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Sample records for evince ontogenetic bias

  1. The coalitional value theory of antigay bias

    NARCIS (Netherlands)

    Winegard, Bo; Reynolds, Tania; Baumeister, Roy F.; Plant, E. Ashby

    2016-01-01

    Research indicates that antigay bias follows a specific pattern (and probably has throughout written history, at least in the West): (a) men evince more antigay bias than women; (b) men who belong to traditionally male coalitions evince more antigay bias than those who do not; (c) antigay bias is

  2. Ontogenetic allometry of the Beagle.

    Science.gov (United States)

    Helmsmüller, Daniela; Wefstaedt, Patrick; Nolte, Ingo; Schilling, Nadja

    2013-10-10

    Mammalian juveniles undergo dramatic changes in body conformation during development. As one of the most common companion animals, the time line and trajectory of a dog's development and its body's re-proportioning is of particular scientific interest. Several ontogenetic studies have investigated the skeletal development in dogs, but none has paid heed to the scapula as a critical part of the mammalian forelimb. Its functional integration into the forelimb changed the correspondence between fore- and hindlimb segments and previous ontogenetic studies observed more similar growth patterns for functionally than serially homologous elements. In this study, the ontogenetic development of six Beagle siblings was monitored between 9 and 51 weeks of age to investigate their skeletal allometry and compare this with data from other lines, breeds and species. Body mass increased exponentially with time; log linear increase was observed up to the age of 15 weeks. Compared with body mass, withers and pelvic height as well as the lengths of the trunk, scapula, brachium and antebrachium, femur and crus exhibited positive allometry. Trunk circumference and pes showed negative allometry in all, pelvis and manus in most dogs. Thus, the typical mammalian intralimb re-proportioning with the proximal limb elements exhibiting positive allometry and the very distal ones showing negative allometry was observed. Relative lengths of the antebrachium, femur and crus increased, while those of the distal elements decreased. Beagles are fully-grown regarding body height but not body mass at about one year of age. Particular attention should be paid to feeding and physical exertion during the first 15 weeks when they grow more intensively. Compared with its siblings, a puppy's size at 9 weeks is a good indicator for its final size. Among siblings, growth duration may vary substantially and appears not to be related to the adult size. Within breeds, a longer time to physically mature is

  3. Quantification of ontogenetic allometry in ammonoids.

    Science.gov (United States)

    Korn, Dieter

    2012-01-01

    Ammonoids are well-known objects used for studies on ontogeny and phylogeny, but a quantification of ontogenetic change has not yet been carried out. Their planispirally coiled conchs allow for a study of "longitudinal" ontogenetic data, that is data of ontogenetic trajectories that can be obtained from a single specimen. Therefore, they provide a good model for ontogenetic studies of geometry in other shelled organisms. Using modifications of three cardinal conch dimensions, computer simulations can model artificial conchs. The trajectories of ontogenetic allometry of these simulations can be analyzed in great detail in a theoretical morphospace. A method for the classification of conch ontogeny and quantification of the degree of allometry is proposed. Using high-precision cross-sections, the allometric conch growth of real ammonoids can be documented and compared. The members of the Ammonoidea show a wide variety of allometric growth, ranging from near isometry to monophasic, biphasic, or polyphasic allometry. Selected examples of Palaeozoic and Mesozoic ammonoids are shown with respect to their degree of change during ontogeny of the conch. © 2012 Wiley Periodicals, Inc.

  4. The limitations of ontogenetic data in phylogenetic analyses

    NARCIS (Netherlands)

    Koenemann, Stefan; Schram, Frederick R.

    2002-01-01

    The analysis of consecutive ontogenetic stages, or events, introduces a new class of data to phylogenetic systematics that are distinctly different from traditional morphological characters and molecular sequence data. Ontogenetic event sequences are distinguished by varying degrees of both a

  5. The ontogenetic osteohistology of Tenontosaurus tilletti.

    Directory of Open Access Journals (Sweden)

    Sarah Werning

    Full Text Available Tenontosaurus tilletti is an ornithopod dinosaur known from the Early Cretaceous (Aptian-Albian Cloverly and Antlers formations of the Western United States. It is represented by a large number of specimens spanning a number of ontogenetic stages, and these specimens have been collected across a wide geographic range (from central Montana to southern Oklahoma. Here I describe the long bone histology of T. tilletti and discuss histological variation at the individual, ontogenetic and geographic levels. The ontogenetic pattern of bone histology in T. tilletti is similar to that of other dinosaurs, reflecting extremely rapid growth early in life, and sustained rapid growth through sub-adult ontogeny. But unlike other iguanodontians, this dinosaur shows an extended multi-year period of slow growth as skeletal maturity approached. Evidence of termination of growth (e.g., an external fundamental system is observed in only the largest individuals, although other histological signals in only slightly smaller specimens suggest a substantial slowing of growth later in life. Histological differences in the amount of remodeling and the number of lines of arrested growth varied among elements within individuals, but bone histology was conservative across sampled individuals of the species, despite known paleoenvironmental differences between the Antlers and Cloverly formations. The bone histology of T. tilletti indicates a much slower growth trajectory than observed for other iguanodontians (e.g., hadrosaurids, suggesting that those taxa reached much larger sizes than Tenontosaurus in a shorter time.

  6. Ontogenetic shifts of heart position in snakes.

    Science.gov (United States)

    Lillywhite, Harvey B; Lillywhite, Steven M

    2017-08-01

    Heart position relative to total body length (TL) varies among snakes, with anterior hearts in arboreal species and more centrally located hearts in aquatic or ground-dwelling species. Anterior hearts decrease the cardiac work associated with cranial blood flow and minimize drops in cranial pressure and flow during head-up climbing. Here, we investigate whether heart position shifts intraspecifically during ontogenetic increases in TL. Insular Florida cottonmouth snakes, Agkistrodon conanti, are entirely ground-dwelling and have a mean heart position that is 33.32% TL from the head. In contrast, arboreal rat snakes, Pantherophis obsoleta, of similar lengths have a mean heart position that is 17.35% TL from the head. In both species, relative heart position shifts craniad during ontogeny, with negative slopes = -.035 and -.021% TL/cm TL in Agkistrodon and Pantherophis, respectively. Using a large morphometric data set available for Agkistrodon (N = 192 individuals, 23-140 cm TL), we demonstrate there is an anterior ontogenetic shift of the heart position within the trunk (= 4.56% trunk length from base of head to cloacal vent), independent of head and tail allometry which are both negative. However, in longer snakes > 100 cm, the heart position reverses and shifts caudally in longer Agkistrodon but continues toward the head in longer individuals of Pantherophis. Examination of data sets for two independent lineages of fully marine snakes (Acrochordus granulatus and Hydrophis platurus), which do not naturally experience postural gravity stress, demonstrate both ontogenetic patterns for heart position that are seen in the terrestrial snakes. The anterior migration of the heart is greater in the terrestrial species, even if TL is standardized to that of the longer P. obsoleta, and compensates for about 5 mmHg gravitational pressure head if they are fully upright. © 2017 Wiley Periodicals, Inc.

  7. On the relationship between ontogenetic and static allometry.

    Science.gov (United States)

    Pélabon, Christophe; Bolstad, Geir H; Egset, Camilla K; Cheverud, James M; Pavlicev, Mihaela; Rosenqvist, Gunilla

    2013-02-01

    Ontogenetic and static allometries describe how a character changes in size when the size of the organism changes during ontogeny and among individuals measured at the same developmental stage, respectively. Understanding the relationship between these two types of allometry is crucial to understanding the evolution of allometry and, more generally, the evolution of shape. However, the effects of ontogenetic allometry on static allometry remain largely unexplored. Here, we first show analytically how individual variation in ontogenetic allometry and body size affect static allometry. Using two longitudinal data sets on ontogenetic and static allometry, we then estimate variances and covariances for the different parameters of the ontogenetic allometry defined in our model and assess their relative contribution to the static allometric slope. The mean ontogenetic allometry is the main parameter that determines the static allometric slope, while the covariance between the ontogenetic allometric slope and body size generates most of the discrepancies between ontogenetic and static allometry. These results suggest that the apparent evolutionary stasis of the static allometric slope is not generated by internal (developmental) constraints but more likely results from external constraints imposed by selection.

  8. Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae) Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae)

    OpenAIRE

    Duellman William E.; Ruiz C. Pedro M.

    1986-01-01

    Color polymorphism is common in many species of marsupial frogs.  Extreme cases of pattern polymorphism are documented in four species. In Amphignathodon guentheri, Castrotheca aureomaculata, G. qriswoldi, and G. helenae juveniles are known to have only one color morph, where as two or more patterns exist in adults. In these species, polymorphism apparently develops ontogenetically. El polimorfismo cromático es común a algunas especies de sapos marsupiales. Casos extremos del modelo de polimo...

  9. On the relationship between ontogenetic and static allometry

    OpenAIRE

    Pelabon, Christophe; Bolstad, Geir Hysing; Egset, Camilla Kalvatn; Cheverud, James M.; Pavlicev, Mihaela; Rosenqvist, Gunilla

    2013-01-01

    Ontogenetic and static allometries describe how a character changes in size when the size of the organism changes during ontogeny and among individuals measured at the same developmental stage, respectively. Understanding the relationship between these two types of allometry is crucial to understanding the evolution of allometry and, more generally, the evolution of shape. However, the effects of ontogenetic allometry on static allometry remain largely unexplored. Here, we first show analytic...

  10. An ontogenetic perspective on individual differences.

    Science.gov (United States)

    Senner, Nathan R; Conklin, Jesse R; Piersma, Theunis

    2015-09-07

    Phenotypic differences among individuals can arise during any stage of life. Although several distinct processes underlying individual differences have been defined and studied (e.g. parental effects, senescence), we lack an explicit, unified perspective for understanding how these processes contribute separately and synergistically to observed variation in functional traits. We propose a conceptual framework based on a developmental view of life-history variation, linking each ontogenetic stage with the types of individual differences originating during that period. In our view, the salient differences among these types are encapsulated by three key criteria: timing of onset, when fitness consequences are realized, and potential for reversibility. To fill a critical gap in this framework, we formulate a new term to refer to individual differences generated during adulthood-reversible state effects. We define these as 'reversible changes in a functional trait resulting from life-history trade-offs during adulthood that affect fitness', highlighting how the adult phenotype can be repeatedly altered in response to environmental variation. Defining individual differences in terms of trade-offs allows explicit predictions regarding when and where fitness consequences should be expected. Moreover, viewing individual differences in a developmental context highlights how different processes can work in concert to shape phenotype and fitness, and lays a foundation for research linking individual differences to ecological and evolutionary theory. © 2015 The Author(s).

  11. Stipules in Apocynaceae: an ontogenetic perspective.

    Science.gov (United States)

    do Valle Capelli, Natalie; Alonso Rodrigues, Bruna; Demarco, Diego

    2017-01-01

    Stipules are leaf structures common in many groups of plants that can take a variety of forms. In Gentianales, interpetiolar stipules are considered a synapomorphy of Rubiaceae; however, some reports in the literature refer to their presence in other families. The goal of this study was to analyze the development of leaf primordia to investigate the possible presence of reduced or modified stipules in Apocynaceae. Shoot apices of 12 genera were analyzed under light and scanning electron microscopy comparatively with one species of Rubiaceae. Early in their development, leaf primordia form two lateral expansions at the base of the petiole (stipules) that give rise to colleters in 11 of the 12 genera of Apocynaceae studied, similarly to the Rubiaceae species. The basal genera have pairs of stipules modified into colleters positioned laterally to the petiole, while other species belonging to the derived subfamilies have interpetiolar stipules that each project towards the opposite stipule and merge, forming a sheathing stipule and from this arc the interpetiolar colleters originate. The ontogenetic study proved for the first time that Apocynaceae is a stipulate family whose stipules are modified into colleters and their absence might be a secondary loss, changing the interpretation of stipule evolution in Gentianales.

  12. Ontogenetic development of vestibular reflexes in amphibians

    Directory of Open Access Journals (Sweden)

    Hans Straka

    2016-11-01

    Full Text Available Vestibulo-ocular reflexes ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt vestibulo-ocular reflexes (VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1-8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.

  13. Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae Ontogenetic polychromatism in marsupial frogs (Anura: Hylidae

    Directory of Open Access Journals (Sweden)

    Duellman William E.

    1986-12-01

    Full Text Available Color polymorphism is common in many species of marsupial frogs.  Extreme cases of pattern polymorphism are documented in four species. In Amphignathodon guentheri, Castrotheca aureomaculata, G. qriswoldi, and G. helenae juveniles are known to have only one color morph, where as two or more patterns exist in adults. In these species, polymorphism apparently develops ontogenetically. El polimorfismo cromático es común a algunas especies de sapos marsupiales. Casos extremos del modelo de polimorfismo son evidentes en cuatro especies Amphignathodon guentheri, Gastrotheca aureomaculata, G. griswoldi, y G. helenae. En estas especies, se sabe que los juveniles tienen sólo un morfo de color; el polimorfismo, al parecer, se desarrolla ontogenéticamente.

  14. Ontogenetic pattern change in amphibians: the case of Salamandra corsica

    Directory of Open Access Journals (Sweden)

    Wouter Beukema

    2011-12-01

    Full Text Available Ontogenetic, post-metamorphic pattern development is a rarely studied topic in amphibian science. As there are indications that the pattern of Salamandra corsica might expand over time, digital image analyses were applied in order to measure several phenotypical variables which were related to the snout vent length. Results show a significant increase of patches which change to irregular shapes while SVL increases. Digital image analysis is identified as a suitable tool to explore pattern shape and change in general, while the documented pattern development in S. corsica might be one of the first quantified cases of post-metamorphic ontogenetic pattern change in amphibians.

  15. Feeding habits, ontogenetic dietary shift and some aspects of ...

    African Journals Online (AJOL)

    The diet composition, ontogenetic dietary shifts and reproduction of the tigerfish Hydrocynus forskahlii (Cuvier, 1819) were studied from 386 fish samples (11.2 cm-69.6 cm total length, TL) collected from Lake Chamo from January to August 2005. From the total number of fish samples 231 (59.8%) that contained food in their ...

  16. Sexual dimorphism based on body proportions and ontogenetic ...

    African Journals Online (AJOL)

    Sexual dimorphism in the Brazilian electric ray Narcine brasiliensis from the south-western Atlantic coast was evaluated based on body proportions and ontogenetic changes. All regions of the body were found to have differences in body proportions between the sexes, except the spiracles. The nature of allometric and ...

  17. Ontogenetic food resource partitioning and feeding strategy in ...

    African Journals Online (AJOL)

    Clarotes laticeps is an important commercial food fish of the River Niger. Information on its food niche and feeding strategy could be useful for the rational exploitation and conservation of the species. Ontogenetic diet switch was investigated in samples of C. laticeps caught forthnightly, in the lower River Niger between ...

  18. Functional traits predict ontogenetic growth trajectories among neotropical trees

    NARCIS (Netherlands)

    Hérault, B.; Bachelot, B.; Poorter, L.; Bongers, F.; Chave, J.; Paine, C.E.T.; Rossi, V.; Baraloto, C.

    2011-01-01

    1. Functional traits are posited to explain interspecific differences in performance, but these relationships are difficult to describe for long-lived organisms such as trees, which exhibit strong ontogenetic changes in demographic rates. Here, we use a size-dependent model of tree growth to test

  19. Stochastic ontogenetic allometry: the statistical dynamics of relative growth.

    Science.gov (United States)

    Papadopoulos, Anthony

    2011-01-01

    In the absence of stochasticity, allometric growth throughout ontogeny is axiomatically described by the logarithm-transformed power-law model, θt = log(a) b + kφ(t), where θt ≡ θ(t) and φt ≡ φ(t) are the logarithmic sizes of two traits at any given time t. Realistically, however, stochasticity is an inherent property of ontogenetic allometry. Due to the inherent stochasticity in both θt and φt, the ontogenetic allometry coefficients, log(a) b and k, can vary with t and have intricate temporal distributions that are governed by the central and mixed moments of the random ontogenetic growth functions, θt and φt. Unfortunately, there is no probabilistic model for analyzing these informative ontogenetic statistical moments. This study treats θt and φt as correlated stochastic processes to formulate the exact probabilistic version of each of the ontogenetic allometry coefficients. In particular, the statistical dynamics of relative growth is addressed by analyzing the allometric growth factors that affect the temporal distribution of the probabilistic version of the relative growth rate, k ≡ Dt(u)/Dt(v), where is the expected value of the ratio of stochastic θt to stochastic φt, and u and v are the numerator and the denominator of , respectively. These allometric growth factors, which provide important insight into ontogenetic allometry but appear only when stochasticity is introduced, describe the central and mixed moments of θt and φt as differentiable real-valued functions of t. Failure to account for the inherent stochasticity in both θt and φt leads not only to the miscalculation of k, but also to the omission of all of the informative ontogenetic statistical moments that affect the size of traits and the timing and rate of development of traits. Furthermore, even though the stochastic process θt and the stochastic process φt are linearly related, k can vary with t.

  20. Ontogenetic study of allometric variation in Homo and Pan mandibles.

    Science.gov (United States)

    Singh, Nandini

    2014-02-01

    Investigating ontogenetic variation and allometry in the mandible can provide valuable insight and aid in addressing questions related to the ontogeny of the skull. Here, patterns of ontogenetic shape change and allometric trajectories were examined in the mandible of 187 sub-adult and adult humans, bonobos, and chimpanzees. Procrustes-based geometric morphometrics was employed to quantify and analyze mandibular form. Thirty three-dimensional landmarks were used to capture the overall morphology of the mandible, and the landmarks were analyzed as a whole and subdivided into separate anterior and posterior units. Principal component analyses in Procrustes shape-space and form-space, and multivariate regressions were used to examine patterns of ontogenetic and allometric shape change. Results suggest that humans are distinct from Pan both in their mandibular morphology, particularly in the anterior-alveolar region, and direction of allometric trajectory. Chimpanzees and bonobos have parallel ontogenetic trajectories, but also show differences in mandibular shape. Species-specific features and adult mandibular shape are established before or by the eruption of the deciduous dentition. This suggests that developmental processes prior to deciduous teeth eruption have a stronger effect establishing taxa-specific phenotypes than later postnatal effects. This additionally implies that divergent trajectories between Pan and Homo do not contribute much to the adult mandibular shape after deciduous teeth eruption. Separate analyses of the anterior-alveolar region and ascending ramus show that these regions are semi-independent in their developmental pattern of shape change and allometry. This implies that allometric variation and ontogenetic shape change in the hominoid mandible is decoupled. Copyright © 2013 Wiley Periodicals, Inc.

  1. Ontogenetic patterns in the dreams of women across the lifespan.

    Science.gov (United States)

    Dale, Allyson; Lortie-Lussier, Monique; De Koninck, Joseph

    2015-12-01

    The present study supports and extends previous research on the developmental differences in women's dreams across the lifespan. The participants included 75 Canadian women in each of 5 age groups from adolescence to old age including 12-17, 18-24, 25-39, 40-64, and 65-85, totaling 375 women. One dream per participant was scored by two independent judges using the method of content analysis. Trend analysis was used to determine the ontogenetic pattern of the dream content categories. Results demonstrated significant ontogenetic decreases (linear trends) for female and familiar characters, activities, aggression, and friendliness. These patterns of dream imagery reflect the waking developmental patterns as proposed by social theories and recognized features of aging as postulated by the continuity hypothesis. Limitations and suggestions for future research including the examining of developmental patterns in the dreams of males are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Media Bias

    OpenAIRE

    Sendhil Mullainathan; Andrei Shleifer

    2002-01-01

    There are two different types of media bias. One bias, which we refer to as ideology, reflects a news outlet's desire to affect reader opinions in a particular direction. The second bias, which we refer to as spin, reflects the outlet's attempt to simply create a memorable story. We examine competition among media outlets in the presence of these biases. Whereas competition can eliminate the effect of ideological bias, it actually exaggerates the incentive to spin stories.

  3. Energy allocation between brain and body during ontogenetic development.

    Science.gov (United States)

    Kubera, Britta; Bosy-Westphal, Anja; Peters, Achim; Braun, Wiebke; Langemann, Dirk; Neugebohren, Stephanie; Heller, Martin; Müller, Manfred James

    2013-01-01

    We here studied how energy is allocated between brain and body both during the ontogenetic development from a child to an adult and during weight loss. We investigated 180 normal weight female and male children and adolescents (aged 6.1-19.9 years) as well as 35 overweight adolescents undergoing weight reduction intervention. 52 normal weight and 42 obese adult women were used for comparison. We assessed brain mass by magnetic-resonance-imaging and body metabolism by indirect calorimetry. To study how energy is allocated between brain and body, we measured plasma insulin, since insulin fulfils the functions of a glucose allocating hormone, i.e., peripheral glucose uptake depends on insulin, central uptake does not. We used reference data obtained in the field of comparative biology. In a brain-body-plot, we calculated the distance between each subject and a reference mammal of comparable size and named the distance "encephalic measure." With higher encephalic measures, more energy is allocated to the brain. We found that ontogenetic development from a child to an adult was indicated by decreasing encephalic measures in females (r = -0.729, P brain increased with weight loss, but decreased during the ontogenetic development from childhood to adolescence. These developmental changes in brain-to-body energy allocation appear to be driven by increasing plasma insulin concentrations. Copyright © 2013 Wiley Periodicals, Inc.

  4. Different ontogenetic processes promote dicliny in Ficus L. (Moraceae)

    Science.gov (United States)

    Basso-Alves, João Paulo; Pereira, Rodrigo Augusto Santinelo; Peng, Yang-Qiong; Teixeira, Simone Pádua

    2014-05-01

    The absence of reproductive organs in flowers may ontogenetically arise from inception or by abortion during development. Ficus L., a species-rich genus of angiosperms, is an interesting model for floral developmental studies because of the diversity of sexual systems it contains. This study compares the floral morphology of Ficus citrifolia (monoecious), Ficus religiosa (monoecious), Ficus racemosa (secondarily monoecious), and Ficus hispida (gynodioecious) across development to establish the ontogenetic pathways that result in diclinous flowers. Figs were collected at various developmental stages and were prepared for surface (scanning electron microscopy) and histological (light microscopy) analyses. Dicliny in Ficus is defined by stamen absence from inception in pistillate flowers and either pistil absence from inception (F. citrifolia, F. racemosa and F. religiosa) or by abortion (F. hispida) in staminate flowers. The perianth is formed by a single whorl of sepals, as found in other families related to Moraceae. The gynoecium is tubular during development, a condition that may be related with pseudomonomery. The staminate and neutral flowers in F. hispida develop by similar mechanisms. The diversity in the sexual systems in Ficus results from combinations of different floral morphs (dicliny), which originate from both previously established ontogenetic mechanisms (loss of reproductive organ function by abortion or from inception). These mechanisms act independently of phylogenetic proximity or mechanisms of sex system evolution in Ficus. Other aspects of floral development observed in Ficus are discussed in relation to their systematic position and reproductive biology.

  5. Ontogenetic stage, plant vigor and sex mediate herbivory loads in a dioecious understory herb

    Science.gov (United States)

    Selaković, Sara; Vujić, Vukica; Stanisavljević, Nemanja; Jovanović, Živko; Radović, Svetlana; Cvetković, Dragana

    2017-11-01

    Plant-herbivore interactions can be mediated by plant apparency, defensive and nutritional quality traits that change through plant ontogeny, resulting in age-specific herbivory. In dioecious species, opposing allocation patterns in defense may lead to sex-biased herbivory. Here, we examine how onto stage and plant sex determine levels of herbivore damage in understory herb Mercurialis perennis under field conditions. We analyzed variation in plant size (height, total leaf area), physical (specific leaf area) and chemical (total phenolic and condensed tannins contents) defense, and nutritional quality (total water, soluble protein and nonstructural carbohydrate contents) during the shift from reproductive to post-reproductive stage. Furthermore, we explored correlations between the analyzed traits and levels of foliar damage. Post-reproductive plants had lower levels of chemical defense, and larger leaf area removed, in spite of having lower nutritive quality. Opposing patterns of intersexual differences were detected in protein and phenolic contents during reproductive stage, while in post-reproductive stage total leaf area was sexually dimorphic. Female-biased herbivory was apparent only after reproduction. Plant size parameters combined with condensed tannins content determined levels of foliar damage during post-reproductive stage, while the only trait covarying with herbivory in reproductive stage was total nonstructural carbohydrate content. Our results support claims of optimal defense theory - sensitive stage of reproduction was better defended. We conclude that different combinations of plant traits mediated interactions with herbivores in mature stages. Differences in reproductive allocation between the sexes may not immediately translate into different levels of damage, stressing the need for considering different ontogenetic stages when exploring sex bias in herbivory.

  6. Intergroup bias.

    Science.gov (United States)

    Hewstone, Miles; Rubin, Mark; Willis, Hazel

    2002-01-01

    This chapter reviews the extensive literature on bias in favor of in-groups at the expense of out-groups. We focus on five issues and identify areas for future research: (a) measurement and conceptual issues (especially in-group favoritism vs. out-group derogation, and explicit vs. implicit measures of bias); (b) modern theories of bias highlighting motivational explanations (social identity, optimal distinctiveness, uncertainty reduction, social dominance, terror management); (c) key moderators of bias, especially those that exacerbate bias (identification, group size, status and power, threat, positive-negative asymmetry, personality and individual differences); (d) reduction of bias (individual vs. intergroup approaches, especially models of social categorization); and (e) the link between intergroup bias and more corrosive forms of social hostility.

  7. Ontogenetic Shape Change in the Chicken Brain: Implications for Paleontology.

    Science.gov (United States)

    Kawabe, Soichiro; Matsuda, Seiji; Tsunekawa, Naoki; Endo, Hideki

    2015-01-01

    Paleontologists have investigated brain morphology of extinct birds with little information on post-hatching changes in avian brain morphology. Without the knowledge of ontogenesis, assessing brain morphology in fossil taxa could lead to misinterpretation of the phylogeny or neurosensory development of extinct species. Hence, it is imperative to determine how avian brain morphology changes during post-hatching growth. In this study, chicken brain shape was compared at various developmental stages using three-dimensional (3D) geometric morphometric analysis and the growth rate of brain regions was evaluated to explore post-hatching morphological changes. Microscopic MRI (μMRI) was used to acquire in vivo data from living and post-mortem chicken brains. The telencephalon rotates caudoventrally during growth. This change in shape leads to a relative caudodorsal rotation of the cerebellum and myelencephalon. In addition, all brain regions elongate rostrocaudally and this leads to a more slender brain shape. The growth rates of each brain region were constant and the slopes from the growth formula were parallel. The dominant pattern of ontogenetic shape change corresponded with interspecific shape changes due to increasing brain size. That is, the interspecific and ontogenetic changes in brain shape due to increased size have similar patterns. Although the shape of the brain and each brain region changed considerably, the volume ratio of each brain region did not change. This suggests that the brain can change its shape after completing functional differentiation of the brain regions. Moreover, these results show that consideration of ontogenetic changes in brain shape is necessary for an accurate assessment of brain morphology in paleontological studies.

  8. Ontogenetic Shape Change in the Chicken Brain: Implications for Paleontology.

    Directory of Open Access Journals (Sweden)

    Soichiro Kawabe

    Full Text Available Paleontologists have investigated brain morphology of extinct birds with little information on post-hatching changes in avian brain morphology. Without the knowledge of ontogenesis, assessing brain morphology in fossil taxa could lead to misinterpretation of the phylogeny or neurosensory development of extinct species. Hence, it is imperative to determine how avian brain morphology changes during post-hatching growth. In this study, chicken brain shape was compared at various developmental stages using three-dimensional (3D geometric morphometric analysis and the growth rate of brain regions was evaluated to explore post-hatching morphological changes. Microscopic MRI (μMRI was used to acquire in vivo data from living and post-mortem chicken brains. The telencephalon rotates caudoventrally during growth. This change in shape leads to a relative caudodorsal rotation of the cerebellum and myelencephalon. In addition, all brain regions elongate rostrocaudally and this leads to a more slender brain shape. The growth rates of each brain region were constant and the slopes from the growth formula were parallel. The dominant pattern of ontogenetic shape change corresponded with interspecific shape changes due to increasing brain size. That is, the interspecific and ontogenetic changes in brain shape due to increased size have similar patterns. Although the shape of the brain and each brain region changed considerably, the volume ratio of each brain region did not change. This suggests that the brain can change its shape after completing functional differentiation of the brain regions. Moreover, these results show that consideration of ontogenetic changes in brain shape is necessary for an accurate assessment of brain morphology in paleontological studies.

  9. Ontogenetic relationships between cranium and mandible in coyotes and hyenas.

    Science.gov (United States)

    La Croix, Suzanne; Holekamp, Kay E; Shivik, John A; Lundrigan, Barbara L; Zelditch, Miriam Leah

    2011-06-01

    Developing animals must resolve the conflicting demands of survival and growth, ensuring that they can function as infants or juveniles while developing toward their adult form. In the case of the mammalian skull, the cranium and mandible must maintain functional integrity to meet the feeding needs of a juvenile even as the relationship between parts must change to meet the demands imposed on adults. We examine growth and development of the cranium and mandible, using a unique ontogenetic series of known-age coyotes (Canis latrans), analyzing ontogenetic changes in the shapes of each part, and the relationship between them, relative to key life-history events. Both cranial and mandibular development conform to general mammalian patterns, but each also exhibits temporally and spatially localized maturational transformations, yielding a complex relationship between growth and development of each part as well as complex patterns of synchronous growth and asynchronous development between parts. One major difference between cranium and mandible is that the cranium changes dramatically in both size and shape over ontogeny, whereas the mandible undergoes only modest shape change. Cranium and mandible are synchronous in growth, reaching adult size at the same life-history stage; growth and development are synchronous for the cranium but not for the mandible. This synchrony of growth between cranium and mandible, and asynchrony of mandibular development, is also characteristic of a highly specialized carnivore, the spotted hyena (Crocuta crocuta), but coyotes have a much less protracted development, being handicapped relative to adults for a much shorter time. Morphological development does not predict life-history events in these two carnivores, which is contrary to what has been reported for two rodent species. The changes seen in skull shape in successive life-history stages suggest that adult functional demands cannot be satisfied by the morphology characterizing

  10. Comparative vs ontogenetic paradigms for tests of the intrinsic mutagenesis hypothesis of aging

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, G.A.

    1979-01-01

    This paper examines certain aspects of the biology of longevity and aging that bear on the role of DNA in the ontogenetic aging process, and on the genetic basis for the differences of longevity among mammal species. (PCS)

  11. Estimating the Ontogenetic Status of an Enantiornithine Bird from the Lower Barremian of El Montsec, Central Pyrenees, Spain

    Directory of Open Access Journals (Sweden)

    Buscalioni, A. D.

    2006-12-01

    Full Text Available An Enantiornithes specimen from El Montsec was initially described as an immature individual based upon qualitative traits such as its relatively large orbit and overall proportions of the skull and the postcranium. In this study we re-evaluate the precise determination of the ontogenetic stage of this individual, establishing a cross-talk among taphonomic, anatomic, and morphometric data. The exceptional preservation of the specimen has allowed pondering ontogenetic influence versus preservational bias in features like the external patterns of bone surfaces, instead of being aprioristically considered due to taphonomic alterations only. The rough texture of the periosteal bone associated with pores in the distal, proximal and mid-shaft areas of the humeral shaft, indicates a subadult stage when compared with long bones of modern birds. Forelimb proportions of embryo and juvenile Enanthiornithes are equivalent to those of adult individuals of other taxa within this clade, though this is not a reliable criterion for establishing a precise ontogenetic stage. The El Montsec specimen may be attributed a close adulthood, yet only if growth regimes in Enantiornithes are considered equivalent to those in Neornithes birds.Un ejemplar de Enantiornithes del Montsec fue inicialmente descrito como un individuo inmaduro sobre la base de caracteres cualitativos tales como su órbita relativamente grande y sus proporciones generales en cuerpo y cráneo. En este estudio se realiza una reevaluación del estado ontogenético preciso de este individuo, estableciendo una argumentación cruzada con datos tafonómicos, anatómicos y morfométricos. La preservación excepcional de este ejemplar ha permitido ponderar la influencia ontogenética versus el sesgo tafonómico en caracteres como los patrones externos de las superficies óseas, en lugar de considerarlos apriorísticamente como debidos únicamente a alteraciones tafonómicas. La textura rugosa del periostio

  12. Factors influencing recruitment of walleye and white bass to three distinct early ontogenetic stages

    Science.gov (United States)

    DeBoer, Jason A.; Pope, Kevin L.

    2015-01-01

    Determining the factors that influence recruitment to sequential ontogenetic stages is critical for understanding recruitment dynamics of fish and for effective management of sportfish, particularly in dynamic and unpredictable environments. We sampled walleye (Sander vitreus) and white bass (Morone chrysops) at 3 ontogenetic stages (age 0 during spring: ‘age-0 larval’; age 0 during autumn: ‘age-0 juvenile’; and age 1 during autumn: ‘age-1 juvenile’) from 3 reservoirs. We developed multiple linear regression models to describe factors influencing age-0 larval, age-0 juvenile and age-1 juvenile walleye and white bass abundance indices. Our models explained 40–80% (68 ± 9%; mean ± SE) and 71%–97% (81 ± 6%) of the variability in catch for walleye and white bass respectively. For walleye, gizzard shad were present in the candidate model sets for all three ontogenetic stages we assessed. For white bass, there was no unifying variable in all three stage-specific candidate model sets, although walleye abundance was present in two of the three white bass candidate model sets. We were able to determine several factors affecting walleye and white bass year-class strength at multiple ontogenetic stages; comprehensive analyses of factors influencing recruitment to multiple early ontogenetic stages are seemingly rare in the literature. Our models demonstrate the interdependency among early ontogenetic stages and the complexities involved with sportfish recruitment.

  13. The evolution of floral ontogenetic allometry in the Andean genus Caiophora (Loasaceae, subfam. Loasoideae).

    Science.gov (United States)

    Strelin, Marina Micaela; Benitez-Vieyra, Santiago; Fornoni, Juan; Klingenberg, Christian Peter; Cocucci, Andrea

    2018-01-01

    The astounding variety of angiosperm flower morphologies has evolved in response to many selective forces. Flower development is highly coordinated and involves developmental associations between size and shape, ontogenetic allometry, which in turn affect the morphology of mature flowers. Although ontogenetic allometries can act as a developmental constraint and may influence adaptive evolution, allometries can evolve themselves and may change rapidly in response to selection. We explored the evolution of ontogenetic allometry in the flowers of 11 species of Loasoideae. Seven species belong to Caiophora, which radiated recently in the central Andes, and contains species that are pollinated by bees, hummingbirds, and small rodents. According to a previous study, the diversification of Caiophora involved departures from simple allometric scaling, but the changes to allometry that enabled flower diversification have not been explored yet. We characterized the ontogenetic allometry of each species with the methods of geometric morphometrics. We studied the evolution of allometries by constructing allometric spaces, in which the allometry of each species is represented by a point and the arrangement of points indicates the relations among allometric trajectories. To examine the history of changes of ontogenetic allometries, we projected the phylogeny into the allometric spaces. Inspection of allometric spaces suggests that ontogenetic variation is limited to a few dominant features. The allometries of the two main functional flower parts under study differ in their evolutionary labilities, and patterns of variation reflect pollination systems, differences in structural organization, and abiotic environmental factors. © 2017 Wiley Periodicals, Inc.

  14. Digestive enzymatic activity during ontogenetic development in zebrafish (Danio rerio).

    Science.gov (United States)

    Guerrera, Maria Cristina; De Pasquale, Francesca; Muglia, Ugo; Caruso, Gabriella

    2015-12-01

    Despite the growing importance of zebrafish (Danio rerio) as an experimental model in biomedical research, some aspect of physiological and related morphological age dependent changes in digestive system during larval development are still unknown. In this paper, a biochemical and morphological study of the digestive tract of zebrafish was undertaken to record the functional changes occurring in this species during its ontogenetic development, particularly from 24 hr to 47 days post fertilization (dpf). Endo- and exo-proteases, as well as α-amylase enzymes, were quantified in zebrafish larvae before first feeding (7 dpf). The most morphologically significant events during the ontogenesis of the gut occurred between 3 dpf (mouth opening) and 7 dpf (end of exocrine pancreas differentiation). The presence of a wide range of digestive enzymes, already active at earlier zebrafish larval stages, closely related with the omnivorous diet of this species. Increasing enzyme activities were found with increasing age, probably in relation with intestinal mucosa folding and consequent absorption surface increase. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 699-706, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  15. Plasticity during Early Brain Development Is Determined by Ontogenetic Potential.

    Science.gov (United States)

    Krägeloh-Mann, Ingeborg; Lidzba, Karen; Pavlova, Marina A; Wilke, Marko; Staudt, Martin

    2017-04-01

    Two competing hypotheses address neuroplasticity during early brain development: the "Kennard principle" describes the compensatory capacities of the immature developing CNS as superior to those of the adult brain, whereas the "Hebb principle" argues that the young brain is especially sensitive to insults. We provide evidence that these principles are not mutually exclusive. Following early brain lesions that are unilateral, the brain can refer to homotopic areas of the healthy hemisphere. This potential for reorganization is unique to the young brain but available only when, during ontogenesis of brain development, these areas have been used for the functions addressed. With respect to motor function, ipsilateral motor tracts can be recruited, which are only available during early brain development. Language can be reorganized to the right after early left hemispheric lesions, as the representation of the language network is initially bilateral. However, even in these situations, compensatory capacities of the developing brain are found to have limitations, probably defined by early determinants. Thus, plasticity and adaptivity are seen only within ontogenetic potential; that is, axonal or cortical structures cannot be recruited beyond early developmental possibilities. The young brain is probably more sensitive and vulnerable to lesions when these are bilateral. This is shown here for bilateral periventricular white matter lesions that clearly have an impact on cortical architecture and function, thus probably interfering with early network building. Georg Thieme Verlag KG Stuttgart · New York.

  16. Ontogenetic regulation of leukocyte recruitment in mouse yolk sac vessels.

    Science.gov (United States)

    Sperandio, Markus; Quackenbush, Elizabeth J; Sushkova, Natalia; Altstätter, Johannes; Nussbaum, Claudia; Schmid, Stephan; Pruenster, Monika; Kurz, Angela; Margraf, Andreas; Steppner, Alina; Schweiger, Natalie; Borsig, Lubor; Boros, Ildiko; Krajewski, Nele; Genzel-Boroviczeny, Orsolya; Jeschke, Udo; Frommhold, David; von Andrian, Ulrich H

    2013-05-23

    In adult mammals, leukocyte recruitment follows a well-defined cascade of adhesion events enabling leukocytes to leave the circulatory system and transmigrate into tissue. Currently, it is unclear whether leukocyte recruitment proceeds in a similar fashion during fetal development. Considering the fact that the incidence of neonatal sepsis increases dramatically with decreasing gestational age in humans, we hypothesized that leukocyte recruitment may be acquired only late during fetal ontogeny. To test this, we developed a fetal intravital microscopy model in pregnant mice and, using LysEGFP (neutrophil reporter) mice, investigated leukocyte recruitment during fetal development. We show that fetal blood neutrophils acquire the ability to roll and adhere on inflamed yolk sac vessels during late fetal development, whereas at earlier embryonic stages (before day E15), rolling and adhesion were essentially absent. Accordingly, flow chamber experiments showed that fetal EGFP(+) blood cells underwent efficient adhesion only when they were harvested on or after E15. Fluorescence-activated cell sorter analysis on EGFP(+) fetal blood cells revealed that surface expression of CXCR2 and less pronounced P-selectin glycoprotein ligand-1 (PSGL-1) begin to increase only late in fetal life. Taken together, our findings demonstrate that inflammation-induced leukocyte recruitment is ontogenetically regulated and enables efficient neutrophil trafficking only during late fetal life.

