl groups at both C3 and C4 positions. The enzyme catalyzes the reversible cleavage of four diastereoisomers (fructose 1,6-bisphosphate (FBP), psicose 1,6-bisphosphate, sorbose 1,6-bisphosphate, and tagatose 1,6-bisphosphate) to dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde 3-phosphate with high catalytic efficiency. To investigate its enzymatic mechanism, high resolution crystal structures were determined of both native enzyme and native enzyme in complex with dihydroxyacetone-P. The electron density map revealed a (alpha/beta)(8) fold in each dimeric subunit. Flash-cooled crystals of native enzyme soaked with dihydroxyacetone phosphate trapped a covalent intermediate with carbanionic character at Lys(205), different from the enamine mesomer bound in stereospecific class I FBP aldolase. Structural analysis indicates extensive active site conservation with respect to class I FBP aldolases, including conserved conformational responses to DHAP binding and conserved stereospecific proton transfer at the DHAP C3 carbon mediated by a proximal water molecule. Exchange reactions with tritiated water and tritium-labeled DHAP at C3 hydrogen were carried out in both solution and crystalline state to assess stereochemical control at C3. The kinetic studies show labeling at both pro-R and pro-S C3 positions of DHAP yet detritiation only at the C3 pro-S-labeled position. Detritiation of the C3 pro-R label was not detected and is consistent with preferential cis-trans isomerism about the C2-C3 bond in the carbanion as the mechanism responsible for C3 epimerization in tagatose-1,6-bisphosphate aldolase. PMID:20427286

  9. DISK AND ENVELOPE STRUCTURE IN CLASS 0 PROTOSTARS. I. THE RESOLVED MASSIVE DISK IN SERPENS FIRS 1

    SciTech Connect

    Enoch, Melissa L.; Duchene, Gaspard; Corder, Stuartt

    2009-12-10

    We present the first results of a program to characterize the disk and envelope structure of typical Class 0 protostars in nearby low-mass star-forming regions. We use Spitzer Infrared Spectrograph (IRS) mid-infrared spectra, high-resolution Combined Array for Research in Millimeter-wave Astronomy (CARMA) 230 GHz continuum imaging, and two-dimensional radiative transfer models to constrain the envelope structure, as well as the size and mass of the circumprotostellar disk in Serpens FIRS 1. The primary envelope parameters (centrifugal radius, outer radius, outflow opening angle, and inclination) are well constrained by the spectral energy distribution (SED), including Spitzer IRAC and MIPS photometry, IRS spectra, and 1.1 mm Bolocam photometry. These together with the excellent uv-coverage (4.5-500 klambda) of multiple antenna configurations with CARMA allow for a robust separation of the envelope and a resolved disk. The SED of Serpens FIRS 1 is best fit by an envelope with the density profile of a rotating, collapsing spheroid with an inner (centrifugal) radius of approximately 600 AU, and the millimeter data by a large resolved disk with M{sub disk} approx 1.0 M {sub sun} and R{sub disk} approx 300 AU. These results suggest that large, massive disks can be present early in the main accretion phase. Results for the larger, unbiased sample of Class 0 sources in the Perseus, Serpens, and Ophiuchus molecular clouds are needed to determine if relatively massive disks are typical in the Class 0 stage.

  10. Beyond the Schoolyard: The Contributions of Parenting Logics, Financial Resources, and Social Institutions to the Social Class Gap in Structured Activity Participation

    PubMed Central

    Bennett, Pamela R.; Lutz, Amy; Jayaram, Lakshmi

    2014-01-01

    We investigate cultural and structural sources of class differences in youth activity participation with interview, survey, and archival data. We find working- and middle-class parents overlap in parenting logics about participation, though differ in one respect: middle-class parents are concerned with customizing children’s involvement in activities, while working-class parents are concerned with achieving safety and social mobility for children through participation. Second, because of financial constraints, working-class families rely on social institutions for participation opportunities, but few are available. Schools act as an equalizing institution by offering low-cost activities, allowing working-class children to resemble middle-class youth in school activities, but they remain disadvantaged in out-of-school activities. School influences are complex, however, as they also contribute to class differences by offering different activities to working- and middle-class youth. Findings raise questions about the extent to which differences in participation reflect class culture rather than the objective realities parents face. PMID:25328250

  11. Structural and biochemical studies reveal UbiG/Coq3 as a class of novel membrane-binding proteins.

    PubMed

    Zhu, Yuwei; Wu, Bo; Zhang, Xu; Fan, Xiaojiao; Niu, Liwen; Li, Xu; Wang, Junfeng; Teng, Maikun

    2015-08-15

    UbiG and Coq3 (orthologue in eukaryotes) are SAM-MTases (S-adenosylmethionine-dependent methyltransferases) that catalyse both O-methylation steps in CoQ biosynthesis from prokaryotes to eukaryotes. However, the detailed molecular mechanism by which they function remains elusive. In the present paper, we report that UbiG/Coq3 defines a novel class of membrane-binding proteins. Escherichia coli UbiG binds specifically to liposomes containing PG (phosphatidylglycerol) or CL (cardiolipin, or diphosphatidylglycerol), two major lipid components of the E. coli plasma membrane, whereas human and yeast Coq3 display a strong preference for liposomes enriched with CL, a signature lipid of the mitochondrial membrane. The crystal structure of UbiG from E. coli was determined at 2.1 Å (1 Å = 0.1 nm) resolution. The structure exhibits a typical Class I SAM-MTase fold with several variations, including a unique insertion between strand β5 and helix α10. This insertion is highly conserved and is required for membrane binding. Mutation of the key residues renders UbiG unable to efficiently bind liposome in vitro and the mutant fails to rescue the phenotype of ΔubiG strain in vivo. Taken together, our results shed light on a novel biochemical function of the UbiG/Coq3 protein. PMID:26251450

  12. Aging Management of Nuclear Power Plant Concrete Structures - Overview and Suggested Research Topics

    SciTech Connect

    Naus, Dan J

    2008-10-01

    Nuclear power plant concrete structures are described and their operating experience noted. Primary considerations related to management of their aging are noted and an indication of their status provided: degradation mechanisms, damage models, and material performance; assessment and remediation (i.e., component selection, in-service inspection, nondestructive examinations, and remedial actions); and estimation of performance at present or some future point in time (i.e., application of structural reliability theory to the design and optimization of in-service inspection/maintenance strategies, and determination of the effects of degradation on plant risk). Several activities are identified that provide background information and data on areas of concern with respect to nondestructive examination of nuclear power plant concrete structures: inspection of thick-walled, heavily-reinforced sections, basemats, and inaccessible areas of the containment metallic pressure boundary. Topics are noted where additional research would be of benefit to aging management of nuclear power plant concrete structures.

  13. Prediction of protein structure classes using hybrid space of multi-profile Bayes and bi-gram probability feature spaces.

    PubMed

    Hayat, Maqsood; Tahir, Muhammad; Khan, Sher Afzal

    2014-04-01

    Proteins are the executants of biological functions in living organisms. Comprehension of protein structure is a challenging problem in the era of proteomics, computational biology, and bioinformatics because of its pivotal role in protein folding patterns. Owing to the large exploration of protein sequences in protein databanks and intricacy of protein structures, experimental and theoretical methods are insufficient for prediction of protein structure classes. Therefore, it is highly desirable to develop an accurate, reliable, and high throughput computational model to predict protein structure classes correctly from polygenetic sequences. In this regard, we propose a promising model employing hybrid descriptor space in conjunction with optimized evidence-theoretic K-nearest neighbor algorithm. Hybrid space is the composition of two descriptor spaces including Multi-profile Bayes and bi-gram probability. In order to enhance the generalization power of the classifier, we have selected high discriminative descriptors from the hybrid space using particle swarm optimization, a well-known evolutionary feature selection technique. Performance evaluation of the proposed model is performed using the jackknife test on three low similarity benchmark datasets including 25PDB, 1189, and 640. The success rates of the proposed model are 87.0%, 86.6%, and 88.4%, respectively on the three benchmark datasets. The comparative analysis exhibits that our proposed model has yielded promising results compared to the existing methods in the literature. In addition, our proposed prediction system might be helpful in future research particularly in cases where the major focus of research is on low similarity datasets. PMID:24384128

  14. A class of monolayer metal halogenides MX2: Electronic structures and band alignments

    NASA Astrophysics Data System (ADS)

    Lu, Feng; Wang, Weichao; Luo, Xiaoguang; Xie, Xinjian; Cheng, Yahui; Dong, Hong; Liu, Hui; Wang, Wei-Hua

    2016-03-01

    With systematic first principles calculations, a class of monolayer metal halogenides MX2 (M = Mg, Ca, Zn, Cd, Ge, Pb; M = Cl, Br, I) has been proposed. Our study indicates that these monolayer materials are semiconductors with the band gaps ranging from 2.03 eV of ZnI2 to 6.08 eV of MgCl2. Overall, the band gap increases with the increase of the electronegativity of the X atom or the atomic number of the metal M. Meanwhile, the band gaps of monolayer MgX2 (X = Cl, Br) are direct while those of other monolayers are indirect. Based on the band edge curvatures, the derived electron (me) and hole (mh) effective masses of MX2 monolayers are close to their corresponding bulk values except that the me of CdI2 is three times larger and the mh for PbI2 is twice larger. Finally, the band alignments of all the studied MX2 monolayers are provided using the vacuum level as energy reference. These theoretical results may not only introduce the monolayer metal halogenides family MX2 into the emerging two-dimensional materials, but also provide insights into the applications of MX2 in future electronic, visible and ultraviolet optoelectronic devices.

  15. The Structure of p85ni in Class IA Phosphoinositide 3-Kinase Exhibits Interdomain Disorder

    PubMed Central

    Sen, K. Ilker; Wu, Haiyan; Backer, Jonathan M.; Gerfen, Gary J.