  17. Ontogenetic trajectories of chimpanzee social play: similarities with humans.

    Directory of Open Access Journals (Sweden)

    Giada Cordoni

    Full Text Available Social play, a widespread phenomenon in mammals, is a multifunctional behavior, which can have many different roles according to species, sex, age, relationship quality between playmates, group membership, context, and habitat. Play joins and cuts across a variety of disciplines leading directly to inquiries relating to individual developmental changes and species adaptation, thus the importance of comparative studies appears evident. Here, we aim at proposing a possible ontogenetic pathway of chimpanzee play (Pan troglodytes and contrast our data with those of human play. Chimpanzee play shows a number of changes from infancy to juvenility. Particularly, solitary and social play follows different developmental trajectories. While solitary play peaks in infancy, social play does not show any quantitative variation between infancy and juvenility but shows a strong qualitative variation in complexity, asymmetry, and playmate choice. Like laughter in humans, the playful expressions in chimpanzees (at the different age phases seem to have a role in advertising cooperative dispositions and intentions thus increasing the likelihood of engaging in solid social relationships. In conclusion, in chimpanzees, as in humans, both play behavior and the signals that accompany play serve multiple functions according to the different age phases.

  18. Home Bias

    OpenAIRE

    田端, 克至; タバタ, カツシ; Katsushi, TABATA

    2002-01-01

    This article discussed on, what we call, the home bias puzzle and international equity investment transactions, in which international security has less been invested in foreign countries After 1989, US and German foreign capital outflow have drastically increased, however. It is the background why this article focuses on these maters. Some changes might be happen in the international financial market. These developments in the world have important implications for us.

  19. Referee Bias

    OpenAIRE

    Dohmen, Thomas; Sauermann, Jan

    2015-01-01

    This paper surveys the empirical literature on the behavior of referees in professional football and other sports. Referees are typically appointed by a principal to be impartial, especially when unbiased referee judgment is vital for the accomplishment of the principal's objective. Answering whether referees make biased decisions and understanding the causes that lead referees to digress from their principal duty of impartiality is therefore fundamental from a theoretical point of view. At t...

  20. Ontogenetic Development of Vestibulo-Ocular Reflexes in Amphibians.

    Science.gov (United States)

    Branoner, Francisco; Chagnaud, Boris P; Straka, Hans

    2016-01-01

    Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters. Moreover, semicircular canal functionality is also required to tune the initially omnidirectional otolith-derived VOR. The tuning is due to a reinforcement of those vestibulo-ocular connections that are co-activated by semicircular canal and otolith inputs during natural head/body motion. This suggests that molecular mechanisms initially guide the basic ontogenetic wiring, whereas semicircular canal-dependent activity is required to establish the spatio-temporal specificity of the reflex. While a robust VOR is activated during passive head/body movements, locomotor efference copies provide the major source for compensatory eye movements during tail- and limb-based swimming of larval and adult frogs. The integration of active/passive motion-related signals for gaze stabilization occurs in central vestibular neurons that are arranged as segmentally iterated functional groups along rhombomere 1-8. However, at variance with the topographic maps of most other sensory systems, the sensory-motor transformation of motion-related signals occurs in segmentally specific neuronal groups defined by the extraocular motor output targets.

  1. Detecting spatial ontogenetic niche shifts in complex dendritic ecological networks

    Science.gov (United States)

    Fields, William R.; Grant, Evan H. Campbell; Lowe, Winsor H.

    2017-01-01

    Ontogenetic niche shifts (ONS) are important drivers of population and community dynamics, but they can be difficult to identify for species with prolonged larval or juvenile stages, or for species that inhabit continuous habitats. Most studies of ONS focus on single transitions among discrete habitat patches at local scales. However, for species with long larval or juvenile periods, affinity for particular locations within connected habitat networks may differ among cohorts. The resulting spatial patterns of distribution can result from a combination of landscape-scale habitat structure, position of a habitat patch within a network, and local habitat characteristics—all of which may interact and change as individuals grow. We estimated such spatial ONS for spring salamanders (Gyrinophilus porphyriticus), which have a larval period that can last 4 years or more. Using mixture models to identify larval cohorts from size frequency data, we fit occupancy models for each age class using two measures of the branching structure of stream networks and three measures of stream network position. Larval salamander cohorts showed different preferences for the position of a site within the stream network, and the strength of these responses depended on the basin-wide spatial structure of the stream network. The isolation of a site had a stronger effect on occupancy in watersheds with more isolated headwater streams, while the catchment area, which is associated with gradients in stream habitat, had a stronger effect on occupancy in watersheds with more paired headwater streams. Our results show that considering the spatial structure of habitat networks can provide new insights on ONS in long-lived species.

  2. Fundamental insights into ontogenetic growth from theory and fish.

    Science.gov (United States)

    Sibly, Richard M; Baker, Joanna; Grady, John M; Luna, Susan M; Kodric-Brown, Astrid; Venditti, Chris; Brown, James H

    2015-11-10

    The fundamental features of growth may be universal, because growth trajectories of most animals are very similar, but a unified mechanistic theory of growth remains elusive. Still needed is a synthetic explanation for how and why growth rates vary as body size changes, both within individuals over their ontogeny and between populations and species over their evolution. Here, we use Bertalanffy growth equations to characterize growth of ray-finned fishes in terms of two parameters, the growth rate coefficient, K, and final body mass, m∞. We derive two alternative empirically testable hypotheses and test them by analyzing data from FishBase. Across 576 species, which vary in size at maturity by almost nine orders of magnitude, K scaled as [Formula: see text]. This supports our first hypothesis that growth rate scales as [Formula: see text] as predicted by metabolic scaling theory; it implies that species that grow to larger mature sizes grow faster as juveniles. Within fish species, however, K scaled as [Formula: see text]. This supports our second hypothesis, which predicts that growth rate scales as [Formula: see text] when all juveniles grow at the same rate. The unexpected disparity between across- and within-species scaling challenges existing theoretical interpretations. We suggest that the similar ontogenetic programs of closely related populations constrain growth to [Formula: see text] scaling, but as species diverge over evolutionary time they evolve the near-optimal [Formula: see text] scaling predicted by metabolic scaling theory. Our findings have important practical implications because fish supply essential protein in human diets, and sustainable yields from wild harvests and aquaculture depend on growth rates.

  3. Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates

    DEFF Research Database (Denmark)

    Glazier, Douglas S.; Hirst, Andrew G.; Atkinson, D.

    2016-01-01

    in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR

  4. Environmental and ontogenetic effects on intraspecific trait variation of a macrophyte species across five ecological scales.

    Directory of Open Access Journals (Sweden)

    Hui Fu

    Full Text Available Although functional trait variability is increasingly used in community ecology, the scale- and size-dependent aspects of trait variation are usually disregarded. Here we quantified the spatial structure of shoot height, branch length, root/shoot ratio and leaf number in a macrophyte species Potamogeton maackianus, and then disentangled the environmental and ontogenetic effects on these traits. Using a hierarchical nested design, we measured the four traits from 681 individuals across five ecological scales: lake, transect, depth stratus, quadrat and individual. A notable high trait variation (coefficient variation: 48-112% was observed within species. These traits differed in the spatial structure, depending on environmental factors of different scales. Shoot height and branch length were most responsive to lake, transect and depth stratus scales, while root/shoot ratio and leaf number to quadrat and individual scales. The trait variations caused by environment are nearly three times higher than that caused by ontogeny, with ontogenetic variance ranging from 21% (leaf number to 33% (branch length of total variance. Remarkably, these traits showed non-negligible ontogenetic variation (0-60% in each ecological scale, and significant shifts in allometric trajectories at lake and depth stratus scales. Our results highlight that environmental filtering processes can sort individuals within species with traits values adaptive to environmental changes and ontogenetic variation of functional traits was non-negligible across the five ecological scales.

  5. Incorporating an ontogenetic perspective into evolutionary theory of sexual size dimorphism.

    Science.gov (United States)

    Chou, Chun-Chia; Iwasa, Yoh; Nakazawa, Takefumi

    2016-02-01

    Sexual size dimorphism (SSD) describes divergent body sizes of adult males and females. While SSD has traditionally been explained by sexual and fecundity selection, recent advances in physiology and developmental biology emphasize that SSD would occur proximately because of sexual differences in ontogenetic growth trajectories (i.e., growth rate and duration). Notably, these ontogenetic traits are subject to energetic or time constraints and thus traded off with fitness components (e.g., survival and reproduction). To elucidate the importance of such ontogenetic trade-offs in the evolution of SSD, we developed a new theoretical framework by extending quantitative genetic models for the evolution of sexual dimorphism in which we reinterpret the trait as body size and reformulate sex-specific fitness in size-dependent manners. More specifically, we assume that higher growth rate or longer growth duration leads to larger body size and higher reproductive success but incurs the cost of lower survivorship or shorter reproduction period. We illustrate how two sexes would optimize ontogenetic growth trajectories in sex-specific ways and exhibit divergent body sizes. The present framework provides new insights into the evolutionary theory of SSD and predictions for empirical testing. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  6. A Parent-Offspring Trade-Off Limits the Evolution of an Ontogenetic Niche Shift

    NARCIS (Netherlands)

    ten Brink, H.; de Roos, A.M.

    2017-01-01

    Many free-living animal species, including the majority of fish, insects, and amphibians, change their food and habitat during their life. Even though these ontogenetic changes in niche are common, it is not well understood which ecological conditions have favored the evolution of these shifts.

  7. Population divergence in the ontogenetic trajectories of foliar terpenes of a Eucalyptus species.

    Science.gov (United States)

    Borzak, Christina L; Potts, Brad M; Davies, Noel W; O'Reilly-Wapstra, Julianne M

    2015-01-01

    The development of plant secondary metabolites during early life stages can have significant ecological and evolutionary implications for plant-herbivore interactions. Foliar terpenes influence a broad range of ecological interactions, including plant defence, and their expression may be influenced by ontogenetic and genetic factors. This study investigates the role of these factors in the expression of foliar terpene compounds in Eucalyptus globulus seedlings. Seedlings were sourced from ten families each from three genetically distinct populations, representing relatively high and low chemical resistance to mammalian herbivory. Cotyledon-stage seedlings and consecutive leaf pairs of true leaves were harvested separately across an 8-month period, and analysed for eight monoterpene compounds and six sesquiterpene compounds. Foliar terpenes showed a series of dynamic changes with ontogenetic trajectories differing between populations and families, as well as between and within the two major terpene classes. Sesquiterpenes changed rapidly through ontogeny and expressed opposing trajectories between compounds, but showed consistency in pattern between populations. Conversely, changed expression in monoterpene trajectories was population- and compound-specific. The results suggest that adaptive opportunities exist for changing levels of terpene content through ontogeny, and evolution may exploit the ontogenetic patterns of change in these compounds to create a diverse ontogenetic chemical mosaic with which to defend the plant. It is hypothesized that the observed genetically based patterns in terpene ontogenetic trajectories reflect multiple changes in the regulation of genes throughout different terpene biosynthetic pathways. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Heritability of hsp70 expression in the beetle Tenebrio molitor: Ontogenetic and environmental effects.

    Science.gov (United States)

    Lardies, Marco A; Arias, María Belén; Poupin, María Josefina; Bacigalupe, Leonardo D

    2014-08-01

    Ectotherms constitute the vast majority of terrestrial biodiversity and are especially likely to be vulnerable to climate warming because their basic physiological functions such as locomotion, growth, and reproduction are strongly influenced by environmental temperature. An integrated view about the effects of global warming will be reached not just establishing how the increase in mean temperature impacts the natural populations but also establishing the effects of the increase in temperature variance. One of the molecular responses that are activated in a cell under a temperature stress is the heat shock protein response (HSP). Some studies that have detected consistent differences among thermal treatments and ontogenetic stages in HSP70 expression have assumed that these differences had a genetic basis and consequently expression would be heritable. We tested for changes in quantitative genetic parameters of HSP70 expression in a half-sib design where individuals of the beetle Tenebrio molitor were maintained in constant and varying thermal environments. We estimated heritability of HSP70 expression using a linear mixed modelling approach in different ontogenetic stages. Expression levels of HSP70 were consistently higher in the variable environment and heritability estimates were low to moderate. The results imply that within each ontogenetic stage additive genetic variance was higher in the variable environment and in adults compared with constant environment and larvae stage, respectively. We found that almost all the genetic correlations across ontogenetic stages and environment were positive. These suggest that directional selection for higher levels of expression in one environment will result in higher expression levels of HSP70 on the other environment for the same ontogenetic stage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Hormonally Mediated Increases in Sex-Biased Gene Expression Accompany the Breakdown of Between-Sex Genetic Correlations in a Sexually Dimorphic Lizard.

    Science.gov (United States)

    Cox, Robert M; Cox, Christian L; McGlothlin, Joel W; Card, Daren C; Andrew, Audra L; Castoe, Todd A

    2017-03-01

    The evolution of sexual dimorphism is predicted to occur through reductions in between-sex genetic correlations (rmf) for shared traits, but the physiological and genetic mechanisms that facilitate these reductions remain largely speculative. Here, we use a paternal half-sibling breeding design in captive brown anole lizards (Anolis sagrei) to show that the development of sexual size dimorphism is mirrored by the ontogenetic breakdown of rmf for body size and growth rate. Using transcriptome data from the liver (which integrates growth and metabolism), we show that sex-biased gene expression also increases dramatically between ontogenetic stages bracketing this breakdown of rmf. Ontogenetic increases in sex-biased expression are particularly evident for genes involved in growth, metabolism, and cell proliferation, suggesting that they contribute to both the development of sexual dimorphism and the breakdown of rmf. Mechanistically, we show that treatment of females with testosterone stimulates the expression of male-biased genes while inhibiting the expression of female-biased genes, thereby inducing male-like phenotypes at both organismal and transcriptomic levels. Collectively, our results suggest that sex-specific modifiers such as testosterone can orchestrate sex-biased gene expression to facilitate the phenotypic development of sexual dimorphism while simultaneously reducing genetic correlations that would otherwise constrain the independent evolution of the sexes.

  10. The ontogenetic scaling of hydrodynamics and swimming performance in jellyfish (Aurelia aurita).

    Science.gov (United States)

    McHenry, Matthew J; Jed, Jason

    2003-11-01

    It is not well understood how ontogenetic changes in the motion and morphology of aquatic animals influence the performance of swimming. The goals of the present study were to understand how changes in size, shape and behavior affect the hydrodynamics of jet propulsion in the jellyfish Aurelia aurita and to explore how such changes affect the ontogenetic scaling of swimming speed and cost of transport. We measured the kinematics of jellyfish swimming from video recordings and simulated the hydrodynamics of swimming with two computational models that calculated thrust generation by paddle and jet mechanisms. Our results suggest that thrust is generated primarily by jetting and that there is negligible thrust generation by paddling. We examined how fluid forces scaled with body mass using the jet model. Despite an ontogenetic increase in the range of motion by the bell diameter and a decrease in the height-to-diameter ratio, we found that thrust and acceleration reaction scaled with body mass as predicted by kinematic similarity. However, jellyfish decreased their pulse frequency with growth, and speed consequently scaled at a lower exponential rate than predicted by kinematic similarity. Model simulations suggest that the allometric growth in Aurelia results in swimming that is slower, but more energetically economical, than isometric growth with a prolate bell shape. The decrease in pulse frequency over ontogeny allows large Aurelia medusae to avoid a high cost of transport but generates slower swimming than if they maintained a high pulse frequency. Our findings suggest that ontogenetic change in the height-to-diameter ratio and pulse frequency of Aurelia results in swimming that is relatively moderate in speed but is energetically economical.

  11. Ontogenetic Variation of Individual and Total Capsaicinoids in Malagueta Peppers (Capsicum frutescens) during Fruit Maturation

    OpenAIRE

    Fayos Avellán, Oreto; Aguiar, Ana Carolina; Jiménez Cantizano, Ana; Ferreiro González, Marta; Garcés Claver, Ana; Martínez, Julián; Mallor Giménez, Cristina; Ruiz Rodríguez, Ana; Palma, Miguel; Carmelo G. Barroso; Gerardo F. Barbero

    2017-01-01

    The ontogenetic variation of total and individual capsaicinoids (nordihydrocapsaicin (n-DHC), capsaicin (C), dihydrocapsaicin (DHC), homocapsaicin (h-C) and homodihydrocapsaicin (h-DHC)) present in Malagueta pepper (Capsicum frutescens) during fruit ripening has been studied. Malagueta peppers were grown in a greenhouse under controlled temperature and humidity conditions. Capsaicinoids were extracted using ultrasound-assisted extraction (UAE) and the extracts were analyzed by ultra-performan...

  12. Ontogenetic variations and feeding habits of a Neotropical annual fish from southern Brazil

    OpenAIRE

    Dias, Tatiana S.; Stein, Ricardo J.; Fialho, Clarice B.

    2017-01-01

    ABSTRACT Knowing the feeding biology of a population and its ontogenetic aspects can help in understanding the functioning of fish assemblages, essential to the conservation of the habitat biodiversity in which these species are found. Annual fishes complete their life cycle in temporary aquatic environments, existing in adult stage only for brief annual periods. Changes in the feeding habits between different size classes could indicate that a species belongs to different feeding groups in d...

  13. Shape shifting predicts ontogenetic changes in metabolic scaling in diverse aquatic invertebrates.

    Science.gov (United States)

    Glazier, Douglas S; Hirst, Andrew G; Atkinson, David

    2015-03-07

    Metabolism fuels all biological activities, and thus understanding its variation is fundamentally important. Much of this variation is related to body size, which is commonly believed to follow a 3/4-power scaling law. However, during ontogeny, many kinds of animals and plants show marked shifts in metabolic scaling that deviate from 3/4-power scaling predicted by general models. Here, we show that in diverse aquatic invertebrates, ontogenetic shifts in the scaling of routine metabolic rate from near isometry (bR = scaling exponent approx. 1) to negative allometry (bR < 1), or the reverse, are associated with significant changes in body shape (indexed by bL = the scaling exponent of the relationship between body mass and body length). The observed inverse correlations between bR and bL are predicted by metabolic scaling theory that emphasizes resource/waste fluxes across external body surfaces, but contradict theory that emphasizes resource transport through internal networks. Geometric estimates of the scaling of surface area (SA) with body mass (bA) further show that ontogenetic shifts in bR and bA are positively correlated. These results support new metabolic scaling theory based on SA influences that may be applied to ontogenetic shifts in bR shown by many kinds of animals and plants. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  14. Ontogenetic anatomy of the distal vagina: relevance for local tumor spread and implications for cancer surgery.

    Science.gov (United States)

    Höckel, Michael; Horn, Lars-Christian; Illig, Romana; Dornhöfer, Nadja; Fritsch, Helga

    2011-08-01

    We have suggested to base cancer surgery on ontogenetic anatomy and the compartment theory of tumor permeation in order to improve local tumor control and to lower treatment-related morbidity. Following the validation of this concept for the uterine cervix, proximal vagina and vulva, this study explores its applicability for the distal vagina. Serial transverse sections of female embryos and fetuses aged 8-17 weeks were assessed for the morphological changes in the region defined by the deep urogenital sinus-vaginal plate complex. Histopathological pattern analysis of local tumor spread was performed with carcinomas of the lower genital tract involving the distal vagina to test the compartment theory. Ontogenetically, the female urethra, urethrovaginal septum, distal vagina and rectovaginal septum represent a morphogenetic unit derived from the deep urogenital sinus-vaginal plate complex. Herein, the posterior urethra, the urethrovaginal septum and the distal vagina form a distinct subcompartment differentiated from the dorsal wall of the urogenital sinus. From 150 consecutive patients with distal vaginectomy as part of their surgical treatment 26 carcinomas of the lower genital tract had infiltrated the distal vagina. All 22 tumors involving the ventral wall invaded the urethra/periurethral tissue. Of the five carcinomas involving the dorsal wall none invaded the rectum/mesorectum. The pattern of local tumor permeation of lower genital tract cancer in the distal vagina can be consistently explained with ontogenetic anatomy and the compartment theory. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Ontogenetic variations and feeding habits of a Neotropical annual fish from southern Brazil

    Directory of Open Access Journals (Sweden)

    Tatiana S. Dias

    Full Text Available ABSTRACT Knowing the feeding biology of a population and its ontogenetic aspects can help in understanding the functioning of fish assemblages, essential to the conservation of the habitat biodiversity in which these species are found. Annual fishes complete their life cycle in temporary aquatic environments, existing in adult stage only for brief annual periods. Changes in the feeding habits between different size classes could indicate that a species belongs to different feeding groups in different growth phases. The aim of this work was to characterize the diet of Cynopoecilus fulgens Costa, 2002 in a temporary flooded area in the coastal plain of southern Brazil, taking into consideration possible alterations in feeding habits in different body size classes caused by ontogenetic changes, to explain the coexistence of these individuals in a short space of time. The diet analysis indicated that C. fulgens is a generalist, consuming small crustaceans and autochthonous insects. Intraspecific differences in diet were determined when compared between nine classes of standard length. Adults fed mainly on autochthonous insects, and juveniles ingested mostly crustaceans, with the population being separated into two trophic groups: invertivores and invertivores with a tendency towards zooplanktivory. It is possible to conclude that the ontogenetic changes in the diet of C. fulgens are related to morphological restrictions due to the size of the individuals, since feeding competitive relations are probably not so evident.

  16. Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications

    Science.gov (United States)

    Lü, Junchang; Currie, Philip J.; Xu, Li; Zhang, Xingliao; Pu, Hanyong; Jia, Songhai

    2013-02-01

    Oviraptorids are a group of specialized non-avian theropod dinosaurs that were generally one to 8 m in body length. New specimens of baby oviraptorids from the Late Cretaceous of Henan Province are some of the smallest individuals known. They include diagnostic characters such as the relative position of the antorbital fenestra and the external naris, distinct opening in the premaxilla anteroventral to the external naris, antorbital fossa partly bordered by premaxilla posterodorsally, lacrimal process of premaxilla does not contact the anterodorsal process of the lacrimal, parietal almost as long as frontal; in dorsal view, posterior margin forms a straight line between the postzygapophyses in each of the fourth and fifth cervicals; femur longer than ilium. They also elucidate the ontogenetic processes of oviraptorids, including fusion of cranial elements and changes in relative body proportions. Hind limb proportions are constant in oviraptorids, regardless of absolute body size or ontogenetic stage. This suggests a sedentary lifestyle that did not involve the pursuit of similar-sized prey. The functional implications for bite force and therefore dietary preferences are better understood through the study of such small animals. The comparison of the measurements of 115 skeletons indicates that oviraptorids maintain their hind limb proportions regardless of ontogenetic stage or absolute size, which is a pattern seen more commonly in herbivores than in carnivores. This may weakly support the hypothesis that oviraptorids are herbivores rather than active carnivores.

  17. Ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae

    Directory of Open Access Journals (Sweden)

    Pedro H.C. Pereira

    2016-10-01

    Full Text Available Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM with similar values for juveniles (86.6%, initial phase (88.1% and terminal phase (88.6% individuals. The second preferred benthos for juveniles was sponge (11.6% compared with initial (4.5% and terminal life phases (1.3%. Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev’s electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean.

  18. Chicken-sized oviraptorid dinosaurs from central China and their ontogenetic implications.

    Science.gov (United States)

    Lü, Junchang; Currie, Philip J; Xu, Li; Zhang, Xingliao; Pu, Hanyong; Jia, Songhai

    2013-02-01

    Oviraptorids are a group of specialized non-avian theropod dinosaurs that were generally one to 8 m in body length. New specimens of baby oviraptorids from the Late Cretaceous of Henan Province are some of the smallest individuals known. They include diagnostic characters such as the relative position of the antorbital fenestra and the external naris, distinct opening in the premaxilla anteroventral to the external naris, antorbital fossa partly bordered by premaxilla posterodorsally, lacrimal process of premaxilla does not contact the anterodorsal process of the lacrimal, parietal almost as long as frontal; in dorsal view, posterior margin forms a straight line between the postzygapophyses in each of the fourth and fifth cervicals; femur longer than ilium. They also elucidate the ontogenetic processes of oviraptorids, including fusion of cranial elements and changes in relative body proportions. Hind limb proportions are constant in oviraptorids, regardless of absolute body size or ontogenetic stage. This suggests a sedentary lifestyle that did not involve the pursuit of similar-sized prey. The functional implications for bite force and therefore dietary preferences are better understood through the study of such small animals. The comparison of the measurements of 115 skeletons indicates that oviraptorids maintain their hind limb proportions regardless of ontogenetic stage or absolute size, which is a pattern seen more commonly in herbivores than in carnivores. This may weakly support the hypothesis that oviraptorids are herbivores rather than active carnivores.

  19. A Conceptual Framework for Mapping Quantitative Trait Loci Regulating Ontogenetic Allometry

    Science.gov (United States)

    Li, Hongying; Huang, Zhongwen; Gai, Junyi; Wu, Song; Zeng, Yanru; Li, Qin; Wu, Rongling

    2007-01-01

    Although ontogenetic changes in body shape and its associated allometry has been studied for over a century, essentially nothing is known about their underlying genetic and developmental mechanisms. One of the reasons for this ignorance is the unavailability of a conceptual framework to formulate the experimental design for data collection and statistical models for data analyses. We developed a framework model for unraveling the genetic machinery for ontogenetic changes of allometry. The model incorporates the mathematical aspects of ontogenetic growth and allometry into a maximum likelihood framework for quantitative trait locus (QTL) mapping. As a quantitative platform, the model allows for the testing of a number of biologically meaningful hypotheses to explore the pleiotropic basis of the QTL that regulate ontogeny and allometry. Simulation studies and real data analysis of a live example in soybean have been performed to investigate the statistical behavior of the model and validate its practical utilization. The statistical model proposed will help to study the genetic architecture of complex phenotypes and, therefore, gain better insights into the mechanistic regulation for developmental patterns and processes in organisms. PMID:18043752

  20. Causal diagrams, information bias, and thought bias.

    Science.gov (United States)

    Shahar, Eyal; Shahar, Doron J

    2010-01-01

    Information bias might be present in any study, including randomized trials, because the values of variables of interest are unknown, and researchers have to rely on substitute variables, the values of which provide information on the unknown true values. We used causal directed acyclic graphs to extend previous work on information bias. First, we show that measurement is a complex causal process that has two components, ie, imprinting and synthesizing. Second, we explain how the unknown values of a variable may be imputed from other variables, and present examples of valid and invalid substitutions for a variable of interest. Finally, and most importantly, we describe a previously unrecognized bias, which may be viewed as antithetical to information bias. This bias arises whenever a variable does not exist in the physical world, yet researchers obtain "information" on its nonexistent values and estimate nonexistent causal parameters. According to our thesis, the scientific literature contains many articles that are affected by such bias.

  1. Bias aware Kalman filters

    DEFF Research Database (Denmark)

    Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

    2006-01-01

    This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model sta...

  2. Contrasting ontogenetic trajectories for phenolic and terpenoid defences in Eucalyptus froggattii

    Science.gov (United States)

    Goodger, Jason Q. D.; Heskes, Allison M.; Woodrow, Ian E.

    2013-01-01

    Background and Aims Plant defence metabolites are considered costly due to diversion of energy and nutrients away from growth. These costs combined with changes in resource availability and herbivory throughout plant ontogeny are likely to promote changes in defence metabolites. A comprehensive understanding of plant defence strategy requires measurement of lifetime ontogenetic trajectories – a dynamic component largely overlooked in plant defence theories. This study aimed to compare ontogenetic trajectories of foliar phenolics and terpenoids. Phenolics are predicted to be inexpensive to biosynthesize, whereas expensive terpenoids also require specialized, non-photosynthetic secretory structures to avoid autotoxicity. Based on these predicted costs, it is hypothesized that phenolics would be maximally deployed early in ontogeny, whereas terpenoids would be maximally deployed later, once the costs of biosynthesis and foregone photosynthesis could be overcome by enhanced resource acquisition. Methods Leaves were harvested from a family of glasshouse-grown Eucalyptus froggattii seedlings, field-grown saplings and the maternal parent tree, and analysed for total terpenoids and phenolics. Key Results Foliar phenolics were highest in young seedlings and lowest in the adult tree. Indeed the ratio of total phenolics to total terpenoids decreased in a significantly exponential manner with plant ontogeny. Most individual terpene constituents increased with plant ontogeny, but some mono- and sesquiterpenes remained relatively constant or even decreased in concentration as plants aged. Conclusions Plant ontogeny can influence different foliar defence metabolites in directionally opposite ways, and the contrasting trajectories support our hypothesis that phenolics would be maximally deployed earlier than terpenoids. The results highlight the importance of examining ontogenetic trajectories of defence traits when developing and testing theories of plant defence, and

  3. EFFECTS OF GROWTH HORMONE ON THE ONTOGENETIC ALLOMETRY OF CRANIOFACIAL BONES

    Science.gov (United States)

    Gonzalez, Paula N.; Kristensen, Erika; Morck, Douglas W.; Boyd, Steven; Hallgrímsson, Benedikt

    2014-01-01

    Organism size is controlled by interactions between genetic and environmental factors mediated by hormones with systemic and local effects. As changes in size are usually not isometric, a considerable diversity in shape can be generated through modifications in the patterns of ontogenetic allometry. In this study we evaluated the role of timing and dose of growth hormone (GH) release on growth and correlated shape changes in craniofacial bones. Using a longitudinal study design, we analyzed GH deficient mice treated with GH supplementation commencing pre- and post-puberty. We obtained 3D in vivo micro-CT images of the skull between 21 and 60 days of age and used geometric morphometrics to analyze size and shape changes among control and GH deficient treated and non-treated mice. The variable levels of circulating GH altered the size and shape of the adult skull, and influenced the cranial base, vault, and face differently. While cranial base synchondroses and facial sutures were susceptible to either the direct or indirect effect of GH supplementation, its effect was negligible on the vault. Such different responses support the role of intrinsic growth trajectories of skeletal components in controlling the modifications induced by systemic factors. Contrary to the expected, the timing of GH treatment did not have an effect on catch-up growth. GH levels also altered the ontogenetic trajectories by inducing changes in their location and extension in the shape space, indicating that differences arose before 21 days and were further accentuated by a truncation of the ontogenetic trajectories in GHD groups. PMID:25098638

  4. Small sample sizes in the study of ontogenetic allometry; implications for palaeobiology.

    Science.gov (United States)

    Brown, Caleb Marshall; Vavrek, Matthew J

    2015-01-01

    Quantitative morphometric analyses, particularly ontogenetic allometry, are common methods used in quantifying shape, and changes therein, in both extinct and extant organisms. Due to incompleteness and the potential for restricted sample sizes in the fossil record, palaeobiological analyses of allometry may encounter higher rates of error. Differences in sample size between fossil and extant studies and any resulting effects on allometric analyses have not been thoroughly investigated, and a logical lower threshold to sample size is not clear. Here we show that studies based on fossil datasets have smaller sample sizes than those based on extant taxa. A similar pattern between vertebrates and invertebrates indicates this is not a problem unique to either group, but common to both. We investigate the relationship between sample size, ontogenetic allometric relationship and statistical power using an empirical dataset of skull measurements of modern Alligator mississippiensis. Across a variety of subsampling techniques, used to simulate different taphonomic and/or sampling effects, smaller sample sizes gave less reliable and more variable results, often with the result that allometric relationships will go undetected due to Type II error (failure to reject the null hypothesis). This may result in a false impression of fewer instances of positive/negative allometric growth in fossils compared to living organisms. These limitations are not restricted to fossil data and are equally applicable to allometric analyses of rare extant taxa. No mathematically derived minimum sample size for ontogenetic allometric studies is found; rather results of isometry (but not necessarily allometry) should not be viewed with confidence at small sample sizes.

  5. Ontogenetic variation in cold tolerance plasticity in Drosophila: is the Bogert effect bogus?

    Science.gov (United States)

    Mitchell, Katherine A.; Sinclair, Brent J.; Terblanche, John S.

    2013-03-01

    Ontogenetic variation in plasticity is important to understanding mechanisms and patterns of thermal tolerance variation. The Bogert effect postulates that, to compensate for their inability to behaviourally thermoregulate, less-mobile life stages of ectotherms are expected to show greater plasticity of thermal tolerance than more-mobile life stages. We test this general prediction by comparing plasticity of thermal tolerance (rapid cold-hardening, RCH) between mobile adults and less-mobile larvae of 16 Drosophila species. We find an RCH response in adults of 13 species but only in larvae of four species. Thus, the Bogert effect is not as widespread as expected.

  6. Bias in surgical research.

    Science.gov (United States)

    Paradis, Carmen

    2008-08-01

    The aim is to discuss the various forms of bias in surgical research, including how it impacts validity and how to recognize and avoid it. The various factors affecting bias in surgical research's design, execution, and reporting were explored. The impact of these factors on internal and external validity in both observational and randomized controlled trials was examined, and recommendations were made for ameliorating the various biases. Identifying bias when interpreting a trial enables surgeons to assess surgical research's internal and external validity. Avoiding bias and/or using methods that minimize bias helps surgeons design and conduct trials with enhanced validity, which can be reliably translated into practice. To accomplish this, surgeons need to be cognizant of susceptibility bias, the applicability of surrogate endpoints, and the use of inappropriate comparators in trial design. They must also be aware of detection, ascertainment, performance and transfer bias in trial execution, and of citation bias in trial reporting. Familiarity with clinical trials' potential biases helps surgeons assess the believability and applicability of research results. Though these biases may sometimes be ameliorated by randomization, blinding, and intervention standardization, these remedies can present distinctive problems to surgical research. This poses a unique need and opportunity for innovation in surgical research design and evaluation. It necessitates that further research be done on methods to improve not only the internal and external validity of surgical trials but also their assessment.

  7. Ontogenetic scaling of metabolism, growth, and assimilation: testing metabolic scaling theory with Manduca sexta larvae.

    Science.gov (United States)

    Sears, Katie E; Kerkhoff, Andrew J; Messerman, Arianne; Itagaki, Haruhiko

    2012-01-01

    Metabolism, growth, and the assimilation of energy and materials are essential processes that are intricately related and depend heavily on animal size. However, models that relate the ontogenetic scaling of energy assimilation and metabolism to growth rely on assumptions that have yet to be rigorously tested. Based on detailed daily measurements of metabolism, growth, and assimilation in tobacco hornworms, Manduca sexta, we provide a first experimental test of the core assumptions of a metabolic scaling model of ontogenetic growth. Metabolic scaling parameters changed over development, in violation of the model assumptions. At the same time, the scaling of growth rate matches that of metabolic rate, with similar scaling exponents both across and within developmental instars. Rates of assimilation were much higher than expected during the first two instars and did not match the patterns of scaling of growth and metabolism, which suggests high costs of biosynthesis early in development. The rapid increase in size and discrete instars observed in larval insect development provide an ideal system for understanding how patterns of growth and metabolism emerge from fundamental cellular processes and the exchange of materials and energy between an organism and its environment.

  8. Variability in connectivity patterns of fish with ontogenetic migrations: Modelling effects of abiotic and biotic factors

    Directory of Open Access Journals (Sweden)

    Susanne Eva Tanner

    2015-10-01

    Full Text Available Connectivity is a critical property of marine fish populations as it drives population replenishment, determines colonization patterns and the resilience of populations to harvest. Understanding connectivity patterns is particularly important in species that present ontogenetic migrations and segregated habitat use during their life history, such as marine species with estuarine nursery areas. Albeit challenging, fish movement can be estimated and quantified using different methodologies depending on the life history stages of interest (e.g. biophysical modelling, otolith chemistry, genetic markers. Relative contributions from estuarine nursery areas to the adult coastal populations were determined using otolith elemental composition and maximum likelihood estimation for four commercially important species (Dicentrarchus labrax, Plathichtys flesus, Solea senegalensis and Solea solea and showed high interannual variability. Here, the effects of abiotic and biotic factors on the observed variability in connectivity rates and extent between estuarine juvenile and coastal adult subpopulations are investigated using generalized linear models (GLM and generalized mixed models (GMM. Abiotic factors impacting both larval and juvenile life history stages are included in the models (e.g. wind force and direction, NAO, water temperature while biotic factors relative to the estuarine residency of juvenile fish are evaluated (e.g. juvenile density, food availability. Factors contributing most to the observed variability in connectivity rates are singled out and compared among species. General trends are identified and results area discussed in the general context of identifying potential management frameworks applicable to different life stages and which may prove useful for ontogenetically migrating species.

  9. Integrating ontogenetic shift, growth and mortality to determine a species' ecological role from isotopic signatures.

    Directory of Open Access Journals (Sweden)

    Nelson F Fontoura

    Full Text Available Understanding species linkages and energy transfer is a basic goal underlying any attempt at ecosystem analysis. Although the first food-web studies were based on gut contents of captured specimens, the assessment of stable isotopes, mainly δ13C and δ15N, has become a standard methodology for wide-range analyses in the last 30 years. Stable isotopes provide information on the trophic level of species, food-web length, and origin of organic matter ingested by consumers. In this study, we analyzed the ontogenetic variability of δ13C and δ15N obtained from samples of three Neotropical fish species: silver sardine (Lycengraulis grossidens, n=46, white lambari (Cyanocharax alburnus, n= 26, and the red-tail lambari (Astyanax fasciatus, n=23 in Pinguela Lagoon, southern Brazil. We developed a new metric, called the Weighted Isotopic Signature (φ 15N or φ 13C, ‰, that incorporates ontogenetic variability, body growth, and natural mortality into a single number.