    2010-01-01

    Regulation of the Class IA PI 3-kinase involves inhibition and stabilization of the catalytic subunit (p110) by the regulatory subunit (p85). Regulation is achieved by 2 major contacts: a stable interface involving the Adapter-Binding Domain (ABD) of p110 and the inter-SH2 (iSH2) domain of p85, and a regulatory interaction between the N-terminal SH2 (nSH2) domain of p85 and the helical domain of p110. In the present study, we have examined the relative orientation of the nSH2 and iSH2 of p85α using site-directed spin labeling and pulsed EPR. Surprisingly, both distance measurements and distance distributions suggest that the nSH2 domain is highly disordered relative to the iSH2 domain. Molecular modeling based on EPR distance restraints suggests that the nSH2 domain moves in a hinge-like manner, sampling a torus space around the proximal end of the iSH2 domain. These data have important implications for the mechanism by which p85/p110 dimers are regulated by phosphopeptides. PMID:20131869

  16. Structural Mechanism of ER Retrieval of MHC Class I by Cowpox

    PubMed Central

    McCoy, William H.; Wang, Xiaoli; Yokoyama, Wayne M.; Hansen, Ted H.; Fremont, Daved H.

    2012-01-01

    One of the hallmarks of viral immune evasion is the capacity to disrupt major histocompatibility complex class I (MHCI) antigen presentation to evade T-cell detection. Cowpox virus encoded protein CPXV203 blocks MHCI surface expression by exploiting the KDEL-receptor recycling pathway, and here we show that CPXV203 directly binds a wide array of fully assembled MHCI proteins, both classical and non-classical. Further, the stability of CPXV203/MHCI complexes is highly pH dependent, with dramatically increased affinities at the lower pH of the Golgi relative to the endoplasmic reticulum (ER). Crystallographic studies reveal that CPXV203 adopts a beta-sandwich fold similar to poxvirus chemokine binding proteins, and binds the same highly conserved MHCI determinants located under the peptide-binding platform that tapasin, CD8, and natural killer (NK)-receptors engage. Mutagenesis of the CPXV203/MHCI interface identified the importance of two CPXV203 His residues that confer low pH stabilization of the complex and are critical to ER retrieval of MHCI. These studies clarify mechanistically how CPXV203 coordinates with other cowpox proteins to thwart antigen presentation. PMID:23209377

  17. Development of integrated damage detection system for international America's Cup class yacht structures using a fiber optic distributed sensor

    NASA Astrophysics Data System (ADS)

    Akiyoshi, Shimada; Naruse, Hiroshi; Uzawa, Kyoshi; Murayama, Hideaki; Kageyama, Kazuro

    2000-06-01

    We constructed a new health monitoring system to detect damage using a fiber optic distributed sensor, namely a Brillouin optical time domain reflectometer (BOTDR), and installed it in International America's Cup Class (IACC) yachts, the Japanese entry in America's Cup 2000. IACC yachts are designed to be as fast as possible, so it is essential that they are lightweight and encounter minimum water resistance. Advanced composite sandwich structures, made with carbon fiber reinforced plastic (CFRP) skins and a honeycomb core, are used to achieve the lightweight structure. Yacht structure designs push the strength of the materials to their limit and so it is important to detect highly stressed or damaged regions that might cause a catastrophic fracture. The BOTDR measures changes in the Brillouin frequency shift caused by distributed strain along one optical fiber. We undertook two experiments: a pulling test and a four point bending test on a composite beam. The former showed that no slippage occurred between the optical fiber glass and its coating. The latter confirmed that a debonding between the skin and the core of 300 mm length could be found with the BOTDR. Next we examined the effectiveness with which this system can assess the structural integrity of IACC yachts. The results show that our system has the potential for use as a damage detection system for smart structures.

  18. Survivability of integrated PVDF film sensors to accelerated ageing conditions in aeronautical/aerospace structures

    NASA Astrophysics Data System (ADS)

    Guzman, E.; Cugnoni, J.; Gmür, T.; Bonhôte, P.; Schorderet, A.

    2013-06-01

    This work validates the use of integrated polyvinylidene fluoride (PVDF) film sensors for dynamic testing, even after being subjected to UV-thermo-hygro-mechanical accelerated ageing conditions. The verification of PVDF sensors’ survivability in these environmental conditions, typically confronted by civil and military aircraft, is the main concern of the study. The evaluation of survivability is made by a comparison of dynamic testing results provided by the PVDF patch sensors subjected to an accelerated ageing protocol, and those provided by neutral non-aged sensors (accelerometers). The available measurements are the time-domain response signals issued from a modal analysis procedure, and the corresponding frequency response functions (FRF). These are in turn used to identify the constitutive properties of the samples by extraction of the modal parameters, in particular the natural frequencies. The composite specimens in this study undergo different accelerated ageing processes. After several weeks of experimentation, the samples exhibit a loss of stiffness, represented by a decrease in the elastic moduli down to 10%. Despite the ageing, the integrated PVDF sensors, subjected to the same ageing conditions, are still capable of providing reliable data to carry out a close followup of these changes. This survivability is a determinant asset in order to use integrated PVDF sensors to perform structural health monitoring (SHM) in the future of full-scale composite aeronautical structures.

  19. A Class of Population Covariance Matrices in the Bootstrap Approach to Covariance Structure Analysis

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai; Hayashi, Kentaro; Yanagihara, Hirokazu

    2007-01-01

    Model evaluation in covariance structure analysis is critical before the results can be trusted. Due to finite sample sizes and unknown distributions of real data, existing conclusions regarding a particular statistic may not be applicable in practice. The bootstrap procedure automatically takes care of the unknown distribution and, for a given…

  20. 49 CFR 176.172 - Structural serviceability of freight containers and vehicles carrying Class 1 (explosive...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... top and bottom side rails, top and bottom end rails, door sill and header, floor cross members, corner... structural members; (iii) More than one splice or an improper splice (such as a lapped splice) in top or bottom end rails or door headers; (iv) More than two splices in any one top or bottom side rail; (v)...

  1. Dimensionality of the Latent Structure and Item Selection via Latent Class Multidimensional IRT Models

    ERIC Educational Resources Information Center

    Bartolucci, F.; Montanari, G. E.; Pandolfi, S.

    2012-01-01

    With reference to a questionnaire aimed at assessing the performance of Italian nursing homes on the basis of the health conditions of their patients, we investigate two relevant issues: dimensionality of the latent structure and discriminating power of the items composing the questionnaire. The approach is based on a multidimensional item…

  2. Weighted Structural Regression: A Broad Class of Adaptive Methods for Improving Linear Prediction.

    ERIC Educational Resources Information Center

    Pruzek, Robert M.; Lepak, Greg M.

    1992-01-01

    Adaptive forms of weighted structural regression are developed and discussed. Bootstrapping studies indicate that the new methods have potential to recover known population regression weights and predict criterion score values routinely better than do ordinary least squares methods. The new methods are scale free and simple to compute. (SLD)

  3. A Study of Enhanced Structured Web-Based Discussion in a Foreign Language Learning Class

    ERIC Educational Resources Information Center

    Chang, Mei-Mei; Lin, Mei-Chen; Tsai, Ming-Jen

    2013-01-01

    This experimental study aimed to investigate the effect of enhanced structured web discussion on EFL students' language production. This effect was measured by the number of T units and by students' use of the cognitive skills identified by Hunt (1965). A total of 27 college students participated in this study. The participants were randomly…

  4. Implications of a Class of Covariance Structure Models for the Development of Measuring Instruments.

    ERIC Educational Resources Information Center

    Bramble, William J.; Wiley, David E.

    The research on covariance structure analysis is reviewed, and various restrictions on the parameter matrices of the general model are delineated. Models employing two particular restrictions (where the matrix of weights is completely specified and is either scaled--by some unknown but estimable matrix of scaling weights--or unscaled) are…

  5. Age at First Episode Modulates Diagnosis-Related Structural Brain Abnormalities in Psychosis.

    PubMed

    Pina-Camacho, Laura; Del Rey-Mejías, Ángel; Janssen, Joost; Bioque, Miquel; González-Pinto, Ana; Arango, Celso; Lobo, Antonio; Sarró, Salvador; Desco, Manuel; Sanjuan, Julio; Lacalle-Aurioles, Maria; Cuesta, Manuel J; Saiz-Ruiz, Jerónimo; Bernardo, Miguel; Parellada, Mara

    2016-03-01

    Brain volume and thickness abnormalities have been reported in first-episode psychosis (FEP). However, it is unclear if and how they are modulated by brain developmental stage (and, therefore, by age at FEP as a proxy). This is a multicenter cross-sectional case-control brain magnetic resonance imaging (MRI) study. Patients with FEP (n = 196), 65.3% males, with a wide age at FEP span (12-35 y), and healthy controls (HC) (n = 157), matched for age, sex, and handedness, were scanned at 6 sites. Gray matter volume and thickness measurements were generated for several brain regions using FreeSurfer software. The nonlinear relationship between age at scan (a proxy for age at FEP in patients) and volume and thickness measurements was explored in patients with schizophrenia spectrum disorders (SSD), affective psychoses (AFP), and HC. Earlier SSD cases (ie, FEP before 15-20 y) showed significant volume and thickness deficits in frontal lobe, volume deficits in temporal lobe, and volume enlargements in ventricular system and basal ganglia. First-episode AFP patients had smaller cingulate cortex volume and thicker temporal cortex only at early age at FEP (before 18-20 y). The AFP group also had age-constant (12-35-y age span) volume enlargements in the frontal and parietal lobe. Our study suggests that age at first episode modulates the structural brain abnormalities found in FEP patients in a nonlinear and diagnosis-dependent manner. Future MRI studies should take these results into account when interpreting samples with different ages at onset and diagnosis. PMID:26371339

  6. A Hierarchical Kinetic Theory of Birth, Death and Fission in Age-Structured Interacting Populations

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Greenman, Chris D.

    2016-07-01

    We develop mathematical models describing the evolution of stochastic age-structured populations. After reviewing existing approaches, we formulate a complete kinetic framework for age-structured interacting populations undergoing birth, death and fission processes in spatially dependent environments. We define the full probability density for the population-size age chart and find results under specific conditions. Connections with more classical models are also explicitly derived. In particular, we show that factorial moments for non-interacting processes are described by a natural generalization of the McKendrick-von Foerster equation, which describes mean-field deterministic behavior. Our approach utilizes mixed-type, multidimensional probability distributions similar to those employed in the study of gas kinetics and with terms that satisfy BBGKY-like equation hierarchies.

  7. A Hierarchical Kinetic Theory of Birth, Death and Fission in Age-Structured Interacting Populations

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Greenman, Chris D.