  10. Performance Tradeoffs, Ontogenetic Conflict, and Multisport Athletes: How is an Ironman Triathlete Like a Frog?

    Science.gov (United States)

    Calsbeek, Ryan; Goedert, Debora

    2017-08-01

    Life-history theory is a cornerstone of modern evolutionary biology that addresses myriad phenomena ranging from demography and population structure to the evolution of aging and senescence. Trade-offs may arise in a number of contexts, from allocation-based (e.g., egg size vs. egg number) to genomic conflicts (e.g., intralocus sexual conflict in which genes that perform well in males perform poorly in females). Here we test for performance tradeoffs in human athletes. We show that in Ironman triathletes, swimming performance trades off with cycling and running performance. The tradeoff appears to be plastic, in that only highly trained athletes experience the tradeoff. We then investigate whether wood frogs (Rana sylvatica) experience similar locomotor performance tradeoffs, to ask whether the divergent environments experienced by tadpoles and frogs leads to ontogenetic conflict (tradeoffs over development). We show that although swimming and jumping performance are positively correlated, antagonistic natural selection may still favor alternative adaptive optima in the two life history stages. However, "adaptive decoupling" of the life stages during metamorphosis may resolve ontogenetic conflict and facilitate independent adaptation to both environments. Thus, whereas performance tradeoffs are general in both systems, the unique selective environment of amphibians has favored the evolution of mechanisms to alleviate the costs of those tradeoffs. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  11. Progressive ontogenetic niche shift over the prolonged immaturity period of wandering albatrosses

    Science.gov (United States)

    Weimerskirch, Henri; Bustamante, Paco; Cherel, Yves

    2017-01-01

    Very little is known about trophic ontogenetic changes over the prolonged immaturity period of long-lived, wide-ranging seabirds. By using blood and feather trophic tracers (δ13C and δ15N, and mercury, Hg), we studied age-related changes in feeding ecology during the immature phase of wandering albatrosses Diomedea exulans when they gradually change from a pure oceanic life to visits to their future breeding grounds. Immatures fed in subtropical waters at high trophic positions during moult. Between- and within-individual variations in isotopic niche were very high, irrespective of age, highlighting wide-ranging exploratory behaviours. In summer, while acting as central-place foragers from their future breeding colony, individuals progressively relied on lower trophic level prey and/or southern latitudes as they aged, until occupying a similar isotopic niche to that of adults. Immatures had exceptionally high Hg burdens, with males having lower Hg concentrations than females, suggesting that they foraged more in subantarctic waters. Our findings suggest a progressive ontogenetic niche shift during central-place foraging of this long-lived species. PMID:29134098

  12. Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837 (Rodentia, Sigmodontinae

    Directory of Open Access Journals (Sweden)

    R. Maestri

    Full Text Available Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal’s development. In this study, using Huxley's formula of allometric growth (1932, we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

  13. Feeding guilds and food resource partitioning in a lake fish assemblage: an ontogenetic approach.

    Science.gov (United States)

    Specziár, A; Rezsu, E T

    2009-07-01

    Ontogenetic diet patterns and trophic guild structure of a 15 species temperate lake fish assemblage were analysed over wide size intervals (up to seven orders of magnitude in body mass), representing practically the whole life span in most species. A two-step objective clustering technique supplemented with other multivariate statistical tools proved that size-related diet changes clearly played an important role in structuring trophic organization of fishes inhabiting Lake Balaton. As many as 13 out of the 15 fish species showed marked size-related dietary changes with two to four ontogenetic feeding stages. At the assemblage level, 11 trophic guilds were separated. Guild membership was size-dependent in 11 fish species that participated in two to four trophic guilds during their life span. The most complex trophic ontogeny was observed in roach Rutilus rutilus and asp Aspius aspius with four guild memberships. This study showed that trophic status of fishes may be very size-sensitive and thus a universal classification of fish species to general trophic guilds, such as 'planktivore', 'benthivore', 'piscivore' or 'herbivore', should be applied very carefully even in environmental monitoring and fisheries management applications, unless it is supported by relevant results of life span diet analyses.

  14. Ontogenetic and static allometry in the human face: contrasting Khoisan and Inuit.

    Science.gov (United States)

    Freidline, Sarah E; Gunz, Philipp; Hublin, Jean-Jacques

    2015-09-01

    Regional differences in modern human facial features are present at birth, and ontogenetic allometry contributes to variation in adults. However, details regarding differential rates of growth and timing among regional groups are lacking. We explore ontogenetic and static allometry in a cross-sectional sample spanning Africa, Europe and North America, and evaluate tempo and mode in two regional groups with very different adult facial morphology, the Khoisan and Inuit. Semilandmark geometric morphometric methods, multivariate statistics and growth simulations were used to quantify and compare patterns of facial growth and development. Regional-specific facial morphology develops early in ontogeny. The Inuit has the most distinct morphology and exhibits heterochronic differences in development compared to other regional groups. Allometric patterns differ during early postnatal development, when significant increases in size are coupled with large amounts of shape changes. All regional groups share a common adult static allometric trajectory, which can be attributed to sexual dimorphism, and the corresponding allometric shape changes resemble developmental patterns during later ontogeny. The amount and pattern of growth and development may not be shared between regional groups, indicating that a certain degree of flexibility is allowed for in order to achieve adult size. In early postnatal development the face is less constrained compared to other parts of the cranium allowing for greater evolvability. The early development of region-specific facial features combined with heterochronic differences in timing or rate of growth, reflected in differences in facial size, suggest different patterns of postnatal growth. © 2015 Wiley Periodicals, Inc.

  15. Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837) (Rodentia, Sigmodontinae).

    Science.gov (United States)

    Maestri, R; Fornel, R; Freitas, T R O; Marinho, J R

    2015-05-01

    Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal's development. In this study, using Huxley's formula of allometric growth (1932), we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

  16. CPI Bias in Korea

    Directory of Open Access Journals (Sweden)

    Chul Chung

    2007-12-01

    Full Text Available We estimate the CPI bias in Korea by employing the approach of Engel’s Law as suggested by Hamilton (2001. This paper is the first attempt to estimate the bias using Korean panel data, Korean Labor and Income Panel Study(KLIPS. Following Hamilton’s model with non­linear specification correction, our estimation result shows that the cumulative CPI bias over the sample period (2000-2005 was 0.7 percent annually. This CPI bias implies that about 21 percent of the inflation rate during the period can be attributed to the bias. In light of purchasing power parity, we provide an interpretation of the estimated bias.

  17. On commercial media bias

    OpenAIRE

    Germano, Fabrizio

    2008-01-01

    Within the spokes model of Chen and Riordan (2007) that allows for non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on quality and bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strongest ef...

  18. Interpretation biases in paranoia.

    Science.gov (United States)

    Savulich, George; Freeman, Daniel; Shergill, Sukhi; Yiend, Jenny

    2015-01-01

    Information in the environment is frequently ambiguous in meaning. Emotional ambiguity, such as the stare of a stranger, or the scream of a child, encompasses possible good or bad emotional consequences. Those with elevated vulnerability to affective disorders tend to interpret such material more negatively than those without, a phenomenon known as "negative interpretation bias." In this study we examined the relationship between vulnerability to psychosis, measured by trait paranoia, and interpretation bias. One set of material permitted broadly positive/negative (valenced) interpretations, while another allowed more or less paranoid interpretations, allowing us to also investigate the content specificity of interpretation biases associated with paranoia. Regression analyses (n=70) revealed that trait paranoia, trait anxiety, and cognitive inflexibility predicted paranoid interpretation bias, whereas trait anxiety and cognitive inflexibility predicted negative interpretation bias. In a group comparison those with high levels of trait paranoia were negatively biased in their interpretations of ambiguous information relative to those with low trait paranoia, and this effect was most pronounced for material directly related to paranoid concerns. Together these data suggest that a negative interpretation bias occurs in those with elevated vulnerability to paranoia, and that this bias may be strongest for material matching paranoid beliefs. We conclude that content-specific biases may be important in the cause and maintenance of paranoid symptoms. Copyright © 2014. Published by Elsevier Ltd.

  19. Political Bias and War

    OpenAIRE

    Jackson, Matthew O.; Morelli, Massimo

    2006-01-01

    We examine how countries' incentives to go to war depend on the "political bias" of their pivotal decision makers. This bias is measured by a decision maker’s risk/ reward ratio from a war compared to that of the country at large. If there is no political bias, then there are mutually acceptable transfers from one country to the other that will avoid a war in the presence of commitment or enforceability of peace treaties. There are cases with a strong enough bias on the part of one or both co...

  20. CPI Bias in Korea

    OpenAIRE

    Chul Chung; KimBonggeun Kim; Myung-Ho Park

    2007-01-01

    We estimate the CPI bias in Korea by employing the approach of Engel’s Law as suggested by Hamilton (2001). This paper is the first attempt to estimate the bias using Korean panel data, Korean Labor and Income Panel Study(KLIPS). Following Hamilton’s model with non­linear specification correction, our estimation result shows that the cumulative CPI bias over the sample period (2000-2005) was 0.7 percent annually. This CPI bias implies that about 21 percent of the inflation rate during the per...

  1. The ontogenetic allometry of body morphology and chemical composition in dairy goat wethers.

    Science.gov (United States)

    Vieira, R A M; Rohem Júnior, N M; Gomes, R S; Oliveira, T S; Bendia, L C R; Azevedo, F H V; Barbosa, D L; Glória, L S; Rodrigues, M T

    2017-08-03

    We studied the ontogenetic growth of goat wethers (castrated male goats) of the Saanen and Swiss Alpine breeds based on a large range of intraspecific body mass (BM). The body parts and the chemical constituents of the empty body were described by the allometric function by using BM and the empty body mass (EBM) as the predictors for morphological traits and chemical composition, respectively. We fitted the allometric scaling function by applying the SAS NLMIXED procedure, but to evaluate assumptions regarding variances in morphological and compositional traits, we combined the scaling function with homoscedastic (MOD1), and the heteroscedastic exponential (MOD2) and power-of-the-mean (MOD3) variance functions. We also predicted the ontogenetic growth by using the traditional log-log transformation and back-transformed results into the arithmetic scale (MOD4). We obtained predictions from MOD4 in the arithmetic scale by a two-step process, and evaluated MOD1, MOD2 and MOD3 by a model selection framework, and compared MOD4 with MOD1, MOD2 and MOD3 based on goodness-of-fit measures. Based on information criteria for model selection, heterogeneous variance functions were more likely to describe 10 over 36 traits with a low level of model selection uncertainty. One trait was predicted by averaging the MOD1 and MOD2 variance functions; and nine traits were better described by averaging the MOD2 and MOD3 variance functions. The predictions for other 16 traits were averaged from MOD1, MOD2 and MOD3. However, MOD4 better described 11 traits according to the goodness-of-fit measures. Depending on the variable being analyzed, the body parts and the chemical amounts exhibited the three types of allometric behavior with respect to BM and EBM, that is, positive, negative and isometric ontogenetic growth. Reference BMs, that is, 20, 27, 35 and 45 kg, were used to compute the net protein and energy requirements based on the first derivative of the scaling function, and the

  2. Benefits of being biased!

    Indian Academy of Sciences (India)

    Administrator

    The genetic code is degenerate: most amino acids are coded by multiple codons. However, it is known that certain ... tems, under certain conditions, it is possible to empirically demonstrate the effects of codon bias at the ... ing the metabolic costs incurred in terms of nonfunctional/ misfunctional proteins. Hence, codon bias ...

  3. Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs.

    Science.gov (United States)

    Foth, Christian; Hedrick, Brandon P; Ezcurra, Martin D

    2016-01-01

    Non-avian saurischian skulls underwent at least 165 million years of evolution and shapes varied from elongated skulls, such as in the theropod Coelophysis, to short and box-shaped skulls, such as in the sauropod Camarasaurus. A number of factors have long been considered to drive skull shape, including phylogeny, dietary preferences and functional constraints. However, heterochrony is increasingly being recognized as an important factor in dinosaur evolution. In order to quantitatively analyse the impact of heterochrony on saurischian skull shape, we analysed five ontogenetic trajectories using two-dimensional geometric morphometrics in a phylogenetic framework. This allowed for the comparative investigation of main ontogenetic shape changes and the evaluation of how heterochrony affected skull shape through both ontogenetic and phylogenetic trajectories. Using principal component analyses and multivariate regressions, it was possible to quantify different ontogenetic trajectories and evaluate them for evidence of heterochronic events allowing testing of previous hypotheses on cranial heterochrony in saurischians. We found that the skull shape of the hypothetical ancestor of Saurischia likely led to basal Sauropodomorpha through paedomorphosis, and to basal Theropoda mainly through peramorphosis. Paedomorphosis then led from Orionides to Avetheropoda, indicating that the paedomorphic trend found by previous authors in advanced coelurosaurs may extend back into the early evolution of Avetheropoda. Not only are changes in saurischian skull shape complex due to the large number of factors that affected it, but heterochrony itself is complex, with a number of possible reversals throughout non-avian saurischian evolution. In general, the sampling of complete ontogenetic trajectories including early juveniles is considerably lower than the sampling of single adult or subadult individuals, which is a major impediment to the study of heterochrony on non-avian dinosaurs

  4. Approximate Bias Correction in Econometrics

    OpenAIRE

    MacKinnon, James G.; Smith Jr., Anthony A

    1995-01-01

    This paper discusses ways to reduce the bias of consistent estimators that are biased in finite samples. It is necessary that the bias function, which relates parameter values to bias, should be estimable by computer simulation or by some other method. If so, bias can be reduced or, in some cases that may not be unrealistic, even eliminated. In general, several evaluations of the bias function will be required to do this. Unfortunately, reducing bias may increase the variance, or even the mea...

  5. Drought Effects on Proanthocyanidins in Sainfoin (Onobrychis viciifolia Scop.) Are Dependent on the Plant's Ontogenetic Stage.

    Science.gov (United States)

    Malisch, Carsten S; Salminen, Juha-Pekka; Kölliker, Roland; Engström, Marica T; Suter, Daniel; Studer, Bruno; Lüscher, Andreas

    2016-12-14

    Sainfoin (Onobrychis viciifolia Scop.) is a forage legume, which improves animal health and the environmental impact of livestock farming due to its proanthocyanidin content. To identify the impact of drought on acetone/water-extractable proanthocyanidin (PA) concentration and composition in the generative and vegetative stages, a rain exclosure experiment was established. Leaves of 120 plants from 5 different sainfoin accessions were sampled repeatedly and analyzed by UPLC-ESI-MS/MS. The results showed distinct differences in response to drought between vegetative and generative plants. Whereas vegetative plants showed a strong response to drought in growth (-56%) and leaf PA concentration (+46%), generative plants showed no response in growth (-2%) or PA concentration (-9%). The PA composition was stable across environments. The five accessions varied in PA concentrations and composition but showed the same pattern of response to the experimental treatments. These results show that the ontogenetic stage at which drought occurs significantly affects the plant's response.

  6. Ontogenetic niche shifts in three Vaccinium species on a sub-alpine mountain side

    DEFF Research Database (Denmark)

    Auffret, Alistair G.; Meineri, Eric; Bruun, Hans Henrik

    2010-01-01

    Background: Climate warming in arctic and alpine regions is expected to result in the altitudinal migration of plant species, but current predictions neglect differences between species' regeneration niche and established niche. Aims: To examine potential recruitment of Vaccinium myrtillus, V....... uliginosum and V. vitis-idaea on a mountain slope in northern Sweden in relation to current adult occurrence. Methods: We combined a seed-sowing experiment in seven community types with adult occurrence observations and species distribution mapping. Results: Emergence of V. myrtillus and V. vitis......-idaea seedlings was significantly related to community type, while V. uliginosum was indifferent, but exhibited the highest average emergence. Adult occurrence was related to community, and ontogenetic niche shifts were observed for all three study species. V. myrtillus was shown to have the highest potential...

  7. Ecological interactions in dinosaur communities: influences of small offspring and complex ontogenetic life histories.

    Science.gov (United States)

    Codron, Daryl; Carbone, Chris; Clauss, Marcus

    2013-01-01

    Because egg-laying meant that even the largest dinosaurs gave birth to very small offspring, they had to pass through multiple ontogenetic life stages to adulthood. Dinosaurs' successors as the dominant terrestrial vertebrate life form, the mammals, give birth to live young, and have much larger offspring and less complex ontogenetic histories. The larger number of juveniles in dinosaur as compared to mammal ecosystems represents both a greater diversity of food available to predators, and competitors for similar-sized individuals of sympatric species. Models of population abundances across different-sized species of dinosaurs and mammals, based on simulated ecological life tables, are employed to investigate how differences in predation and competition pressure influenced dinosaur communities. Higher small- to medium-sized prey availability leads to a normal body mass-species richness (M-S) distribution of carnivorous dinosaurs (as found in the theropod fossil record), in contrast to the right-skewed M-S distribution of carnivorous mammals (as found living members of the order Carnivora). Higher levels of interspecific competition leads to a left-skewed M-S distribution in herbivorous dinosaurs (as found in sauropods and ornithopods), in contrast to the normal M-S distribution of large herbivorous mammals. Thus, our models suggest that differences in reproductive strategy, and consequently ontogeny, explain observed differences in community structure between dinosaur and mammal faunas. Models also show that the largest dinosaurian predators could have subsisted on similar-sized prey by including younger life stages of the largest herbivore species, but that large predators likely avoided prey much smaller than themselves because, despite predicted higher abundances of smaller than larger-bodied prey, contributions of small prey to biomass intake would be insufficient to satisfy meat requirements. A lack of large carnivores feeding on small prey exists in mammals

  8. Ontogenetic changes in limb bone structural proportions in mountain gorillas (Gorilla beringei beringei).

    Science.gov (United States)

    Ruff, Christopher B; Burgess, M Loring; Bromage, Timothy G; Mudakikwa, Antoine; McFarlin, Shannon C

    2013-12-01

    Behavioral studies indicate that adult mountain gorillas (Gorilla beringei) are the most terrestrial of all nonhuman hominoids, but that infant mountain gorillas are much more arboreal. Here we examine ontogenetic changes in diaphyseal strength and length of the femur, tibia, humerus, radius, and ulna in 30 Virunga mountain gorillas, including 18 immature specimens and 12 adults. Comparisons are also made with 14 adult western lowland gorillas (Gorilla gorilla gorilla), which are known to be more arboreal than adult mountain gorillas. Infant mountain gorillas have significantly stronger forelimbs relative to hind limbs than older juveniles and adults, but are nonsignificantly different from western lowland gorilla adults. The change in inter-limb strength proportions is abrupt at about two years of age, corresponding to the documented transition to committed terrestrial quadrupedalism in mountain gorillas. The one exception is the ulna, which shows a gradual increase in strength relative to the radius and other long bones during development, possibly corresponding to the gradual adoption of stereotypical fully pronated knuckle-walking in older juvenile gorillas. Inter-limb bone length proportions show a contrasting developmental pattern, with hind limb/forelimb length declining rapidly from birth to five months of age, and then showing no consistent change through adulthood. The very early change in length proportions, prior to significant independent locomotion, may be related to the need for relatively long forelimbs for climbing in a large-bodied hominoid. Virunga mountain gorilla older juveniles and adults have equal or longer forelimb relative to hind limb bones than western lowland adults. These findings indicate that both ontogenetically and among closely related species of Gorilla, long bone strength proportions better reflect actual locomotor behavior than bone length proportions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Ontogenetic scaling of fore- and hind limb posture in wild chacma baboons (Papio hamadryas ursinus.

    Directory of Open Access Journals (Sweden)

    Biren A Patel

    Full Text Available Large-scale interspecific studies of mammals ranging between 0.04-280 kg have shown that larger animals walk with more extended limb joints. Within a taxon or clade, however, the relationship between body size and joint posture is less straightforward. Factors that may affect the lack of congruence between broad and narrow phylogenetic analyses of limb kinematics include limited sampling of (1 ranges of body size, and/or (2 numbers of individuals. Unfortunately, both issues are inherent in laboratory-based or zoo locomotion research. In this study, we examined the relationship between body mass and elbow and knee joint angles (our proxies of fore- and hind limb posture, respectively in a cross-sectional ontogenetic sample of wild chacma baboons (Papio hamadryas ursinus habituated in the De Hoop Nature Reserve, South Africa. Videos were obtained from 33 individuals of known age (12 to ≥ 108 months and body mass (2-29.5 kg during walking trials. Results show that older, heavier baboons walk with significantly more extended knee joints but not elbow joints. This pattern is consistent when examining only males, but not within the female sample. Heavier, older baboons also display significantly less variation in their hind limb posture compared to lighter, young animals. Thus, within this ontogenetic sample of a single primate species spanning an order of magnitude in body mass, hind limb posture exhibited a postural scaling phenomenon while the forelimbs did not. These findings may further help explain 1 why younger mammals (including baboons tend to have relatively stronger bones than adults, and 2 why humeri appear relatively weaker than femora (in at least baboons. Finally, this study demonstrates how field-acquired kinematics can help answer fundamental biomechanical questions usually addressed only in animal gait laboratories.

  10. Adrenarche in bonobos (Pan paniscus): evidence from ontogenetic changes in urinary dehydroepiandrosterone-sulfate levels.

    Science.gov (United States)

    Behringer, Verena; Hohmann, Gottfried; Stevens, Jeroen M G; Weltring, Anja; Deschner, Tobias

    2012-07-01

    Adrenarche is characterized by the onset of adrenal secretions of increasing amounts of dehydroepiandrosterone-sulfate (DHEA-S). While the function of adrenarche remains a matter of speculation, evidence suggests that the morphological and physiological changes related to it are restricted to humans and closely related primates. Within the primate order, adrenarche has been described only in humans and chimpanzees, but bonobos, the sister species of chimpanzees, have not yet been studied regarding the early ontogenetic changes such as adrenarche. While bonobos and chimpanzees share many morphological and behavioral characteristics, they differ in a number of behavioral traits, and there is a growing interest in terms of the physiological differences that can be linked to species-specific patterns of social behavior. In this study, we measured urinary DHEA-S levels to determine whether bonobos experience physiological changes that are indicative of adrenarche. We measured DHEA-S in urine using ELISA and analyzed its levels in the samples from 53 bonobos aged 1-18 years. Our results show that bonobos experience an increase in DHEA-S levels after 5 years of age, which is comparable with the patterns observed in humans and chimpanzees. This indicates that bonobos do undergo adrenarche and that the timing of onset is similar to that of the two Pan species. The extraction procedures described in this report demonstrate the use of urine for monitoring ontogenetic changes in DHEA-S excretion. If applicable to other species, the technique would facilitate more research on the evolutionary origin of adrenarche and other developmental processes.

  11. Evidence of Niche Partitioning under Ontogenetic Influences among Three Morphologically Similar Siluriformes in Small Subtropical Streams

    Science.gov (United States)

    Bonato, Karine Orlandi; Fialho, Clarice Bernhardt

    2014-01-01

    Ontogenetic influences in patterns of niche breadth and feeding overlap were investigated in three species of Siluriformes (Heptapterus sp., Rhamdia quelen and Trichomycterus poikilos) aiming at understanding the species coexistence. Samplings were conducted bimonthly by electrofishing technique from June/2012 to June/2013 in ten streams of the northwestern state of Rio Grande do Sul, Brazil. The stomach contents of 1,948 individuals were analyzed by volumetric method, with 59 food items identified. In general Heptapterus sp. consumed a high proportion of Aegla sp., terrestrial plant remains and Megaloptera; R. quelen consumed fish, and Oligochaeta, followed by Aegla sp.; while the diet of T. poikilos was based on Simuliidae, Ephemeroptera and Trichoptera. Specie segregation was observed in the NMDS. Through PERMANOVA analysis feeding differences among species, and between a combination of species plus size classes were observed. IndVal showed which items were indicators of these differences. Niche breadth values were high for all species. The niche breadth values were low only for the larger size of R. quelen and Heptapterus sp. while T. poikilos values were more similar. Overall the species were a low feeding overlap values. The higher frequency of high feeding overlap was observed for interaction between Heptapterus sp. and T. poikilos. The null model confirmed the niche partitioning between the species. The higher frequency of high and intermediate feeding overlap values were reported to smaller size classes. The null model showed resource sharing between the species/size class. Therefore, overall species showed a resource partitioning because of the use of occasional items. However, these species share resources mainly in the early ontogenetic stages until the emphasized change of morphological characteristics leading to trophic niche expansion and the apparent segregation observed. PMID:25340614

  12. Ontogenetically-regulated male sterility in tissue culture - induced and spontaneous sorghum mutants

    Directory of Open Access Journals (Sweden)

    Elkonin L.A.

    2003-01-01

    Full Text Available Variability of male fertility expression in the AS-1 line, a somaclonal variant obtained from tissue culture of CMS-plant, and in the progeny of revenant '124-1' obtained from fertile tiller, which developed on CMS-plant transferred from the field to the greenhouse, was investigated. Both revertants were characterized by similar expression of male fertility during plant ontogenesis: the panicle on the main tiller was almost completely sterile whereas formation of fertile pollen grains and seed set were observed on the panicles of the shoot tillers. A clear basipetal gradient of male fertility was manifested on all panicles: the base had significantly higher per cent of fertile pollen grains in comparison with the middle part, while in the top the anthers were either absent or had few sterile pollen grains. Such an ontogenetically-regulated restoration of male fertility was controlled by nuclear genes and could be transferred through the pollen in crosses with progenitor CMS-line. Growing of AS-1 plants in the growth chambers simultaneously under a long (16/8 and a short (12/12 daylength conditions demonstrated that differences of fertility level in different tillers was not caused by change of photoperiod during plant ontogenesis and functioning of photoperiod-sensitive fertility restoring gene. Whereas, the ontogenetically-regulated expression of male fertility in both revenants was temperature-dependent and was clearly manifested under relatively cool conditions during 2-week period before the beginning of anthesis of the first panicle (average daily temperature 21°C. The increase of the average daily temperature by 2-3 С resulted in sharp increase of male fertility level. Possibility of using AS-1 line in a new "two-line system" of hybrid seed production, which require only two lines (sterile mutant and fertility restorer, is discussed.

  13. Ecological interactions in dinosaur communities: influences of small offspring and complex ontogenetic life histories.

    Directory of Open Access Journals (Sweden)

    Daryl Codron

    Full Text Available Because egg-laying meant that even the largest dinosaurs gave birth to very small offspring, they had to pass through multiple ontogenetic life stages to adulthood. Dinosaurs' successors as the dominant terrestrial vertebrate life form, the mammals, give birth to live young, and have much larger offspring and less complex ontogenetic histories. The larger number of juveniles in dinosaur as compared to mammal ecosystems represents both a greater diversity of food available to predators, and competitors for similar-sized individuals of sympatric species. Models of population abundances across different-sized species of dinosaurs and mammals, based on simulated ecological life tables, are employed to investigate how differences in predation and competition pressure influenced dinosaur communities. Higher small- to medium-sized prey availability leads to a normal body mass-species richness (M-S distribution of carnivorous dinosaurs (as found in the theropod fossil record, in contrast to the right-skewed M-S distribution of carnivorous mammals (as found living members of the order Carnivora. Higher levels of interspecific competition leads to a left-skewed M-S distribution in herbivorous dinosaurs (as found in sauropods and ornithopods, in contrast to the normal M-S distribution of large herbivorous mammals. Thus, our models suggest that differences in reproductive strategy, and consequently ontogeny, explain observed differences in community structure between dinosaur and mammal faunas. Models also show that the largest dinosaurian predators could have subsisted on similar-sized prey by including younger life stages of the largest herbivore species, but that large predators likely avoided prey much smaller than themselves because, despite predicted higher abundances of smaller than larger-bodied prey, contributions of small prey to biomass intake would be insufficient to satisfy meat requirements. A lack of large carnivores feeding on small prey

  14. Ontogenetic shifts in plant-plant interactions in a rare cycad within angiosperm communities.

    Science.gov (United States)

    Álvarez-Yépiz, Juan C; Búrquez, Alberto; Dovčiak, Martin

    2014-06-01

    Gymnosperms and angiosperms can co-occur within the same habitats but key plant traits are thought to give angiosperms an evolutionary competitive advantage in many ecological settings. We studied ontogenetic changes in competitive and facilitative interactions between a rare gymnosperm (Dioon sonorense, our target species) and different plant and abiotic neighbours (conspecific-cycads, heterospecific-angiosperms, or abiotic-rocks) from 2007 to 2010 in an arid environment of northwestern Mexico. We monitored survival and growth of seedlings, juveniles, and adults of the cycad Dioon sonorense to evaluate how cycad survival and relative height growth rate (RHGR) responded to intra- and interspecific competition, canopy openness, and nearest neighbour. We tested spatial associations among D. sonorense life stages and angiosperm species and measured ontogenetic shifts in cycad shade tolerance. Canopy openness decreased cycad survival while intraspecific competition decreased survival and RHGR during early ontogeny. Seedling survival was higher in association with rocks and heterospecific neighbours where intraspecific competition was lower. Shade tolerance decreased with cycad ontogeny reflecting the spatial association of advanced stages with more open canopies. Interspecific facilitation during early ontogeny of our target species may promote its persistence in spite of increasing interspecific competition in later stages. We provide empirical support to the long-standing assumption that marginal rocky habitats serve as refugia from angiosperm competition for slow-growing gymnosperms such as cycads. The lack of knowledge of plant-plant interactions in rare or endangered species may hinder developing efficient conservation strategies (e.g. managing for sustained canopy cover), especially under the ongoing land use and climatic changes.

  15. Ecological Interactions in Dinosaur Communities: Influences of Small Offspring and Complex Ontogenetic Life Histories

    Science.gov (United States)

    Codron, Daryl; Carbone, Chris; Clauss, Marcus

    2013-01-01

    Because egg-laying meant that even the largest dinosaurs gave birth to very small offspring, they had to pass through multiple ontogenetic life stages to adulthood. Dinosaurs’ successors as the dominant terrestrial vertebrate life form, the mammals, give birth to live young, and have much larger offspring and less complex ontogenetic histories. The larger number of juveniles in dinosaur as compared to mammal ecosystems represents both a greater diversity of food available to predators, and competitors for similar-sized individuals of sympatric species. Models of population abundances across different-sized species of dinosaurs and mammals, based on simulated ecological life tables, are employed to investigate how differences in predation and competition pressure influenced dinosaur communities. Higher small- to medium-sized prey availability leads to a normal body mass-species richness (M-S) distribution of carnivorous dinosaurs (as found in the theropod fossil record), in contrast to the right-skewed M-S distribution of carnivorous mammals (as found living members of the order Carnivora). Higher levels of interspecific competition leads to a left-skewed M-S distribution in herbivorous dinosaurs (as found in sauropods and ornithopods), in contrast to the normal M-S distribution of large herbivorous mammals. Thus, our models suggest that differences in reproductive strategy, and consequently ontogeny, explain observed differences in community structure between dinosaur and mammal faunas. Models also show that the largest dinosaurian predators could have subsisted on similar-sized prey by including younger life stages of the largest herbivore species, but that large predators likely avoided prey much smaller than themselves because, despite predicted higher abundances of smaller than larger-bodied prey, contributions of small prey to biomass intake would be insufficient to satisfy meat requirements. A lack of large carnivores feeding on small prey exists in mammals

  16. Ontogenetic convergence and evolution of foot morphology in European cave salamanders (Family: Plethodontidae

    Directory of Open Access Journals (Sweden)

    Nistri Annamaria

    2010-07-01

    Full Text Available Abstract Background A major goal in evolutionary biology is to understand the evolution of phenotypic diversity. Both natural and sexual selection play a large role in generating phenotypic adaptations, with biomechanical requirements and developmental mechanisms mediating patterns of phenotypic evolution. For many traits, the relative importance of selective and developmental components remains understudied. Results We investigated ontogenetic trajectories of foot morphology in the eight species of European plethodontid cave salamander to test the hypothesis that adult foot morphology was adapted for climbing. Using geometric morphometrics and other approaches, we found that developmental patterns in five species displayed little morphological change during growth (isometry, where the extensive interdigital webbing in adults was best explained as the retention of the juvenile morphological state. By contrast, three species exhibited significant allometry, with an increase in interdigital webbing during growth. Phylogenetic analyses revealed that multiple evolutionary transitions between isometry and allometry of foot webbing have occurred in this lineage. Allometric parameters of foot growth were most similar to those of a tropical species previously shown to be adapted for climbing. Finally, interspecific variation in adult foot morphology was significantly reduced as compared to variation among juveniles, indicating that ontogenetic convergence had resulted in a common adult foot morphology across species. Conclusions The results presented here provide evidence of a complex history of phenotypic evolution in this clade. The common adult phenotype exhibited among species reveals that selection plays an important part in generating patterns of foot diversity in the group. However, developmental trajectories arriving at this common morphology are distinct; with some species displaying developmental stasis (isometry, while others show an increase

  17. Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae

    Directory of Open Access Journals (Sweden)

    Luis P. Lamas

    2014-12-01

    Full Text Available Emus (Dromaius novaehollandiae are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths and calculated muscle physiological cross sectional area (PCSA and average tendon cross sectional area from emus across three ontogenetic stages (n = 17, body masses from 3.6 to 42 kg. The data were analysed by reduced major axis regression to determine how these biomechanically relevant aspects of morphology scaled with body mass. Muscle mass and PCSA showed a marked trend towards positive allometry (26 and 27 out of 34 muscles respectively and fascicle length showed a more mixed scaling pattern. The long tendons of the main digital flexors scaled with positive allometry for all characteristics whilst other tendons demonstrated a less clear scaling pattern. Finally, the two longer bones of the limb (tibiotarsus and tarsometatarsus also exhibited positive allometry for length, and two others (femur and first phalanx of digit III had trends towards isometry. These results indicate that emus experience a relative increase in their muscle force-generating capacities, as well as potentially increasing the force-sustaining capacities of their tendons, as they grow. Furthermore, we have clarified anatomical descriptions and provided illustrations of the pelvic limb muscle–tendon units in emus.

  18. Media Bias and Reputation

    OpenAIRE

    Matthew Gentzkow; Shapiro, Jesse M.

    2005-01-01

    A Bayesian consumer who is uncertain about the quality of an information source will infer that the source is of higher quality when its reports conform to the consumer's prior expectations. We use this fact to build a model of media bias in which firms slant their reports toward the prior beliefs of their customers in order to build a reputation for quality. Bias emerges in our model even though it can make all market participants worse off. The model predicts that bias will be less severe w...

  19. Biased predecision processing.

    Science.gov (United States)

    Brownstein, Aaron L

    2003-07-01

    Decision makers conduct biased predecision processing when they restructure their mental representation of the decision environment to favor one alternative before making their choice. The question of whether biased predecision processing occurs has been controversial since L. Festinger (1957) maintained that it does not occur. The author reviews relevant research in sections on theories of cognitive dissonance, decision conflict, choice certainty, action control, action phases, dominance structuring, differentiation and consolidation, constructive processing, motivated reasoning, and groupthink. Some studies did not find evidence of biased predecision processing, but many did. In the Discussion section, the moderators are summarized and used to assess the theories.

  20. Introduction to Unconscious Bias

    Science.gov (United States)

    Schmelz, Joan T.

    2010-05-01

    We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.

  1. History of bias.

    Science.gov (United States)

    Vineis, Paolo

    2002-01-01

    Epidemiologists have always been conscious of the importance of controlling for distortions, although the definition itself of bias has changed over time. Central to this discussions in the past was the relative vulnerability of different study designs to bias and uncontrollable confounding (confounding being clearly distinguishable from bias, as a problem of inter-mixed causal effects due to the non-random distribution of risk factors within the study population). In particular, controversy arose over aspects of case-control study design. Also a formulation of "typologies of bias" during the 1970s helped to define some of the most important sources of distortion in the design, analysis and interpretation of epidemiological studies. The subsequent period--until now--has been characterised by more formal and systematic definitions.

  2. Biases in casino betting

    Directory of Open Access Journals (Sweden)

    James Sundali

    2006-07-01

    Full Text Available We examine two departures of individual perceptions of randomness from probability theory: the hot hand and the gambler's fallacy, and their respective opposites. This paper's first contribution is to use data from the field (individuals playing roulette in a casino to demonstrate the existence and impact of these biases that have been previously documented in the lab. Decisions in the field are consistent with biased beliefs, although we observe significant individual heterogeneity in the population. A second contribution is to separately identify these biases within a given individual, then to examine their within-person correlation. We find a positive and significant correlation across individuals between hot hand and gambler's fallacy biases, suggesting a common (root cause of the two related errors. We speculate as to the source of this correlation (locus of control, and suggest future research which could test this speculation.

  3. Increasingly minimal bias routing

    Science.gov (United States)

    Bataineh, Abdulla; Court, Thomas; Roweth, Duncan

    2017-02-21

    A system and algorithm configured to generate diversity at the traffic source so that packets are uniformly distributed over all of the available paths, but to increase the likelihood of taking a minimal path with each hop the packet takes. This is achieved by configuring routing biases so as to prefer non-minimal paths at the injection point, but increasingly prefer minimal paths as the packet proceeds, referred to herein as Increasing Minimal Bias (IMB).

  4. Measuring agricultural policy bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    2010-01-01

    that the agricultural price incentive bias generally perceived to exist during the 1980s was largely eliminated during the 1990s. Results also demonstrate that general equilibrium effects and country-specific characteristics are crucial for determining the sign and magnitude of agricultural bias. Our comprehensive...... protection measure is therefore uniquely suited to capture the full impact of trade policies on relative agricultural price incentives....

  5. Stable isotope evidence of ontogenetic changes in the diet of gizzard shad Dorosoma cepedianum

    DEFF Research Database (Denmark)

    De Brabandere, Loreto; Catalano, M.J.; Frazer, T.K.

    2009-01-01

    composition of the adult fish suggested an increasing importance of zooplankton in the diet, although benthic food sources remained part of the diet of all D. cepedianum collected in this study. The results indicated that benthic feeding is used by D. cepedianum of all sizes, suggesting that biomanipulation......Stable sulphur isotopic composition (d34S) of gizzard shad Dorosoma cepedianum was used to investigate the seasonal and ontogenetic variation in the diet of young and adult fish. This study evaluated fish from a hypereutrophic lake that had recently undergone a 40% reduction of large (>300 mm total...... length, LT) D. cepedianum biomass as part of a biomanipulation experiment, which aimed at reducing internal nutrient loading. Dorosoma cepedianum d34S values showed evidence of ontogenetic changes with young fish (200 mm LT). The d34S...

  6. Ontogenetic patterns and temperature-dependent growth rates in early life stages of Pacific cod (Gadus macrocephalus)

    OpenAIRE

    Hurst, Thomas P.; Benjamin J. Laurel; Ciannelli, Lorenzo

    2010-01-01

    Pacific cod (Gadus macrocephalus) is an important component of fisheries and food webs in the North Pacific Ocean and Bering Sea. However, vital rates of early life stages of this species have yet to be described in detail. We determined the thermal sensitivity of growth rates of embryos, preflexion and postflexion larvae, and postsettlement juveniles. Growth rates (length and mass) at each ontogenetic stage were measured in three replicate tanks at four to five temperatures. Nonl...

  7. Simulating publication bias

    DEFF Research Database (Denmark)

    Paldam, Martin

    are made by data variation, while the model is the same. It appears that SR0 generates narrow funnels much at odds with observed funnels, while the other four funnels look more realistic. SR1 to SR4 give the mean a substantial bias that confirms the prior causing the bias. The FAT-PET MRA works well......Economic research typically runs J regressions for each selected for publication – it is often selected as the ‘best’ of the regressions. The paper examines five possible meanings of the word ‘best’: SR0 is ideal selection with no bias; SR1 is polishing: selection by statistical fit; SR2...... is censoring: selection by the size of estimate; SR3 selects the optimal combination of fit and size; and SR4 selects the first satisficing result. The last four SRs are steered by priors and result in bias. The MST and the FAT-PET have been developed for detection and correction of such bias. The simulations...

  8. USING OF MSC WITH DIFFERENT ONTOGENETIC MATURITY FOR CORRECTION OF CHRONIC FIBROSING LIVER DAMAGE

    Directory of Open Access Journals (Sweden)

    M. Y. Shagidulin

    2013-01-01

    Full Text Available Aim. To compare the effectiveness of MSC with different degree of ontogenetic maturity (MSC bone marrow – MSC BM and MSC umbilical cord – MSC UC on regenerative processes in injured liver. Methods. In 4 groups of experiments on Wistar rats (n = 80 with a model of fibrotic toxic liver damage (FLD it was studied the effect of MSCs with different degree of ontogenetic maturity on recovery processes at the regeneration of damaged liver: 1 gr. – Control, 2 gr. and 3 gr. introduction of MSC BM, included in Sphero®GEL-long in doses of 2.5 ×106 and 5.0 x 106 cells, respectively, and 4 gr. – introduction of MSC UC in the form of cell-spheroids (8–10 × 105 cells. The cells were injected into the damaged liver in 7 days after the end of FDL-modeling. The effect of cell therapy was studied during 180 days. The effectiveness of corrective therapy was evaluated by the results of functional and morphological investigations of livers (histological control of parenchymal and nonparenchy- mal liver tissue. Results. MSC BM in both doses and MSC UC contributed to a more rapid normalization of liver enzyme indices compared with the control (1 gr., but the differences in the rate of recovery of disturbed enzymatic liver functions between groups 2, 3 and 4 – were absent. In 90 days after the cell application it was determined a more pronounced recovery activity of cells in groups 3 and 4; in 180 days the more pronounced activation of recovery processes was observed in group 3; but in group 4 the sclerotic processes were more pro- nounced in this period. Conclusion. For the induction of recovery processes in damage liver it is advisable not to use the MSC UC, but to use MSC BM in the Sphero®GEL, because MSC BM exert not only local but also systemic immune-regulatory effect, increasing the pool of T-reg. cells, which are additional carriers of regenera- tion information in organism. 

  9. Measuring Agricultural Bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    shares and intersectoral linkages - are crucial for determining the sign and magnitude of trade policy bias. The GE-ERP measure is therefore uniquely suited to capture the full impact of trade policies on agricultural price incentives. A Monte Carlo procedure confirms that the results are robust......The measurement issue is the key issue in the literature on trade policy-induced agri-cultural price incentive bias. This paper introduces a general equilibrium effective rate of protection (GE-ERP) measure, which extends and generalizes earlier partial equilibrium nominal protection measures....... For the 15 sample countries, the results indicate that the agricultural price incentive bias, which was generally perceived to exist during the 1980s, was largely eliminated during the 1990s. The results also demonstrate that general equilibrium effects and country-specific characteristics - including trade...

  10. Obesity Stigma and Bias.

    Science.gov (United States)

    Fruh, Sharon M; Nadglowski, Joe; Hall, Heather R; Davis, Sara L; Crook, Errol D; Zlomke, Kimberly

    2016-01-01

    Overweight and obesity are escalating in epidemic proportions in the United States. Individuals with overweight and obesity are often reluctant to seek medical help, not only for weight reduction but also for any health issue because of perceived provider discrimination. Providers who are biased against individuals with obesity can hinder our nation's effort to effectively fight the obesity epidemic. By addressing weight bias in the provider setting, individuals affected by obesity may be more likely to engage in a meaningful and productive discussion of weight. Providers need to be the go-to source for obesity-focused information on new and emerging treatments.

  11. Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs

    Directory of Open Access Journals (Sweden)

    Christian Foth

    2016-01-01

    Full Text Available Non-avian saurischian skulls underwent at least 165 million years of evolution and shapes varied from elongated skulls, such as in the theropod Coelophysis, to short and box-shaped skulls, such as in the sauropod Camarasaurus. A number of factors have long been considered to drive skull shape, including phylogeny, dietary preferences and functional constraints. However, heterochrony is increasingly being recognized as an important factor in dinosaur evolution. In order to quantitatively analyse the impact of heterochrony on saurischian skull shape, we analysed five ontogenetic trajectories using two-dimensional geometric morphometrics in a phylogenetic framework. This allowed for the comparative investigation of main ontogenetic shape changes and the evaluation of how heterochrony affected skull shape through both ontogenetic and phylogenetic trajectories. Using principal component analyses and multivariate regressions, it was possible to quantify different ontogenetic trajectories and evaluate them for evidence of heterochronic events allowing testing of previous hypotheses on cranial heterochrony in saurischians. We found that the skull shape of the hypothetical ancestor of Saurischia likely led to basal Sauropodomorpha through paedomorphosis, and to basal Theropoda mainly through peramorphosis. Paedomorphosis then led from Orionides to Avetheropoda, indicating that the paedomorphic trend found by previous authors in advanced coelurosaurs may extend back into the early evolution of Avetheropoda. Not only are changes in saurischian skull shape complex due to the large number of factors that affected it, but heterochrony itself is complex, with a number of possible reversals throughout non-avian saurischian evolution. In general, the sampling of complete ontogenetic trajectories including early juveniles is considerably lower than the sampling of single adult or subadult individuals, which is a major impediment to the study of heterochrony on

  12. Ontogenetic Variation of Individual and Total Capsaicinoids in Malagueta Peppers (Capsicum frutescens) during Fruit Maturation.

    Science.gov (United States)

    Fayos, Oreto; de Aguiar, Ana Carolina; Jiménez-Cantizano, Ana; Ferreiro-González, Marta; Garcés-Claver, Ana; Martínez, Julián; Mallor, Cristina; Ruiz-Rodríguez, Ana; Palma, Miguel; Barroso, Carmelo G; Barbero, Gerardo F

    2017-05-03

    The ontogenetic variation of total and individual capsaicinoids (nordihydrocapsaicin (n-DHC), capsaicin (C), dihydrocapsaicin (DHC), homocapsaicin (h-C) and homodihydrocapsaicin (h-DHC)) present in Malagueta pepper (Capsicum frutescens) during fruit ripening has been studied. Malagueta peppers were grown in a greenhouse under controlled temperature and humidity conditions. Capsaicinoids were extracted using ultrasound-assisted extraction (UAE) and the extracts were analyzed by ultra-performance liquid chromatography (UHPLC) with fluorescence detection. A significant increase in the total content of capsaicinoids was observed in the early days (between 12 and 33). Between day 33 and 40 there was a slight reduction in the total capsaicinoid content (3.3% decrease). C was the major capsaicinoid, followed by DHC, n-DHC, h-C and h-DHC. By considering the evolution of standardized values of the capsaicinoids it was verified that n-DHC, DHC and h-DHC (dihydrocapsaicin-like capsaicinoids) present a similar behavior pattern, while h-C and C (capsaicin-like capsaicinoids) show different evolution patterns.

  13. Biological effects of selenium compounds with a particular attention to the ontogenetic development.

    Science.gov (United States)

    Ošt'ádalová, I

    2012-01-01

    Selenium is a trace element that is essential for living organism. Its beneficial effect is, however, expressed in a very narrow dosage range: the high and low doses of selenium are connected with pathological manifestations. The toxicity depends on the chemical form of selenium, state of organism, interactions with heavy metals and on the stage of ontogenetic development. Whereas one dose of sodium selenite (20 micromol/kg b.w.) is lethal in adult rats, suckling rats are entirely resistant. However, within one week after administration of the same dose, cataract of eye lens developed. The highest incidence of cataract was observed in 10-day-old animals and it decreased until day 20. From postnatal day 20 to day 40 the rats were resistant to both the lethal and cataractogenic effects of selenium. The incidence of cataract may be suppressed by premature weaning, lower hydration of suckling, change of water soluble/water insoluble lens protein ratio, thyroxine treatment, and by interaction with mercury. By means of its oxidative and reduction properties, selenium is involved in the maintenance of the cell redox homeostasis. Typical example is its possible cardioprotective effect: selenium decreased number of arrhythmias, reduced infarct size and improved the contractile recovery after ischemia/reperfusion injury. Selenium supplementation may thus increase cardiac tolerance to ischemic damage.

  14. Ontogenetic variation in the sensory structures on the pedipalps of cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

    Science.gov (United States)

    Townsend, Victor R; Enzmann, Bruce P

    2018-01-01

    In arachnids, pedipalps are highly variable appendages that may be used in feeding, courtship, defense, and agonistic encounters. In cosmetid harvestmen, adults have pedipalps that feature flattened femora, spoon-shaped tibiae, and robust tarsal claws. In contrast, the pedipalps of nymphs are elongate with cylindrical podomeres and are adorned with delicate pretarsi. In this study, we used scanning electron microscopy to examine the distribution of cuticular structures (e.g., sensilla chaetica, pores) on the elements of the pedipalps of adults and nymphs of three species of cosmetid harvestmen. Our results indicate that there is considerable ontogenetic variation in the morphology of the trochanter, femur, patella, tibia, and tarsus. The pretarsus of the nymph has a ventral patch of setae that is absent from the adult tarsal claw. We observed this structure on all three cosmetid species as well as on the pedipalps of an additional seven morphospecies of nymphs collected in Belize and Costa Rica. This structure may represent a previously unrecognized autapomorphy for Cosmetidae. Examinations of the pedipalps of antepenultimate nymphs of additional gonyleptoidean harvestmen representing the families Ampycidae, Cranaidae, Manaosbiidae, and Stygnidae revealed the occurrence of unusual, plumose tarsal setae, but no setal patches on the tarsal claw. © 2017 Wiley Periodicals, Inc.

  15. Environment-dependent plasticity and ontogenetic changes in the brain of hatchery-reared Atlantic salmon

    DEFF Research Database (Denmark)

    Näslund, J.; Larsen, Martin Hage; Thomassen, S.T.

    2017-01-01

    Lowered rearing density has repeatedly been shown to increase the performance of hatchery-reared salmonids stocked into natural environments. One possible mechanism for this pattern could be that lower densities enhance brain development, which has been shown to be the case in other hatchery enha...... the opposite pattern was observed for telencephalon. Overall, these results reveal substantial brain plasticity depending on the surrounding environment as well as ontogenetic adaptive changes in the brain of the Atlantic salmon......Lowered rearing density has repeatedly been shown to increase the performance of hatchery-reared salmonids stocked into natural environments. One possible mechanism for this pattern could be that lower densities enhance brain development, which has been shown to be the case in other hatchery...... enhancement strategies, like environmental enrichment. Here, we investigated the size of the brain in hatcheryreared Atlantic salmon Salmo salar kept at standard (high) and reduced (low) tank densities. In contrast to our predictions, we found that fish reared at high density had larger dry mass of cerebellum...

  16. Ontogenetic shifts in morphology and resource use of cisco Coregonus artedi.

    Science.gov (United States)

    Muir, A M; Vecsei, P; Pratt, T C; Krueger, C C; Power, M; Reist, J D

    2013-02-01

    Two previously described lacustrine cisco Coregonus spp. morphs [i.e. a small (cisco Coregonus artedi. Geometric body shape did not differ between the two size classes nor could they be differentiated by 24 size-corrected linear measurements, indicating that the two groups had similar phenotypes. Strong, positive correlations between all linear characters and geometric centroid size (a composite variable of fish body length, mass and age) suggested that body morphology changed with age as fish grew. Total gillraker number (N(GR)) increased with L(F) according to: N(GR) = 36.3 + 0.034L(F). Differences in gillraker number and phenotype with age and size were explained by shifts in habitat and trophic resource use. Relative abundance within 0-30, 30-60, 60-90 and >90 m depth strata differed between size classes suggesting that morphology changed when fish shifted their habitat as they grew older. Large C. artedi had lower δ(13)C and slightly higher δ(15)N, indicating greater reliance on pelagic prey resources (i.e. more or larger zooplankton, such as Mysis spp.), compared to small C. artedi, which relied slightly more on benthic prey. Gillraker shape and number have always been used as key diagnostic characters in coregonine taxonomy; based on the findings presented here, ontogenetic shifts should be accounted for in resulting classifications. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

  17. Structure-function relationships in the integument of Salamandra salamandra during ontogenetic development.

    Science.gov (United States)

    Pederzoli, Aurora; Gambarelli, A; Gabbay, Shosh; Rozman, A; Katz, U

    2002-06-01

    Morphological, cytological and transport properties of the integument of Salamandra salamandra were investigated during natural ontogenetic development, from birth to adult. Three stages were operationally defined: I, larvae, from birth to metamorphosis; II, metamorphosis (judged externally by the colour change and loss of the gills); and III, post-metamorphosis to adult. Pieces of skin were fixed at various stages for immunocytochemical examinations, and the electrical properties were investigated on parallel pieces. Distinct cellular changes take place in the skin during metamorphosis, and lectin (PNA, WGA and ConA) binding indicates profound changes in glycoprotein composition of cell membranes, following metamorphosis. Band 3 and carbonic anhydrase I (CA I) were confined to mitochondria-rich (MR)-like cells, and were detected only in the larval stage. CA II on the other hand, was detected both in MR-like and in MR cells following metamorphosis. The electrical studies show that the skin becomes more tight (transepithelial resistance increases) upon metamorphosis, followed by manifestation of amiloride-sensitive short-circuit current (I(SC)) indicating that functional Na+ uptake has been acquired. The skin of metamorphosed adults had no finite transepithelial Cl- conductance, and band 3 was not detected in its MR cells. The functional properties of MR-like and MR cells remain to be established.

  18. Ontogenetic migration of the mental foramen in Neandertals and modern humans.

    Science.gov (United States)

    Williams, Frank L'Engle; Krovitz, Gail E

    2004-10-01

    Since the nineteenth century, researchers have noted that Neandertal and modern human adults differ in mental foramen position, although the ontogenetic changes in the position of this feature have only recently come under the scrutiny of paleoanthropologists. Research on mental foramen position has focused on whether this feature is inferior to a particular tooth. However, tooth position may not be a reliable indicator of mental foramen position because of variability in tooth size within and between taxa and during eruption events. As opposed to observing the mental foramen with respect to the postcanine teeth, we examined linear distances from the mental foramen to other mandibular landmarks. Modern human adults may appear truncated, or paedomorphic, in mental foramen position with respect to Neandertal adults. However, infants of the two taxa differ substantially in anterior mandibular form. The initial differences in the shape of the mental region may be related to the embryological position of the mental foramen in modern humans and its role in the development of the mental trigone. The shape changes that accrue thereafter, possibly from faster mandibular growth rates in Neandertals, further distinguish the adults from one another. Although mandibular shape differences exist from early infancy onwards, adults of the two taxa are broadly similar in bi-mental foramen breadth with respect to mandibular size. For this reason, qualitative assessments of mental foramen position may provide less taxonomic information than previously thought.

  19. A Parent-Offspring Trade-Off Limits the Evolution of an Ontogenetic Niche Shift.

    Science.gov (United States)

    Ten Brink, Hanna; de Roos, André M

    2017-07-01

    Many free-living animal species, including the majority of fish, insects, and amphibians, change their food and habitat during their life. Even though these ontogenetic changes in niche are common, it is not well understood which ecological conditions have favored the evolution of these shifts. Using an adaptive dynamics approach, we show that it is evolutionarily advantageous to switch to an alternative food source in the course of ontogeny when this results in a higher intake rate for the switching consumers. Individuals are, however, not able to specialize on this new food source when this negatively affects the performance early in life on the original food source. Selection on these early life stages is so strong that in species with a complete diet shift, evolution results in large juveniles and adults that are maladapted to the alternative food source while their offspring are specialized on the original food source when young. These outcomes suggest strong selection to decouple the different life stages, such that they can maximize their performance on different food sources independently from each other. Metamorphosis could be a way to decouple the different life stages and therefore evolve in species that feed on multiple food sources during their life.

  20. Ontogenetic variations and structural adjustments in mammals evolving prolonged to continuous dental growth

    Science.gov (United States)

    Gomes Rodrigues, Helder; Lefebvre, Rémi; Fernández-Monescillo, Marcos; Mamani Quispe, Bernardino; Billet, Guillaume

    2017-07-01

    Studying dental ontogeny in mammals can provide valuable insight on the evolution of their masticatory apparatus and their related adaptations. The multiple acquisitions of a prolonged to continuous growth of teeth in herbivorous mammals in response to high abrasion represent an intensively investigated issue. However, the ontogenetic and architectural patterns associated with these repeated dental innovations remain poorly known. Here, we focused on two case studies corresponding to distant mammalian clades, the extinct Mesotheriidae (Notoungulata), which shared some striking dental features with the extant Ctenodactylidae (Rodentia). We studied the impact of prolonged to continuous growth of molars on their occlusal complexity, their relative size and their dynamics in the jaw. We found that variations of occlusal complexity patterns are the result of paedomorphic or peramorphic heterochronic processes impacting dental crown. We showed that variations in both upper and lower molar proportions generally follow the inhibitory developmental cascade model. In that context, prolonged dental growth implies transitory adjustments due to wear, and also involves dental migration and loss when combined with molar lengthening. Interestingly, these features may be present in many mammals having prolonged dental growth, and emphasize the crucial need of considering these aspects in future evolutionary and developmental studies.

  1. Investigation of different ontogenetic stages of Raillietiella sp. (Pentastomida: Cephalobaenida): ionical glands.

    Science.gov (United States)

    Stender-Seidel, S; Thomas, G; Böckeler, W

    1999-05-01

    The ionic glands of Raillietiella sp. were investigated ultrastructurally in different ontogenetic stages. Modifications of the ultrastructure, number, and distribution of ionic glands were observed after the invasion of the primary larvae into the invertebrate intermediate host and after the invasion of the infective larvae into the vertebrate final host. On the basis of a comparison of the ultrastructure of ionic glands in Raillietiella sp. with that of other pentastomids described in the literature, a general conformity of pentastomid ionic glands can be stated. We propose a defined nomenclature that is integrated into the complete nomenclature of the pentastomid gland system and summarize the synonyms of the ionic glands. Ultrahistochemical chloride detection by energy-dispersive X-ray analysis shows the function of the ionic glands for chloride regulation. Remarkably, in Raillietiella sp., ionic glands also exist in the female genital system. Ionic glands with two central cells occur in cephalobaenids. The existence of ionic glands in Cephalobaena tetrapoda, which has thus far been doubted, can be proved.

  2. DESCRIPTION OF AN EARLY ONTOGENETIC EVOLUTIONARY STEP IN LEPIDORBITOIDES (LEPIDORBITOIDES BISAMBERGENSIS ASYMMETRICA, EARLY MAASTRICHTIAN (CENTRAL TURKEY

    Directory of Open Access Journals (Sweden)

    ERCAN ÖZCAN

    2001-03-01

    Full Text Available Lepidorbitoides bisambergensis is characterised by having a ‘quadriserial’ embryo without any chamberlet directly arising from the deuteroconch and is a very diagnostic and common species in Lower Maastrichtian flysch successions in Anatolia. Some populations of this species present an early ontogenetic morphologic feature which is characterised by distinctly asymmetric early chamber arrangement recognised in the horizontal sections. This asymmetry is mainly caused by the pronounced difference in the size of auxiliary chamberlets which rest on both, protoconch and deuteroconch and also enhanced by the development of unequal number of chamberlets in the series arising from these auxiliary chamberlets on the protoconchal side. These asymmetric specimens are commonly identified in stratigraphic horizons below the symmetric ones after the introduction of a new auxiliary chamberlet and progressively replaced by symmetric ones in the younger populations. Asymmetric "quadriserial" specimens representing the early phylogenetic stage of L. bisambergensis described in the stratigraphic horizons corresponding to G. havanensis and G. aegyptiaca (? zones are thought to deserve a particular taxonomic status and are attributed to Lepidorbitoides bisambergensis asymmetrica Özcan & Özkan-Altiner, 1999a. 

  3. Ontogenetic variations in flush development are indicative of low temperature tolerance in Hevea brasiliensis clones

    Directory of Open Access Journals (Sweden)

    K.K. Vinod

    2013-12-01

    Full Text Available Para rubber (Hevea brasiliensis trees are naturally adapted to the Amazonian tropical climate. In India rubber trees are traditionally cultivated in the warm humid tropics of the south. Northeast India is a non-traditional area for rubber cultivation. A major limiting factor on tree growth in the northeast region is stress due to low temperature. Being a deciduous tree, rubber trees exhibit annual natural defoliation prior to the winter season, and ensuing new leaf growth usually coincides with the low temperature period. Flushing behaviour of trees during this period provides an opportunity to assess their winter hardiness. A study was carried out on five clones, RRIM 600, SCATC 93/114, GT 1, PB 5/51 and Haiken 1, to evaluate phenological behaviour of leaf growth during the period of low temperature stress. Trees were monitored for expansion of leaf area, internode length, petiole length and development of chlorophyll. Wide variation was observed among these clones for all the traits. SCATC 93/114 was better adapted for low temperature stress as this clone was found to have faster expansion of leaf area and better chlorophyll development, followed by Haiken 1. PB 5/51 was found to show poor performance during low temperature. Haiken 1 and PB 5/51 also exhibited better relative growth rate during winter months confirming their low temperature tolerance. Ontogenetic variations in leaf development are good indicators of assessing inherent cold tolerance in Hevea clones.

  4. Ontogenetic variations in flush development are indicative of low temperature tolerance in Hevea brasiliensis clones

    Directory of Open Access Journals (Sweden)

    K.K. Vinod

    2010-09-01

    Full Text Available Para rubber (Hevea brasiliensis trees are naturally adapted to the Amazonian tropical climate. In India rubber trees are traditionally cultivated in the warm humid tropics of the south. Northeast India is a non-traditional area for rubber cultivation. A major limiting factor on tree growth in the northeast region is stress due to low temperature. Being a deciduous tree, rubber trees exhibit annual natural defoliation prior to the winter season, and ensuing new leaf growth usually coincides with the low temperature period. Flushing behaviour of trees during this period provides an opportunity to assess their winter hardiness. A study was carried out on five clones, RRIM 600, SCATC 93/114, GT 1, PB 5/51 and Haiken 1, to evaluate phenological behaviour of leaf growth during the period of low temperature stress. Trees were monitored for expansion of leaf area, internode length, petiole length and development of chlorophyll. Wide variation was observed among these clones for all the traits. SCATC 93/114 was better adapted for low temperaturestress as this clone was found to have faster expansion of leaf area and better chlorophyll development, followed by Haiken 1. PB 5/51 was found to show poor performance during low temperature. Haiken 1 and PB 5/51 also exhibited better relative growth rate during winter months confirming their low temperature tolerance. Ontogenetic variations in leaf development are good indicators of assessing inherent cold tolerance in Hevea clones.

  5. [On filo- and ontogenetic development of dopaminergic regylation of wakefulness-sleep cycle in vertabrates].

    Science.gov (United States)

    Oganesian, G A; Aristakesian, E A; Romanova, I V; Vataev, S I; Kuzik, V V

    2012-10-01

    The comparative immunohistochemical researches of dofamine containing neurons and fibers are carried uot in telencephalic and diencephalic departments of the brain in different vertebratts (adults rats, rats aged 14 and 30 days and frogs). For analysis of quantitative changes dynamics in thyrozinhydroxylase, D1 and D2 immunoreactive material in sleep-wakefulness cycle the model of sleepdeprivation is used. There are found the facts of morphofunctional correlations in the reactions of dophaminergic system during ontogeny and phylogeny. Besides, the pharmacological effects of dofamine agonist and antagonists on the sleep-wakefulness cycle in young rats and in frogs are shown. So, dopamine and its agonist apomorphine increase in sleep-wakefulness cycle duration of sleep-like state ofcataplexy (homolog of the sleep) in frogs, in 30-day-old rats it increase the share of wakefulness and catalepsy. D1 receptors antagonist (SCH 23390) adminisrated to frogs, caused increase of wakefulness and catatonic type states duration, where as D2 receptors antagonist (apomorphine) increased cataleptic condition. Administration of dopamine antagonist (haloperidol) to 30-day-old rats previously causes the increase of cataleptic state, after which the slow wave sleep state is enhanced. The questions of phylo-, ontogenetic formation of dopaminergic system regulating role in sleep-wakefulness cycle, when transition mainly from neurosecretory diencephalic influences of dophamine to the mainly neurotransmittory functins of telencephalic regions occured, is discussed.

  6. Vertical movement patterns and ontogenetic niche expansion in the tiger shark, Galeocerdo cuvier.

    Science.gov (United States)

    Afonso, André S; Hazin, Fábio H V

    2015-01-01

    Sharks are top predators in many marine ecosystems and can impact community dynamics, yet many shark populations are undergoing severe declines primarily due to overfishing. Obtaining species-specific knowledge on shark spatial ecology is important to implement adequate management strategies for the effective conservation of these taxa. This is particularly relevant concerning highly-mobile species that use wide home ranges comprising coastal and oceanic habitats, such as tiger sharks, Galeocerdo cuvier. We deployed satellite tags in 20 juvenile tiger sharks off northeastern Brazil to assess the effect of intrinsic and extrinsic factors on depth and temperature usage. Sharks were tracked for a total of 1184 d and used waters up to 1112 m in depth. The minimum temperature recorded equaled 4°C. All sharks had a clear preference for surface (sharks used mostly shallow (sharks spending considerably more time in surface (shark habitat was observed, with generalized linear models estimating a ~4-fold increase in maximum diving depth from 150- to 300-cm size-classes. The time spent in the upper 5 m of the water column did not vary ontogenetically but shark size was the most important factor explaining the utilization of deeper water layers. Young-of-the-year tiger sharks seem to associate with shallow, neritic habitats but they progressively move into deeper oceanic habitats as they grow larger. Such an early plasticity in habitat use could endow tiger sharks with access to previously unavailable prey, thus contributing to a wider ecological niche.

  7. Ontogenetic selection on hatchery salmon in the wild: natural selection on artificial phenotypes.

    Science.gov (United States)

    Bailey, Michael M; Lachapelle, Kevin A; Kinnison, Michael T

    2010-07-01

    Captive rearing often alters the phenotypes of organisms that are destined for release into the wild. Natural selection on these unnatural phenotypes could have important consequences for the utility of captive rearing as a restoration approach. We show that normal hatchery practices significantly advance the development of endangered Atlantic salmon (Salmo salar) fry by 30+ days. As a result, hatchery fry might be expected to face strong natural selection resulting from their developmental asynchrony. We investigated patterns of ontogenetic selection acting on hatchery produced salmon fry by experimentally manipulating fry development stage at stocking. Contrary to simple predictions, we found evidence for strong stabilizing selection on the ontogeny of unfed hatchery fry, with weaker evidence for positive directional selection on the ontogeny of fed fry. These selection patterns suggest a seasonally independent tradeoff between abiotic or biotic selection favoring advanced development and physiological selection linked to risk of starvation in unfed fry. We show, through a heuristic exercise, how such selection on ontogeny may exacerbate problems in restoration efforts by impairing fry productivity and reducing effective population sizes by 13-81%.

  8. Benefits of being biased!

    Indian Academy of Sciences (India)

    Permanent link: http://www.ias.ac.in/article/fulltext/jgen/083/02/0113-0115. Keywords. codon bias; alcohol dehydrogenase; Darwinian fitness; Drosophila melanogaster. Author Affiliations. Sutirth Dey1. Evolutionary Biology Laboratory, Evolutionary & Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific ...

  9. Are tree ontogenetic structure and allometric relationship independent of vegetation formation type? A case study with Cordia oncocalyx in the Brazilian caatinga

    Science.gov (United States)

    Silveira, Andréa P.; Martins, Fernando R.; Araújo, Francisca S.

    2012-08-01

    In temperate and tropical rainforests, ontogenetic structure and allometry during tree ontogeny are often associated with light gradients. Light is not considered a limiting resource in deciduous thorny woodland (DTW), but establishment and growth occur during a short rainy period, when the canopy is fully leaved and light in the understory may be modified. Our aim was to investigate whether the light gradient in DTW and the biomechanical limitations of tree growth would be enough to produce an ontogenetic structure and allometric growth similar to rainforest canopy trees. We investigated the ontogenetic stages and diameter-height relationship of Cordia oncocalyx (Boraginaceae), a dominant canopy tree of the DTW of semiarid northeastern Brazil. We tagged, measured and classified the ontogenetic stages of 2.895 individuals in a 1 ha area (5°6'58.1″S and 40°52'19.4″W). In the rainy season only 4.7% of the light falling on the canopy reached the ground. Initial ontogenetic stages, mainly infant (50.9%) and seedling (42.1%), were predominant in the population, with the remaining 7% distributed among juvenile, immature, virginile and reproductive. The ontogenetic structure was similar to that of rainforest tree species, but the population formed both permanent seed and infant banks in response to long dry periods and erratic rainy spells. Like many other Boraginaceae tree species in tropical rainforests, C. oncocalyx has a Prévost architectural model, but allometric growth was quite different from rainforest trees. C. oncocalyx invested slightly more in diameter at first, then in height and finally invested greatly in diameter and attained an asymptotic height. The continued high investment in diameter growth at late stages and the asymptotic height point to low tree density and more frequent xylem embolism as the main drivers of tree allometric shape in DTW. This indicates that tree ontogenetic structure and allometric relationships depend on vegetation

  10. Variations of Salminus hilarii diet (Ostariophysi, Characidae: seasonal and ontogenetic effects

    Directory of Open Access Journals (Sweden)

    GA Villares Junior

    Full Text Available AbstractThis study described the variations seasonal and ontogenetic of Salminus hilarii diet. Samples were collected in the Sorocaba River, São Paulo, Brazil, one of the few rivers where individuals of the species still occur in a higher frequency. The preys consumed were analyzed by Importance Alimentary Index (AIi. To determine similarities between year seasons, the AIi data were analyzed by the Morisita-Horn index and reduced in cluster analysis, along with a statistical comparison made by one-way ANOSIM test (5%. The feeding activity was analyzed according to the stomach repletion index and compared among the year seasons using non parametric variance analysis Kruskal-Wallis test (5%. Comparison of prey consumed between immature and adult individuals was made by Spearman correlation (5%. A Pearson correlation (5% was applied between the standard length of the fish and prey consumed, as well as between the mouth and prey heights. The analyzes of stomach contents showed that the diet of this species was exclusively piscivorous, with significant difference of prey consumption during the period, the same happening among adult and immature individuals. It was observed that these fishes use to swallow their prey whole and that significant correlations between size of predator and prey size can be observed. There is also correlation between the mouth height and the maximum prey depth. Salminus hilarii feeds on the available prey, and the species food composition and feeding activity depends on prey`s abundance, their size and morphology, as do the water temperatures.

  11. Ontogenetic changes in digestive enzyme activities and the amino acid profile of starry flounder Platichthys stellatus

    Science.gov (United States)

    Song, Zhidong; Wang, Jiying; Qiao, Hongjin; Li, Peiyu; Zhang, Limin; Xia, Bin

    2016-09-01

    Ontogenetic changes in digestive enzyme activities and the amino acid (AA) profile of starry flounder, Platichthys stellatus, were investigated and limiting amino acids were estimated compared with the essential AA profile between larvae and live food to clarify starry flounder larval nutritional requirements. Larvae were collected at the egg stage and 0, 2, 4, 7, 12, 17, 24 days after hatching (DAH) for analysis. Larvae grew from 1.91 mm at hatching to 12.13 mm at 24 DAH. Trypsin and chymotrypsin activities changed slightly by 4 DAH and then increased significantly 4 DAH. Pepsin activity increased sharply beginning 17 DAH. Lipase activity increased significantly 4 DAH and increased progressively with larval growth. Amylase activity was also detected in newly hatched larvae and increased 7 DAH followed by a gradual decrease. High free amino acid (FAA) content was detected in starry flounder eggs (110.72 mg/g dry weight). Total FAA content dropped to 43.29 mg/g in 4-DAH larvae and then decreased gradually to 13.74 mg/g in 24-DAH larvae. Most FAAs (except lysine and methionine) decreased >50% in 4-DAH larvae compared with those in eggs and then decreased to the lowest values in 24-DAH larvae. Changes in the protein amino acid (PAA) profile were much milder than those observed for FAAs. Most PAAs increased gradually during larval development, except lysine and phenylalanine. The percentages of free threonine, valine, isoleucine, and leucine decreased until the end of the trial, whereas the protein forms of these four AAs followed the opposite trend. A comparison of the essential AA composition of live food (rotifers, Artemia nauplii, and Artemia metanauplii) and larvae suggested that methionine was potentially the first limiting AA. These results may help develop starry flounder larviculture methods by solving the AA imbalance in live food. Moreover, the increased digestive enzyme activities indicate the possibility of introducing artificial compound feed.

  12. Ontogenetic development of digestive functionality in golden pompano Trachinotus ovatus (Linnaeus 1758).

    Science.gov (United States)

    Ma, Zhenhua; Guo, Huayang; Zheng, Panlong; Wang, Long; Jiang, Shigui; Qin, Jian G; Zhang, Dianchang

    2014-08-01

    Ontogenetic development of the digestive system in golden pompano (Trachinotus ovatus, Linnaeus 1758) larvae was histologically and enzymatically studied from hatch to 32 day post-hatch (DPH). The development of digestive system in golden pompano can be divided into three phases: phase I starting from hatching and ending at the onset of exogenous feeding; phase II starting from first feeding (3 DPH) and finishing at the formation of gastric glands; and phase III starting from the appearance of gastric glands on 15 DPH and continuing onward. The specific activities of trypsin, amylase, and lipase increased sharply from the onset of first feeding to 5-7 DPH, followed by irregular fluctuations. Toward the end of this study, the specific activities of trypsin and amylase showed a declining trend, while the lipase activity remained at similar levels as it was at 5 DPH. The specific activity of pepsin was first detected on 15 DPH and increased with fish age. The dynamics of digestive enzymes corresponded to the structural development of the digestive system. The enzyme activities tend to be stable after the formation of the gastric glands in fish stomach on 15 DPH. The composition of digestive enzymes in larval pompano indicates that fish are able to digest protein, lipid and carbohydrate at early developmental stages. Weaning of larval pompano is recommended from 15 DPH onward. Results of the present study lead to a better understanding of the ontogeny of golden pompano during the larval stage and provide a guide to feeding and weaning of this economically important fish in hatcheries.

  13. Ontogenetic variation in the mandibular ramus of great apes and humans.

    Science.gov (United States)

    Terhune, Claire E; Robinson, Chris A; Ritzman, Terrence B

    2014-06-01

    Considerable variation exists in mandibular ramus form among primates, particularly great apes and humans. Recent analyses of adult ramal morphology have suggested that features on the ramus, especially the coronoid process and sigmoid notch, can be treated as phylogenetic characters that can be used to reconstruct relationships among great ape and fossil hominin taxa. Others have contended that ramal morphology is more influenced by function than phylogeny. In addition, it remains unclear how ontogeny of the ramus contributes to adult variation in great apes and humans. Specifically, it is unclear whether differences among adults appear early and are maintained throughout ontogeny, or if these differences appear, or are enhanced, during later development. To address these questions, the present study examined a broad ontogenetic sample of great apes and humans using two-dimensional geometric morphometric analysis. Variation within and among species was summarized using principal component and thin plate spline analyses, and Procrustes distances and discriminant function analyses were used to statistically compare species and age classes. Results suggest that morphological differences among species in ramal morphology appear early in ontogeny and persist into adulthood. Morphological differences among adults are particularly pronounced in the height and angulation of the coronoid process, the depth and anteroposterior length of the sigmoid notch, and the inclination of the ramus. In all taxa, the ascending ramus of the youngest specimens is more posteriorly inclined in relation to the occlusal plane, shifting to become more upright in adults. These results suggest that, although there are likely functional influences over the form of the coronoid process and ramus, the morphology of this region can be profitably used to differentiate among great apes, modern humans, and fossil hominid taxa. Copyright © 2014 Wiley Periodicals, Inc.

  14. The Ontogenetically Variable Trophic Niche of a Praying Mantid Revealed by Stable Isotope Analysis.

    Science.gov (United States)

    Hurd, Lawrence E; Dehart, Pieter A P; Taylor, Joseph M; Campbell, Meredith C; Shearer, Megan M

    2015-04-01

    Praying mantids have been shown to exert strong influences on arthropod community composition. However, they may not occupy the same trophic level throughout their lives. Trophic shifting over a life cycle could explain the documented variation in results from field studies, but specific interactions of predators within food webs have been difficult to determine simply by comparing control and treatment assemblages in field experiments. We examined the trophic position of the Chinese praying mantid, Tenodera aridifolia sinensis (Saussure), using stable isotope analysis (SIA). We measured the δ(13)C and δ(15)N of field-collected arthropods, and of laboratory groups of mantids fed known diets of these arthropods chosen from the most abundant trophic guilds: herbivores (sap feeders and plant chewers), and carnivores. We also collected mantids from the field over a growing season and compared their SIA values to those of the laboratory groups. Both δ(13)C and δ(15)N of mantids fed carnivorous prey (spiders or other mantids) were higher than those fed herbivores (grasshoppers). SIA values from field-collected mantids were highly variable, and indicated that they did not take prey from trophic guilds in proportion to their abundances, i.e., were not frequency-dependent predators. Further, δ(15)N decreased from a high at egg hatch to a low at the third instar as early nymphs fed mainly on lower trophic levels, and increased steadily thereafter as they shifted to feeding on higher levels. We suggest that the community impact of generalist predators can be strongly influenced by ontogenetic shifts in diet. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Ontogenetic variations in the venom proteome of the Amazonian snake Bothrops atrox

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    Sousa Marcelo V

    2006-05-01

    Full Text Available Abstract Background Bothrops atrox is responsible for the majority of snakebite accidents in the Brazilian Amazon region. Previous studies have demonstrated that the biological and pharmacological activities of B. atrox venom alter with the age of the animal. Here, we present a comparative proteome analysis of B. atrox venom collected from specimens of three different stages of maturation: juveniles, sub-adults and adults. Results Optimized conditions for two-dimensional gel electrophoresis (2-DE of pooled venom samples were achieved using immobilized pH gradient (IPG gels of non-linear 3–10 pH range during the isoelectric focusing step and 10–20% gradient polyacrylamide gels in the second dimension. Software-assisted analysis of the 2-DE gels images demonstrated differences in the number and intensity of spots in juvenile, sub-adult and adult venoms. Although peptide mass fingerprinting (PMF failed to identify even a minor fraction of spots, it allowed us to group spots that displayed similar peptide maps. The spots were subjected to a combination of tandem mass spectrometry and Mascot and MS BLAST database searches that identified several classes of proteins, including metalloproteinases, serine proteinases, lectins, phospholipases A2, L-amino oxidases, nerve growth factors, vascular endothelial growth factors and cysteine-rich secretory proteins. Conclusion The analysis of B. atrox samples from specimens of different ages by 2-DE and mass spectrometry suggested that venom proteome alters upon ontogenetic development. We identified stage specific and differentially expressed polypeptides that may be responsible for the activities of the venom in each developmental stage. The results provide insight into the molecular basis of the relation between symptomatology of snakebite accidents in humans and the venom composition. Our findings underscore the importance of the use of venoms from individual specimen at various stages of maturation for

  16. Relative feeding specialization may depress ontogenetic, seasonal, and sexual variations in diet: the endemic lizard Cnemidophorus littoralis (Teiidae

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    Teixeira-Filho P. F.