    2016-05-01

    We develop mathematical models describing the evolution of stochastic age-structured populations. After reviewing existing approaches, we formulate a complete kinetic framework for age-structured interacting populations undergoing birth, death and fission processes in spatially dependent environments. We define the full probability density for the population-size age chart and find results under specific conditions. Connections with more classical models are also explicitly derived. In particular, we show that factorial moments for non-interacting processes are described by a natural generalization of the McKendrick-von Foerster equation, which describes mean-field deterministic behavior. Our approach utilizes mixed-type, multidimensional probability distributions similar to those employed in the study of gas kinetics and with terms that satisfy BBGKY-like equation hierarchies.

  8. Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

    NASA Astrophysics Data System (ADS)

    Giordano, V. M.; Ruta, B.

    2016-01-01

    Understanding and controlling physical aging, that is, the spontaneous temporal evolution of out-of-equilibrium systems, represents one of the greatest tasks in material science. Recent studies have revealed the existence of a complex atomic motion in metallic glasses, with different aging regimes in contrast with the typical continuous aging observed in macroscopic quantities. By combining dynamical and structural synchrotron techniques, here for the first time we directly connect previously identified microscopic structural mechanisms with the peculiar atomic motion, providing a broader unique view of their complexity. We show that the atomic scale is dominated by the interplay between two processes: rearrangements releasing residual stresses related to a cascade mechanism of relaxation, and medium range ordering processes, which do not affect the local density, likely due to localized relaxations of liquid-like regions. As temperature increases, a surprising additional secondary relaxation process sets in, together with a faster medium range ordering, likely precursors of crystallization.

  9. Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

    PubMed Central

    Giordano, V. M.; Ruta, B

    2016-01-01

    Understanding and controlling physical aging, that is, the spontaneous temporal evolution of out-of-equilibrium systems, represents one of the greatest tasks in material science. Recent studies have revealed the existence of a complex atomic motion in metallic glasses, with different aging regimes in contrast with the typical continuous aging observed in macroscopic quantities. By combining dynamical and structural synchrotron techniques, here for the first time we directly connect previously identified microscopic structural mechanisms with the peculiar atomic motion, providing a broader unique view of their complexity. We show that the atomic scale is dominated by the interplay between two processes: rearrangements releasing residual stresses related to a cascade mechanism of relaxation, and medium range ordering processes, which do not affect the local density, likely due to localized relaxations of liquid-like regions. As temperature increases, a surprising additional secondary relaxation process sets in, together with a faster medium range ordering, likely precursors of crystallization. PMID:26787443

  10. Structural and vibrational relaxations during aging of an ultralow-expansion glass

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroshi; Ohtake, Yurie; Hirata, Shu; Morinaga, Atsuo

    2016-05-01

    We accurately measured the aging of an ultralow-expansion (ULE) glass for 1250 days using a diode laser resonated in the glass cavity at -3.3 °C, where the glass has zero thermal expansion coefficient. We observed that the glass shows exponential and linear decreases in length In addition, it is theoretically shown that glass aging is a nonlinear irreversible process with the spontaneous relaxations of a linear contraction and a dissipated heat. The origin for the linear contraction is an osmotic pressure which is spontaneously generated during glass aging, and the origin for the dissipated heat is the irreversibility on thermal vibrations of molecules. The result obtained is a verification of the Glansdorff-Prigogine evolutional criterion, which is first applied to a structural relaxation phenomenon in this paper. We conclude that a glass reaches a steady nonequilibrium state, which has the dissipative structure both in a steady configurational state and in steady irreversible processes.

  11. [Age structure and dynamics of Quercus wutaishanica population in Lingkong Mountain of Shanxi Province, China].

    PubMed

    Zhang, Jie; Shangguan, Tie-Liang; Duan, Yi-Hao; Guo, Wei; Liu, Wei-Hua; Guo, Dong-Gang

    2014-11-01

    Using the plant survivorship theory, the age structure, and the relationship between tree height and diameter (DBH) of Quercus wutaishanica population in Lingkong Mountain were analyzed, and the static life table was compiled and the survival curve plotted. The shuttle shape in age structure of Q. wutaishanica population suggested its temporal stability. The linear regression significantly fitted the positive correlation between tree height and DBH. The maximal life expectancy was observed among the trees beyond the age of the highest mortality and coincided with the lowest point of mortality density, suggesting the strong vitality of the seedlings and young trees that survived in the natural selection and intraspecific competition. The population stability of the Q. wutaishanica population was characterized by the Deevey-II of the survival curve. The dynamic pattern was characterized by the recession in the early phase, growth in the intermediate phase, and stability in the latter phase. PMID:25898607

  12. The Knowledge of Memory Aging Questionnaire: Factor Structure and Correlates in a Lifespan Sample.

    PubMed

    Calamia, Matthew; Reese-Melancon, Celinda; Cherry, Katie E; Hawley, Karri S; Jazwinski, S Michal

    2016-03-01

    The authors examined the factor structure of the Knowledge of Memory Aging Questionnaire (KMAQ) [1] using confirmatory factor analysis in a lifespan sample of 933 individuals who ranged in age from 18 to 101. Participants were college students at Louisiana State University and adults from the community enrolled in the Louisiana Healthy Aging Study (LHAS). A two-factor solution was expected, consistent with the normal and pathological memory aging dimensions that comprise the KMAQ. A bi-factor solution with items loading on a general response bias factor and either a normal or pathological knowledge-specific factor showed good model fit. Knowledge scores were correlated with demographic and cognitive performance variables. Implications of these data for clinical settings and research are considered. PMID:27505021

  13. The Knowledge of Memory Aging Questionnaire: Factor Structure and Correlates in a Lifespan Sample

    PubMed Central

    Calamia, Matthew; Reese-Melancon, Celinda; Cherry, Katie E.; Hawley, Karri S.; Jazwinski, S. Michal

    2016-01-01

    The authors examined the factor structure of the Knowledge of Memory Aging Questionnaire (KMAQ) [1] using confirmatory factor analysis in a lifespan sample of 933 individuals who ranged in age from 18 to 101. Participants were college students at Louisiana State University and adults from the community enrolled in the Louisiana Healthy Aging Study (LHAS). A two-factor solution was expected, consistent with the normal and pathological memory aging dimensions that comprise the KMAQ. A bi-factor solution with items loading on a general response bias factor and either a normal or pathological knowledge-specific factor showed good model fit. Knowledge scores were correlated with demographic and cognitive performance variables. Implications of these data for clinical settings and research are considered. PMID:27505021

  14. Socio-Demographic Determinants of Economic Growth: Age-Structure, Preindustrial Heritage and Sociolinguistic Integration

    ERIC Educational Resources Information Center

    Crenshaw, Edward; Robison, Kristopher

    2010-01-01

    This study establishes a socio-demographic theory of international development derived from selected classical and contemporary sociological theories. Four hypotheses are tested: (1. population growth's effect on development depends on age-structure; (2. historic population density (used here as an indicator of preindustrial social complexity)…

  15. Dissecting simulated disc galaxies - I. The structure of mono-age populations

    NASA Astrophysics Data System (ADS)

    Martig, Marie; Minchev, Ivan; Flynn, Chris

    2014-08-01

    We study seven simulated disc galaxies, three with a quiescent merger history, and four with mergers in their last 9 Gyr of evolution. We compare their structure at z = 0 by decomposing them into `mono-age populations' (MAPs) of stars within 500 Myr age bins. All studied galaxies undergo a phase of merging activity at high redshift, so that stars older than 9 Gyr are found in a centrally concentrated component, while younger stars are mostly found in discs. We find that most MAPs have simple exponential radial and vertical density profiles, with a scaleheight that typically increases with age. Because a large range of merger histories can create populations with simple structures, this suggests that the simplicity of the structure of mono-abundance populations observed in the Milky Way by Bovy et al. is not necessarily a direct indicator of a quiescent history for the Milky Way. Similarly, the anticorrelation between scalelength and scaleheight does not necessarily imply a merger-free history. However, mergers produce discontinuities between thin and thick disc components, and jumps in the age-velocity relation. The absence of a structural discontinuity between thin and thick disc observed in the Milky Way would seem to be a good indicator that no merger with a mass ratio larger than 1:15-1:10 occurred in the last 9 Gyr. Mergers at higher redshift might nevertheless be necessary to produce the thickest, hottest components of the Milky Way's disc.

  16. 77 FR 27815 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-11

    ... Register on June 22, 2010 (75 FR 35510). The NRC staff has determined that existing guidance in the SRP-LR... Register notice (76 FR 69292) to request public comments on draft LR-ISG-2011-01 (ADAMS Accession No... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water...

  17. Sparse representation of brain aging: extracting covariance patterns from structural MRI.

    PubMed

    Su, Longfei; Wang, Lubin; Chen, Fanglin; Shen, Hui; Li, Baojuan; Hu, Dewen

    2012-01-01

    An enhanced understanding of how normal aging alters brain structure is urgently needed for the early diagnosis and treatment of age-related mental diseases. Structural magnetic resonance imaging (MRI) is a reliable technique used to detect age-related changes in the human brain. Currently, multivariate pattern analysis (MVPA) enables the exploration of subtle and distributed changes of data obtained from structural MRI images. In this study, a new MVPA approach based on sparse representation has been employed to investigate the anatomical covariance patterns of normal aging. Two groups of participants (group 1:290 participants; group 2:56 participants) were evaluated in this study. These two groups were scanned with two 1.5 T MRI machines. In the first group, we obtained the discriminative patterns using a t-test filter and sparse representation step. We were able to distinguish the young from old cohort with a very high accuracy using only a few voxels of the discriminative patterns (group 1:98.4%; group 2:96.4%). The experimental results showed that the selected voxels may be categorized into two components according to the two steps in the proposed method. The first component focuses on the precentral and postcentral gyri, and the caudate nucleus, which play an important role in sensorimotor tasks. The strongest volume reduction with age was observed in these clusters. The second component is mainly distributed over the cerebellum, thalamus, and right inferior frontal gyrus. These regions are not only critical nodes of the sensorimotor circuitry but also the cognitive circuitry although their volume shows a relative resilience against aging. Considering the voxels selection procedure, we suggest that the aging of the sensorimotor and cognitive brain regions identified in this study has a covarying relationship with each other. PMID:22590522

  18. Structure and function of Neisseria gonorrhoeae MtrF illuminates a class of antimetabolite efflux pumps.

    PubMed

    Su, Chih-Chia; Bolla, Jani Reddy; Kumar, Nitin; Radhakrishnan, Abhijith; Long, Feng; Delmar, Jared A; Chou, Tsung-Han; Rajashankar, Kanagalaghatta R; Shafer, William M; Yu, Edward W

    2015-04-01

    Neisseria gonorrhoeae is an obligate human pathogen and the causative agent of the sexually transmitted disease gonorrhea. The control of this disease has been compromised by the increasing proportion of infections due to antibiotic-resistant strains, which are growing at an alarming rate. N. gonorrhoeae MtrF is an integral membrane protein that belongs to the AbgT family of transporters for which no structural information is available. Here, we describe the crystal structure of MtrF, revealing a dimeric molecule with architecture distinct from all other families of transporters. MtrF is a bowl-shaped dimer with a solvent-filled basin extending from the cytoplasm to halfway across the membrane bilayer. Each subunit of the transporter contains nine transmembrane helices and two hairpins, posing a plausible pathway for substrate transport. A combination of the crystal structure and biochemical functional assays suggests that MtrF is an antibiotic efflux pump mediating bacterial resistance to sulfonamide antimetabolite drugs. PMID:25818299

  19. Advances in Structural Integrity Analysis Methods for Aging Metallic Airframe Structures with Local Damage

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Newman, James C., Jr.; Harris, Charles E.; Piascik, Robert S.; Young, Richard D.; Rose, Cheryl A.