    2003-01-01

    Full Text Available We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22º57'S, 43º50'W, Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm³, and grouped in four classes (active, sedentary, and clumped preys, and plant material. The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry. Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA. Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.

  17. Relative feeding specialization may depress ontogenetic, seasonal, and sexual variations in diet: the endemic lizard Cnemidophorus littoralis (Teiidae

    Directory of Open Access Journals (Sweden)

    P. F. Teixeira-Filho

    Full Text Available We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22º57'S, 43º50'W, Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm³, and grouped in four classes (active, sedentary, and clumped preys, and plant material. The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry. Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA. Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.

  18. Evaluating hair as a predictor of blood mercury: the influence of ontogenetic phase and life history in pinnipeds

    Science.gov (United States)

    Peterson, Sarah H.; McHuron, Elizabeth A.; Kennedy, Stephanie N.; Ackerman, Joshua T.; Rea, Lorrie D.; Castellini, J. Margaret; O'Hara, Todd M.; Costa, Daniel P.

    2016-01-01

    Mercury (Hg) biomonitoring of pinnipeds increasingly utilizes nonlethally collected tissues such as hair and blood. The relationship between total Hg concentrations ([THg]) in these tissues is not well understood for marine mammals, but it can be important for interpretation of tissue concentrations with respect to ecotoxicology and biomonitoring. We examined [THg] in blood and hair in multiple age classes of four pinniped species. For each species, we used paired blood and hair samples to quantify the ability of [THg] in hair to predict [THg] in blood at the time of sampling and examined the influence of varying ontogenetic phases and life history of the sampled animals. Overall, we found that the relationship between [THg] in hair and blood was affected by factors including age class, weaning status, growth, and the time difference between hair growth and sample collection. Hair [THg] was moderately to strongly predictive of current blood [THg] for adult female Steller sea lions (Eumetopias jubatus), adult female California sea lions (Zalophus californianus), and adult harbor seals (Phoca vitulina), whereas hair [THg] was poorly predictive or not predictive (different times of year) of blood [THg] for adult northern elephant seals (Mirounga angustirostris). Within species, except for very young pups, hair [THg] was a weaker predictor of blood [THg] for prereproductive animals than for adults likely due to growth, variability in foraging behavior, and transitions between ontogenetic phases. Our results indicate that the relationship between hair [THg] and blood [THg] in pinnipeds is variable and that ontogenetic phase and life history should be considered when interpreting [THg] in these tissues.

  19. Retrospective characterization of ontogenetic shifts in killer whale diets via δ13C and δ15N analysis of teeth

    Science.gov (United States)

    Newsome, Seth D.; Etnier, Michael A.; Monson, Daniel H.; Fogel, Marilyn L.

    2009-01-01

    Metabolically inert, accretionary structures such as the dentin growth layers in teeth provide a life history record of individual diet with near-annual resolution. We constructed ontogenetic δ13C and δ15N profiles by analyzing tooth dentin growth layers from 13 individual killer whales Orcinus orca collected in the eastern northeast Pacific Ocean between 1961 and 2003. The individuals sampled were 6 to 52 yr old, representing 2 ecotypes—resident and transient—collected across ~25° of latitude. The average isotopic values of transient individuals (n = 10) are consistent with a reliance on mammalian prey, while the average isotopic values of residents (n = 3) are consistent with piscivory. Regardless of ecotype, most individuals show a decrease in δ15N values of ~2.5‰ through the first 3 yr of life, roughly equivalent to a decrease of one trophic level. We interpret this as evidence of gradual weaning, after which, ontogenetic shifts in isotopic values are highly variable. A few individuals (n = 2) maintained relatively stable δ15N and δ13C values throughout the remainder of their lives, whereas δ15N values of most (n = 11) increased by ~1.5‰, suggestive of an ontogenetic increase in trophic level. Significant differences in mean δ13C and δ15N values among transients collected off California suggest that individuality in prey preferences may be prevalent within this ecotype. Our approach provides retrospective individual life history and dietary information that cannot be obtained through traditional field observations of free-ranging and elusive species such as killer whales, including unique historic ecological information that pre-dates modern studies. By providing insights into individual diet composition, stable isotope analysis of teeth and/or bones may be the only means of evaluating a number of hypothesized historical dietary shifts in killer whales of the northeast Pacific Ocean

  20. Cognitive bias modification for depression

    OpenAIRE

    Koster, Ernst; Hoorelbeke, Kristof

    2015-01-01

    The past decades have witnessed intense research on valence-specific information processing biases in depression. Cognitive bias modification (CBM) is a technique that attempts to experimentally modify processing biases through extended computerized training to understand their causal role in the maintenance of depression. Moreover, reducing maladaptive processing biases has clinical potential. The current paper discusses the current state-of-the-art on CBM at the level of attentional, interp...

  1. Cognitive bias modification: induced interpretive biases affect memory.

    Science.gov (United States)

    Tran, Tanya B; Hertel, Paula T; Joormann, Jutta

    2011-02-01

    Previous research has shown that it is possible to experimentally induce interpretive biases using ambiguous scenarios. This study extends past findings by examining the effects of cognitive bias modification for interpretation on subsequent scenario recall. Participants were trained to interpret emotionally ambiguous passages in either a positive or negative direction. Transfer of the training to novel scenarios was tested. After training, participants were also asked to recall details from these novel scenarios. The results indicate that the training was effective in inducing the intended group differences in interpretive bias. Importantly, participants exhibited memory biases that corresponded to their training condition. These results suggest that manipulating interpretive biases can result in corresponding changes in memory. Findings from this study highlight the importance of future research on the relation among cognitive biases and on the possibility of modifying cognitive biases in emotional disorders. PsycINFO Database Record (c) 2011 APA, all rights reserved.

  2. Test Bias and the Elimination of Racism

    Science.gov (United States)

    Sedlacek, William E.

    1977-01-01

    Three types of test bias are discussed: content bias, atmosphere bias, and use bias. Use bias is considered the most important. Tests reflect the bias in society, and eliminating test bias means eliminating racism and sexism in society. A six-stage model to eliminate racism and sexism is presented. (Author)

  3. Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata

    Science.gov (United States)

    Ennen, Joshua R.; Lindeman, Peter V.; Lovich, Jeffrey E.

    2015-01-01

    Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves.

  4. Ontogenetic modulation of branch size, shape, and biomechanics produces diversity across habitats in the Bursera simaruba clade of tropical trees.

    Science.gov (United States)

    Rosell, Julieta A; Olson, Mark E; Aguirre-Hernández, Rebeca; Sánchez-Sesma, Francisco J

    2012-01-01

    Organismal size and shape inseparably interact with tissue biomechanical properties. It is therefore essential to understand how size, shape, and biomechanics interact in ontogeny to produce morphological diversity. We estimated within species branch length-diameter allometries and reconstructed the rates of ontogenetic change along the stem in mechanical properties across the simaruba clade in the tropical tree genus Bursera, measuring 376 segments from 97 branches in nine species in neotropical dry to rain forest. In general, species with stiffer materials had longer, thinner branches, which became stiffer more quickly in ontogeny than their counterparts with more flexible materials. We found a trend from short stature and flexible tissues to tall statures and stiff tissues across an environmental gradient of increasing water availability, likely reflecting a water storage-mechanical support tradeoff. Ontogenetic variation in size, shape, and mechanics results in diversity of habits, for example, rapid length extension, sluggish diameter expansion, and flexible tissues results in a liana, as in Bursera instabilis. Even species of similar habit exhibited notable changes in tissue mechanical properties with increasing size, illustrating the inseparable relationship between organismal proportions and their tissue mechanics in the ontogeny and evolution of morphological diversity. © 2012 Wiley Periodicals, Inc.

  5. As the sword grows: individual variation and ontogenetic effects of a sexually selected trait on locomotor performance in Xiphophorus hellerii.

    Science.gov (United States)

    Oufiero, Christopher E; Jugo, Kristine; Tran, Paulina; Garland, Theodore

    2012-01-01

    Previous studies aimed at detecting costs of sexually selected traits have yielded mixed results partly because of variable methods. We present a novel approach: a repeated-measures design to examine individual variation in locomotor performance of male Xiphophorus hellerii as the sexually selected sword develops ontogenetically and to determine whether the growth of a sexually selected trait alters consistency of performance. Individual differences in sprint speed, critical swimming speed (stamina), and relative sword length were statistically repeatable over 9 wk. However, using the Akaike Information Criterion corrected for small sample sizes, the best-fit predictive models for swimming performance did not include sword length or relative sword length. Furthermore, in less supported models and within-week comparisons, there was no statistically significant effect of sword length on performance. These results suggest little effect of the sword on locomotor abilities, which is inconsistent with results from some previous experimental manipulations, possibly because compensatory traits develop ontogenetically in parallel with the sword. However, our results are consistent with correlational studies of natural variation that suggest no locomotor cost of the sword. These results do not necessarily imply a complete lack of a cost to the sword but rather lack of a functional cost for swimming performance.

  6. Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris

    Directory of Open Access Journals (Sweden)

    Colby eMoore

    2014-06-01

    Full Text Available Northern elephant seals (Mirounga angustirostris (NES are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb concentrations in the longissimus dorsi (LD muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults may provide a protection against ischemia reperfusion (IR injury in vasoconstricted peripheral skeletal muscle.

  7. Evolution of extreme ontogenetic allometric diversity and heterochrony in pythons, a clade of giant and dwarf snakes.

    Science.gov (United States)

    Esquerré, Damien; Sherratt, Emma; Keogh, J Scott

    2017-12-01

    Ontogenetic allometry, how species change with size through their lives, and heterochony, a decoupling between shape, size, and age, are major contributors to biological diversity. However, macroevolutionary allometric and heterochronic trends remain poorly understood because previous studies have focused on small groups of closely related species. Here, we focus on testing hypotheses about the evolution of allometry and how allometry and heterochrony drive morphological diversification at the level of an entire species-rich and diverse clade. Pythons are a useful system due to their remarkably diverse and well-adapted phenotypes and extreme size disparity. We collected detailed phenotype data on 40 of the 44 species of python from 1191 specimens. We used a suite of analyses to test for shifts in allometric trajectories that modify morphological diversity. Heterochrony is the main driver of initial divergence within python clades, and shifts in the slopes of allometric trajectories make exploration of novel phenotypes possible later in divergence history. We found that allometric coefficients are highly evolvable and there is an association between ontogenetic allometry and ecology, suggesting that allometry is both labile and adaptive rather than a constraint on possible phenotypes. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  8. Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata.

    Science.gov (United States)

    Ennen, Joshua R; Lindeman, Peter V; Lovich, Jeffrey E

    2015-06-01

    Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves.

  9. Ontogenetic trajectory and allometry of Diplonychus rusticus (Fabricius), an Oriental aquatic bug (Hemiptera: Belostomatidae) from the Western Ghats of India.

    Science.gov (United States)

    Doke, Dnyaneshwar; Morey, Rashmi; Dahanukar, Neelesh; Padhye, Sameer M; Paripatyadar, Shruti V

    2017-03-01

    Despite being one of the dominant groups in freshwater ecosystems, morphological and ontogenetic studies on aquatic Hemiptera have received little attention in the Oriental region. We present the ontogenetic trajectory and allometry of the widespread Oriental belostomatid species, Diplonychus rusticus (Fabricius) for the first time. We have measured nine different morphological variables throughout the growth of the bug using both field captured and laboratory reared specimens. Our results suggest that the developmental instars can be distinguished by the size variables, as seen in the Principal Component Analysis. On the basis of a CHAID (Chi-squared Automatic Interaction Detection) based regression tree, we also show that the characters - total length without head and maximum width - prove to be adequate for effective instar identification. The multivariate allometric growth pattern shows that different body parts exhibit different types of allometry. This is apparent in the allometry exhibited by forelegs and mid and hind legs, which show allometry of opposite polarities. This may be due to the different functions attributed to these body parts. Our results show that the growth pattern in D. rusticus is comparable with the New World genus Belostoma, suggesting a conserved growth pattern in the family Belostomatidae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. IgG-switched CLL has a distinct immunogenetic signature from the common MD variant: ontogenetic implications.

    Science.gov (United States)

    Vardi, Anna; Agathangelidis, Andreas; Sutton, Lesley-Ann; Chatzouli, Maria; Scarfò, Lydia; Mansouri, Larry; Douka, Vassiliki; Anagnostopoulos, Achilles; Darzentas, Nikos; Rosenquist, Richard; Ghia, Paolo; Belessi, Chrysoula; Stamatopoulos, Kostas

    2014-01-15

    Immunoglobulin G-switched chronic lymphocytic leukemia (G-CLL) is a rare variant of CLL, whose origin and ontogenetic relationship to the common IgM/IgD (MD-CLL) variant remains undefined. Here, we sought for clues about the ontogeny of G-CLL versus MD-CLL by profiling the relevant IG gene repertoires. Using purpose-built bioinformatics methods, we performed detailed immunogenetic profiling of a multinational CLL cohort comprising 1,256 cases, of which 1,087 and 169 expressed IG mu/delta and gamma heavy chains, respectively. G-CLL has a highly skewed IG gene repertoire that is distinct from MD-CLL, especially in terms of (i) overuse of the IGHV4-34 and IGHV4-39 genes and (ii) differential somatic hypermutation (SHM) load. Repertoire differences were also found when comparing subgroups with similar SHM status and were mainly attributed to the exclusive representation in G-CLL of two major subsets with quasi-identical (stereotyped) B-cell receptors. These subsets, namely #4 (IGHV4-34/IGKV2-30) and #8 (IGHV4-39/IGKV1(D)-39), were found to display sharply contrasting SHM and clinical behavior. G-CLL exhibits an overall distinct immunogenetic signature from MD-CLL, prompting speculations about distinct ontogenetic derivation and/or immune triggering. The reasons underlying the differential regulation of SHM among G-CLL cases remain to be elucidated. ©2013 AACR.

  11. Bias modification training can alter approach bias and chocolate consumption.

    Science.gov (United States)

    Schumacher, Sophie E; Kemps, Eva; Tiggemann, Marika

    2016-01-01

    Recent evidence has demonstrated that bias modification training has potential to reduce cognitive biases for attractive targets and affect health behaviours. The present study investigated whether cognitive bias modification training could be applied to reduce approach bias for chocolate and affect subsequent chocolate consumption. A sample of 120 women (18-27 years) were randomly assigned to an approach-chocolate condition or avoid-chocolate condition, in which they were trained to approach or avoid pictorial chocolate stimuli, respectively. Training had the predicted effect on approach bias, such that participants trained to approach chocolate demonstrated an increased approach bias to chocolate stimuli whereas participants trained to avoid such stimuli showed a reduced bias. Further, participants trained to avoid chocolate ate significantly less of a chocolate muffin in a subsequent taste test than participants trained to approach chocolate. Theoretically, results provide support for the dual process model's conceptualisation of consumption as being driven by implicit processes such as approach bias. In practice, approach bias modification may be a useful component of interventions designed to curb the consumption of unhealthy foods. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Sizing of SRAM Cell with Voltage Biasing Techniques for Reliability Enhancement of Memory and PUF Functions

    Directory of Open Access Journals (Sweden)

    Chip-Hong Chang

    2016-08-01

    Full Text Available Static Random Access Memory (SRAM has recently been developed into a physical unclonable function (PUF for generating chip-unique signatures for hardware cryptography. The most compelling issue in designing a good SRAM-based PUF (SPUF is that while maximizing the mismatches between the transistors in the cross-coupled inverters improves the quality of the SPUF, this ironically also gives rise to increased memory read/write failures. For this reason, the memory cells of existing SPUFs cannot be reused as storage elements, which increases the overheads of cryptographic system where long signatures and high-density storage are both required. This paper presents a novel design methodology for dual-mode SRAM cell optimization. The design conflicts are resolved by using word-line voltage modulation, dynamic voltage scaling, negative bit-line and adaptive body bias techniques to compensate for reliability degradation due to transistor downsizing. The augmented circuit-level techniques expand the design space to achieve a good solution to fulfill several otherwise contradicting key design qualities for both modes of operation, as evinced by our statistical analysis and simulation results based on complementary metal–oxide–semiconductor (CMOS 45 nm bulk Predictive Technology Model.

  13. Diagnostic biases in translational bioinformatics.

    Science.gov (United States)

    Han, Henry

    2015-08-01

    With the surge of translational medicine and computational omics research, complex disease diagnosis is more and more relying on massive omics data-driven molecular signature detection. However, how to detect and prevent possible diagnostic biases in translational bioinformatics remains an unsolved problem despite its importance in the coming era of personalized medicine. In this study, we comprehensively investigate the diagnostic bias problem by analyzing benchmark gene array, protein array, RNA-Seq and miRNA-Seq data under the framework of support vector machines for different model selection methods. We further categorize the diagnostic biases into different types by conducting rigorous kernel matrix analysis and provide effective machine learning methods to conquer the diagnostic biases. In this study, we comprehensively investigate the diagnostic bias problem by analyzing benchmark gene array, protein array, RNA-Seq and miRNA-Seq data under the framework of support vector machines. We have found that the diagnostic biases happen for data with different distributions and SVM with different kernels. Moreover, we identify total three types of diagnostic biases: overfitting bias, label skewness bias, and underfitting bias in SVM diagnostics, and present corresponding reasons through rigorous analysis. Compared with the overfitting and underfitting biases, the label skewness bias is more challenging to detect and conquer because it can be easily confused as a normal diagnostic case from its deceptive accuracy. To tackle this problem, we propose a derivative component analysis based support vector machines to conquer the label skewness bias by achieving the rivaling clinical diagnostic results. Our studies demonstrate that the diagnostic biases are mainly caused by the three major factors, i.e. kernel selection, signal amplification mechanism in high-throughput profiling, and training data label distribution. Moreover, the proposed DCA-SVM diagnosis provides a

  14. Gender bias affects forests worldwide

    Science.gov (United States)

    Marlène Elias; Susan S Hummel; Bimbika S Basnett; Carol J.P. Colfer

    2017-01-01

    Gender biases persist in forestry research and practice. These biases result in reduced scientific rigor and inequitable, ineffective, and less efficient policies, programs, and interventions. Drawing from a two-volume collection of current and classic analyses on gender in forests, we outline five persistent and inter-related themes: gendered governance, tree tenure,...

  15. Official bias in intergenerational transmission

    NARCIS (Netherlands)

    Besemer, S.; Farrington, D.P.; Bijleveld, C.C.J.H.

    2013-01-01

    We investigated to what extent children of convicted parents might have a higher risk of a conviction themselves because criminal justice systems, such as the police and courts, focus more attention towards certain criminal families - a concept called official bias. Bias was measured using several

  16. Heuristic Biases in Mathematical Reasoning

    Science.gov (United States)

    Inglis, Matthew; Simpson, Adrian

    2005-01-01

    In this paper we briefly describe the dual process account of reasoning, and explain the role of heuristic biases in human thought. Concentrating on the so-called matching bias effect, we describe a piece of research that indicates a correlation between success at advanced level mathematics and an ability to override innate and misleading…

  17. Bias in clinical intervention research

    DEFF Research Database (Denmark)

    Gluud, Lise Lotte

    2006-01-01

    Research on bias in clinical trials may help identify some of the reasons why investigators sometimes reach the wrong conclusions about intervention effects. Several quality components for the assessment of bias control have been suggested, but although they seem intrinsically valid, empirical...

  18. Setting the reference for the use of Chironomus sancticaroli (Diptera: Chironomidae as bioindicator: Ontogenetic pattern of larval head structures

    Directory of Open Access Journals (Sweden)

    Débora Rebechi

    2012-04-01

    Full Text Available Species of Chironomidae are widely used as bioindicators of water quality, since their larvae undergo morphological deformities when in contact with sediment contaminated with chemicals. In this work we endeavored to study the morphology of head structures (antennae, mandible, mentum, pecten epipharyngis, ventromental plate and premandible throughout the development of the four larval instars of Chironomus sancticaroli Strixino & Strixino, 1981, which can be used in environmental impact analyses. Our results show that it is possible to differentiate among larval instars by doing a quantitative analysis on the number of striae on the ventromental plates. The six structures analyzed changed during larval ontogeny. These changes are part of the ontogeny of the immature stages not exposed to xenobiotics. We believe that the morphological pattern defined in this work can be used for comparisons with ontogenetic changes observed in field studies conducted in polluted environments.

  19. Ontogenetic body-mass scaling of nitrogen excretion relates to body surface area in diverse pelagic invertebrates

    DEFF Research Database (Denmark)

    Hirst, Andrew G.; Lilley, M.K.S.; Glazier, D.S.

    2017-01-01

    . Among diverse pelagic invertebrates that change shape during ontogeny, recent analysis has demonstrated a significant positive correlation between the body-mass allometry of respiration rates (measured as the ontogenetic body mass-scaling exponent bR) and the allometry of body surface area (b......A, as predicted from body-shape changes using a Euclidean model). As many pelagic invertebrates use a large portion of their external body surface for both resource uptake and waste excretion, we predicted that body-mass scaling exponents for rates of excretion of soluble N (bN) should also then relate...... to the degree of body-shape change during growth. We tested this hypothesis using literature data on bN for 39 species of pelagic invertebrates across five different phyla, and find strong support: bN is significantly positively correlated with predicted bA, whilst also co-varying with bR. Intraspecific...

  20. Ontogenetic and among-individual variation in foraging strategies of northeast Pacific white sharks based on stable isotope analysis.

    Science.gov (United States)

    Kim, Sora L; Tinker, M Tim; Estes, James A; Koch, Paul L

    2012-01-01

    There is growing evidence for individuality in dietary preferences and foraging behaviors within populations of various species. This is especially important for apex predators, since they can potentially have wide dietary niches and a large impact on trophic dynamics within ecosystems. We evaluate the diet of an apex predator, the white shark (Carcharodon carcharias), by measuring the stable carbon and nitrogen isotope composition of vertebral growth bands to create lifetime records for 15 individuals from California. Isotopic variations in white shark diets can reflect within-region differences among prey (most importantly related to trophic level), as well as differences in baseline values among the regions in which sharks forage, and both prey and habitat preferences may shift with age. The magnitude of isotopic variation among sharks in our study (>5‰ for both elements) is too great to be explained solely by geographic differences, and so must reflect differences in prey choice that may vary with sex, size, age and location. Ontogenetic patterns in δ(15)N values vary considerably among individuals, and one third of the population fit each of these descriptions: 1) δ(15)N values increased throughout life, 2) δ(15)N values increased to a plateau at ∼5 years of age, and 3) δ(15)N values remained roughly constant values throughout life. Isotopic data for the population span more than one trophic level, and we offer a qualitative evaluation of diet using shark-specific collagen discrimination factors estimated from a 3+ year captive feeding experiment (Δ(13)C(shark-diet) and Δ(15)N(shark-diet) equal 4.2‰ and 2.5‰, respectively). We assess the degree of individuality with a proportional similarity index that distinguishes specialists and generalists. The isotopic variance is partitioned among differences between-individual (48%), within-individuals (40%), and by calendar year of sub-adulthood (12%). Our data reveal substantial ontogenetic and

  1. Ontogenetic and among-individual variation in foraging strategies of northeast Pacific white sharks based on stable isotope analysis

    Science.gov (United States)

    Kim, S.L.; Tinker, M. Tim; Estes, J.A.; Koch, P.L.

    2012-01-01

    There is growing evidence for individuality in dietary preferences and foraging behaviors within populations of various species. This is especially important for apex predators, since they can potentially have wide dietary niches and a large impact on trophic dynamics within ecosystems. We evaluate the diet of an apex predator, the white shark (Carcharodon carcharias), by measuring the stable carbon and nitrogen isotope composition of vertebral growth bands to create lifetime records for 15 individuals from California. Isotopic variations in white shark diets can reflect within-region differences among prey (most importantly related to trophic level), as well as differences in baseline values among the regions in which sharks forage, and both prey and habitat preferences may shift with age. The magnitude of isotopic variation among sharks in our study (>5‰ for both elements) is too great to be explained solely by geographic differences, and so must reflect differences in prey choice that may vary with sex, size, age and location. Ontogenetic patterns in δ15N values vary considerably among individuals, and one third of the population fit each of these descriptions: 1) δ15N values increased throughout life, 2) δ15N values increased to a plateau at ~5 years of age, and 3) δ15N values remained roughly constant values throughout life. Isotopic data for the population span more than one trophic level, and we offer a qualitative evaluation of diet using shark-specific collagen discrimination factors estimated from a 3+ year captive feeding experiment (Δ13Cshark-diet and Δ15Nshark-diet equal 4.2‰ and 2.5‰, respectively). We assess the degree of individuality with a proportional similarity index that distinguishes specialists and generalists. The isotopic variance is partitioned among differences between-individual (48%), within-individuals (40%), and by calendar year of sub-adulthood (12%). Our data reveal substantial ontogenetic and individual dietary

  2. Ontogenetic and among-individual variation in foraging strategies of northeast Pacific white sharks based on stable isotope analysis.

    Directory of Open Access Journals (Sweden)

    Sora L Kim

    Full Text Available There is growing evidence for individuality in dietary preferences and foraging behaviors within populations of various species. This is especially important for apex predators, since they can potentially have wide dietary niches and a large impact on trophic dynamics within ecosystems. We evaluate the diet of an apex predator, the white shark (Carcharodon carcharias, by measuring the stable carbon and nitrogen isotope composition of vertebral growth bands to create lifetime records for 15 individuals from California. Isotopic variations in white shark diets can reflect within-region differences among prey (most importantly related to trophic level, as well as differences in baseline values among the regions in which sharks forage, and both prey and habitat preferences may shift with age. The magnitude of isotopic variation among sharks in our study (>5‰ for both elements is too great to be explained solely by geographic differences, and so must reflect differences in prey choice that may vary with sex, size, age and location. Ontogenetic patterns in δ(15N values vary considerably among individuals, and one third of the population fit each of these descriptions: 1 δ(15N values increased throughout life, 2 δ(15N values increased to a plateau at ∼5 years of age, and 3 δ(15N values remained roughly constant values throughout life. Isotopic data for the population span more than one trophic level, and we offer a qualitative evaluation of diet using shark-specific collagen discrimination factors estimated from a 3+ year captive feeding experiment (Δ(13C(shark-diet and Δ(15N(shark-diet equal 4.2‰ and 2.5‰, respectively. We assess the degree of individuality with a proportional similarity index that distinguishes specialists and generalists. The isotopic variance is partitioned among differences between-individual (48%, within-individuals (40%, and by calendar year of sub-adulthood (12%. Our data reveal substantial ontogenetic and

  3. Growth trajectories in the cave bear and its extant relatives: an examination of ontogenetic patterns in phylogeny.

    Science.gov (United States)

    Fuchs, Manuela; Geiger, Madeleine; Stange, Madlen; Sánchez-Villagra, Marcelo R

    2015-11-02

    The study of postnatal ontogeny can provide insights into evolution by offering an understanding of how growth trajectories have evolved resulting in adult morphological disparity. The Ursus lineage is a good subject for studying cranial and mandibular shape and size variation in relation to postnatal ontogeny and phylogeny because it is at the same time not diverse but the species exhibit different feeding ecologies. Cranial and mandibular shapes of Ursus arctos (brown bear), U. maritimus (polar bear), U. americanus (American black bear), and the extinct U. spelaeus (cave bear) were examined, using a three-dimensional geometric morphometric approach. Additionally, ontogenetic series of crania and mandibles of U. arctos and U. spelaeus ranging from newborns to senile age were sampled. The distribution of specimens in morphospace allowed to distinguish species and age classes and the ontogenetic trajectories U. arctos and U. spelaeus were found to be more similar than expected by chance. Cranial shape changes during ontogeny are largely size related whereas the evolution of cranial shape disparity in this clade appears to be more influenced by dietary adaptation than by size and phylogeny. The different feeding ecologies are reflected in different cranial and mandibular shapes among species. The cranial and mandibular shape disparity in the Ursus lineage appears to be more influenced by adaptation to diet than by size or phylogeny. In contrast, the cranial and mandibular shape changes during postnatal ontogeny in U. arctos and U. spelaeus are probably largely size related. The patterns of morphospace occupation of the cranium and the mandible in adults and through ontogeny are different.

  4. Ontogenetic allometry constrains cranial shape of the head-first burrowing worm lizard Cynisca leucura (Squamata: Amphisbaenidae).

    Science.gov (United States)

    Hipsley, Christy A; Rentinck, Marc-Nicolas; Rödel, Mark-Oliver; Müller, Johannes

    2016-09-01

    Amphisbaenians are fossorial, predominantly limbless squamate reptiles with distinct cranial shapes corresponding to specific burrowing behaviors. Due to their cryptic lifestyles and the scarcity of museum specimens, little is known of their intraspecific variation, particularly regarding cranial osteology. This represents a critical lack of information, because the majority of morphological investigations of squamate relationships are based on cranial characters. We investigated cranial variation in the West African Coast Worm Lizard Cynisca leucura, a round-headed member of the Amphisbaenidae. Using geometric morphometric analyses of three-dimensional computed tomographic scans, we found that cranial osteology of C. leucura is highly conserved, with the majority of shape changes occurring during growth as the cranium becomes more slender and elongate, accompanied by increasing interdigitation among the dermal roofing bones. Elements of the ventral portion of the cranium remain loosely connected in adults, possibly as a protective mechanism against repeated compression and torsion during burrow excavation. Intraspecific variation was strongly correlated with size change from juveniles to adults, indicating a dominant role of ontogenetic allometry in determining cranial shape. We found no evidence of sexual dimorphism, either during growth or among adults. Given the fossorial habits of C. leucura, we hypothesize that cranial allometry is under strong stabilizing selection to maintain adequate proportions for head-first digging, thereby constraining the ability of individuals to respond to differing selection pressures, including sexual selection and variation in diet or microhabitat. For species in which digging imposes less mechanical stress (e.g., in softer sand), allometric associations during growth may be weakened, allowing changes to the ontogenetic trajectory and subsequent morphological traits. Such developmental dissociation between size and shape, known

  5. Large-scale galaxy bias

    Science.gov (United States)

    Jeong, Donghui; Desjacques, Vincent; Schmidt, Fabian

    2018-01-01

    Here, we briefly introduce the key results of the recent review (arXiv:1611.09787), whose abstract is as following. This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy (or halo) statistics. We then review the excursion set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

  6. Observational biases for transiting planets

    Science.gov (United States)

    Kipping, David M.; Sandford, Emily

    2016-12-01

    Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 au of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.

  7. Administrative bias in South Africa

    Directory of Open Access Journals (Sweden)

    E S Nwauche

    2005-01-01

    Full Text Available This article reviews the interpretation of section 6(2(aii of the Promotion of Administrative Justice Act which makes an administrator “biased or reasonably suspected of bias” a ground of judicial review. In this regard, the paper reviews the determination of administrative bias in South Africa especially highlighting the concept of institutional bias. The paper notes that inspite of the formulation of the bias ground of review the test for administrative bias is the reasonable apprehension test laid down in the case of President of South Africa v South African Rugby Football Union(2 which on close examination is not the same thing. Accordingly the paper urges an alternative interpretation that is based on the reasonable suspicion test enunciated in BTR Industries South Africa (Pty Ltd v Metal and Allied Workers Union and R v Roberts. Within this context, the paper constructs a model for interpreting the bias ground of review that combines the reasonable suspicion test as interpreted in BTR Industries and R v Roberts, the possibility of the waiver of administrative bias, the curative mechanism of administrative appeal as well as some level of judicial review exemplified by the jurisprudence of article 6(1 of the European Convention of Human Rights, especially in the light of the contemplation of the South African Magistrate Court as a jurisdictional route of judicial review.

  8. Cognitive Biases Questionnaire for psychosis.

    Science.gov (United States)

    Peters, Emmanuelle R; Moritz, Steffen; Schwannauer, Matthias; Wiseman, Zoe; Greenwood, Kathryn E; Scott, Jan; Beck, Aaron T; Donaldson, Catherine; Hagen, Roger; Ross, Kerry; Veckenstedt, Ruth; Ison, Rebecca; Williams, Sally; Kuipers, Elizabeth; Garety, Philippa A

    2014-03-01

    The Cognitive Biases Questionnaire for psychosis (CBQp) was developed to capture 5 cognitive distortions (jumping to conclusions, intentionalising, catastrophising, emotional reasoning, and dichotomous thinking), which are considered important for the pathogenesis of psychosis. Vignettes were adapted from the Cognitive Style Test (CST),(1) relating to "Anomalous Perceptions" and "Threatening Events" themes. Scale structure, reliability, and validity were investigated in a psychosis group, and CBQp scores were compared with those of depressed and healthy control samples. The CBQp showed good internal consistency and test-retest reliability. The 5 biases were not independent, with a 2-related factor scale providing the best fit. This structure suggests that the CBQp assesses a general thinking bias rather than distinct cognitive errors, while Anomalous Perception and Threatening Events theme scores can be used separately. Total CBQp scores showed good convergent validity with the CST, but individual biases were not related to existing tasks purporting to assess similar reasoning biases. Psychotic and depressed populations scored higher than healthy controls, and symptomatic psychosis patients scored higher than their nonsymptomatic counterparts, with modest relationships between CBQp scores and symptom severity once emotional disorders were partialled out. Anomalous Perception theme and Intentionalising bias scores showed some specificity to psychosis. Overall, the CBQp has good psychometric properties, although it is likely that it measures a different construct to existing tasks, tentatively suggested to represent a bias of interpretation rather than reasoning, judgment or decision-making processes. It is a potentially useful tool in both research and clinical arenas.

  9. Cognitive Bias in Systems Verification

    Science.gov (United States)

    Larson, Steve

    2012-01-01

    Working definition of cognitive bias: Patterns by which information is sought and interpreted that can lead to systematic errors in decisions. Cognitive bias is used in diverse fields: Economics, Politics, Intelligence, Marketing, to name a few. Attempts to ground cognitive science in physical characteristics of the cognitive apparatus exceed our knowledge. Studies based on correlations; strict cause and effect is difficult to pinpoint. Effects cited in the paper and discussed here have been replicated many times over, and appear sound. Many biases have been described, but it is still unclear whether they are all distinct. There may only be a handful of fundamental biases, which manifest in various ways. Bias can effect system verification in many ways . Overconfidence -> Questionable decisions to deploy. Availability -> Inability to conceive critical tests. Representativeness -> Overinterpretation of results. Positive Test Strategies -> Confirmation bias. Debiasing at individual level very difficult. The potential effect of bias on the verification process can be managed, but not eliminated. Worth considering at key points in the process.

  10. Heuristics and bias in homeopathy.

    Science.gov (United States)

    Souter, K

    2006-10-01

    The practice of Homeopathy ought to be strictly logical. In the Organon Samuel Hahnemann gives the impression that the unprejudiced observer should be able to follow an algorithmic route to the simillimum in every case. Judgement and Decision Research, however, indicates that when people grapple with complex systems like homeopathy they are more likely to use heuristics or empirical rules to help them reach a solution. Thus Hahnemann's concept of the unprejudiced observer is virtually impossible to attain. There is inevitable bias in both case-taking and remedy selection. Understanding the types of bias may enable the practitioner to reduce his/her own bias.

  11. Integration and search engine bias

    OpenAIRE

    de Corniere, A; Taylor, G.

    2014-01-01

    Competition authorities all over the world worry that integration between search engines (mainly Google) and publishers could lead to abuses of dominant position. In particular, one concern is that of own-content bias, meaning that Google would bias its rankings in favor of the publishers it owns or has an interest in, to the detriment of competitors and users. In order to investigate this issue, we develop a theoretical framework in which the search engine (i) allocates users across publishe...

  12. Political bias: a content analysis

    OpenAIRE

    Jarochová, Erika

    2015-01-01

    This thesis aims to chart political bias in the news coverage during the election campaigns in years 2006, 2010 and 2013 in three the most widely read serious newspapers in the Czech Republic. The thesis summarizes theoretical framework of political bias. Newspapers in liberal-democratic countries should inform about political parties balanced. Content analysis was used to analyze the newspapers. This thesis compares the information balance in newspapers from several perspectives. It compares...

  13. Procrastination with variable present bias

    OpenAIRE

    Gravin, Nick; Immorlica, Nicole; Lucier, Brendan; Pountourakis, Emmanouil

    2016-01-01

    Individuals working towards a goal often exhibit time inconsistent behavior, making plans and then failing to follow through. One well-known model of such behavioral anomalies is present-bias discounting: individuals over-weight present costs by a bias factor. This model explains many time-inconsistent behaviors, but can make stark predictions in many settings: individuals either follow the most efficient plan for reaching their goal or procrastinate indefinitely. We propose a modification in...

  14. Preferences, country bias, and international trade

    NARCIS (Netherlands)

    S. Roy (Santanu); J.M.A. Viaene (Jean-Marie)

    1998-01-01

    textabstractAnalyzes international trade where consumer preferences exhibit country bias. Why country biases arise; How trade can occur in the presence of country bias; Implication for the pattern of trade and specialization.

  15. Ontogenetic study of the skull in modern humans and the common chimpanzees: neotenic hypothesis reconsidered with a tridimensional Procrustes analysis.

    Science.gov (United States)

    Penin, Xavier; Berge, Christine; Baylac, Michel

    2002-05-01

    Heterochronic studies compare ontogenetic trajectories of an organ in different species: here, the skulls of common chimpanzees and modern humans. A growth trajectory requires three parameters: size, shape, and ontogenetic age. One of the great advantages of the Procrustes method is the precise definition of size and shape for whole organs such as the skull. The estimated ontogenetic age (dental stages) is added to the plot to give a graphical representation to compare growth trajectories. We used the skulls of 41 Homo sapiens and 50 Pan troglodytes at various stages of growth. The Procrustes superimposition of all specimens was completed by statistical procedures (principal component analysis, multivariate regression, and discriminant function) to calculate separately size-related shape changes (allometry common to chimpanzees and humans), and interspecific shape differences (discriminant function). The results confirm the neotenic theory of the human skull (sensu Gould [1977] Ontogeny and Phylogeny, Cambridge: Harvard University Press; Alberch et al. [1979] Paleobiology 5:296-317), but modify it slightly. Human growth is clearly retarded in terms of both the magnitude of changes (size-shape covariation) and shape alone (size-shape dissociation) with respect to the chimpanzees. At the end of growth, the adult skull in humans reaches an allometric shape (size-related shape) which is equivalent to that of juvenile chimpanzees with no permanent teeth, and a size which is equivalent to that of adult chimpanzees. Our results show that human neoteny involves not only shape retardation (paedomorphosis), but also changes in relative growth velocity. Before the eruption of the first molar, human growth is accelerated, and then strongly decelerated, relative to the growth of the chimpanzee as a reference. This entails a complex process, which explains why these species reach the same overall (i.e., brain + face) size in adult stage. The neotenic traits seem to concern

  16. Ontogenetic changes in feeding and food preferences of the dog conch Laevistrombus canarium Linnaeus 1758 (Mollusca: Gastropoda) from Merambong shoal, Malaysia

    Science.gov (United States)

    Husna, Wan Nurul Wan Hassan; Mazlan, Abd Ghaffar; Cob, Zaidi Che

    2017-09-01

    Laevistrombus canarium is one of the marine gastropod mollusks that have high commercial value, particularly in the aquaculture sector in Malaysia. This study was conducted to determine the feeding and food items of L. canarium at different ontogenetic stages (juveniles, sub-adults and adults) from Merambong shoals, Malaysia. Field observations on feeding activity were conducted, followed by detailed laboratory analysis on the stomach content. Five-minutes observations on randomly selected individuals were conducted at the field sampling site and their feeding activities were recorded with reference to age stage. Various shell sizes from each ontogenetic stage were randomly collected and quickly anaesthetized with ice and preserved in 10% formalin before being transported to the laboratory for stomach content analyses. Field observations showed that L. canarium mainly grazed on epiphytes occurring on seagrass (46.67%), followed by sediment surface (40%) and epiphytes occurring on macroalgae (13.33%). Stomach content analyses showed a significant difference ( P Food items found in the conch stomach include diatoms, detritus, foraminifera, seagrass and macroalgae fragments, sand particles and shell fragments. The Index of Relative Importance (%IRI) indicates three main types of food dominated the three ontogenetic stages namely diatoms, sand particles and detritus. However, no significant difference ( P >0.05) was detected between the three main food items (diatoms, sand particles and detritus) among the ontogenetic stages. Therefore, feeding activity revealed the role of the dog conch in the marine food network. While, classification of the types of food consumed by L. canarium through stomach content analysis determines the particular position of the gastropod in the food chain. Further studies are needed to provide a better insight between trophic relationships of L. canarium with marine ecosystem.