    2003-01-01

    Analysis methodologies for predicting fatigue-crack growth from rivet holes in panels subjected to cyclic loads and for predicting the residual strength of aluminum fuselage structures with cracks and subjected to combined internal pressure and mechanical loads are described. The fatigue-crack growth analysis methodology is based on small-crack theory and a plasticity induced crack-closure model, and the effect of a corrosive environment on crack-growth rate is included. The residual strength analysis methodology is based on the critical crack-tip-opening-angle fracture criterion that characterizes the fracture behavior of a material of interest, and a geometric and material nonlinear finite element shell analysis code that performs the structural analysis of the fuselage structure of interest. The methodologies have been verified experimentally for structures ranging from laboratory coupons to full-scale structural components. Analytical and experimental results based on these methodologies are described and compared for laboratory coupons and flat panels, small-scale pressurized shells, and full-scale curved stiffened panels. The residual strength analysis methodology is sufficiently general to include the effects of multiple-site damage on structural behavior.

  20. Evaluation of aged concrete structures for continued service in nuclear power plants

    SciTech Connect

    Naus, D.J.; Marchbanks, M.F.; Arndt, E.G.

    1988-01-01

    Results are summarized of a study on concrete component aging and its significance relative to continued service of nuclear power plants (NPPs) beyond the initial period for which they were granted operating licenses. Progress is presented of a second study being conducted to identify and provide acceptance criteria for structural safety issues which the USNRC staff will need to address when applications are submitted for continued service of NPPs. Major activities under this program include: development of a materials property data base, establishment of structural component assessment and repair procedures, and development of a methodology for determination of structural reliability. 19 refs., 5 figs., 3 tabs.

  1. Evaluation of aged concrete structures for continued service in nuclear power plants

    SciTech Connect

    Naus, D.J.; Marchbanks, M.F.; Arndt, E.G.

    1988-01-01

    Results are summarized of a study on concrete component aging and its significance relative to continued service of nuclear power plants (NPPs) beyond the initial period for which they were granted operating licenses. Progress is presented of a second study being conducted to identify and provide acceptance criteria for structural safety issues which the USNRC staff will need to address when applications are submitted for continued service of NPPs. Major activities under this program include: development of a materials property data base, establishment of structural component assessment and repair procedures, and development of a methodology for determination of structural reliability.

  2. An artificial intelligence-based structural health monitoring system for aging aircraft

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.; Tang, Stanley S.; Chen, K. L.

    1993-01-01

    To reduce operating expenses, airlines are now using the existing fleets of commercial aircraft well beyond their originally anticipated service lives. The repair and maintenance of these 'aging aircraft' has therefore become a critical safety issue, both to the airlines and the Federal Aviation Administration. This paper presents the results of an innovative research program to develop a structural monitoring system that will be used to evaluate the integrity of in-service aerospace structural components. Currently in the final phase of its development, this monitoring system will indicate when repair or maintenance of a damaged structural component is necessary.

  3. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg- 0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300 F for 24 hours. In this study, a two-step aging treatment was developed through a comprehensive 24 full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175 F and 250 F. The second step aging temperatures was

  4. A new class of atomic basis functions for accurate electronic structure calculations of molecules

    NASA Astrophysics Data System (ADS)

    Laikov, Dimitri N.

    2005-11-01

    A new general approach is developed for obtaining systematic sequences of atomic single-particle basis sets for use in correlated electronic structure calculations of molecules. All the constituent functions are defined as the solutions of variational problems and are of three types: a minimal Hartree-Fock set, additional functions to represent low-lying excited configurations, and general functions for describing electron correlation. The latter are determined to minimize a functional derived from the closed-shell second-order correlation energy expression. Generally-contracted Gaussian expansions are developed to approximate these general functions in the non-relativistic case and within a scalar-relativistic approximation.

  5. Age structure of owned dogs under compulsory culling in a visceral leishmaniasis endemic area.

    PubMed

    Bortoletto, Danielly Vieira; Utsunomiya, Yuri Tani; Perri, Silvia Helena Venturoli; Ferreira, Fernando; Nunes, Cáris Maroni

    2016-01-01

    The age structure of the dog population is essential for planning and evaluating control programs for zoonotic diseases. We analyzed data of an owned-dog census in order to characterize, for the first time, the structure of a dog population under compulsory culling in a visceral leishmaniasis endemic area (Panorama, São Paulo State, Brazil) that recorded a dog-culling rate of 28% in the year of the study. Data on 1,329 households and 1,671 owned dogs revealed an owned dog:human ratio of 1:7. The mean age of dogs was estimated at 1.73 years; the age pyramid indicated high birth and mortality rates at the first year of age with an estimated cumulative mortality of 78% at the third year of age and expected life span of 2.75 years. In spite of the high mortality, a growth projection simulation suggested that the population has potential to grow in a logarithmic scale over the years. The estimated parameters can be further applied in models to maximize the impact and minimize financial inputs of visceral leishmaniasis control measures. PMID:27598014

  6. Benefits of gregarious feeding by aposematic caterpillars depend on group age structure.

    PubMed

    Campbell, Stuart A; Stastny, Michael

    2015-03-01

    Gregarious feeding is a common feature of herbivorous insects and can range from beneficial (e.g. dilution of predation risk) to costly (e.g. competition). Group age structure should influence these costs and benefits, particularly when old and young larvae differ in their feeding mode or apparency to predators. We investigated the relative value of gregarious feeding by aposematic larvae of Uresiphita reversalis that we observed feeding in groups of mixed ages and variable densities on wild Lupinus diffusus. In a manipulative field experiment, the survivorship and growth of young larvae were enhanced in the presence of older conspecifics, but not in large groups of similarly aged larvae. Estimates of insect damage and induced plant responses suggest that mixed-age groups enhance plant quality for young larvae while avoiding competition. We conclude that benefits of gregariousness in this species are contingent on group age structure, a finding of significance for the ecology and evolution of gregariousness and other social behaviours. PMID:25399243

  7. Diversified Anchoring Features the Peptide Presentation of DLA-88*50801: First Structural Insight into Domestic Dog MHC Class I.

    PubMed

    Xiao, Jin; Xiang, Wangzhen; Chai, Yan; Haywood, Joel; Qi, Jianxun; Ba, Limin; Qi, Peng; Wang, Ming; Liu, Jun; Gao, George F

    2016-09-15

    Canines represent a crucial animal model for studying human diseases and organ transplantation, as well as the evolution of domestic animals. MHCs, with a central role in cellular immunity, are commonly used in the study of dog population genetics and genome evolution. However, the molecular basis for the peptide presentation of dog MHC remains largely unknown. In this study, peptide presentation by canine MHC class I DLA-88*50801 was structurally determined, revealing diversified anchoring modes of the binding peptides. Flexible and large pockets composed of both hydrophobic and hydrophilic residues can accommodate pathogen-derived peptides with diverse anchor residues, as confirmed by thermostability measurements. Furthermore, DLA-88*50801 contains an unusual α2 helix with a large coil in the TCR contact region. These results further our understanding of canine T cell immunity through peptide presentation of MHC class I and shed light on the molecular basis for vaccine development for canine infectious diseases, for example, canine distemper virus. PMID:27511732

  8. Rational prescription of drugs within similar therapeutic or structural class for gastrointestinal disease treatment: Drug metabolism and its related interactions

    PubMed Central

    Zhou, Quan; Yan, Xiao-Feng; Zhang, Zhong-Miao; Pan, Wen-Sheng; Zeng, Su

    2007-01-01

    AIM: To review and summarize drug metabolism and its related interactions in prescribing drugs within the similar therapeutic or structural class for gastrointestinal disease treatment so as to promote rational use of medicines in clinical practice. METHODS: Relevant literature was identified by performing MEDLINE/Pubmed searches covering the period from 1988 to 2006. RESULTS: Seven classes of drugs were chosen, including gastric proton pump inhibitors, histamine H2-receptor antagonists, benzamide-type gastroprokinetic agents, selective 5-HT3 receptor antagonists, fluoroquinolones, macrolide antibiotics and azole antifungals. They showed significant differences in metabolic profile (i.e., the fraction of drug metabolized by cytochrome P450 (CYP), CYP reaction phenotype, impact of CYP genotype on interindividual pharmacokinetics variability and CYP-mediated drug-drug interaction potential). Many events of severe adverse drug reactions and treatment failures were closely related to the ignorance of the above issues. CONCLUSION: Clinicians should acquaint themselves with what kind of drug has less interpatient variability in clearance and whether to perform CYP genotyping prior to initiation of therapy. The relevant CYP knowledge helps clinicians to enhance the management of patients with gastrointestinal disease who may require treatment with polytherapeutic regimens. PMID:17948937

  9. Structure and mechanism of action of the hydroxy aryl aldehyde class of IRE1 endoribonuclease inhibitors

    PubMed Central

    Sanches, Mario; Duffy, Nicole M.; Talukdar, Manisha; Thevakumaran, Nero; Chiovitti, David; Canny, Marella D.; Lee, Kenneth; Kurinov, Igor; Uehling, David; Al-awar, Rima; Poda, Gennadiy; Prakesch, Michael; Wilson, Brian; Tam, Victor; Schweitzer, Colleen; Toro, Andras; Lucas, Julie L.; Vuga, Danka; Lehmann, Lynn; Durocher, Daniel; Zeng, Qingping; Patterson, John B.; Sicheri, Frank

    2014-01-01

    Endoplasmic reticulum (ER) stress activates the unfolded protein response and its dysfunction is linked to multiple diseases. The stress transducer IRE1α is a transmembrane kinase endoribonuclease (RNase) that cleaves mRNA substrates to re-establish ER homeostasis. Aromatic ring systems containing hydroxy-aldehyde moieties, termed hydroxy aryl aldehydes (HAA), selectively inhibit IRE1α RNase and thus represent a novel chemical series for therapeutic development. We solved crystal structures of murine IRE1α in complex with three HAA inhibitors. HAA inhibitors engage a shallow pocket at the RNase active site through pi-stacking interactions with His910 and Phe889, an essential Schiff base with Lys907 and a H-bond with Tyr892. Structure activity studies and mutational analysis of contact residues define the optimal chemical space of inhibitors and validate the inhibitor binding site. These studies lay the foundation for understanding both the biochemical and cellular functions of IRE1α using small molecule inhibitors and suggest new avenues for inhibitor design. PMID:25164867

  10. The effect of gender and age structure on municipal waste generation in Poland

    SciTech Connect

    Talalaj, Izabela Anna Walery, Maria

    2015-06-15

    Highlights: • An effect of gender and age structure on municipal waste generation was presented. • The waste accumulation index is influenced by a number of unemployed women. • Greater share of women in society contributes to greater waste production. • A model describing the analyzed dependences was determined. - Abstract: In this study the effect of gender and age structure on municipal waste generation was investigated. The data from 10-year period, from 2001 to 2010 year, were taken into consideration. The following parameters of gender and age structure were analyzed: men and woman quantity, female to male ratio, number of working, pre-working and post-working age men/women, number of unemployed men/women. The results have showed a strong correlation of annual per capita waste generation rate with number of unemployed women (r = 0.70) and female to male ratio (r = 0.81). This indicates that waste generation rate is more depended on ratio of men and women that on quantitative size of each group. Using the regression analysis a model describing the dependence between female to male ratio, number of unemployed woman and waste quantity was determined. The model explains 70% of waste quantity variation. Obtained results can be used both to improve waste management and to a fuller understanding of gender behavior.

  11. A comparison of the structure of solute clusters formed during thermal ageing and irradiation.

    PubMed

    Hyde, J M; Sha, G; Marquis, E A; Morley, A; Wilford, K B; Williams, T J

    2011-05-01

    Nanometre scale clusters form in Cu-containing reactor pressure vessel (RPV) steels during neutron irradiation. These clusters have a deleterious effect on mechanical properties, which can result in embrittlement and limit the reactor operating life. Thermal ageing of RPV steels can also induce the formation of solute clusters but it is not clear how similar these are to those formed during irradiation. In this work atom probe tomography, combined with detailed structural assessments of the structure of solute clusters, is used to address this issue. A series of thermal ageing heat treatments has been performed on several high- and low-Ni RPV welds to produce 1-4 nm diameter solute clusters. The same materials have also been neutron irradiated. The results show that CuMnNiSi enriched clusters formed during thermal ageing have, on average, higher Cu contents and lower Mn, Ni and Si contents than those found in irradiation-induced clusters. The effect of increasing bulk Ni is to encourage the formation of clusters with significantly higher Ni content, slightly higher Mn and Si contents and significantly lower Cu contents. At very high doses and dose rates MnNiSi enriched clusters can form even in high-Cu welds. Despite differences in the compositions of individual clusters formed during irradiation and during thermal ageing, clusters in both exhibit similar structure. In particular, well developed clusters in both materials have Cu-enriched cores whose peripheries are enriched in Ni, Mn and, in most cases, Si. PMID:21227587

  12. Gene structure, expression and chromosomal localization of murine theta class glutathione transferase mGSTT1-1.

    PubMed Central

    Whittington, A; Vichai, V; Webb, G; Baker, R; Pearson, W; Board, P

    1999-01-01

    We have isolated and characterized a cDNA and partial gene encoding a murine subfamily 1 Theta class glutathione transferase (GST). The cDNA derived from mouse GSTT1 has an open reading frame of 720 bp encoding a peptide of 240 amino acids with a calculated molecular mass of 27356 Da. The encoded protein shares only 51% deduced amino acid sequence identity with mouse GSTT2, but greater than 80% deduced amino acid sequence identity with rat GSTT1 and human GSTT1. Mouse GSTT1-1 was expressed in Escherichia coli as an N-terminal 6x histidine-tagged protein and purified using immobilized-metal affinity chromatography on nickel-agarose. The yield of the purified recombinant protein from E. coli cultures was approx. 14 mg/l. Recombinant mouse GSTT1-1 was catalytically active towards 1, 2-epoxy-3-(p-nitrophenoxy)propane, 4-nitrobenzyl chloride and dichloromethane. Low activity towards 1-menaphthyl sulphate and 1-chloro-2,4-dinitrobenzene was detected, whereas mouse GSTT1-1 was inactive towards ethacrynic acid. Recombinant mouse GSTT1-1 exhibited glutathione peroxidase activity towards cumene hydroperoxide and t-butyl hydroperoxide, but was inactive towards a range of secondary lipid-peroxidation products, such as the trans-alk-2-enals and trans,trans-alka-2,4-dienals. Mouse GSTT1 mRNA is most abundant in mouse liver and kidney, with some expression in intestinal mucosa. Mouse GSTT1 mRNA is induced in liver by phenobarbital, but not by butylated hydroxyanisole, beta-napthoflavone or isosafrole. The structure of mouse GSTT1 is conserved with that of the subfamily 2 Theta class GST genes mouse GSTT2 and rat GSTT2, comprising five exons interrupted by four introns. The mouse GSTT1 gene was found, by in situ hybridization, to be clustered with mouse GSTT2 on chromosome 10 at bands B5-C1. This region is syntenic with the location of the human Theta class GSTs clustered on chromosome 22q11.2. Similarity searches of a mouse-expressed sequence tag database suggest that there may

  13. Definitions of fitness in age-structured populations: Comparison in the haploid case.

    PubMed

    Lessard, Sabin; Soares, Cintia

    2016-02-21

    Fisher's (1930) Fundamental Theorem of Natural Selection (FTNS), and in particular the development of an explicit age-structured version of the theorem, is of everlasting interest. In a recent paper, Grafen (2015a) argues that Fisher regarded his theorem as justifying individual rather than population fitness maximization. The argument relies on a new definition of fitness in age-structured populations in terms of individual birth and death rates and age-specific reproductive values in agreement with a principle of neutrality. The latter are frequency-dependent and defined without reference to genetic variation. In the same paper, it is shown that the rate of increase in the mean of the breeding values of fitness weighted by the reproductive values, but keeping the breeding values constant as in Price (1972) is equal to the additive genetic variance in fitness. Therefore, this partial change is obtained by keeping constant not only the genotypic birth and death rates but also the mean age-specific birth and death rates from which the age-specific reproductive values are defined. In this paper we reaffirm that the Malthusian parameter which measures the relative rate of increase or decrease in reproductive value of each genotype in a continuous-time age-structured population is the definition of fitness used in Fisher's (1930) FTNS. This is shown by considering an age-structured asexual haploid population with constant age-specific birth and death (or survival) parameters for each type. Although the original statement of the FTNS is for a diploid population, this simplified haploid model allows us to address the definition of fitness meant in this theorem without the complexities and effects of a changing genic environment. In this simplified framework, the rate of change in mean fitness in continuous time is expected to be exactly equal to the genetic variance in fitness (or to the genetic variance in fitness divided by the mean fitness in discrete time), which can

  14. Methanotrophic community structure of aged refuse and its capability for methane bio-oxidation.

    PubMed

    Mei, Juan; Wang, Li; Han, Dan; Zhao, Youcai

    2011-01-01

    Aged refuse from waste landfills closed for eight years was examined and found to contain rich methanotrophs capable of biooxidation for methane. Specially, community structure and methane oxidation capability of methanotrophs in the aged refuse were studied. The amount of methanotrophs ranged 61.97 x 10(3)-632.91 x 10(3) cells/g (in dry basis) in aged refuse from Shanghai Laogang Landfill. Type I and II methanotrophs were found in the aged refuse in the presence of sterilized sewage sludge and only Type I methanotrophs were detected in the presence of nitrate minimal salt medium (NMS). The clone sequences of the pmoA gene obtained from the aged refuse were similar to the pmoA gene of Methylobacter Methylocaldum, and Methylocystis, and two clones were distinct with known genera of Type I methanotrophs according to phylogenetic analysis. Aged refuse enriched with NMS was used for methane biological oxidation and over 93% conversions were obtained. PMID:21790062

  15. ALPS: The Age-Layered Population Structure for Reducing the Problem of Premature Convergence

    NASA Technical Reports Server (NTRS)

    Hornby, Gregory S.

    2006-01-01

    To reduce the problem of premature convergence we define a new attribute of an individual, its age, and propose the Age-Layered Population Structure (ALPS), in which age is used to restrict competition and breeding between members of the population. ALPS differs from a typical EA by segregating individuals into different age-layers by their age - a measure of how long the genetic material has been in the population - and by regularly replacing all individuals in the bottom layer with randomly generated ones. The introduction of new, randomly generated individuals at regular intervals results in an EA that is never completely converged and is always looking at new parts of the fitness landscape. By using age to restrict competition and breeding search is able to develop promising young individuals without them being dominated by older ones. We demonstrate the effectiveness of the ALPS algorithm on an antenna design problem in which evolution with ALPS produces antennas more than twice as good as does evolution with two other types of EAs. Further analysis shows that the ALPS model does allow the offspring of newly generated individuals to move the population out of mediocre local-optima to better parts of the fitness landscape.