  17. Ontogenetic Change in the Temporal Region of the Early Permian Parareptile Delorhynchus cifellii and the Implications for Closure of the Temporal Fenestra in Amniotes.

    Directory of Open Access Journals (Sweden)

    Yara Haridy

    Full Text Available A juvenile specimen of Delorhynchus cifellii, collected from the Early Permian fissure-fill deposits of Richards Spur, Oklahoma, permits the first detailed study of cranial ontogeny in this parareptile. The specimen, consisting of a partially articulated skull and mandible, exhibits several features that identify it as juvenile. The dermal tuberosities that ornament the dorsal side and lateral edges of the largest skull of D. cifellii specimens, are less prominent in the intermediate sized holotype, and are absent in the new specimen. This indicates that the new specimen represents an earlier ontogenetic stage than all previously described members of this species. In addition, the incomplete interdigitation of the sutures, most notably along the fronto-nasal contact, plus the proportionally larger sizes of the orbit and temporal fenestrae further support an early ontogenetic stage for this specimen. Comparisons between this juvenile and previously described specimens reveal that the size and shape of the temporal fenestra in Delorhynchus appear to vary through ontogeny, due to changes in the shape and size of the bordering cranial elements. The jugal of the juvenile specimen is tri-radiate and similar in outline with those found in other amniotes with temporal fenestrae. The available growth series of D. cifellii shows that the jugal gradually becomes a more robust, tetra-radiate element, as the proportionate size of the temporal fenestra is reduced. Ontogenetic changes of other elements that form the border of the fenestra also contribute to its reduction. This growth series provides valuable new information regarding the ontogenetic trajectory of the temporal fenestra in a Palaeozoic reptile, which may be applicable to the evolutionary event of loss of temporal fenestration in other amniotes.

  18. Ontogenetic changes in the bacterial symbiont community of the tropical demosponge Amphimedon queenslandica: metamorphosis is a new beginning

    Directory of Open Access Journals (Sweden)

    Rebecca A Fieth

    2016-11-01

    Full Text Available Vertical transmission of bacterial symbionts, which is known in many species of sponge (Porifera, is expected to promote strong fidelity between the partners. Combining 16S rRNA gene amplicon sequencing and electron microscopy, we have assayed the relative abundance of vertically-inherited bacterial symbionts in several stages of the life cycle of Amphimedon queenslandica, a tropical coral reef sponge. We reveal that adult A. queenslandica house a low diversity microbiome dominated by just three proteobacterial OTUs, with a single gammaprotebacterium clearly dominant through much of the life cycle. This ontogenetic perspective has revealed that, although vertical transmission occurs very early in development, the inherited symbionts do not maintain proportional dominance of the bacterial community at every developmental stage. A reproductive bottleneck in the A. queenslandica life cycle is larval settlement, when a free-swimming pelagic larva settles out of the water column onto the benthos and completes metamorphoses into the sessile body plan within just 3 to 4 days. During this dramatic life cycle transition, an influx of environmentally-derived bacteria leads to a major reorganization of the microbiome, potentially challenging the fidelity and persistence of the vertically-inherited symbiotic relationships. However, dominance of the primary, vertically-inherited symbionts is restored in adult sponges. The mechanisms underlying ontogenetic changes in the bacterial community are unknown, including how the dominance of the primary symbionts is restored in the adult sponge – does the host or symbiont regulate this process? Using high-resolution transcriptional profiling in multiple stages of the A. queenslandica life cycle combined with this natural perturbation of the microbiome immediately following larval settlement, we are beginning to identify candidate host genes associated with animal-bacterial crosstalk. Among the sponge host genes

  19. Modulation by K+ Plus NH4+ of microsomal (Na+, K+-ATPase activity in selected ontogenetic stages of the diadromous river shrimp Macrobrachium amazonicum (Decapoda, Palaemonidae.

    Directory of Open Access Journals (Sweden)

    Francisco A Leone

    Full Text Available We investigate the synergistic stimulation by K(+ plus NH4 (+ of (Na(+, K(+-ATPase activity in microsomal preparations of whole zoea I and decapodid III, and in juvenile and adult river shrimp gills. Modulation of (Na(+, K(+-ATPase activity is ontogenetic stage-specific, and particularly distinct between juveniles and adults. Although both gill enzymes exhibit two different sites for K(+ and NH4 (+ binding, in the juvenile enzyme, these two sites are equivalent: binding by both ions results in slightly stimulated activity compared to that of a single ionic species. In the adult enzyme, the sites are not equivalent: when one ion occupies its specific binding site, (Na(+, K(+-ATPase activity is stimulated synergistically by ≈ 50% on binding of the complementary ion. Immunolocalization reveals the enzyme to be distributed predominantly throughout the intralamellar septum in the gill lamellae of juveniles and adults. Western blot analyses demonstrate a single immunoreactive band, suggesting a single (Na(+, K(+-ATPase α-subunit isoform that is distributed into different density membrane fractions, independently of ontogenetic stage. We propose a model for the modulation by K(+ and NH4 (+ of gill (Na(+, K(+-ATPase activity. These findings suggest that the gill enzyme may be regulated by NH4 (+ during ontogenetic development in M. amazonicum.

  20. Modulation by K+ Plus NH4+ of microsomal (Na+, K+)-ATPase activity in selected ontogenetic stages of the diadromous river shrimp Macrobrachium amazonicum (Decapoda, Palaemonidae).

    Science.gov (United States)

    Leone, Francisco A; Bezerra, Thais M S; Garçon, Daniela P; Lucena, Malson N; Pinto, Marcelo R; Fontes, Carlos F L; McNamara, John C

    2014-01-01

    We investigate the synergistic stimulation by K(+) plus NH4 (+) of (Na(+), K(+))-ATPase activity in microsomal preparations of whole zoea I and decapodid III, and in juvenile and adult river shrimp gills. Modulation of (Na(+), K(+))-ATPase activity is ontogenetic stage-specific, and particularly distinct between juveniles and adults. Although both gill enzymes exhibit two different sites for K(+) and NH4 (+) binding, in the juvenile enzyme, these two sites are equivalent: binding by both ions results in slightly stimulated activity compared to that of a single ionic species. In the adult enzyme, the sites are not equivalent: when one ion occupies its specific binding site, (Na(+), K(+))-ATPase activity is stimulated synergistically by ≈ 50% on binding of the complementary ion. Immunolocalization reveals the enzyme to be distributed predominantly throughout the intralamellar septum in the gill lamellae of juveniles and adults. Western blot analyses demonstrate a single immunoreactive band, suggesting a single (Na(+), K(+))-ATPase α-subunit isoform that is distributed into different density membrane fractions, independently of ontogenetic stage. We propose a model for the modulation by K(+) and NH4 (+) of gill (Na(+), K(+))-ATPase activity. These findings suggest that the gill enzyme may be regulated by NH4 (+) during ontogenetic development in M. amazonicum.

  1. Interpretation bias characterizes trait rumination.

    Science.gov (United States)

    Mor, Nilly; Hertel, Paula; Ngo, Thuy Anh; Shachar, Tal; Redak, Shimrit

    2014-03-01

    Rumination, a maladaptive cognitive style of responding to negative mood, is thought to be maintained by a variety of cognitive biases. However, it is unknown whether rumination is characterized by interpretation biases. Two experiments examined the link between rumination and interpretation biases, revealed in lexical-decision tasks (LDT). A homograph with both benign and ruminative or otherwise negative meaning was presented on each trial and followed by a letter string, to which participants responded by judging whether it was a word or a non-word. Letter strings were non-words or words related or unrelated to one meaning of the homograph. In both experiments, faster latencies to respond to targets related to the ruminative meaning of the homographs were produced by students with higher scores on self-report measures of rumination. Moreover, these biases were associated with both brooding, the maladaptive form of rumination, and reflection, the more adaptive component. No measure of rumination was significantly correlated with general biases toward negative meaning (Experiment 1) or with threatening interpretations of homographs (Experiment 2). The paucity of available rumination-related homographs dictated the use of non-fully randomized stimuli presentation (Experiment 1) or the use of only one set of the meanings associated with the homographs (Experiment 2). Rumination is associated with a tendency to interpret ambiguous information in a rumination-consistent manner. This tendency may exacerbate ruminative thinking and can possibly be a target for future intervention. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Gender bias in academic recruitment

    DEFF Research Database (Denmark)

    Abramo, Giovanni; D’Angelo, Ciriaco Andrea; Rosati, Francesco

    2016-01-01

    It is well known that women are underrepresented in the academic systems of many countries. Gender discrimination is one of the factors that could contribute to this phenomenon. This study considers a recent national academic recruitment campaign in Italy, examining whether women are subject...... to more or less bias than men. The findings show that no gender-related differences occur among the candidates who benefit from positive bias, while among those candidates affected by negative bias, the incidence of women is lower than that of men. Among the factors that determine success in a competition...... for an academic position, the number of the applicant’s career years in the same university as the committee members assumes greater weight for male candidates than for females. Being of the same gender as the committee president is also a factor that assumes greater weight for male applicants. On the other hand...

  3. Anchoring bias in online voting

    Science.gov (United States)

    Yang, Zimo; Zhang, Zi-Ke; Zhou, Tao

    2012-12-01

    Voting online with explicit ratings could largely reflect people's preferences and objects' qualities, but ratings are always irrational, because they may be affected by many unpredictable factors like mood, weather and other people's votes. By analyzing two real systems, this paper reveals a systematic bias embedding in the individual decision-making processes, namely people tend to give a low rating after a low rating, as well as a high rating following a high rating. This so-called anchoring bias is validated via extensive comparisons with null models, and numerically speaking, the extent of bias decays with voting interval in a logarithmic form. Our findings could be applied in the design of recommender systems and considered as important complementary materials to previous knowledge about anchoring effects on financial trades, performance judgments, auctions, and so on.

  4. Venom Profiling of a Population of the Theraphosid Spider Phlogius crassipes Reveals Continuous Ontogenetic Changes from Juveniles through Adulthood.

    Science.gov (United States)

    Santana, Renan C; Perez, David; Dobson, James; Panagides, Nadya; Raven, Robert J; Nouwens, Amanda; Jones, Alun; King, Glenn F; Fry, Bryan G

    2017-03-25

    Theraphosid spiders (tarantulas) are venomous arthropods found in most tropical and subtropical regions of the world. Tarantula venoms are a complex cocktail of toxins with potential use as pharmacological tools, drugs and bioinsecticides. Although numerous toxins have been isolated from tarantula venoms, little research has been carried out on the venom of Australian tarantulas. We therefore investigated the venom profile of the Australian theraphosid spider Phlogius crassipes and examined whether there are ontogenetic changes in venom composition. Spiders were divided into four ontogenic groups according to cephalothorax length, then the venom composition of each group was examined using gel electrophoresis and mass spectrometry. We found that the venom of P. crassipes changes continuously during development and throughout adulthood. Our data highlight the need to investigate the venom of organisms over the course of their lives to uncover and understand the changing functions of venom and the full range of toxins expressed. This in turn should lead to a deeper understanding of the organism's ecology and enhance the potential for biodiscovery.

  5. Characterization of the juvenile green turtle (Chelonia mydas) microbiome throughout an ontogenetic shift from pelagic to neritic habitats

    Science.gov (United States)

    Price, James T.; Paladino, Frank V.; Lamont, Margaret M.; Witherington, Blair E.; Bates, Scott T.; Soule, Tanya

    2017-01-01

    The gut microbiome of herbivorous animals consists of organisms that efficiently digest the structural carbohydrates of ingested plant material. Green turtles (Chelonia mydas) provide an interesting model of change in these microbial communities because they undergo a pronounced shift from a surface-pelagic distribution and omnivorous diet to a neritic distribution and herbivorous diet. As an alternative to direct sampling of the gut, we investigated the cloacal microbiomes of juvenile green turtles before and after recruitment to neritic waters to observe any changes in their microbial community structure. Cloacal swabs were taken from individual turtles for analysis of the 16S rRNA gene sequences using Illumina sequencing. One fecal sample was also obtained, allowing for a preliminary comparison with the bacterial community of the cloaca. We found significant variation in the juvenile green turtle bacterial communities between pelagic and neritic habitats, suggesting that environmental and dietary factors support different bacterial communities in green turtles from these habitats. This is the first study to characterize the cloacal microbiome of green turtles in the context of their ontogenetic shifts, which could provide valuable insight into the origins of their gut bacteria and how the microbial community supports their shift to herbivory.

  6. Ontogenetic variability in old and new collections of Dicranophyllum gallicum Grand’Eury from the late Palaeozoic of Europe

    Science.gov (United States)

    Pas, Jorik Van Der; Poppe, Linda; Waveren, Isabel M. Van

    2017-01-01

    Abstract Dicranophyllum gallicum Grand’Eury is described by means of a morphometric analysis of eighty two samples from various old and new localities in western and central Europe. Stem, leaf cushions, leaf scars, leaves, axillary structures and potential seeds are described in detail, and discussed in comparison to earlier studies. The encountered variability in size and structure is shown to be higher than what was described earlier. The organisation of the leaf cushion and scar density vary gradually with the stem width, while stratigraphic position and ecology do not relate to it. It is concluded that the described variability represents an ontogenetic feature rather than a phylogenetic or ecologic one. The juvenile plants are characterised by small stems, a high leaf scar density and elongated leaf cushions with a dominant apical field, while mature specimens are characterized by a wide stem, a relatively low leaf scar density and relatively wide leaf cushions with a pronounced basal field. Axillary shoots and potential seeds of D. gallicum are described and illustrated in detail for the first time. A reconstruction based on the studied material is presented. PMID:29213207

  7. Statistical parametric mapping of the regional distribution and ontogenetic scaling of foot pressures during walking in Asian elephants (Elephas maximus).

    Science.gov (United States)

    Panagiotopoulou, Olga; Pataky, Todd C; Hill, Zoe; Hutchinson, John R

    2012-05-01

    Foot pressure distributions during locomotion have causal links with the anatomical and structural configurations of the foot tissues and the mechanics of locomotion. Elephant feet have five toes bound in a flexible pad of fibrous tissue (digital cushion). Does this specialized foot design control peak foot pressures in such giant animals? And how does body size, such as during ontogenetic growth, influence foot pressures? We addressed these questions by studying foot pressure distributions in elephant feet and their correlation with body mass and centre of pressure trajectories, using statistical parametric mapping (SPM), a neuro-imaging technology. Our results show a positive correlation between body mass and peak pressures, with the highest pressures dominated by the distal ends of the lateral toes (digits 3, 4 and 5). We also demonstrate that pressure reduction in the elephant digital cushion is a complex interaction of its viscoelastic tissue structure and its centre of pressure trajectories, because there is a tendency to avoid rear 'heel' contact as an elephant grows. Using SPM, we present a complete map of pressure distributions in elephant feet during ontogeny by performing statistical analysis at the pixel level across the entire plantar/palmar surface. We hope that our study will build confidence in the potential clinical and scaling applications of mammalian foot pressures, given our findings in support of a link between regional peak pressures and pathogenesis in elephant feet.

  8. A study of ontogenetic level of language development and gender differences affecting language use in Acehnese language

    Directory of Open Access Journals (Sweden)

    Muhammad Aulia

    2017-03-01

    Full Text Available There have been numerous studies analysing gender differences in language use. Most of them predominantly adopted static or hierarchical approach with obsolete understanding of gender differences. Concurrently with the high demand of socio-cultural aspects inclusion in language development studies, the research of gender in language use has also driven to the same direction with mixed talk and the use of dynamic approach as an alternative for more inclusive socio-cultural spectrum. Two student university classes were observed and their classroom conversations in mixed gender were meticulously selected for detailed analysis via N-VIVO. The study shows that social dimensions such as power, status, economy, and identity seem to be influential to Acehnese language users in mixed talks. Yet, some mixed talks are more likely to be affected by individual ontogenetic language development; the dominance of talk is relatively fading and mutual-respect is bold. Therefore, the advocacy for the dynamic approach to conducting further research in this domain is decisively important. It is also crucial for more thorough and deep analysis on the genetic language development of speakers such as their social backgrounds and study or learning experiences. This paper draws merely a minor part of a larger research project conducted in Aceh and is expected to be a trigger for future studies.

  9. Ontogenetic variability in old and new collections of Dicranophyllum gallicum Grand’Eury from the late Palaeozoic of Europe

    Directory of Open Access Journals (Sweden)

    Jorik Van der Pas

    2017-10-01

    Full Text Available Dicranophyllum gallicum Grand’Eury is described by means of a morphometric analysis of eighty two samples from various old and new localities in western and central Europe. Stem, leaf cushions, leaf scars, leaves, axillary structures and potential seeds are described in detail, and discussed in comparison to earlier studies. The encountered variability in size and structure is shown to be higher than what was described earlier. The organisation of the leaf cushion and scar density vary gradually with the stem width, while stratigraphic position and ecology do not relate to it. It is concluded that the described variability represents an ontogenetic feature rather than a phylogenetic or ecologic one. The juvenile plants are characterised by small stems, a high leaf scar density and elongated leaf cushions with a dominant apical field, while mature specimens are characterized by a wide stem, a relatively low leaf scar density and relatively wide leaf cushions with a pronounced basal field. Axillary shoots and potential seeds of D. gallicum are described and illustrated in detail for the first time. A reconstruction based on the studied material is presented.

  10. A new species of slender coralsnake from Colombia, and its clinal an ontogenetic variation (Serpentes, Elapidae: Leptomicrurus

    Directory of Open Access Journals (Sweden)

    William W. Lamar

    2003-09-01

    Full Text Available Leptomicrurus renjifoi is described from tropical semi-deciduous forest of the eastern Colombian llanos. It is one of the smallest species in the genus, is most similar to L. scutiventris, and it may be distinguished from known congeners by a combination of color, pattern, and scale characters. Evidence for the recognition of Leptomicrurus is convincing, although its members were recently thought to comprise a closely related assemblage within Micrurus. A supposedly aberrant specimen of L. scutiventris may indicate clinal or ontogenetic variation in patternLeptomicrurus renjifoi es una nueva especie de serpiente elápida del bosque tropical semi-decíduo de los llanos orientales de Colombia. Es una de las especies más pequeñas del género, se asemeja más a L. scutiventris, y se distingue de sus congéneres por una combinación de color, patrón, y carácteres de escamación. Existe suficiente evidencia morfológica para reconocer Leptomicrurus como género independiente, aunque hasta hace poco sus miembros fueron considerados como un grupo compacto dentro del género Micrurus

  11. Ontogenetic changes in the craniomandibular skeleton of the abelisaurid dinosaur Majungasaurus crenatissimus from the Late Cretaceous of Madagascar

    Directory of Open Access Journals (Sweden)

    Nirina O. Ratsimbaholison

    2016-06-01

    Full Text Available Abelisaurid theropods were one of the most diverse groups of predatory dinosaurs in Gondwana during the Cretaceous. The group is characterized by a tall, wide skull and robust cervical region. This morphology is thought to have facilitated specialized feeding behaviors such as prolonged contact with prey. The Late Cretaceous abelisaurid Majungasaurus crenatissimus typifies this abelisaurid cranial morphotype. Recent fossil discoveries of this species include a partial growth series that allows for the first time an investigation of ontogenetic variation in cranial morphology in a representative abelisaurid. Herein we examine growth trajectories in the shape of individual cranial bones and articulated skulls of Majungasaurus using geometric morphometrics. Several major changes in skull shape were observed through ontogeny, including an increase in the height of the jugal, postorbital, and quadratojugal, an increase in the extent of the contacts between bones, and a decrease in the circumference of the orbit. The skull transitions from relatively short in the smallest individual to tall and robust in large adults, as is seen in other theropods. Such morphological change during ontogeny would likely have resulted in different biomechanical properties and feeding behaviors between small and large individuals. These findings provide a post-hatching developmental framework for understanding the evolution of the distinctive tall skull morphology seen in abelisaurids and other large-sized theropod dinosaurs.

  12. Without Bias: A Guidebook for Nondiscriminatory Communication.

    Science.gov (United States)

    Pickens, Judy E., Ed.; And Others

    This guidebook discusses ways to eliminate various types of discrimination from business communications. Separately authored chapters discuss eliminating racial and ethnic bias; eliminating sexual bias; achieving communication sensitive about handicaps of disabled persons; eliminating bias from visual media; eliminating bias from meetings,…

  13. Measurement Bias Detection through Factor Analysis

    Science.gov (United States)

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

  14. Collection Development and the Psychology of Bias

    Science.gov (United States)

    Quinn, Brian

    2012-01-01

    The library literature addressing the role of bias in collection development emphasizes a philosophical approach. It is based on the notion that bias can be controlled by the conscious act of believing in certain values and adhering to a code of ethics. It largely ignores the psychological research on bias, which suggests that bias is a more…

  15. Bias in Dynamic Monte Carlo Alpha Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Sweezy, Jeremy Ed [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nolen, Steven Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Terry R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trahan, Travis John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-06

    A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.

  16. Medical practice and anthropological bias.

    Science.gov (United States)

    Bolton, J

    1995-06-01

    The purpose of this article is twofold: to describe some of the biases common to anthropological investigations of healing, particularly Biomedical healing; and to suggest that the physician-anthropologist is uniquely positioned to avoid some of these biases and to make valid contributions to the understanding of the practice of healing. Biases described are methodological (the tendency to formal-symbolic analyses rather than practical-instrumental understanding of behavior, transference and the observer effect), ontological (due to the estrangement of the anthropologist from his culture, other disciplines and his subjects, romanticization of the Other and celebration of the exotic over the mundane), and conventional or stylistic (the minimal importance given to emotional or psychological aspects of behavior, the emphasis on visual and linguistic understanding over other forms of investigation, unsophisticated use of medical texts as an indicator of clinical practice, a characteristic mode of reductionism, and the failure to elicit the responses of the subjects to interpretations made by anthropologists). As native-ethnographer, the M.D./Ph.D. physician-anthropologist may avoid some of these biases and offer complementary interpretations of healing.

  17. Gender bias in teaching evaluations

    NARCIS (Netherlands)

    Mengel, Friederike; Sauermann, Jan; Zölitz, Ulf Zoelitz

    2017-01-01

    This paper provides new evidence on gender bias in teaching evaluations. We exploit a quasi-experimental dataset of 19,952 student evaluations of university faculty in a context where students are randomly allocated to female or male instructors. Despite the fact that neither students’ grades nor

  18. Attentional Bias in Math Anxiety

    Directory of Open Access Journals (Sweden)

    Orly eRubinsten

    2015-10-01

    Full Text Available Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety as well (i.e., a persistent negative reaction to math. Twenty seven participants (14 with high levels of math anxiety and 13 with low levels of math anxiety were presented with a novel computerized numerical version of the well established dot probe task. One of 6 types of prime stimuli, either math related or typically neutral, were presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks. Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in math anxiety. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words. These findings suggest that attentional bias is linked to unduly intense math anxiety symptoms.

  19. Perception bias in route choice

    NARCIS (Netherlands)

    Vreeswijk, Jacob Dirk; Thomas, Tom; van Berkum, Eric C.; van Arem, Bart

    2014-01-01

    Travel time is probably one of the most studied attributes in route choice. Recently, perception of travel time received more attention as several studies have shown its importance in explaining route choice behavior. In particular, travel time estimates by travelers appear to be biased against non-

  20. Exploring Attribution Theory and Bias

    Science.gov (United States)

    Robinson, Jessica A.

    2017-01-01

    Courses: This activity can be used in a wide range of classes, including interpersonal communication, introduction to communication, and small group communication. Objectives: After completing this activity, students should be able to: (1) define attribution theory, personality attribution, situational attribution, and attribution bias; (2)…

  1. KERNELS THROUGH BIAS REDUCTION TECHNIQUE

    African Journals Online (AJOL)

    IMPROVING THE CHOICE OF HIGHER ORDER UNIVARIATE. KERNELS THROUGH BIAS REDUCTION TECHNIQUE. J. E. Osemwenkhae and J. I. Odiase. Department of Math ematics. University of Benin. Benin City, Nigeria. ABSTRACT. Within the last two decades, higher order nnivariate kernels ha/ve been under focus ...

  2. Perception bias in route choice

    NARCIS (Netherlands)

    Vreeswijk, Jacob Dirk; Thomas, Tom; van Berkum, Eric C.; van Arem, Bart

    2014-01-01

    Travel time is probably one of the most studied attributes in route choice. Recently, perception of travel time received more attention as several studies have shown its importance in explaining route choice behavior. In particular, travel time estimates by travelers appear to be biased against

  3. Comparative findings of voice and speech: language processing at an early ontogenetic age in quantitative EEG mapping.

    Science.gov (United States)

    Radicevic, Z; Vujovic, M; Jelicic, L; Sovilj, M

    2008-02-01

    Quantitative EEG mapping in powers of electrical activity, concentration of main powers and area of concentration in relation to the side of presentation (left, right, and bihemisphery) and closer location was done on a 24-day-old infant first, and again when the infant was 2.5 months. EEG responses are analyzed in following acoustic modalities: (1) specific (native language speech of mother and unfamiliar female, unfamiliar female speech of foreign language); (2) unspecific (passive period). Familiar and unfamiliar texts present the contents of speech material. Comparative findings on two different ages showed that the infant maintains the processing scheme of unfamiliar stimulus (passive period, foreign language), and also very similar processing scheme of unfamiliar voice regardless if the text in native language is familiar or unfamiliar. During stimulation with familiar or unfamiliar text in native language, which is read by mother, processing type is significantly changed in relation to the age at the time of examination. While a 24-day-old infant shows a similar scheme in processing the familiar and the unfamiliar voices in native language, at the age of 2.5 months, this scheme of processing is changed, especially for theta rhythm, which now has bihemisphery presentation (at earlier stage it has right-side presentation) in the F-C-P region, what is practically the same region where also delta rhythm is processed. However, the sample of unfamiliar voice in native language observed in subsequent period, when the infant was 2.5 months old, maintains the same processing location as it has at an earlier ontogenetic stage, when the infant was 24 days old, regarding the theta rhythm processed in the F-C-P region with right-side presentation, and delta rhythm processed in C-P region with bihemisphery presentation. Post stimuli periods observed when the infant was 2.5 months old show obviously differentiation of theta and delta rhythms' samples and their

  4. Ontogenetic investigation of underwater hearing capabilities in loggerhead sea turtles (Caretta caretta) using a dual testing approach.

    Science.gov (United States)

    Lavender, Ashley L; Bartol, Soraya M; Bartol, Ian K

    2014-07-15

    Sea turtles reside in different acoustic environments with each life history stage and may have different hearing capacity throughout ontogeny. For this study, two independent yet complementary techniques for hearing assessment, i.e. behavioral and electrophysiological audiometry, were employed to (1) measure hearing in post-hatchling and juvenile loggerhead sea turtles Caretta caretta (19-62 cm straight carapace length) to determine whether these migratory turtles exhibit an ontogenetic shift in underwater auditory detection and (2) evaluate whether hearing frequency range and threshold sensitivity are consistent in behavioral and electrophysiological tests. Behavioral trials first required training turtles to respond to known frequencies, a multi-stage, time-intensive process, and then recording their behavior when they were presented with sound stimuli from an underwater speaker using a two-response forced-choice paradigm. Electrophysiological experiments involved submerging restrained, fully conscious turtles just below the air-water interface and recording auditory evoked potentials (AEPs) when sound stimuli were presented using an underwater speaker. No significant differences in behavior-derived auditory thresholds or AEP-derived auditory thresholds were detected between post-hatchling and juvenile sea turtles. While hearing frequency range (50-1000/1100 Hz) and highest sensitivity (100-400 Hz) were consistent in audiograms pooled by size class for both behavior and AEP experiments, both post-hatchlings and juveniles had significantly higher AEP-derived than behavior-derived auditory thresholds, indicating that behavioral assessment is a more sensitive testing approach. The results from this study suggest that post-hatchling and juvenile loggerhead sea turtles are low-frequency specialists, exhibiting little differences in threshold sensitivity and frequency bandwidth despite residence in acoustically distinct environments throughout ontogeny. © 2014

  5. Spatial, temporal and ontogenetic variation in diet of anchovy ( Engraulis encrasicolus) on the Algerian coast (SW Mediterranean)

    Science.gov (United States)

    Bacha, M.; Amara, R.

    2009-11-01

    The diet of anchovy Engraulis encrasicolus was studied in three regions (Béjaia, Bénisaf and Ghazaouet) along the Algerian coast. Ontogenetic, spatial and seasonal variations in anchovy diet were investigated using multivariate analyses and analysed in relation with sea surface temperature and chlorophyll- a. 46 prey taxa of varying size between 0.57 mm ( Euterpina acutifrons) and 6.8 mm (fish larvae) were recorded. Whatever the season, the region or the fish size, anchovy is exclusively zooplanktivorous and copepods were the most present prey, constituting 87% by number of the prey taken and found in 98% of the anchovy stomachs examined. However, their occurrence and number varied according to the different areas, seasons and fish size. During its first year of life, anchovy feeds almost exclusively on copepods (mainly small and medium size prey). As anchovy grows, copepods are gradually substituted by large crustaceans such as decapods and amphipods. Hierarchical cluster analysis, analysis of similarities (ANOSIM) and similarities percentage (SIMPER) indicated a distinct diet of anchovy of the bay of Bejaia from those of the bays of Bénisaf and Ghazaouet probably due to differences in hydrologic conditions. Diet differences also occurred between seasons. Summer and spring have distinct prey assemblages each and showed low diet similarities with the two other seasons. More prey species were found in the diet during winter (36) and autumn (30) and the vacuity index was lower in winter. Temporal variability in satellite-derived chlorophyll- a matched the seasonal variability in the diversity of the anchovy prey and feeding intensity as reflected by the vacuity index, suggesting further investigation of the potential use of satellite-derived chlorophyll- a data as a proxy for anchovy feeding intensity.

  6. Ontogenetic behavior and migration of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, and shortnose sturgeon, A. brevirostrum, with notes on social behavior

    Science.gov (United States)

    Kynard, B.; Horgan, M.

    2002-01-01

    Ontogenetic behavior of Hudson River Atlantic sturgeon and Connecticut River shortnose sturgeon early life intervals were similar during laboratory observations. After hatching, free embryos were photonegative and sought cover. When embryos developed into larvae, fish left cover, were photopositive, and initiated downstream migration. Free embryos may remain at the spawning site instead of migrating downstream because the risk of predation at spawning sites is low. The two species are sympatric, but not closely related, so the similarities in innate behaviors suggest common adaptations, not phylogenetlc relationship. Atlantic sturgeon migrated downstream for 12 days (peak, first 6 days), shortnose sturgeon migrated for 3 days, and year-0 juveniles of both species did not resume downstream migration. Short or long migrations of larvae may reflect different styles related to the total migratory distance from spawning sites to juvenile rearing areas. Atlantic sturgeon need to move a short distance to reach rearing areas and they had a long 1-step migration of 6-12 days. In contrast, shortnose sturgeon need to move a long distance to reach all rearing areas. This may be accomplished by a 2-step migration, of which the brief migration of larvae is only the first step. Early migrant Atlantic sturgeon were nocturnal, while late migrants were diurnal, and shortnose sturgeon were diurnal. These diel differences may also be adaptations for long (Atlantic sturgeon) or short (shortnose sturgeon) migrations. Cultured shortnose sturgeon, and possibly Atlantic sturgeon, have a dominance hierarchy with large fish dominant when competing for limited foraging space. Social behavior may be more important in the life history of wild sturgeons than is generally recognized.

  7. Ontogenetic behavior and dispersal of Sacramento River white sturgeon, Acipenser transmontanus, with a note on body color

    Science.gov (United States)

    Kynard, B.; Parker, E.

    2005-01-01

    We studied Sacramento River white sturgeon, Acipenser transmontanus, in the laboratory to develop a conceptual model of ontogenetic behavior and provide insight into probable behavior of wild sturgeon. After hatching, free embryos initiated a low intensity, brief downstream dispersal during which fish swam near the bottom and were photonegative. The weak, short dispersal style and behavior of white sturgeon free embryos contrasts greatly with the intense, long dispersal style and behavior (photopositive and swimming far above the bottom) of dispersing free embryos of other sturgeon species. If spawned eggs are concentrated within a few kilometers downstream of a spawning site, the adaptive significance of the free embryo dispersal is likely to move fish away from the egg deposition site to avoid predation and reduce fish density prior to feeding. Larvae foraged on the open bottom, swam white sturgeon populations may be a mis-match between the innate fish dispersal and post-dispersal rearing habitat, which is now highly altered by damming and reservoirs. Sacramento River white sturgeon has a two-step downstream dispersal by the free embryo and juvenile life intervals. Diel activity of all life intervals peaked at night, whether fish were dispersing or foraging. Nocturnal behavior is likely a response to predation, which occurs during both activities. An intense black-tail body color was present on foraging larvae, but was weak or absent on the two life intervals that disperse. Black-tail color may be an adaptation for avoiding predation, signaling among aggregated larvae, or both, but not for dispersal. ?? Springer 2005.

  8. Morphological systematics of the kipunji (Rungwecebus kipunji) and the ontogenetic development of phylogenetically informative characters in the Papionini.

    Science.gov (United States)

    Gilbert, Christopher C; Stanley, William T; Olson, Link E; Davenport, Tim R B; Sargis, Eric J

    2011-06-01

    Since its discovery and description, the systematic position of the kipunji (Rungwecebus kipunji) has been a matter of debate. Although it was first placed in the mangabey genus Lophocebus, subsequent molecular studies indicated that the kipunji is most closely related to baboons (Papio). However, the kipunji does not appear to possess cranial features typical of Papio, thus necessitating the erection of a new genus, Rungwecebus. The recovery of an M2-stage subadult male kipunji voucher specimen, in addition to the original M1-stage subadult male voucher specimen, has since allowed further study. Here, we describe the craniodental morphology of the newly acquired kipunji specimen and present a phylogenetic analysis of Rungwecebus craniodental morphology using quantitative and qualitative characters. We examined the skulls of 76 M1- and M2-stage subadult males representing all extant papionin genera, taking note of character states that are static throughout ontogeny. To control for ontogenetic changes, only those characters expressing unchanged character states between subadult and adult specimens were coded for Rungwecebus and entered into a larger, recently published 151-character matrix of adult male morphology. To account for allometry, the narrow allometric coding method and the general allometric coding method were applied. The resulting most parsimonious trees suggest that Rungwecebus is phylogenetically closest to Lophocebus, a result consistent with initial morphological descriptions. However, due to the large amount of missing data for Rungwecebus, there are low bootstrap support values associated with any relationships within the larger Theropithecus/Papio/Lophocebus/Rungwecebus grouping. Taken in combination with previous molecular, phenetic, and ecological studies, the results of this study suggest that Rungwecebus is best regarded as a distinct genus closely related to Papio, Lophocebus, and Theropithecus. Adult morphological specimens are necessary

  9. Types of Research Bias Encountered in IR.

    Science.gov (United States)

    Gabr, Ahmed; Kallini, Joseph Ralph; Desai, Kush; Hickey, Ryan; Thornburg, Bartley; Kulik, Laura; Lewandowski, Robert J; Salem, Riad

    2016-04-01

    Bias is a systemic error in studies that leads to inaccurate deductions. Relevant biases in the field of IR and interventional oncology were identified after reviewing articles published in the Journal of Vascular and Interventional Radiology and CardioVascular and Interventional Radiology. Biases cited in these articles were divided into three categories: preinterventional (health care access, participation, referral, and sample biases), periinterventional (contamination, investigator, and operator biases), and postinterventional (guarantee-time, lead time, loss to follow-up, recall, and reporting biases). Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  10. Self-biased transconductance amplifier

    Science.gov (United States)

    Amendola, Gilles; Blanchard, Yves; Exertier, Anne; Spirkovitch, Serge; Lu, Guo N.; Alquie, George

    1999-09-01

    A CMOS, self-biased transconductance amplifier has been designed to be associated and integrated with a silicon capacitive microphone. To meet requirements especially on gain sensitivity, power consumption, and minimization of parasite capacitance effect, we have proposed a cascode structure with the cascode transistor source used as signa input. Switched-capacitor techniques have been applied for realizing self-bias for the amplifier and ensuring its high- gain operation. The proposed amplifier has been designed and fabricated in a 0.8 micrometers CMOS process. It has a surface area of 210 micrometers by 170 micrometers . Experimental results obtained from measuring the fabricated chip show a high-gain sensitivity and a low power dissipation for the amplifier. Results of simulations and measurements have been discussed.

  11. Variable-bias coin tossing

    Science.gov (United States)

    Colbeck, Roger; Kent, Adrian

    2006-03-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT.

  12. Belief bias and relational reasoning.

    Science.gov (United States)

    Roberts, Maxwell J; Sykes, Elizabeth D A

    2003-01-01

    When people evaluate categorical syllogisms, they tend to reject unbelievable conclusions and accept believable ones irrespective of their validity. Typically, this effect is particularly marked for invalid conclusions that are possible, but do not necessarily follow, given the premises. However, smaller believability effects can also be detected for other types of conclusion. Three experiments are reported here, in which an attempt was made to determine whether belief bias effects can manifest themselves on the relational inference task. Subjects evaluated the validity of conclusions such as William the Conqueror was king after the Pyramids were built (temporal task) or Manchester is north of Bournemouth (spatial task) with respect to their premises. All of the major findings for equivalent categorical syllogism tasks were replicated. However, the overall size of the main effect of believability appears to be related to task presentation, a phenomenon not previously identified for categorical syllogisms and which current theories of belief bias have difficulty explaining.