  16. Structure activity relationships of 4-hydroxy-2-pyridones: A novel class of antituberculosis agents.

    PubMed

    Ng, Pearly Shuyi; Manjunatha, Ujjini H; Rao, Srinivasa P S; Camacho, Luis R; Ma, Ngai Ling; Herve, Maxime; Noble, Christian G; Goh, Anne; Peukert, Stefan; Diagana, Thierry T; Smith, Paul W; Kondreddi, Ravinder Reddy

    2015-12-01

    Pyridone 1 was identified from a high-throughput cell-based phenotypic screen against Mycobacterium tuberculosis (Mtb) including multi-drug resistant tuberculosis (MDR-TB) as a novel anti-TB agent and subsequently optimized series using cell-based Mtb assay. Preliminary structure activity relationship on the isobutyl group with higher cycloalkyl groups at 6-position of pyridone ring has enabled us to significant improvement of potency against Mtb. The lead compound 30j, a dimethylcyclohexyl group on the 6-position of the pyridone, displayed desirable in vitro potency against both drug sensitive and multi-drug resistant TB clinical isolates. In addition, 30j displayed favorable oral pharmacokinetic properties and demonstrated in vivo efficacy in mouse model. These results emphasize the importance of 4-hydroxy-2-pyridones as a new chemotype and further optimization of properties to treat MDR-TB. PMID:26544629

  17. New classes of integrals inherent in the mathematical structure of extended equations describing superconducting systems

    NASA Astrophysics Data System (ADS)

    Gonczarek, Ryszard; Krzyzosiak, Mateusz; Gonczarek, Adam; Jacak, Lucjan

    2015-06-01

    In this paper, we discuss the mathematical structure of the s-wave superconducting gap and other quantitative characteristics of superconducting systems. In particular, we evaluate and discuss integrals inherent in fundamental equations describing superconducting systems. The results presented here extend the approach formulated by Abrikosov and Maki, which was restricted to the first-order expansion. A few infinite families of integrals are derived and allow us to express the fundamental equations by means of analytic formulas. They can be then exploited in order to find some quantitative characteristics of superconducting systems by the method of successive approximations. We show that the results can be applied to some modern formalisms in order to study high-Tc superconductors and other superconducting materials of the new generation.

  18. Analysing collimator structure effects in head-scatter calculations for IMRT class fields using scatter raytracing.

    PubMed

    Naqvi, S A; Sarfaraz, M; Holmes, T; Yu, C X; Li, X A

    2001-07-01

    The frequent blocking of the irradiated volume in intensity modulated radiation therapy (IMRT) makes the head-scatter fraction of the incident photon fluence more significant than that in conventional therapy with open fields. On the other hand. certain collimator configurations block scatter photons directed to a given observation point while allowing primary photons to be transmitted. The 'anomalous blocking' makes the primary field a poor indicator of the scatter fluence. Since large MU-to-cGy ratios in IMRT can magnify head-scatter uncertainties, it becomes necessary to accurately model both the effective scatter source and the collimator structure that limits the scatter reaching the irradiated volume. First we obtain a dual-source model, using a Taylor series expansion to derive the effective scatter source distribution from the data measured for the Elekta SL20 linac equipped with a multi-leaf collimator (MLC). Then, using a raytracing algorithm, we calculate the transmission of scatter rays from the effective scatter source plane to points in the patient plane. The method can account for the anomalous blocking of scatter by the MLC leaves and the backup diaphragms. For a variety of collimator settings tested, the calculations agree with measurements to an accuracy of 0.002psi10 x 10, where psi10 x 10 is the total (primary + scatter) photon fluence of an open 10 x 10 cm2 field for the same MU delivered. Although the significance of collimator structure in IMRT depends strongly on fields shapes employed for the delivery, potential cumulative errors on the order of a few per cent can be avoided in fluence calculations if the proposed method is used. PMID:11474941

  19. The Role of Structural Dynamics of Actin in Class-Specific Myosin Motility

    PubMed Central

    Noguchi, Taro Q. P.; Morimatsu, Masatoshi; Iwane, Atsuko H.; Yanagida, Toshio; Uyeda, Taro Q. P.

    2015-01-01

    The structural dynamics of actin, including the tilting motion between the small and large domains, are essential for proper interactions with actin-binding proteins. Gly146 is situated at the hinge between the two domains, and we previously showed that a G146V mutation leads to severe motility defects in skeletal myosin but has no effect on motility of myosin V. The present study tested the hypothesis that G146V mutation impaired rotation between the two domains, leading to such functional defects. First, our study showed that depolymerization of G146V filaments was slower than that of wild-type filaments. This result is consistent with the distinction of structural states of G146V filaments from those of the wild type, considering the recent report that stabilization of actin filaments involves rotation of the two domains. Next, we measured intramolecular FRET efficiencies between two fluorophores in the two domains with or without skeletal muscle heavy meromyosin or the heavy meromyosin equivalent of myosin V in the presence of ATP. Single-molecule FRET measurements showed that the conformations of actin subunits of control and G146V actin filaments were different in the presence of skeletal muscle heavy meromyosin. This altered conformation of G146V subunits may lead to motility defects in myosin II. In contrast, distributions of FRET efficiencies of control and G146V subunits were similar in the presence of myosin V, consistent with the lack of motility defects in G146V actin with myosin V. The distribution of FRET efficiencies in the presence of myosin V was different from that in the presence of skeletal muscle heavy meromyosin, implying that the roles of actin conformation in myosin motility depend on the type of myosin. PMID:25945499

  20. Intermolecular Overlap Geometry Gives Two Classes of Fulleride Superconductor: Electronic Structure of 38K Tc Cs3C60

    NASA Astrophysics Data System (ADS)

    Darling, G. R.; Ganin, A. Y.; Rosseinsky, M. J.; Takabayashi, Y.; Prassides, K.

    2008-09-01

    Superconductivity emerges for the A15 polymorph of the fulleride Cs3C60 upon compression to a pressure of ˜4kbar. Using density functional theory we study the bonding in the A15 phase as a function of unit cell volume comparing it to that in the fcc polymorph. We find that, despite its smaller packing density, the bcc-derived A15 phase has both a substantially wider bandwidth for the partially occupied t1u band and a higher density of states at the Fermi level. This result can be traced to the striking differences in the nature of the interanion overlap in the A15 and fcc structures showing that the A15 Cs3C60 phase is not simply yet another superconducting fulleride albeit with a very high Tc—the two sphere packings (body centered versus face centered) observed experimentally produce two electronically distinct classes of fulleride superconductors.

  1. Optimal control problems of epidemic systems with parameter uncertainties: application to a malaria two-age-classes transmission model with asymptomatic carriers.

    PubMed

    Mwanga, Gasper G; Haario, Heikki; Capasso, Vicenzo

    2015-03-01

    The main scope of this paper is to study the optimal control practices of malaria, by discussing the implementation of a catalog of optimal control strategies in presence of parameter uncertainties, which is typical of infectious diseases data. In this study we focus on a deterministic mathematical model for the transmission of malaria, including in particular asymptomatic carriers and two age classes in the human population. A partial qualitative analysis of the relevant ODE system has been carried out, leading to a realistic threshold parameter. For the deterministic model under consideration, four possible control strategies have been analyzed: the use of Long-lasting treated mosquito nets, indoor residual spraying, screening and treatment of symptomatic and asymptomatic individuals. The numerical results show that using optimal control the disease can be brought to a stable disease free equilibrium when all four controls are used. The Incremental Cost-Effectiveness Ratio (ICER) for all possible combinations of the disease-control measures is determined. The numerical simulations of the optimal control in the presence of parameter uncertainty demonstrate the robustness of the optimal control: the main conclusions of the optimal control remain unchanged, even if inevitable variability remains in the control profiles. The results provide a promising framework for the designing of cost-effective strategies for disease controls with multiple interventions, even under considerable uncertainty of model parameters. PMID:25481226

  2. Geodynamic setting of mineralization of Mississippi Valley-type deposits in world-class Sichuan-Yunnan-Guizhou Zn-Pb triangle, southwest China: Implications from age-dating studies in the past decade and the Sm-Nd age of Jinshachang deposit

    NASA Astrophysics Data System (ADS)

    Zhang, Changqing; Wu, Yue; Hou, Lin; Mao, Jingwen

    2015-05-01

    The Sichuan-Yunnan-Guizhou (S-Y-G) Zn-Pb triangle is a world-class metallogenic belt in southwestern China that contains hundreds of carbonate-hosted giant-to-small epigenetic Zn-Pb deposits. Here, we provide an overview of the ore geology, geochemistry and ore-forming fluids of the major Zn-Pb deposits in this area. These deposits are most likely Mississippi Valley-type (MVT) deposits that formed as a result of the regional migration of basinal brines along large fault systems and more minor secondary structures. The Sm-Nd age (201 ± 6.2 Ma) of ore-stage fluorite from the Jinshachang Zn-Pb deposit, within northeast Yunnan province, China, reveals this deposit formed during the Late Triassic, consistent with the majority of the published isotopic ages for other Zn-Pb deposits in the S-Y-G MVT triangle. These fluorite samples have initial 87Sr/86Sr ratios of 0.711385-0.711463 and εNd values of -8.4 to -8.7, confirming the basin-related nature of the mineralizing fluids. Published geochronological data combined with basic features of MVT deposits (e.g., geology, geochemistry, and ore-forming fluids) and the geological evolution of the study area has enabled us to develop a model for the Zn-Pb mineralization, where this word-class MVT belt has formed as a result of the regional-scale migration of basinal fluids coincident with tectonic activity along ore-controlling structures (e.g., thrust-fold systems). Both the fluid migration and the tectonic activity were probably triggered by the late Indosinian Orogeny, which in turn was a response to the closure of the Paleo-Tethys Ocean.

  3. Core and Large-Scale Structure of the 2000 November 24 X-Class Flare and Coronal Mass Ejection

    NASA Technical Reports Server (NTRS)

    Wang, Haimin; Gallagher, Peter; Yurchyshyn, Vasyl; Yang, Guo; Godde, Philip R.

    2002-01-01

    In this paper, we present three important aspects of the XI .8 flare and the associated coronal mass ejection (CME) that occurred on 2000 November 24: (1) The source of the flare is clearly associated with a magnetic channel structure, as was noted in a study by Zirin & Wang , which is due to a combination of flux emergence inside the leading edge of the penumbra of the major leading sunspot and proper motion of the sunspot group. The channel structure provides evidence for twisted flux ropes that can erupt, forming the core of a CME, and may be a common property of several superactive regions that have produced multiple X-class flares in the past. (2) There are actually three flare ribbons visible. The first can be seen moving away from the flare site, while the second and third make up a stationary ribbon near the leader spot. The moving ribbons could be due to a shock associated with the erupting flux rope or due to the interaction of erupting rope and the surrounding magnetic fields. In either case, the ribbon motion does not fit the classical Kopp-Pneuman model, in which the separation of ribbons is due to magnetic reconnection at successively higher and higher coronal altitudes. (3) From the coronal dimming observed with the EUV Imaging Telescope (EIT), the CME involved a much larger region than the initial X-class flare. By comparing high-resolution full-disk Ha and EIT observations, we found that a remote dimming area is cospatial with the enhanced Ha emission. This result is consistent with the recent model of Yokoyama & Shibata that some dimming areas near footpoints may be due to chromospheric evaporation.

  4. Structure and Characterization of Flavolipids, a Novel Class of Biosurfactants Produced by Flavobacterium sp. Strain MTN11

    PubMed Central

    Bodour, Adria A.; Guerrero-Barajas, Claudia; Jiorle, Beth V.; Malcomson, Mark E.; Paull, Amanda K.; Somogyi, Arpad; Trinh, Long N.; Bates, Robert B.; Maier, Raina M.

    2004-01-01

    Herein we report the structure and selected properties of a new class of biosurfactants that we have named the flavolipids. The flavolipids exhibit a unique polar moiety that features citric acid and two cadaverine molecules. Flavolipids were produced by a soil isolate, Flavobacterium sp. strain MTN11 (accession number AY162137), during growth in mineral salts medium, with 2% glucose as the sole carbon and energy source. MTN11 produced a mixture of at least 37 flavolipids ranging from 584 to 686 in molecular weight (MW). The structure of the major component (23%; MW = 668) was determined to be 4-[[5-(7-methyl-(E)-2-octenoylhydroxyamino)pentyl]amino]-2-[2-[[5-(7-methyl-(E)-2-octenoylhydroxyamino)pentyl]amino]-2-oxoethyl]-2-hydroxy-4-oxobutanoic acid. The partially purified flavolipid mixture isolated from strain MTN11 exhibited a critical micelle concentration of 300 mg/liter and reduced surface tension to 26.0 mN/m, indicating strong surfactant activity. The flavolipid mixture was a strong and stable emulsifier even at concentrations as low as 19 mg/liter. It was also an effective solubilizing agent, and in a biodegradation study, it enhanced hexadecane mineralization by two isolates, MTN11 (100-fold) and Pseudomonas aeruginosa ATCC 9027 (2.5-fold), over an 8-day period. The flavolipid-cadmium stability constant was measured to be 3.61, which is comparable to that for organic ligands such as oxalic acid and acetic acid. In summary, the flavolipids represent a new class of biosurfactants that have potential for use in a variety of biotechnological and industrial applications. PMID:14711632

  5. Structural Basis for the Presentation of Tumor-Associated MHC Class II-Restricted Phosphopeptides to CD4+ T Cells

    SciTech Connect

    Li, Y.; Depontieu, F; Sidney, J; Salay, T; Engelhard, V; Hunt, D; Sette, A; Topalian, S; Mariuzza, R

    2010-01-01

    Dysregulated protein phosphorylation is a hallmark of malignant transformation. Transformation can generate major histocompatibility complex (MHC)-bound phosphopeptides that are differentially displayed on tumor cells for specific recognition by T cells. To understand how phosphorylation alters the antigenic identity of self-peptides and how MHC class II molecules present phosphopeptides for CD4{sup +} T-cell recognition, we determined the crystal structure of a phosphopeptide derived from melanoma antigen recognized by T cells-1 (pMART-1), selectively expressed by human melanomas, in complex with HLA-DR1. The structure revealed that the phosphate moiety attached to the serine residue at position P5 of pMART-1 is available for direct interactions with T-cell receptor (TCR) and that the peptide N-terminus adopts an unusual conformation orienting it toward TCR. This structure, combined with measurements of peptide affinity for HLA-DR1 and of peptide-MHC recognition by pMART-1-specific T cells, suggests that TCR recognition is focused on the N-terminal portion of pMART-1. This recognition mode appears to be distinct from that of foreign antigen complexes but is remarkably reminiscent of the way autoreactive TCRs engage self- or altered self-peptides, consistent with the tolerogenic nature of tumor-host immune interactions.

  6. Effects of Age and Hearing Loss on the Processing of Auditory Temporal Fine Structure.

    PubMed

    Moore, Brian C J

    2016-01-01

    Within the cochlea, broadband sounds like speech and music are filtered into a series of narrowband signals, each of which can be considered as a relatively slowly varying envelope (ENV) imposed on a rapidly oscillating carrier (the temporal fine structure, TFS). Information about ENV and TFS is conveyed in the timing and short-term rate of nerve spikes in the auditory nerve. There is evidence that both hearing loss and increasing age adversely affect the ability to use TFS information, but in many studies the effects of hearing loss and age have been confounded. This paper summarises evidence from studies that allow some separation of the effects of hearing loss and age. The results suggest that the monaural processing of TFS information, which is important for the perception of pitch and for segregating speech from background sounds, is adversely affected by both hearing loss and increasing age, the former being more important. The monaural processing of ENV information is hardly affected by hearing loss or by increasing age. The binaural processing of TFS information, which is important for sound localisation and the binaural masking level difference, is also adversely affected by both hearing loss and increasing age, but here the latter seems more important. The deterioration of binaural TFS processing with increasing age appears to start relatively early in life. The binaural processing of ENV information also deteriorates somewhat with increasing age. The reduced binaural processing abilities found for older/hearing-impaired listeners may partially account for the difficulties that such listeners experience in situations where the target speech and interfering sounds come from different directions in space, as is common in everyday life. PMID:27080640

  7. Structured additive regression modeling of age of menarche and menopause in a breast cancer screening program.

    PubMed

    Duarte, Elisa; de Sousa, Bruno; Cadarso-Suarez, Carmen; Rodrigues, Vitor; Kneib, Thomas

    2014-05-01

    Breast cancer risk is believed to be associated with several reproductive factors, such as early menarche and late menopause. This study is based on the registries of the first time a woman enters the screening program, and presents a spatio-temporal analysis of the variables age of menarche and age of menopause along with other reproductive and socioeconomic factors. The database was provided by the Portuguese Cancer League (LPCC), a private nonprofit organization dealing with multiple issues related to oncology of which the Breast Cancer Screening Program is one of its main activities. The registry consists of 259,652 records of women who entered the screening program for the first time between 1990 and 2007 (45-69-year age group). Structured Additive Regression (STAR) models were used to explore spatial and temporal correlations with a wide range of covariates. These models are flexible enough to deal with a variety of complex datasets, allowing us to reveal possible relationships among the variables considered in this study. The analysis shows that early menarche occurs in younger women and in municipalities located in the interior of central Portugal. Women living in inland municipalities register later ages for menopause, and those born in central Portugal after 1933 show a decreasing trend in the age of menopause. Younger ages of menarche and late menopause are observed in municipalities with a higher purchasing power index. The analysis performed in this study portrays the time evolution of the age of menarche and age of menopause and their spatial characterization, adding to the identification of factors that could be of the utmost importance in future breast cancer incidence research. PMID:24615881

  8. Genus age, provincial area and the taxonomic structure of marine faunas

    PubMed Central

    Harnik, Paul G.; Jablonski, David; Krug, Andrew Z.; Valentine, James W.

    2010-01-01

    Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf–Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area. PMID:20534619

  9. Genus age, provincial area and the taxonomic structure of marine faunas.

    PubMed

    Harnik, Paul G; Jablonski, David; Krug, Andrew Z; Valentine, James W

    2010-11-22

    Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf-Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area. PMID:20534619

  10. Structure elucidation of hexabromocyclododecanes--a class of compounds with a complex stereochemistry.

    PubMed

    Heeb, Norbert V; Schweizer, W Bernd; Kohler, Martin; Gerecke, Andreas C

    2005-09-01

    Hexabromocyclododecanes (HBCDs) are high production volume chemicals (16700 t worldwide in 2001) used as flame-retardants for plastics and textiles. HBCDs exhibit typical properties of persistent organic pollutants (POPs). They are highly lipophilic and accumulate in biota. Increasing environmental concentrations of HBCDs, mostly reported as sum values, have been observed. As such, HBCDs have to be considered as potential emerging POPs, but their occurrence and environmental fate have not yet been addressed at the level of individual HBCD stereoisomers. Considering the six stereogenic centers of HBCDs, 16 stereoisomers, six diastereomeric pairs of enantiomers as well as four meso forms, can be deduced. Herein, we report spectroscopic and chromatographic data for eight out of 16 possible HBCD stereoisomers, which were isolated from a technical product. Six stereoisomers were identified as three pairs of enantiomers ((+/-) alpha-, beta-, and gamma-HBCDs), differing in optical rotation and chromatographic retention on a chiral phase. The crystal structures of these pairs of enantiomers were determined. Another two of these eight HBCD stereoisomers, not yet described in the literature, showed no optical rotation and are tentatively assigned as meso forms (delta- and epsilon-HBCD). The given spectroscopic and chromatographic information allows the unambiguous identification of eight HBCD stereoisomers and the occurrence, fate, and toxicology of these individual stereoisomers can now be studied. PMID:16157171

  11. Fine structural changes in the lateral vestibular nucleus of aging rats

    NASA Technical Reports Server (NTRS)

    Johnson, J. E., Jr.; Miquel, J.

    1974-01-01

    The fine structure of the lateral vestibular nucleus was investigated in Sprague-Dawley rats, that were sacrified at 4 weeks, 6-8 weeks, 6-8 months, and 18-20 months of age. In the neuronal perikaria, the following age-associated changes were seen with increasing frequency with advancing age: rodlike nuclear inclusions and nuclear membrane invaginations; cytoplasmic dense bodies with the characteristics of lipofuscin; and moderate disorganization of the granular endoplasmic reticulum. Dense bodies were also seen in glial cells. Rats 18 to 20 months old showed dendritic swellings, axonal degeneration, and an apparent increase in the number of axosomatic synaptic terminals containing flattened vesicles (presumed to be inhibitory in function).