  13. Girl child and gender bias.

    Science.gov (United States)

    Chowdhry, D P

    1995-01-01

    This article identifies gender bias against female children and youth in India. Gender bias is based on centuries-old religious beliefs and sayings from ancient times. Discrimination is reflected in denial or ignorance of female children's educational, health, nutrition, and recreational needs. Female infanticide and selective abortion of female fetuses are other forms of discrimination. The task of eliminating or reducing gender bias will involve legal, developmental, political, and administrative measures. Public awareness needs to be created. There is a need to reorient the education and health systems and to advocate for gender equality. The government of India set the following goals for the 1990s: to protect the survival of the girl child and practice safe motherhood; to develop the girl child in general; and to protect vulnerable girl children in different circumstances and in special groups. The Health Authorities should monitor the laws carefully to assure marriage after the minimum age, ban sex determination of the fetus, and monitor the health and nutrition of pre-school girls and nursing and pregnant mothers. Mothers need to be encouraged to breast feed, and to breast feed equally between genders. Every village and slum area needs a mini health center. Maternal mortality must decline. Primary health centers and hospitals need more women's wards. Education must be universally accessible. Enrollments should be increased by educating rural tribal and slum parents, reducing distances between home and school, making curriculum more relevant to girls, creating more female teachers, and providing facilities and incentives for meeting the needs of girl students. Supplementary income could be provided to families for sending girls to school. Recreational activities must be free of gender bias. Dowry, sati, and devdasi systems should be banned.

  14. Opinion dynamics with confirmation bias.

    Directory of Open Access Journals (Sweden)

    Armen E Allahverdyan

    Full Text Available Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science.We formulate a (non-Bayesian model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect-when consecutively exposed to two opinions, the preference is given to the last opinion (recency or the first opinion (primacy -and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties.The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development.

  15. Opinion dynamics with confirmation bias.

    Science.gov (United States)

    Allahverdyan, Armen E; Galstyan, Aram

    2014-01-01

    Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect-when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) -and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development.

  16. A pharmacological primer of biased agonism.

    Science.gov (United States)

    Andresen, Bradley T

    2011-06-01

    Biased agonism is one of the fastest growing topics in G protein-coupled receptor pharmacology; moreover, biased agonists are used in the clinic today: carvedilol (Coreg®) is a biased agonist of beta-adrenergic receptors. However, there is a general lack of understanding of biased agonism when compared to traditional pharmacological terminology. Therefore, this review is designed to provide a basic introduction to classical pharmacology as well as G protein-coupled receptor signal transduction in order to clearly explain biased agonism for the non-scientist clinician and pharmacist. Special emphasis is placed on biased agonists of the beta-adrenergic receptors, as these drugs are highly prescribed, and a hypothetical scenario based on current clinical practices and proposed mechanisms for treating disease is discussed in order to demonstrate the need for a more thorough understanding of biased agonism in clinical settings. Since biased agonism provides a novel mechanism for treating disease, greater emphasis is being placed to develop biased agonists; therefore, it is important for biased agonism to be understood in equal measure of traditional pharmacological concepts. This review, along with many others, can be used to teach the basic concepts of biased agonism, and this review also serves to introduce the subsequent reviews that examine, in more depth, the relevance of biased agonism towards the angiotensin type 1 receptor, parathyroid hormone receptor, and natural biased ligands towards chemokine receptors.

  17. Modulation of carbon and nitrogen allocation in Urtica dioica and Plantago major by elevated CO{sub 2}. Impact of accumulation of nonstructural carbohydrates and ontogenetic drift

    Energy Technology Data Exchange (ETDEWEB)

    Hertog, J. den; Stulen, I.; Fonseca, F.; Delea, P.

    1996-10-01

    Doubling the atmospheric CO{sub 2} concentration from 350 to 700 {mu} l{sup -1} increased the relative growth rate (RGR) of hydroponically grown Urtica dioica L. and Plantagomajor ssp. pleiospherma Pilger only for the first 10-14 days. Previous experiments with P. major indicated that RGR did not respond i proportion to the rate of photosynthesis. The impact of changes in leaf morphology, dry matter partitioning, dry matter chemical composition and ontogenetic drift on this discrepancy is analysed. Soon after the start of the treatment, carbohydrate concentrations were higher at elevated CO{sub 2}; largely due to starch accumulation. An increase in the percentage of leaf dry matter and decreases in the specific leaf area (SLA) and the shoot nitrogen concentration were correlated with an increase in the total nonstructural carbohydrate concentration (TNC). A combination of accumulation of soluble sugars and starch and ontogenetic drift explains the decrease in SLA at the elevated CO{sub 2} level. A similar ontogenetic effect of elevated CO{sub 2} was observed on the specific root length (SRL). Shoot nitrogen concentration and percentage leaf dry matter were not affected. The net diurnal fluctuation of the carbohydrate pool in P. major was equal for both CO{sub 2} concentrations, indicating that the growth response to elevated CO{sub 2} may be ruled by other variables such as sink strength. Elevated CO{sub 2} did not greatly influence the partitioning of nitrogen between soluble and insoluble, reduced N and nitrate, nor the allocation of dry matter between leaf, stem and root. That the root to shoot ratio (F/S) was not affected by elevated CO{sub 2} implies that, to maintain a balanced activity between roots and shoot, no shift in partitioning of dry matter upon doubling of the atmospheric CO{sub 2} concentration is required. (AB)

  18. Ontogenetic changes in the expression of immune related genes in response to immunostimulants and resistance against white spot syndrome virus in Litopenaeus vannamei.

    Science.gov (United States)

    Rajkumar, T; Taju, G; Abdul Majeed, S; Sinwan Sajid, M; Santhosh Kumar, S; Sivakumar, S; Thamizhvanan, S; Vimal, S; Sahul Hameed, A S

    2017-11-01

    In recent years, researchers have focused on viral and plant immunostimulants which could have beneficial effects in disease prevention and control in shrimp culture. At present, the application of the recombinant VP28 protein (r-VP28) and herbal immunostimulant has been considered as a more effective approach to prevent white spot syndrome (WSS) by enhancing the immune response in shrimp. In the present study, expression of selected immune related genes in response to r-VP28 and herbal immunostimulant mix (HIM) were separately studied qualitatively and quantitatively by RT-PCR and real time PCR, respectively during ontogenetic development from nauplius to juvenile stage in Litopenaeus vannamei. The mRNA expression level of immune related genes such as anti-lipopolysaccharides (ALF), Lysozyme, cMnSOD, Crustin, Prophenoloxidase, Tumor necrosis factor receptor-associated factor 6 (TRAF6) and Haemocyanin were found to be up-regulated significantly in different ontogenetic development stages of shrimp fed with r-VP28 and HIM formulated diets. Relative percent survival (RPS) was determined in shrimp fed with immunostimulants formulated diets after oral challenge with WSSV. The survival of WSSV challenged shrimp was found to be higher in immunostimulants treated groups when compared to untreated group. The results of PCR, ELISA and real time PCR revealed the absence of WSSV in WSSV-challenged shrimp after 20 days of treatment with immunostimulants. Among these immunostimulants, HIM was found to be more effective when compared to r-VP28. After a survey of literature, we are of the opinion that this might be the first report on the expression of immune genes during ontogenetic development of L. vannamei in response to immunostimulants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Matrilateral Bias in Human Grandmothering

    Directory of Open Access Journals (Sweden)

    Martin Daly

    2017-09-01

    Full Text Available Children receive more care and resources from their maternal grandmothers than from their paternal grandmothers. This asymmetry is the “matrilateral bias” in grandmaternal investment. Here, we synopsize the evolutionary theories that predict such a bias, and review evidence of its cross-cultural generality and magnitude. Evolutionists have long maintained that investing in a daughter’s child yields greater fitness returns, on average, than investing in a son’s child because of paternity uncertainty: the son’s putative progeny may have been sired by someone else. Recent theoretical work has identified an additional natural selective basis for the matrilateral bias that may be no less important: supporting grandchildren lightens the load on their mother, increasing her capacity to pursue her fitness in other ways, and if she invests those gains either in her natal relatives or in children of a former or future partner, fitness returns accrue to the maternal, but not the paternal, grandmother. In modern democracies, where kinship is reckoned bilaterally and no postmarital residence norms restrict grandmaternal access to grandchildren, many studies have found large matrilateral biases in contact, childcare, and emotional closeness. In other societies, patrilineal ideology and postmarital residence with the husband’s kin (virilocality might be expected to have produced a patrilateral bias instead, but the available evidence refutes this hypothesis. In hunter-gatherers, regardless of professed norms concerning kinship and residence, mothers get needed help at and after childbirth from their mothers, not their mothers-in-law. In traditional agricultural and pastoral societies, patrilineal and virilocal norms are common, but young mothers still turn to their natal families for crucial help, and several studies have documented benefits, including reduced child mortality, associated with access to maternal, but not paternal, grandmothers. Even

  20. Intrapopulation variability in the timing of ontogenetic habitat shifts in sea turtles revealed using δ15 N values from bone growth rings.

    Science.gov (United States)

    Turner Tomaszewicz, Calandra N; Seminoff, Jeffrey A; Peckham, S Hoyt; Avens, Larisa; Kurle, Carolyn M

    2017-05-01

    Determining location and timing of ontogenetic shifts in the habitat use of highly migratory species, along with possible intrapopulation variation in these shifts, is essential for understanding mechanisms driving alternate life histories and assessing overall population trends. Measuring variations in multi-year habitat-use patterns is especially difficult for remote oceanic species. To investigate the potential for differential habitat use among migratory marine vertebrates, we measured the naturally occurring stable nitrogen isotope (δ15 N) patterns that differentiate distinct ocean regions to create a 'regional isotope characterization', analysed the δ15 N values from annual bone growth layer rings from dead-stranded animals, and then combined the bone and regional isotope data to track individual animal movement patterns over multiple years. We used humeri from juvenile North Pacific loggerhead turtles (Caretta caretta), animals that undergo long migrations across the North Pacific Ocean (NPO), using multiple discrete regions as they develop to adulthood. Typical of many migratory marine species, ontogenetic changes in habitat use throughout their decades-long juvenile stage is poorly understood, but each potential habitat has unique foraging opportunities and spatially explicit natural and anthropogenic threats that could affect key life-history parameters. We found a bimodal size/age distribution in the timing that juveniles underwent an ontogenetic habitat shift from the oceanic central North Pacific (CNP) to the neritic east Pacific region near the Baja California Peninsula (BCP) (42·7 ± 7·2 vs. 68·3 ± 3·4 cm carapace length, 7·5 ± 2·7 vs. 15·6 ± 1·7 years). Important to the survival of this population, these disparate habitats differ considerably in their food availability, energy requirements and threats, and these differences can influence life-history parameters such as growth, survival and future fecundity. This is the first

  1. Integrated "omics" profiling indicates that miRNAs are modulators of the ontogenetic venom composition shift in the Central American rattlesnake, Crotalus simus simus.

    Science.gov (United States)

    Durban, Jordi; Pérez, Alicia; Sanz, Libia; Gómez, Aarón; Bonilla, Fabián; Rodríguez, Santos; Chacón, Danilo; Sasa, Mahmood; Angulo, Yamileth; Gutiérrez, José M; Calvete, Juan J

    2013-04-10

    Understanding the processes that drive the evolution of snake venom is a topic of great research interest in molecular and evolutionary toxinology. Recent studies suggest that ontogenetic changes in venom composition are genetically controlled rather than environmentally induced. However, the molecular mechanisms underlying these changes remain elusive. Here we have explored the basis and level of regulation of the ontogenetic shift in the venom composition of the Central American rattlesnake, Crotalus s. simus using a combined proteomics and transcriptomics approach. Proteomic analysis showed that the ontogenetic shift in the venom composition of C. s. simus is essentially characterized by a gradual reduction in the expression of serine proteinases and PLA2 molecules, particularly crotoxin, a β-neurotoxic heterodimeric PLA2, concominantly with an increment of PI and PIII metalloproteinases at age 9-18 months. Comparison of the transcriptional activity of the venom glands of neonate and adult C. s. simus specimens indicated that their transcriptomes exhibit indistinguisable toxin family profiles, suggesting that the elusive mechanism by which shared transcriptomes generate divergent venom phenotypes may operate post-transcriptionally. Specifically, miRNAs with frequency count of 1000 or greater exhibited an uneven distribution between the newborn and adult datasets. Of note, 590 copies of a miRNA targeting crotoxin B-subunit was exclusively found in the transcriptome of the adult snake, whereas 1185 copies of a miRNA complementary to a PIII-SVMP mRNA was uniquely present in the newborn dataset. These results support the view that age-dependent changes in the concentration of miRNA modulating the transition from a crotoxin-rich to a SVMP-rich venom from birth through adulthood can potentially explain what is observed in the proteomic analysis of the ontogenetic changes in the venom composition of C. s. simus. Existing snake venom toxins are the result of early

  2. Integrated “omics” profiling indicates that miRNAs are modulators of the ontogenetic venom composition shift in the Central American rattlesnake, Crotalus simus simus

    Science.gov (United States)

    2013-01-01

    Background Understanding the processes that drive the evolution of snake venom is a topic of great research interest in molecular and evolutionary toxinology. Recent studies suggest that ontogenetic changes in venom composition are genetically controlled rather than environmentally induced. However, the molecular mechanisms underlying these changes remain elusive. Here we have explored the basis and level of regulation of the ontogenetic shift in the venom composition of the Central American rattlesnake, Crotalus s. simus using a combined proteomics and transcriptomics approach. Results Proteomic analysis showed that the ontogenetic shift in the venom composition of C. s. simus is essentially characterized by a gradual reduction in the expression of serine proteinases and PLA2 molecules, particularly crotoxin, a β-neurotoxic heterodimeric PLA2, concominantly with an increment of PI and PIII metalloproteinases at age 9–18 months. Comparison of the transcriptional activity of the venom glands of neonate and adult C. s. simus specimens indicated that their transcriptomes exhibit indistinguisable toxin family profiles, suggesting that the elusive mechanism by which shared transcriptomes generate divergent venom phenotypes may operate post-transcriptionally. Specifically, miRNAs with frequency count of 1000 or greater exhibited an uneven distribution between the newborn and adult datasets. Of note, 590 copies of a miRNA targeting crotoxin B-subunit was exclusively found in the transcriptome of the adult snake, whereas 1185 copies of a miRNA complementary to a PIII-SVMP mRNA was uniquely present in the newborn dataset. These results support the view that age-dependent changes in the concentration of miRNA modulating the transition from a crotoxin-rich to a SVMP-rich venom from birth through adulhood can potentially explain what is observed in the proteomic analysis of the ontogenetic changes in the venom composition of C. s. simus. Conclusions Existing snake venom

  3. A novel length back-calculation approach accounting for ontogenetic changes in the fish length - otolith size relationship during the early life of sprat (Sprattus sprattus)

    DEFF Research Database (Denmark)

    Guenther, Claudia C.; Temming, Axel; Baumann, Hannes

    2012-01-01

    An individual-based length back-calculation method was developed for juvenile Baltic sprat (Sprattus sprattus), accounting for ontogenetic changes in the relationship between fish length and otolith length. In sprat, metamorphosis from larvae to juveniles is characterized by the coincidence of low...... length growth, strong growth in body height, and maximal otolith growth. Consequently, the method identifies a point of metamorphosis for an individual as the otolith radius at maximum increment widths. By incorporating this information in our back-calculation method, estimated length growth...

  4. A new species of Hyla (Anura: Hylidae) from the Sierra Mixes, Oaxaca, Mexico, with comments on ontogenetic variation in the tadpoles

    Science.gov (United States)

    Ustach, P.C.; Mendelson, J.R.; McDiarmid, R.W.; Campbell, J.A.

    2000-01-01

    We describe a new species of Hyla that differs from the similar-loohng species H. pentheter by reaching a larger size, ha\\iing a smaller tympanum, more webbing on the feet, more extensive nuptial excrescences, and a different color pattern on the flanks. \\Ve tentatively place this new species in the phenetic assemblage commonly referred to as the H. bistincta group. \\Ve describe and illlistrate the tadpole and discuss ontogenetic variation among tadpoles, with reference to existing information on tadpoles of other species from the H. bistincta group.

  5. The Probability Distribution for a Biased Spinner

    Science.gov (United States)

    Foster, Colin

    2012-01-01

    This article advocates biased spinners as an engaging context for statistics students. Calculating the probability of a biased spinner landing on a particular side makes valuable connections between probability and other areas of mathematics. (Contains 2 figures and 1 table.)

  6. Primate enamel evinces long period biological timing and regulation of life history.

    Science.gov (United States)

    Bromage, Timothy G; Hogg, Russell T; Lacruz, Rodrigo S; Hou, Chen

    2012-07-21

    The factor(s) regulating the combination of traits that define the overall life history matrix of mammalian species, comprising attributes such as brain and body weight, age at sexual maturity, lifespan and others, remains a complete mystery. The principal objectives of the present research are (1) to provide evidence for a key variable effecting life history integration and (2) to provide a model for how one would go about investigating the metabolic mechanisms responsible for this rhythm. We suggest here that a biological rhythm with a period greater than the circadian rhythm is responsible for observed variation in primate life history. Evidence for this rhythm derives from studies of tooth enamel formation. Enamel contains an enigmatic periodicity in its microstructure called the striae of Retzius, which develops at species specific intervals in units of whole days. We refer to this enamel rhythm as the repeat interval (RI). For primates, we identify statistically significant relationships between RI and all common life history traits. Importantly, RI also correlates with basal and specific metabolic rates. With the exception of estrous cyclicity, all relationships share a dependence upon body mass. This dependence on body mass informs us that some aspect of metabolism is responsible for periodic energy allocations at RI timescales, regulating cell proliferation rates and growth, thus controlling the pace, patterning, and co-variation of life history traits. Estrous cyclicity relates to the long period rhythm in a body mass-independent manner. The mass-dependency and -independency of life history relationships with RI periodicity align with hypothalamic-mediated neurosecretory anterior and posterior pituitary outputs. We term this period the Havers-Halberg Oscillation (HHO), in reference to Clopton Havers, a 17th Century hard tissue anatomist, and Franz Halberg, a long-time explorer of long-period rhythms. We propose a mathematical model that may help elucidate the underlying physiological mechanism responsible for the HHO. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Expectancy bias mediates the link between social anxiety and memory bias for social evaluation.

    Science.gov (United States)

    Caouette, Justin D; Ruiz, Sarah K; Lee, Clinton C; Anbari, Zainab; Schriber, Roberta A; Guyer, Amanda E

    2015-01-01

    Social anxiety (SA) involves a multitude of cognitive symptoms related to fear of evaluation, including expectancy and memory biases. We examined whether memory biases are influenced by expectancy biases for social feedback in SA. We hypothesised that, faced with a socially evaluative event, people with higher SA would show a negative expectancy bias for future feedback. Furthermore, we predicted that memory bias for feedback in SA would be mediated by expectancy bias. Ninety-four undergraduate students (55 women, mean age = 19.76 years) underwent a two-visit task that measured expectations about (Visit 1) and memory of (Visit 2) feedback from unknown peers. Results showed that higher levels of SA were associated with negative expectancy bias. An indirect relationship was found between SA and memory bias that was mediated by expectancy bias. The results suggest that expectancy biases are in the causal path from SA to negative memory biases for social evaluation.

  8. Attentional bias predicts heroin relapse following treatment

    NARCIS (Netherlands)

    Marissen, Marlies A. E.; Franken, Ingmar H. A.; Waters, Andrew J.; Blanken, Peter; van den Brink, Wim; Hendriks, Vincent M.

    2006-01-01

    AIMS: Previous studies have shown that abstinent heroin addicts exhibit an attentional bias to heroin-related stimuli. It has been suggested that attentional bias may represent a vulnerability to relapse into drug use. In the present study, the predictive value of pre-treatment attentional bias on

  9. Using Newspapers to Study Media Bias.

    Science.gov (United States)

    Kirman, Joseph M.

    1992-01-01

    Suggests that students can learn to recognize media bias by studying media reports of current events or historical topics. Describes a study unit using media coverage of the second anniversary of the Palestinian uprising against Israel. Discusses lesson objectives, planning, defining bias teaching procedures, and criteria for determining bias. (DK)

  10. Opinion Dynamics with Confirmation Bias

    Science.gov (United States)

    Allahverdyan, Armen E.; Galstyan, Aram

    2014-01-01

    Background Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. Methodology/Principal Findings We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect–when consecutively exposed to two opinions, the preference is given to the last opinion (recency) or the first opinion (primacy) –and relates recency to confirmation bias. Finally, we study the model in the case of repeated persuasion and analyze its convergence properties. Conclusions The standard Bayesian approach to probabilistic opinion revision is inadequate for describing the observed phenomenology of persuasion process. The simple non-Bayesian model proposed here does agree with this phenomenology and is capable of reproducing a spectrum of effects observed in psychology: primacy-recency phenomenon, boomerang effect and cognitive dissonance. We point out several limitations of the model that should motivate its future development. PMID:25007078

  11. Bias in Peripheral Depression Biomarkers

    DEFF Research Database (Denmark)

    Carvalho, André F; Köhler, Cristiano A; Brunoni, André R

    2016-01-01

    BACKGROUND: To aid in the differentiation of individuals with major depressive disorder (MDD) from healthy controls, numerous peripheral biomarkers have been proposed. To date, no comprehensive evaluation of the existence of bias favoring the publication of significant results or inflating effect......-analysis would equal the one of its largest study. A significant summary effect size estimate was observed for 20 biomarkers. We observed an excess of statistically significant studies in 21 meta-analyses. The summary effect size of the meta-analysis was higher than the effect of its largest study in 25 meta...

  12. Ratio Bias and Policy Preferences

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Tue

    2016-01-01

    Numbers permeate modern political communication. While current scholarship on framing effects has focused on the persuasive effects of words and arguments, this article shows that framing of numbers can also substantially affect policy preferences. Such effects are caused by ratio bias, which...... regarding salient political issues such as education and taxes. Furthermore, the effects of numerical framing are found across most groups of the population, largely regardless of their political predisposition and their general ability to understand and use numerical information. These findings have...

  13. Spatio-temporal variability in ontogenetic guild structure of an intertidal fish assemblage in central Chile Variabilidad espacio-temporal en la estructura de gremios ontogenéticos de un ensamble de peces intermareales de Chile central

    Directory of Open Access Journals (Sweden)

    PATRICIA A BERRÍOS

    2011-12-01

    Full Text Available Species resource use can vary throughout ontogeny, potentially affecting community dynamics. This can be particularly important for species facing high variability in environmental conditions and going through several orders of magnitude in size, as intertidal fishes. However, the influence of the resulting ontogenetic changes in guild membership on the spatio-temporal structure of fish assemblages remains virtually unknown. Here we assessed the spatial and temporal variability in the ontogenetic feeding guild (OFG structure of the fish assemblage inhabiting the temperate rocky intertidal zone along central Chilean coast. This was done applying principal component analysis (PCA and randomization tests (R-test on the relative OFG composition of fish assemblages, obtained from seasonal samples from ten pools located at two heights in the intertidal zone in three localities between 33° and 34° S. Overall, the PCA and R-tests suggest that spatial variability dominated over temporal variability in OFG structure, mainly due to a higher representation of omnivore species at high intertidal pools in two of the three sampled localities. However, phenology-related changes in the representation of fish size-classes (i.e. carnivore recruitment in spring-summer along with ontogenetic differences in habitat selection (e.g., selection for low intertidal pools by bigger-sized carnivore OFG contributed to both spatial and temporal differentiation in OFG structure. Finally, the relative representation of each OFG correlated with that of their dominant species, without evidence for density compensation. This suggests low levels of functional redundancy among species in each OFG, highlighting the vulnerability of assemblage functioning to size-biased disturbances as fishing.El uso de los recursos puede variar a través de la ontogenia, afectando potencialmente las dinámicas comunitarias. Esto puede ser de particular importancia en especies que enfrentan alta

  14. Differential ontogenetic exposure to obesogenic environment induces hyperproliferative status and nuclear receptors imbalance in the rat prostate at adulthood.

    Science.gov (United States)

    Pytlowanciv, Eloísa Zanin; Pinto-Fochi, Maria Etelvina; Reame, Vanessa; Gobbo, Marina Guimarães; Ribeiro, Daniele Lisboa; Taboga, Sebastião Roberto; Góes, Rejane Maira

    2016-05-01

    Experimental data indicate that high-fat diet (HFD) may alter proliferative activity and prostate health. However, the consequences of HFD exposure during different periods of ontogenetic development on prostate histophysiology remain to be elucidated. Herein, we compare the influence of obesogenic environment (OE) due to maternal obesity and HFD at different periods of life on proliferative activity and nuclear receptors frequency in the rat ventral prostate and a possible relationship with metabolic and hormonal alterations. Male Wistar rats (19 weeks old), treated with balanced chow (Control group-C; 3% high-fat, 3.5 Kcal/g), were compared with those exposed to HFD (20% high-fat, 4.9 kcal/g) during gestation (G-maternal obesity), gestation and lactation (GL), from post-weaning to adulthood (WA), from lactation to adulthood (LA) and from gestation to adulthood (GA). After the experimental period, the ventral prostate lobes were removed and analyzed with different methods. Metabolic data indicated that G and GL rats became insulin resistant and WA, LA, and GA became insulin resistant and obese. There was a strong inverse correlation between serum testosterone (∼133% lower) and leptin levels (∼467% higher) in WA, LA, and GA groups. Estrogen serum levels increased in GA, and insulin levels increased in all groups, especially in WA (64.8×). OE-groups exhibited prostatic hypertrophy, since prostate weight increased ∼40% in G, GL, LA, and GA and 31% in WA. As indicated by immunohistochemistry, all HFD-groups except G exhibited an increase in epithelial cell proliferation (PCNA-positive) and a decrease in frequency of AR- and ERβ-positive epithelial cells; there was also an increment of ERα-positive stromal cells in comparison with control. Cells containing PPARγ increased in both epithelium and stroma of all OE groups and those expressing LXRα decreased, particularly in groups OE-exposed during gestation (G, GL and GA). OE leads to prostate hypertrophy

  15. The ontogenetic transformation of the mesosaurid tarsus: a contribution to the origin of the primitive amniotic astragalus

    Directory of Open Access Journals (Sweden)

    Graciela Piñeiro

    2016-05-01

    Full Text Available The hypotheses about the origin of the primitive amniotic tarsus are very speculative. Early studies argued that the origin of the astragalus, one of the largest proximal bones in the tarsus of basal amniotes, was produced by either the fusion of two, three, or even four of the original tarsal bones, the intermedium, the tibiale and the proximal centralia (c4 and c3, or that the intermedium alone transforms into the primitive astragalus. More recent studies have shown that the structure of the tarsus in Captorhinus supports the former hypothesis about a fusion of the intermedium, the tibiale, the proximal centrale (c4 and eventually c3, producing a purportedly multipartite structure of the amniotic astragalus, but the issue remained contentious. Very well preserved tarsi of the Early Permian aquatic amniote Mesosaurus tenuidens Gervais, 1864–1865, which represent the most complete ontogenetic succession known for a basal amniote (the other exceptional one is provided by the Late Permian diapsid Hovasaurus boulei Piveteau, 1926, suggest that there is more than one ossification center for the astragalus and that these fuse during late embryonic stages or maybe early after birth. A non-hatched Mesosaurus in an advanced stage of development shows that the tarsus is represented by a single bone, most probably the astragalus, which seems to be formed by the suturing of three bones, here interpreted as being the intermedium, the tibiale, probably already integrated to the c4 in an earlier stage of the development, and the c3. An amniote-like tarsal structure is observed in very basal Carboniferous and Permian tetrapods such as Proterogyrinus, Gephyrostegus, the diadectids Diadectes and Orobates, some microsaurs like Tuditanus and Pantylus and possibly Westlothiana, taxa that were all considered as true amniotes in their original descriptions. Therefore, the structure of the amniotic tarsus, including the configuration of the proximal series formed by

  16. Osteology, Phylogeny, Taphonomy, and Ontogenetic Histology of Oryctodromeus cubicularis, from the Middle Cretaceous (Albian-Cenomanian) of Montana and Idaho

    Science.gov (United States)

    Krumenacker, L. J.

    Oryctodromeus is a small bipedal dinosaur known from middle Cretaceous (95-100 My) Wayan Formation of Idaho and the Vaughn Member of the Blackleaf Formation of Montana. This taxon is hypothesized to be a burrowing dinosaur, which cared for its young within these burrows. This dissertation is a broad three-part treatment of this taxon, and excepting the introductory and concluding chapters this dissertation consists of three main chapters. Chapter two describes the osteology and phylogenetic relationships of this animal. Notable features of the Oryctodromeus skeleton described include a network of ossified tendons along the vertebral column that completely ensheath the tail, a long tail that forms more than half the length of the animal, and unusual femoral heads whose morphology may be related to burrowing behavior. The first full skeletal and skull reconstructions of this animal are presented. Chapter three investigates patterns of preservation of Oryctodromeus. Data suggests that preservation of single to multiple individuals of this taxon typically occurred in burrows that may be difficult to impossible to recognize in the fossil record. New examples of burrows from Oryctodromeus from the Vaughn and Wayan, as well as additional evidence for social behavior, are also described. A third chapter details the ontogenetic histology, growth rates and patterns of skeletal fusion based on seven limb elements (femora and tibiae) from different individuals. Based on the data in this dissertation, three growth stages can be recognized in Oryctodromeus based on bone histology. Juveniles are defined by more rapidly growing fibrolamellar tissue, sub-adults are defined by a cortex of inner fibrolamellar tissue and outer zonal parallel fibered tissue, and near-adult individuals have tissue similar to sub adults with dense avascular bone in the outermost cortex that signals a decrease in growth rate. LAG's suggest a minimum age of six to seven years for more mature individuals

  17. An inclusive taxonomy of behavioral biases

    Directory of Open Access Journals (Sweden)

    David Peón

    2017-07-01

    Full Text Available This paper overviews the theoretical and empirical research on behavioral biases and their influence in the literature. To provide a systematic exposition, we present a unified framework that takes the reader through an original taxonomy, based on the reviews of relevant authors in the field. In particular, we establish three broad categories that may be distinguished: heuristics and biases; choices, values and frames; and social factors. We then describe the main biases within each category, and revise the main theoretical and empirical developments, linking each bias with other biases and anomalies that are related to them, according to the literature.

  18. Parasites as biological tags to track an ontogenetic shift in the feeding behaviour of Gadus morhua off West and East Greenland.

    Science.gov (United States)

    Münster, Julian; Klimpel, Sven; Fock, Heino O; MacKenzie, Ken; Kuhn, Thomas

    2015-07-01

    Parasites, being an integral part of every ecosystem and trophically transmitted along the food webs, can provide detailed insights into the structure of food webs and can close the information gap between short-term stomach content analyses and long-term fish otolith analyses. They are useful for tracking ontogenetic shifts in the host's diet, the occurrence of specific organisms or migratory behaviour of their hosts, even in inaccessible environments. In the present study, stomach content analyses and parasitological examinations were performed on 70 Atlantic cod Gadus morhua, one of the most important high-level predators of small fish in the North Atlantic, caught during one research vessel cruise from West and East Greenlandic waters. Analyses revealed significant differences in fish size with higher values for East Greenland (average total length (TL) of 50.5 cm) compared to West Greenland (average TL of 33.3 cm). Clear differences were also present in prey and parasite composition. Crustacea was the main food source for all fish (IRI = 10082.70), while the importance of teleosts increased with fish size. With a prevalence of 85 % in West Greenland and 100 % in East Greenland, Nematoda were the most abundant parasite group. The results indicate an ontogenetic shift in the diet, which are discussed in the context of the common distribution theory, stock dynamics and migratory behaviour.

  19. Vertebrate lungs: structure, topography and mechanics. A comparative perspective of the progressive integration of respiratory system, locomotor apparatus and ontogenetic development.

    Science.gov (United States)

    Duncker, Hans-Rainer

    2004-12-15

    Vertebrate lungs are highly diverse in their structure, topographical position, ventilation mechanisms, constructional integration into the locomotor apparatus, and the interrelationships with the mode of their ontogenetic development. Vertebrate lungs evolved as supplementary air-breathing organs in primary fishes, being ventilated by buccal pumping. In most recent fishes the lungs are transformed into the hydrostatic swimbladder. This basic type of unicameral lungs and their buccal pumping ventilation are also found in recent amphibians. Land vertebrates developed a very efficient aspiration type of ventilation. In most recent reptiles the lungs are subdivided into three rows of lung chambers, enlarging the exchange surface in correlation to their increasing metabolic needs. The avian respiratory apparatus, with its volume-constant lungs and highly compliant air sacs, and the mammalian broncho-alveolar lung, with its very low compliance, are both derived from multicameral lungs. The avian and the mammalian respiratory systems are integrated very differently with the specific constructions of their locomotor apparatusses and the specific mode of their ontogenetic development.

  20. Diet-morphology relationship in the stream-dwelling characid Deuterodon stigmaturus (Gomes, 1947 (Characiformes: Characidae is partially conditioned by ontogenetic development

    Directory of Open Access Journals (Sweden)

    Renato Bolson Dala-Corte

    Full Text Available ABSTRACT We tested whether interindividual variations in diet composition within a population of Deuterodon stigmaturus can be explained by morphological differences between individuals, and whether diet-morphology relationships are dependent on the ontogenetic development. We analyzed diet of 75 specimens sampled in a coastal stream of Southern Brazil. Variation in stomach content was summarized with a Principal Coordinate Analysis (PCoA. The retained PCoA axes were tested as response to standard length (SL, and to values of intestine length (IL and mouth length (ML independent of body size, using linear mixed-effects models (LMM. The most consumed food items by D. stigmaturus were filamentous algae (41%, terrestrial plants (20.3%, detritus (12%, and aquatic invertebrates (8.8%. The LMMs showed that SL was positively related to consumption of terrestrial plants, whereas IL independent of SL was negatively related to aquatic invertebrates and positively related to filamentous algae. When body sized was held constant, ML was not related to diet variation. Interindividual diet differences conditioned to body size suggest that individuals shift their trophic niche and function in the ecosystem along the ontogenetic development. Relationships between intestine length and diet composition suggest interindividual differences in foraging ability and digestibility of distinct food items.

  1. Ontogenetic variation in the stratum granulosum of the epidermis of Chaetophractus vellerosus (Xenarthra, Dasypodidae) in relation to the development of cornified scales.

    Science.gov (United States)

    Krmpotic, Cecilia M; Carlini, Alfredo A; Galliari, Fernando C; Favaron, Phelipe; Miglino, María A; Scarano, Alejo C; Barbeito, Claudio G

    2014-12-01

    The epidermis of mammals is characterized by having a stratum granulosum that produces an orthokeratotic stratum corneum, different from the typical reptilian parakeratotic stratum. Nonetheless, some mammals show distinct degrees of parakeratosis in epidermal regions with few or no pilose follicles (e.g., areas subjacent to cornified scales). With respect to the epidermis and the development of cornified scales in the Dasypodidae, previous studies have supported the presence of a continuous stratum granulosum without any variations during ontogeny. This condition, in which the cornified scales develop without a loss of the stratum granulosum, was interpreted as primitive for eutherians. The present contribution expands the knowledge on the epidermis of Chaetophractus vellerosus in distinct ontogenetic stages in order to determine whether the cornified scales show the same developmental pattern as in other eutherians. The presence of a stratum granulosum in C. vellerosus neonates and its reduction in more advanced ontogenetic stages, in direct relationship with cornified scale development, supports the hypothesis that the partial parakeratosis in the xenarthran integument is secondary, as in other eutherians, and can be interpreted as a derived character state. Copyright © 2014 Elsevier GmbH. All rights reserved.

  2. Managing bias in ROC curves

    Science.gov (United States)

    Clark, Robert D.; Webster-Clark, Daniel J.

    2008-03-01

    Two modifications to the standard use of receiver operating characteristic (ROC) curves for evaluating virtual screening methods are proposed. The first is to replace the linear plots usually used with semi-logarithmic ones (pROC plots), including when doing "area under the curve" (AUC) calculations. Doing so is a simple way to bias the statistic to favor identification of "hits" early in the recovery curve rather than late. A second suggested modification entails weighting each active based on the size of the lead series to which it belongs. Two weighting schemes are described: arithmetic, in which the weight for each active is inversely proportional to the size of the cluster from which it comes; and harmonic, in which weights are inversely proportional to the rank of each active within its class. Either scheme is able to distinguish biased from unbiased screening statistics, but the harmonically weighted AUC in particular emphasizes the ability to place representatives of each class of active early in the recovery curve.

  3. Gender Bias Affects Forests Worldwide

    Directory of Open Access Journals (Sweden)

    Marlène Elias

    2017-04-01

    Full Text Available Gender biases persist in forestry research and practice. These biases result in reduced scientific rigor and inequitable, ineffective, and less efficient policies, programs, and interventions. Drawing from a two-volume collection of current and classic analyses on gender in forests, we outline five persistent and inter-related themes: gendered governance, tree tenure, forest spaces, division of labor, and ecological knowledge. Each emerges across geographic regions in the northern and southern hemisphere and reflects inequities in women’s and men’s ability to make decisions about and benefit from trees, forests, and their products. Women’s ability to participate in community-based forest governance is typically less than men’s, causing concern for social equity and forest stewardship. Women’s access to trees and their products is commonly more limited than men’s, and mediated by their relationship with their male counterparts. Spatial patterns of forest use reflect gender norms and taboos, and men’s greater access to transportation. The division of labor results in gender specialization in the collection of forest products, with variations in gender roles across regions. All these gender differences result in ecological knowledge that is distinct but also complementary and shifting across the genders. The ways gender plays out in relation to each theme may vary across cultures and contexts, but the influence of gender, which intersects with other factors of social differentiation in shaping forest landscapes, is global.

  4. Workplace ageism: discovering hidden bias.

    Science.gov (United States)

    Malinen, Sanna; Johnston, Lucy

    2013-01-01

    BACKGROUND/STUDY CONTEXT: Research largely shows no performance differences between older and younger employees, or that older workers even outperform younger employees, yet negative attitudes towards older workers can underpin discrimination. Unfortunately, traditional "explicit" techniques for assessing attitudes (i.e., self-report measures) have serious drawbacks. Therefore, using an approach that is novel to organizational contexts, the authors supplemented explicit with implicit (indirect) measures of attitudes towards older workers, and examined the malleability of both. This research consists of two studies. The authors measured self-report (explicit) attitudes towards older and younger workers with a survey, and implicit attitudes with a reaction-time-based measure of implicit associations. In addition, to test whether attitudes were malleable, the authors measured attitudes before and after a mental imagery intervention, where the authors asked participants in the experimental group to imagine respected and valued older workers from their surroundings. Negative, stable implicit attitudes towards older workers emerged in two studies. Conversely, explicit attitudes showed no age bias and were more susceptible to change intervention, such that attitudes became more positive towards older workers following the experimental manipulation. This research demonstrates the unconscious nature of bias against older workers, and highlights the utility of implicit attitude measures in the context of the workplace. In the current era of aging workforce and skill shortages, implicit measures may be necessary to illuminate hidden workplace ageism.

  5. Observations and Models of Galaxy Assembly Bias

    Science.gov (United States)

    Campbell, Duncan A.