  12. Significance of locally intensified strain aging to the fracture toughness of welded steel structures

    SciTech Connect

    Dawes, M.G.

    1995-12-31

    A review of past studies shows that tests on specimens notched after welding can give overestimates of the fracture toughness that occurs at the tips of flaws present during welding. This situation results from locally intensified straining and aging embrittlement (LISAE), which has been shown to trigger low stress brittle fractures in both notched and welded wide plate tension tests, and welded structures in service. Although the relative susceptibilities of steels to strain aging embrittlement are sometimes assessed by testing bulk strained and aged samples, the results of such tests may be optimistic. A summary is given of work to develop a fracture toughness test method for LISAE. The new test will give increased confidence and accuracy in fracture assessments, be of use in selecting tough materials, and aid the development of materials that are resistant to LISAE.

  13. Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug

    PubMed Central

    Marschallinger, Julia; Schäffner, Iris; Klein, Barbara; Gelfert, Renate; Rivera, Francisco J.; Illes, Sebastian; Grassner, Lukas; Janssen, Maximilian; Rotheneichner, Peter; Schmuckermair, Claudia; Coras, Roland; Boccazzi, Marta; Chishty, Mansoor; Lagler, Florian B.; Renic, Marija; Bauer, Hans-Christian; Singewald, Nicolas; Blümcke, Ingmar; Bogdahn, Ulrich; Couillard-Despres, Sebastien; Lie, D. Chichung; Abbracchio, Maria P.; Aigner, Ludwig

    2015-01-01

    As human life expectancy has improved rapidly in industrialized societies, age-related cognitive impairment presents an increasing challenge. Targeting histopathological processes that correlate with age-related cognitive declines, such as neuroinflammation, low levels of neurogenesis, disrupted blood–brain barrier and altered neuronal activity, might lead to structural and functional rejuvenation of the aged brain. Here we show that a 6-week treatment of young (4 months) and old (20 months) rats with montelukast, a marketed anti-asthmatic drug antagonizing leukotriene receptors, reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. By using gene knockdown and knockout approaches, we demonstrate that the effect is mediated through inhibition of the GPR17 receptor. This work illustrates that inhibition of leukotriene receptor signalling might represent a safe and druggable target to restore cognitive functions in old individuals and paves the way for future clinical translation of leukotriene receptor inhibition for the treatment of dementias. PMID:26506265

  14. Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug.

    PubMed

    Marschallinger, Julia; Schäffner, Iris; Klein, Barbara; Gelfert, Renate; Rivera, Francisco J; Illes, Sebastian; Grassner, Lukas; Janssen, Maximilian; Rotheneichner, Peter; Schmuckermair, Claudia; Coras, Roland; Boccazzi, Marta; Chishty, Mansoor; Lagler, Florian B; Renic, Marija; Bauer, Hans-Christian; Singewald, Nicolas; Blümcke, Ingmar; Bogdahn, Ulrich; Couillard-Despres, Sebastien; Lie, D Chichung; Abbracchio, Maria P; Aigner, Ludwig

    2015-01-01

    As human life expectancy has improved rapidly in industrialized societies, age-related cognitive impairment presents an increasing challenge. Targeting histopathological processes that correlate with age-related cognitive declines, such as neuroinflammation, low levels of neurogenesis, disrupted blood-brain barrier and altered neuronal activity, might lead to structural and functional rejuvenation of the aged brain. Here we show that a 6-week treatment of young (4 months) and old (20 months) rats with montelukast, a marketed anti-asthmatic drug antagonizing leukotriene receptors, reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. By using gene knockdown and knockout approaches, we demonstrate that the effect is mediated through inhibition of the GPR17 receptor. This work illustrates that inhibition of leukotriene receptor signalling might represent a safe and druggable target to restore cognitive functions in old individuals and paves the way for future clinical translation of leukotriene receptor inhibition for the treatment of dementias. PMID:26506265

  15. Parametric Geometry, Structured Grid Generation, and Initial Design Study for REST-Class Hypersonic Inlets

    NASA Technical Reports Server (NTRS)

    Ferlemann, Paul G.; Gollan, Rowan J.

    2010-01-01

    Computational design and analysis of three-dimensional hypersonic inlets with shape transition has been a significant challenge due to the complex geometry and grid required for three-dimensional viscous flow calculations. Currently, the design process utilizes an inviscid design tool to produce initial inlet shapes by streamline tracing through an axisymmetric compression field. However, the shape is defined by a large number of points rather than a continuous surface and lacks important features such as blunt leading edges. Therefore, a design system has been developed to parametrically construct true CAD geometry and link the topology of a structured grid to the geometry. The Adaptive Modeling Language (AML) constitutes the underlying framework that is used to build the geometry and grid topology. Parameterization of the CAD geometry allows the inlet shapes produced by the inviscid design tool to be generated, but also allows a great deal of flexibility to modify the shape to account for three-dimensional viscous effects. By linking the grid topology to the parametric geometry, the GridPro grid generation software can be used efficiently to produce a smooth hexahedral multiblock grid. To demonstrate the new capability, a matrix of inlets were designed by varying four geometry parameters in the inviscid design tool. The goals of the initial design study were to explore inviscid design tool geometry variations with a three-dimensional analysis approach, demonstrate a solution rate which would enable the use of high-fidelity viscous three-dimensional CFD in future design efforts, process the results for important performance parameters, and perform a sample optimization.

  16. Optimal control for an age-structured model for the transmission of hepatitis B.

    PubMed

    Djidjou Demasse, Ramses; Tewa, Jean-Jules; Bowong, Samuel; Emvudu, Yves

    2016-08-01

    One of the characteristics of HBV transmission is the age structure of the host population and the vertical transmission of the disease. That is the infection is transmitted directly from infected mother to an embryo, fetus, or baby during pregnancy or childbirth (the perinatal infection). We formulated an age-structured model for the transmission dynamics of HBV with differential infectivity: symptomatic and asymptomatic infections. The model without intervention strategies is completely analyzed. We compute the basic reproduction number which determines the outcome of the disease. We also compute equilibria and study their stability. The sensitivity analysis of the initial model parameters is performed (to determine the impact of control-related parameters on outbreak severity). Using optimal control theory, we determine the cost-effective balance of three interventions methods which minimizes HBV-related deaths as well as the costs associated with intervention. PMID:26676356

  17. The contribution of age structure to cell population responses to targeted therapeutics

    PubMed Central

    Gabriel, Pierre; Garbett, Shawn P.; Quaranta, Vito; Tyson, Darren R.; Webb, Glenn F.

    2013-01-01

    Cells grown in culture act as a model system for analyzing the effects of anticancer compounds, which may affect cell behavior in a cell cycle position-dependent manner. Cell synchronization techniques have been generally employed to minimize the variation in cell cycle position. However, synchronization techniques are cumbersome and imprecise and the agents used to synchronize the cells potentially have other unknown effects on the cells. An alternative approach is to determine the age structure in the population and account for the cell cycle positional effects post hoc. Here we provide a formalism to use quantifiable lifespans from live cell microscopy experiments to parameterize an age-structured model of cell population response. PMID:22796330

  18. Surface structural changes of naturally aged silicone and EPDM composite insulators

    SciTech Connect

    Vlastos, A.E. ); Gubanski, S.M. )

    1991-04-01

    In a long-term outdoor test with high direct and alternating voltages, silicone and EPDM rubber composite insulators have, at the beginning, shown a superior performance to that of glass and porcelain insulators. In the long-term test, however, the silicone rubber composite insulator has, in spite of the ageing of both insulator types, kept its good performance, while the performance of the EPDM rubber composite insulator was drastically deteriorated. In order to get a better insight into results obtained, the wettability and the surface structural changes of the insulators were studied by the drop deposition method (using a goniometer) and by advanced techniques such as SEM, ESCA, FTIR and SIMS respectively. The results show that the differences in performance have to be found in the differences in the surface structural changes and in the dynamic ability of the surface to compensate the ageing.

  19. DETERMINING THE EFFECTS OF RADIATION ON AGING CONCRETE STRUCTURES OF NUCLEAR REACTORS

    SciTech Connect

    Serrato, M.

    2010-01-29

    The U.S. Department of Energy Office of Environmental Management (DOE-EM) is responsible for the Decontamination and Decommissioning (D&D) of nuclear facilities throughout the DOE Complex. Some of these facilities will be completely dismantled, while others will be partially dismantled and the remaining structure will be stabilized with cementitious fill materials. The latter is a process known as In-Situ Decommissioning (ISD). The ISD decision process requires a detailed understanding of the existing facility conditions, and operational history. System information and material properties are need for aged nuclear facilities. This literature review investigated the properties of aged concrete structures affected by radiation. In particular, this review addresses the Savannah River Site (SRS) isotope production nuclear reactors. The concrete in the reactors at SRS was not seriously damaged by the levels of radiation exposure. Loss of composite compressive strength was the most common effect of radiation induced damage documented at nuclear power plants.

  20. Experimental febrile seizures induce age-dependent structural plasticity and improve memory in mice.

    PubMed

    Tao, K; Ichikawa, J; Matsuki, N; Ikegaya, Y; Koyama, R

    2016-03-24

    Population-based studies have demonstrated that children with a history of febrile seizure (FS) perform better than age-matched controls at hippocampus-dependent memory tasks. Here, we report that FSs induce two distinct structural reorganizations in the hippocampus and bidirectionally modify future learning abilities in an age-dependent manner. Compared with age-matched controls, adult mice that had experienced experimental FSs induced by hyperthermia (HT) on postnatal day 14 (P14-HT) performed better in a cognitive task that requires dentate granule cells (DGCs). The enhanced memory performance correlated with an FS-induced persistent increase in the density of large mossy fiber terminals (LMTs) of the DGCs. The memory enhancement was not observed in mice that had experienced HT-induced seizures at P11 which exhibited abnormally located DGCs in addition to the increased LMT density. The ectopic DGCs of the P11-HT mice were abolished by the diuretic bumetanide, and this pharmacological treatment unveiled the masked memory enhancement. Thus, this work provides a novel basis for age-dependent structural plasticity in which FSs influence future brain function. PMID:26794590