    2017-01-01

    The assembly history of dark matter haloes imparts various correlations between a halo’s physical properties and its large scale environment, i.e. assembly bias. It is common for models of the galaxy-halo connection to assume that galaxy properties are only a function of halo mass, implicitly ignoring how assembly bias may affect galaxies. Recently, programs to model and constrain the degree to which galaxy properties are influenced by assembly bias have been undertaken; however, the extent and character of galaxy assembly bias remains a mystery. Nevertheless, characterizing and modeling galaxy assembly bias is an important step in understanding galaxy evolution and limiting any systematic effects assembly bias may pose in cosmological measurements using galaxy surveys.I will present work on modeling and constraining the effect of assembly bias in two galaxy properties: stellar mass and star-formation rate. Conditional abundance matching allows for these galaxy properties to be tied to halo formation history to a variable degree, making studies of the relative strength of assembly bias possible. Galaxy-galaxy clustering and galactic conformity, the degree to which galaxy color is correlated between neighbors, are sensitive observational measures of galaxy assembly bias. I will show how these measurements can be used to constrain galaxy assembly bias and the peril of ignoring it.

  6. [Ontogenetic conditions of unemployment].

    Science.gov (United States)

    Buchtová, Božena; Smajs, Josef; Kulhavý, Viktor; Okrajek, Petr; Kukla, Lubomír

    2014-01-01

    Previous unemployment studies mostly dealt with unemployments economic causes and consequences. Hidden causes of male unemployment, independent from socio-economic circumstances of a society, could consist, besides others, in natural biological factors - family experience during childhood. Theoretical background of our study included the concept of psychical deprivation, the concept of human ontogenesis developmental stages of E. Erikson and knowledge of biodromal psychology. Using data from the European Longitudinal Study of Parenthood and Childhood international project we compared groups of employed and unemployed men by means of a retrospective survey and we studied the following: 1. What differences there were in their childhood; 2. To what extent educational approaches transfer from parents to their children; 3. What influence has negative experience from childhood on the future assertion of men in the labour market. The survey set consisted of 3141 (88.7%) employed men and 399 (11.3%) unemployed men in 1991-1992. Basic research data were acquired by means of questionnaires. Relative risk was used to compare the groups of the employed and the unemployed. The employed men are more likely to be from complete families then the unemployed men. The unemployed men, in comparison to the employed men, 2.08 times more frequently spent their childhood in orphanages, children's villages or in foster families, 3.89 times more frequently attended special schools, 2.22 times more frequently lived away from home until the age of 18 and 2.51 times more frequently lived in detention centres or in diagnostic institutes until the age of 18 (p unemployed men were psychically and physically abused in their childhood. Consequences of negative experience from childhood decrease the chances of inclusion of young men into the labour market. Social roles of young men (future fathers) could be also distorted by such experience. Social integration and social success rate of the unemployed men group therefore develops in an unfavourable direction.

  7. Social reward shapes attentional biases.

    Science.gov (United States)

    Anderson, Brian A

    2016-01-01

    Paying attention to stimuli that predict a reward outcome is important for an organism to survive and thrive. When visual stimuli are associated with tangible, extrinsic rewards such as money or food, these stimuli acquire high attentional priority and come to automatically capture attention. In humans and other primates, however, many behaviors are not motivated directly by such extrinsic rewards, but rather by the social feedback that results from performing those behaviors. In the present study, I examine whether positive social feedback can similarly influence attentional bias. The results show that stimuli previously associated with a high probability of positive social feedback elicit value-driven attentional capture, much like stimuli associated with extrinsic rewards. Unlike with extrinsic rewards, however, such stimuli also influence task-specific motivation. My findings offer a potential mechanism by which social reward shapes the information that we prioritize when perceiving the world around us.

  8. Symmetry as Bias: Rediscovering Special Relativity

    Science.gov (United States)

    Lowry, Michael R.

    1992-01-01

    This paper describes a rational reconstruction of Einstein's discovery of special relativity, validated through an implementation: the Erlanger program. Einstein's discovery of special relativity revolutionized both the content of physics and the research strategy used by theoretical physicists. This research strategy entails a mutual bootstrapping process between a hypothesis space for biases, defined through different postulated symmetries of the universe, and a hypothesis space for physical theories. The invariance principle mutually constrains these two spaces. The invariance principle enables detecting when an evolving physical theory becomes inconsistent with its bias, and also when the biases for theories describing different phenomena are inconsistent. Structural properties of the invariance principle facilitate generating a new bias when an inconsistency is detected. After a new bias is generated. this principle facilitates reformulating the old, inconsistent theory by treating the latter as a limiting approximation. The structural properties of the invariance principle can be suitably generalized to other types of biases to enable primal-dual learning.

  9. Political Accountability, Electoral Control, and Media Bias

    OpenAIRE

    Adachi, Takanori; Hizen, Yoichi

    2012-01-01

    Are anti-establishment mass media really useful in preventing politicians from behaving dishonestly? This paper proposes a voting model for analyzing how differences in the direction of media bias affect politicians' behavior. In particular, the probability of corruption by an incumbent is higher (than that in the case of no media bias) if and only if the mass media have some degree of "anti-incumbent" bias (i.e., information favorable to the incumbent is converted into unfavorable news about...

  10. Bias Blind Spot: Structure, Measurement, and Consequences

    OpenAIRE

    Scopelliti, I.; Morewedge, C. K.; McCormick, E.; Min, L.; LeBrecht, S.; Kassam, K.

    2015-01-01

    People exhibit a bias blind spot: they are less likely to detect bias in themselves than in others. We report the development and validation of an instrument to measure individual differences in the propensity to exhibit the bias blind spot that is unidimensional, internally consistent, has high test-retest reliability, and is discriminated from measures of intelligence, decision making ability, and personality traits related to self-esteem, self-enhancement, and self-presentation. The scale ...

  11. Electric control of exchange bias training.

    Science.gov (United States)

    Echtenkamp, W; Binek, Ch

    2013-11-01

    Voltage-controlled exchange bias training and tunability are introduced. Isothermal voltage pulses are used to reverse the antiferromagnetic order parameter of magnetoelectric Cr(2)O(3), and thus continuously tune the exchange bias of an adjacent CoPd film. Voltage-controlled exchange bias training is initialized by tuning the antiferromagnetic interface into a nonequilibrium state incommensurate with the underlying bulk. Interpretation of these hitherto unreported effects contributes to new understanding in electrically controlled magnetism.

  12. Bias in the Classroom: Are We Guilty?

    Science.gov (United States)

    Bellamy, Nedaro

    1994-01-01

    Describes a study designed to determine whether teachers' unconscious classroom behaviors and teaching strategies showed gender or racial bias. Included in the article are strategies for change. (ZWH)

  13. Bias Sources and Corrections in TEOM Technology.

    Science.gov (United States)

    Page, S J

    2013-01-01

    Researchers at the National Institute for Occupational Safety and Health have used tapered element oscillating microbalances (TEOM) in laboratory settings. The TEOMs have assessed the mass concentration of laboratory-generated particulates in experimental dust chambers and provided a reference method for comparison with other particulate-measuring instruments. Current NIOSH research is focused on further adapting TEOM technology as a wearable personal dust monitor (PDM) for coal mine workers. The history of TEOM technology describes the oscillating tapered tube mathematically as a simple harmonic oscillator. However, analysis of the new PDM test data showed a bias dependency on the starting frequency f o. This result prompted a rigorous investigation to uncover the source of the bias and if the bias source is applicable to the 1400 TEOM. Based on the above results, a significantly improved theoretical description of TEOM performance has been developed. Average bias for each group of PDMs is calculated and compared to the results of the accuracy tests performed. Accompanying these biases are estimates of the average bias spans of the new PDMs in comparison to the pre-commercial PDMs. The theory was also applied to the Model 1400 TEOM data to evaluate whether there is agreement. The new theory of TEOM operation provides a good account for both the bias and bias span. Given that TEOM technology has been used for decades around the world to monitor atmospheric particulate contaminants as well as many other aerosols, quantification and correction of this source of bias should result in more accurate assessments.

  14. Adaptable history biases in human perceptual decisions

    Science.gov (United States)

    Abrahamyan, Arman; Silva, Laura Luz; Dakin, Steven C.; Gardner, Justin L.

    2016-01-01

    When making choices under conditions of perceptual uncertainty, past experience can play a vital role. However, it can also lead to biases that worsen decisions. Consistent with previous observations, we found that human choices are influenced by the success or failure of past choices even in a standard two-alternative detection task, where choice history is irrelevant. The typical bias was one that made the subject switch choices after a failure. These choice history biases led to poorer performance and were similar for observers in different countries. They were well captured by a simple logistic regression model that had been previously applied to describe psychophysical performance in mice. Such irrational biases seem at odds with the principles of reinforcement learning, which would predict exquisite adaptability to choice history. We therefore asked whether subjects could adapt their irrational biases following changes in trial order statistics. Adaptability was strong in the direction that confirmed a subject’s default biases, but weaker in the opposite direction, so that existing biases could not be eradicated. We conclude that humans can adapt choice history biases, but cannot easily overcome existing biases even if irrational in the current context: adaptation is more sensitive to confirmatory than contradictory statistics. PMID:27330086

  15. Forensic experts' perceptions of expert bias.

    Science.gov (United States)

    Commons, Michael Lamport; Miller, Patrice Marie; Li, Eva Yujia; Gutheil, Thomas Gordon

    2012-01-01

    How do expert witnesses perceive the possible biases of their fellow expert witnesses? Participants, who were attendees at a workshop at the American Academy of Psychiatry and Law were asked to rate for their biasing potential a number of situations that might affect the behavior of an opposing expert. A Rasch analysis produced a linear scale as to the perceived biasing potential of these different kinds of situations from the most biasing to the least biasing. Working for only one side in both civil and criminal cases had large scaled values and also were the first factor. In interesting contrast, a) an opposing expert also serving as the litigant's treater and b) an opposing expert being viewed as a "hired gun" (supplying an opinion only for money) were two situations viewed as not very biasing. Order of Hierarchical Complexity also accounted for items from the 1st, 2nd and 3rd factors. The result suggests that the difficulty in understanding the conceptual basis of bias underlies the perception of how biased a behavior or a situation is. The more difficult to understand the questionnaire item, the less biasing its behavior or situation is perceived by participants. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Expert witness perceptions of bias in experts.

    Science.gov (United States)

    Commons, Michael Lamport; Miller, Patrice Marie; Gutheil, Thomas G

    2004-01-01

    A pilot study of perceptions of different sources of expert bias, as well as of personal investment in case outcomes, was performed among attendees at a workshop at an annual meeting of the American Academy of Psychiatry and the Law. Participants were asked to rate hypothetical responses by experts to various case outcomes and the biasing potential of different kinds of situations for opposing or other experts. A factor analysis produced two factors. Factor 1 included questions about situations that were obviously biasing (such as working only for the defense). Factor 2 included questions assessing the potential of certain situations to cause bias in experts, or how likely experts thought other experts were to be biased. In general, experts identified only four areas to be overtly biasing. All occurred within situations in which experts worked only for one or the other side of civil or criminal cases. Experts otherwise thought other experts were reasonably bias free and well able to compensate for any bias when it occurred. The data suggest that experts may deal with bias by turning down cases that may cause them personal discomfort.

  17. Attribution bias and social anxiety in schizophrenia

    Directory of Open Access Journals (Sweden)

    Amelie M. Achim

    2016-06-01

    Full Text Available Studies on attribution biases in schizophrenia have produced mixed results, whereas such biases have been more consistently reported in people with anxiety disorders. Anxiety comorbidities are frequent in schizophrenia, in particular social anxiety disorder, which could influence their patterns of attribution biases. The objective of the present study was thus to determine if individuals with schizophrenia and a comorbid social anxiety disorder (SZ+ show distinct attribution biases as compared with individuals with schizophrenia without social anxiety (SZ− and healthy controls. Attribution biases were assessed with the Internal, Personal, and Situational Attributions Questionnaire in 41 individual with schizophrenia and 41 healthy controls. Results revealed the lack of the normal externalizing bias in SZ+, whereas SZ− did not significantly differ from healthy controls on this dimension. The personalizing bias was not influenced by social anxiety but was in contrast linked with delusions, with a greater personalizing bias in individuals with current delusions. Future studies on attribution biases in schizophrenia should carefully document symptom presentation, including social anxiety.

  18. Biases in the production and reception of collective knowledge: the case of hindsight bias in Wikipedia.

    Science.gov (United States)

    Oeberst, Aileen; von der Beck, Ina; D Back, Mitja; Cress, Ulrike; Nestler, Steffen

    2017-04-17

    The Web 2.0 enabled collaboration at an unprecedented level. In one of the flagships of mass collaboration-Wikipedia-a large number of authors socially negotiate the world's largest compendium of knowledge. Several guidelines in Wikipedia restrict contributions to verifiable information from reliable sources to ensure recognized knowledge. Much psychological research demonstrates, however, that individual information processing is biased. This poses the question whether individual biases translate to Wikipedia articles or whether they are prevented by its guidelines. The present research makes use of hindsight bias to examine this question. To this end, we analyzed foresight and hindsight versions of Wikipedia articles regarding a broad variety of events (Study 1). We found the majority of articles not to contain traces of hindsight bias-contrary to prior individual research. However, for a particular category of events-disasters-we found robust evidence for hindsight bias. In a lab experiment (Study 2), we then examined whether individuals' hindsight bias is translated into articles under controlled conditions and tested whether collaborative writing-as present in Wikipedia-affects the resultant bias (vs. individual writing). Finally, we investigated the impact of biased Wikipedia articles on readers (Study 3). As predicted, biased articles elicited a hindsight bias in readers, who had not known of the event previously. Moreover, biased articles also affected individuals who knew about the event already, and who had already developed a hindsight bias: biased articles further increased their hindsight.

  19. Dipole-induced exchange bias.

    Science.gov (United States)

    Torres, Felipe; Morales, Rafael; Schuller, Ivan K; Kiwi, Miguel

    2017-11-09

    The discovery of dipole-induced exchange bias (EB), switching from negative to positive sign, is reported in systems where the antiferromagnet and the ferromagnet are separated by a paramagnetic spacer (AFM-PM-FM). The magnitude and sign of the EB is determined by the cooling field strength and the PM thickness. The same cooling field yields negative EB for thin spacers, and positive EB for thicker ones. The EB decay profile as a function of the spacer thickness, and the change of sign, are attributed to long-ranged dipole coupling. Our model, which accounts quantitatively for the experimental results, ignores the short range interfacial exchange interactions of the usual EB theories. Instead, it retains solely the long range dipole field that allows for the coupling of the FM and AFM across the PM spacer. The experiments allow for novel switching capabilities of long range EB systems, while the theory allows description of the structures where the FM and AFM are not in atomic contact. The results provide a new approach to design novel interacting heterostructures.

  20. Taxonomic review of the tree frog genus Rhacophorus from the Western Ghats, India (Anura: Rhacophoridae), with description of ontogenetic colour changes and reproductive behavior.

    Science.gov (United States)

    Biju, S D; Kamei, Rachunliu G; Mahony, Stephen; Thomas, Ashish; Garg, Sonali; Sircar, Gargi; Suyesh, Robin

    2013-01-01

    A taxonomic revision of the Western Ghats species from the genus Rhacophorus is presented. Based on museum studies and new collections from localities spanning the known range of Western Ghats Rhacophorus, we review the four known species of this genus, their type specimens, current taxonomic status and their geographic distribution on the basis of morphological and molecular data. The holotypes of Rhacophorus calcadensis, R. lateralis and R. nialabaricus are redescribed. The previously unidentified holotype of Rhacophorus inalabaricus is herein fixed. Descriptions of ontogenetic colour change (OCC) in the Western Ghats Rhacophorus are provided and we conjecture the taxonomic utility of OCC. Additionally we provide observations on nesting behaviour of each species, and report multiple male participation during amplexus, oviposition and foam nest construction in R. lateralis and R. malabaricus.

  1. Seasonal and ontogenetic variations in the diet of Cichla kelberi Kullander and Ferreira, 2006 introduced in an artificial lake in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    LM Gomiero

    Full Text Available The diet of Cichla kelberi introduced in an artificial lake in Leme-SP was predominantly composed of common fish species (Oreochromis niloticus and C. kelberi. In the spring and summer, the most consumed item was O. niloticus. However, cannibalism was very common for this species. The high frequencies of O. niloticus and C. kelberi reveal that this species is adapted to a seasonal cycle, feeding on the most common prey in each period of the year, with a reduction of foraging activity during the winter. The diets were different among the immature and mature individuals suggesting that there are ontogenetic differences, mainly related to prey type, such as: Ephemeroptera consumed by the immature peacock bass and fish by the mature ones, besides the size of the prey.

  2. Attention bias modification training under working memory load increases the magnitude of change in attentional bias

    NARCIS (Netherlands)

    Clarke, P.J.F.; Branson, S.; Chen, N.T.M.; Van Bockstaele, B.; Salemink, E.; MacLeod, C.; Notebaert, L.

    2017-01-01

    BACKGROUND AND OBJECTIVES: Attention bias modification (ABM) procedures have shown promise as a therapeutic intervention, however current ABM procedures have proven inconsistent in their ability to reliably achieve the requisite change in attentional bias needed to produce emotional benefits. This

  3. Snake venomics across genus Lachesis. Ontogenetic changes in the venom composition of Lachesis stenophrys and comparative proteomics of the venoms of adult Lachesis melanocephala and Lachesis acrochorda.

    Science.gov (United States)

    Madrigal, Marvin; Sanz, Libia; Flores-Díaz, Marietta; Sasa, Mahmood; Núñez, Vitelbina; Alape-Girón, Alberto; Calvete, Juan J

    2012-12-21

    We report the proteomic analysis of ontogenetic changes in venom composition of the Central American bushmaster, Lachesis stenophrys, and the characterization of the venom proteomes of two congeneric pitvipers, Lachesis melanocephala (black-headed bushmaster) and Lachesis acrochorda (Chochoan bushmaster). Along with the previous characterization of the venom proteome of Lachesis muta muta (from Bolivia), our present outcome enables a comparative overview of the composition and distribution of the toxic proteins across genus Lachesis. Comparative venomics revealed the close kinship of Central American L. stenophrys and L. melanocephala and support the elevation of L. acrochorda to species status. Major ontogenetic changes in the toxin composition of L. stenophrys venom involves quantitative changes in the concentration of vasoactive peptides and serine proteinases, which steadily decrease from birth to adulthood, and age-dependent de novo biosynthesis of Gal-lectin and snake venom metalloproteinases (SVMPs). The net result is a shift from a bradykinin-potentiating and C-type natriuretic peptide (BPP/C-NP)-rich and serine proteinase-rich venom in newborns and 2-years-old juveniles to a (PI>PIII) SVMP-rich venom in adults. Notwithstanding minor qualitative and quantitative differences, the venom arsenals of L. melanocephala and L. acrochorda are broadly similar between themselves and also closely mirror those of adult L. stenophrys and L. muta venoms. The high conservation of the overall composition of Central and South American bushmaster venoms provides the ground for rationalizing the "Lachesis syndrome", characterized by vagal syntomatology, sensorial disorders, hematologic, and cardiovascular manifestations, documented in envenomings by different species of this wide-ranging genus. This finding let us predict that monospecific Lachesic antivenoms may exhibit paraspecificity against all congeneric species. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Ontogenetic Characterization of the Intestinal Microbiota of Channel Catfish through 16S rRNA Gene Sequencing Reveals Insights on Temporal Shifts and the Influence of Environmental Microbes

    Science.gov (United States)

    Bledsoe, Jacob W.; Peterson, Brian C.; Swanson, Kelly S.; Small, Brian C.

    2016-01-01

    Aquaculture recently overtook capture fisheries as the largest producer of food fish, but to continue increasing fish production the industry is in search of better methods of improving fish health and growth. Pre- and probiotic supplementation has gained attention as a means of solving these issues, however, for such approaches to be successful, we must first gain a more holistic understanding of the factors influencing the microbial communities present in the intestines of fish. In this study, we characterize the bacterial communities associated with the digestive tract of a highly valuable U.S. aquaculture species, channel catfish Ictalurus punctatus, over the first 193 days of life to evaluate temporal changes that may occur throughout ontogenetic development of the host. Intestinal microbiota were surveyed with high-throughput DNA sequencing of 16S rRNA V4 gene amplicons derived from fish at 3, 65, 125, and 193 days post hatch (dph), while also characterizing the environmental microbes derived from the water supply and the administered diets. Microbial communities inhabiting the intestines of catfish early in life were dynamic, with significant shifts occurring up to 125 dph when the microbiota somewhat stabilized, as shifts were less apparent between 125 to 193 dph. Bacterial phyla present in the gut of catfish throughout ontogeny include Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria; with the species Cetobacterium somerae and Plesiomonas shigelloides showing the highest abundance in the catfish microbiota after 3 dph. Comparisons of the gut microbiota to the environmental microbes reveals that the fish gut is maintained as a niche habitat, separate from the overall microbial communities present in diets and water-supply. Although, there is also evidence that the environmental microbiota serves as an inoculum to the fish gut. Our results have implications for future research related to channel catfish biology and culture, and increase our

  5. Re-evaluation on the diversity of the polyphyletic genus Metaurostylopsis (Ciliophora, Hypotricha): ontogenetic, morphologic, and molecular data suggest the establishment of a new genus Apourostylopsis n. g.

    Science.gov (United States)

    Song, Weibo; Wilbert, Norbert; Li, Liqiong; Zhang, Qianqian

    2011-01-01

    The urostylid genus Metaurostylopsis Song et al., 2001 was considered to be a well-outlined taxon. Nevertheless, recent evidence, including morphological, ontogenetic, and molecular information, have consistently revealed conflicts among congeners, regarding their systematic relationships, ciliature patterns, and origins of ciliary organelles. In the present work, the morphogenetic and morphogenetic features were re-checked and compared, and the phylogeny of nominal species was analysed based on information inferred from the small subunit ribosomal RNA (SS rRNA) gene sequence. In addition, the binary divisional process in a new isolate of Metaurostylopsis struederkypkeae Shao et al., 2008 is described. All results obtained reveal that the genus is a polyphyletic assemblage whose nominal congeners fall into three clades within the core Urostylida, based on SS rRNA gene sequences. These three clades not match the groups inferred from morphological/morphogenetical evidences. Some conflicting data from molecular and ontogenetic studies also indicate that single-gene information might not be consistently reliable in detecting the phylogenetic relationships among closely related groups and comprehensive multi-gene analyses are necessary to give a more exact evaluation for this divergent assemblage. According to our new understandings, five forms are confirmed to be true Metaurostylopsis. The morphotype Metaurostylopsis sinica Shao et al., 2008 should be excluded from the genus and represents a distinct type, and, thus, a new genus Apourostylopsis n. g. with it as the type specie, i.e. Apourostylopsis sinica (Shao et al., 2008) n. comb. © 2010 The Author(s). Journal of Eukaryotic Microbiology © 2010 International Society of Protistologists.

  6. The reaction of European lobster larvae (Homarus gammarus) to different quality food: effects of ontogenetic shifts and pre-feeding history.

    Science.gov (United States)

    Schoo, Katherina L; Aberle, Nicole; Malzahn, Arne M; Schmalenbach, Isabel; Boersma, Maarten

    2014-02-01

    Young larval stages of many organisms represent bottlenecks in the life-history of many species. The high mortality commonly observed in, for example, decapod larvae has often been linked to poor nutrition, with most studies focussing on food quantity. Here, we focus instead on the effects of quality and have investigated its effects on the nutritional condition of lobster larvae. We established a tri-trophic food chain consisting of the cryptophyte Rhodomonas salina, the calanoid copepod Acartia tonsa and larvae of the European lobster Homarus gammarus. In a set of experiments, we manipulated the C:N:P stoichiometry of the primary producers, and accordingly those of the primary consumer. In a first experiment, R. salina was grown under N- and P-limitation and the nutrient content of the algae was manipulated by addition of the limiting nutrient to create a food quality gradient. In a second experiment, the effect on lobster larvae of long- and short-term exposure to food of varying quality during ontogenetic development was investigated. The condition of the lobster larvae was negatively affected even by subtle N- and P-nutrient limitations of the algae. Furthermore, younger lobster larvae were more vulnerable to nutrient limitation than older ones, suggesting an ontogenetic shift in the capacity of lobster larvae to cope with low quality food. The results presented here might have substantial consequences for the survival of lobster larvae in the field, as, in the light of future climate change and re-oligotrophication of the North Sea, lobster larvae might face marked changes in temperature and nutrient conditions, thus significantly altering their condition and growth.

  7. Media bias under direct and indirect government control: when is the bias smaller?

    OpenAIRE

    Abhra Roy

    2015-01-01

    We present an analytical framework to compare media bias under direct and indirect government control. In this context, we show that direct control can lead to a smaller bias and higher welfare than indirect control. We further show that the size of the advertising market affects media bias only under direct control. Media bias, under indirect control, is not affected by the size of the advertising market.

  8. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...

  9. Distinctive Characteristics of Sexual Orientation Bias Crimes

    Science.gov (United States)

    Stacey, Michele

    2011-01-01

    Despite increased attention in the area of hate crime research in the past 20 years, sexual orientation bias crimes have rarely been singled out for study. When these types of crimes are looked at, the studies are typically descriptive in nature. This article seeks to increase our knowledge of sexual orientation bias by answering the question:…

  10. Monotheism versus an innate bias towards mentalizing.

    Science.gov (United States)

    Costello, Fintan John

    2016-01-01

    Norenzayan et al.'s account for the spread of monotheistic "Big God" religions sees these religions originating as by-products of innate cognitive biases. These biases produce polytheistic rather than monotheistic systems, however, and so do not explain the origin of monotheism. Accounts where monotheism arises from polytheism (for political reasons, for example) appear better able to explain the spread of monotheism.

  11. Gender Bias: Inequities in the Classroom.

    Science.gov (United States)

    Love, Reeve

    1993-01-01

    This article explores sex bias in curricular materials for elementary and secondary schools. Sex bias is defined as a set of unconscious behaviors that, in themselves, are often trivial and generally favorable. Although these behaviors do not hurt if they happen only once, they can cause a great deal of harm if a pattern develops that serves to…

  12. EVIDENCE OF NATIONALISTIC BIAS IN MUAYTHAI

    Directory of Open Access Journals (Sweden)

    Tony D. Myers

    2006-07-01

    Full Text Available MuayThai is a combat sport with a growing international profile but limited research conducted into judging practices and processes. Problems with judging of other subjectively judged combat sports have caused controversy at major international tournaments that have resulted in changes to scoring methods. Nationalistic bias has been central to these problems and has been identified across a range of sports. The aim of this study was to examine nationalistic bias in MuayThai. Data were collected from the International Federation of MuayThai Amateur (IFMA World Championships held in Almaty, Kazakhstan September 2003 and comprised of tournament results from 70 A-class MuayThai bouts each judged by between five and nine judges. Bouts examined featured 62 competitors from 21 countries and 25 judges from 11 countries. Results suggested that nationalistic bias was evident. The bias observed equated to approximately one round difference between opposing judges over the course of a bout (a mean of 1.09 (SE=0.50 points difference between judges with opposing affilations. The number of neutral judges used meant that this level of bias generally did not influence the outcome of bouts. Future research should explore other ingroup biases, such as nearest neighbour bias and political bias as well as investigating the feasibility adopting an electronic scoring system

  13. Racially Biased Policing: Determinants of Citizen Perceptions

    Science.gov (United States)

    Weitzer, Ronald; Tuch, Steven A.

    2005-01-01

    The current controversy surrounding racial profiling in America has focused renewed attention on the larger issue of racial bias by the police. Yet little is known about the extent of police racial bias and even less about public perceptions of the problem. This article analyzes recent national survey data on citizens' views of and reported…

  14. Problems of Bias in History Textbooks.

    Science.gov (United States)

    Romanowski, Michael H.

    1996-01-01

    Argues that oftentimes simple parallel constructions and choice of examples reflect an unconscious bias in history textbooks. Reveals a number of these, particularly related to the United States' treatment of minorities in World War II. Advocates using strategies to identify and challenge biases in history textbooks. (MJP)

  15. The Battle over Studies of Faculty Bias

    Science.gov (United States)

    Gravois, John

    2007-01-01

    The American Federation of Teachers (AFT) recently commissioned a study to review the research that finds liberal bias run amok in academe. Believing that the AFT is not a dispassionate observer of this debate, this article provides "The Chronicle of Higher Education's" survey of the genre. The studies reviewed include: (1) "Political Bias in the…

  16. Reducing status quo bias in choice experiments

    DEFF Research Database (Denmark)

    Bonnichsen, Ole; Ladenburg, Jacob

    In stated preference literature, the tendency to choose the alternative representing the status quo situation seems to exceed real life status quo effects. Accordingly, status quo bias can be a problem. In Choice Experiments, status quo bias is found to be strongly correlated with protest attitudes...

  17. Reducing status quo bias in choice experiments

    DEFF Research Database (Denmark)

    Bonnichsen, Ole; Ladenburg, Jacob

    2015-01-01

    to be superior, i.e. a status quo effect. However, in the stated preference literature, the tendency to choose the alternative representing the status quo situation seems to exceed real life status quo effects. Accordingly, status quo bias can be a problem. In the Choice Experiment literature, status quo bias...

  18. Length-biased Weighted Maxwell Distribution

    Directory of Open Access Journals (Sweden)

    Kanak Modi

    2015-12-01

    Full Text Available The concept of length-biased distribution can be employed in development of proper models for life-time data. In this paper, we develop the length-biased form of Weighted Maxwell distribution (WMD. We study the statistical properties of the derived distribution including moments, moment generating function, hazard rate, reverse hazard rate, Shannon entropy and estimation of parameters

  19. Biased trapping issue on weighted hierarchical networks

    Indian Academy of Sciences (India)

    In this paper, we present trapping issues of weight-dependent walks on weighted hierarchical networks which are based on the classic scale-free hierarchical networks. Assuming that edge's weight is used as local information by a random walker, we introduce a biased walk. The biased walk is that a walker, at each step, ...

  20. Sex Bias in Individual Education Plans.

    Science.gov (United States)

    Nemzoff, Ruth

    1993-01-01

    Studies how sex bias influences the process of preparing and implementing individual education plans (IEPs) under the Education for the Handicapped Act. Conversations with 20 mothers of disabled children reveal the multiple effects of bias and result in recommendations for improved IEPs. (SLD)

  1. Selection Bias and the Degree Effect.

    Science.gov (United States)

    Frazis, Harley

    1993-01-01

    Analysis of National Longitudinal Study data used an ordered probit model of schooling choice to correct for selection bias. Evidence indicates that selection bias does not account for the high rate of return for completing college compared to having "some college." (SK)

  2. Fandom Biases Retrospective Judgments Not Perception

    National Research Council Canada - National Science Library

    Huff, Markus; Papenmeier, Frank; Maurer, Annika E; Meitz, Tino G. K; Garsoffky, Bärbel; Schwan, Stephan

    2017-01-01

    ... hand, for dynamic real-life events, visual processing has been found to be highly synchronous among viewers. Thus, while in a seminal study fandom as a particularly strong case of attitudes did bias judgments of a sports event, it left the question open whether attitudes do bias prior processing stages. Here, we investigated influences of fandom...

  3. A specific attentional bias in suicide attempters

    NARCIS (Netherlands)

    Becker, E.S.; Strohbach, D.; Rinck, M.

    1999-01-01

    Selective attention in patients after an attempted suicide was investigated to find out whether a specific attentional bias for suicide-related materials exists and to clarify the possible role of emotions in the bias. Thirty-one patients who had previously attempted to commit suicide and 31 control

  4. G Protein-coupled Receptor Biased Agonism.

    Science.gov (United States)

    Hodavance, Sima Y; Gareri, Clarice; Torok, Rachel D; Rockman, Howard A

    2016-03-01

    G protein-coupled receptors are the largest family of targets for current therapeutics. The classic model of their activation was binary, where agonist binding induced an active conformation and subsequent downstream signaling. Subsequently, the revised concept of biased agonism emerged, where different ligands at the same G protein-coupled receptor selectively activate one downstream pathway versus another. Advances in understanding the mechanism of biased agonism have led to the development of novel ligands, which have the potential for improved therapeutic and safety profiles. In this review, we summarize the theory and most recent breakthroughs in understanding biased signaling, examine recent laboratory investigations concerning biased ligands across different organ systems, and discuss the promising clinical applications of biased agonism.

  5. Production bias and cluster annihilation: Why necessary?

    DEFF Research Database (Denmark)

    Singh, B.N.; Trinkaus, H.; Woo, C.H.

    1994-01-01

    the primary cluster density is high. Therefore, a sustained high swelling rate driven by production bias must involve the annihilation of primary clusters at sinks. A number of experimental observations which are unexplainable in terms of the conventional dislocation bias for monointerstitials is considered....... It is found that the production bias and cluster annihilation are necessary to explain these observations, with, in many cases, the explicit consideration of the annihilation of the primary interstitial clusters.......-field approach. The production bias approach, on the other hand, is based on the physical features of the cascade damage and is therefore considered to be more appropriate for describing the damage accumulation under cascade damage conditions. However, production bias can not produce high a swelling rate when...

  6. Sampling bias on cup anemometer mean winds

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, L.; Hansen, O.F.; Hoejstrup, J. [Risoe National Laboratory, Roskilde (Denmark)

    2003-07-01

    The cup anemometer signal can be sampled in several ways to obtain the mean wind speed. Here we discuss the sampling of series of mean wind speeds from consecutive rotor rotations, followed by unweighted and weighted averaging. It is shown that the unweighted averaging creates a positive bias on the long-term mean wind speed, which is at least one order of magnitude larger than the positive bias from the weighted averaging, also known as the sample-and-hold method. For a homogeneous, neutrally stratified flow the first biases are 1%-2%. For comparison the biases due to fluctuations of the three wind velocity components and due to calibration non-linearity are determined under the same conditions. The largest of these is the v-bias from direction fluctuations. The calculations pertain to the Risoe P2546A model cup anemometer. (author)

  7. Childhood obesity: issues of weight bias.

    Science.gov (United States)

    Washington, Reginald L

    2011-09-01

    Although the effects of obesity on children's physical health are well documented, the social consequences of obesity are less well described and may not be addressed in intervention programs. Weight bias may take several forms. It may result in teasing and discrimination and may affect employment and educational opportunities. Health care providers may limit care of overweight or obese children. The media promote weight bias in multiple ways. Some parents are biased against their obese children. In an effort to avoid weight bias, new efforts to reduce obesity must be evaluated to determine whether these efforts do, in fact, add to the problem. It is important to understand that the weight bias that obese youth face is just as serious as the physical consequences of excessive weight on the welfare of the child.

  8. A Simulation Platform for Quantifying Survival Bias

    DEFF Research Database (Denmark)

    Mayeda, Elizabeth Rose; Tchetgen Tchetgen, Eric J; Power, Melinda C

    2016-01-01

    Bias due to selective mortality is a potential concern in many studies and is especially relevant in cognitive aging research because cognitive impairment strongly predicts subsequent mortality. Biased estimation of the effect of an exposure on rate of cognitive decline can occur when mortality i......-mortality situations. This simulation platform provides a flexible tool for evaluating biases in studies with high mortality, as is common in cognitive aging research.......Bias due to selective mortality is a potential concern in many studies and is especially relevant in cognitive aging research because cognitive impairment strongly predicts subsequent mortality. Biased estimation of the effect of an exposure on rate of cognitive decline can occur when mortality...... is a common effect of exposure and an unmeasured determinant of cognitive decline and in similar settings. This potential is often represented as collider-stratification bias in directed acyclic graphs, but it is difficult to anticipate the magnitude of bias. In this paper, we present a flexible simulation...

  9. Quantifying publication bias in meta-analysis.

    Science.gov (United States)

    Lin, Lifeng; Chu, Haitao

    2017-11-15

    Publication bias is a serious problem in systematic reviews and meta-analyses, which can affect the validity and generalization of conclusions. Currently, approaches to dealing with publication bias can be distinguished into two classes: selection models and funnel-plot-based methods. Selection models use weight functions to adjust the overall effect size estimate and are usually employed as sensitivity analyses to assess the potential impact of publication bias. Funnel-plot-based methods include visual examination of a funnel plot, regression and rank tests, and the nonparametric trim and fill method. Although these approaches have been widely used in applications, measures for quantifying publication bias are seldom studied in the literature. Such measures can be used as a characteristic of a meta-analysis; also, they permit comparisons of publication biases between different meta-analyses. Egger's regression intercept may be considered as a candidate measure, but it lacks an intuitive interpretation. This article introduces a new measure, the skewness of the standardized deviates, to quantify publication bias. This measure describes the asymmetry of the collected studies' distribution. In addition, a new test for publication bias is derived based on the skewness. Large sample properties of the new measure are studied, and its performance is illustrated using simulations and three case studies. © 2017, The International Biometric Society.

  10. Automation bias in electronic prescribing.

    Science.gov (United States)

    Lyell, David; Magrabi, Farah; Raban, Magdalena Z; Pont, L G; Baysari, Melissa T; Day, Richard O; Coiera, Enrico

    2017-03-16

    Clinical decision support (CDS) in e-prescribing can improve safety by alerting potential errors, but introduces new sources of risk. Automation bias (AB) occurs when users over-rely on CDS, reducing vigilance in information seeking and processing. Evidence of AB has been found in other clinical tasks, but has not yet been tested with e-prescribing. This study tests for the presence of AB in e-prescribing and the impact of task complexity and interruptions on AB. One hundred and twenty students in the final two years of a medical degree prescribed medicines for nine clinical scenarios using a simulated e-prescribing system. Quality of CDS (correct, incorrect and no CDS) and task complexity (low, low + interruption and high) were varied between conditions. Omission errors (failure to detect prescribing errors) and commission errors (acceptance of false positive alerts) were measured. Compared to scenarios with no CDS, correct CDS reduced omission errors by 38.3% (p < .0001, n = 120), 46.6% (p < .0001, n = 70), and 39.2% (p < .0001, n = 120) for low, low + interrupt and high complexity scenarios respectively. Incorrect CDS increased omission errors by 33.3% (p < .0001, n = 120), 24.5% (p < .009, n = 82), and 26.7% (p < .0001, n = 120). Participants made commission errors, 65.8% (p < .0001, n = 120), 53.5% (p < .0001, n = 82), and 51.7% (p < .0001, n = 120). Task complexity and interruptions had no impact on AB. This study found evidence of AB omission and commission errors in e-prescribing. Verification of CDS alerts is key to avoiding AB errors. However, interventions focused on this have had limited success to date. Clinicians should remain vigilant to the risks of CDS failures and verify CDS.

  11. Recent updates on GPCR biased agonism.

    Science.gov (United States)

    Pupo, André S; Duarte, Diego A; Lima, Vanessa; Teixeira, Larissa B; Parreiras-E-Silva, Lucas T; Costa-Neto, Claudio M

    2016-10-01

    G protein-coupled receptors (GPCRs) are the most important targets for drug discovery and not surprisingly ∼40% of all drugs currently in the market act on these receptors. Currently, one of the most active areas in GPCRs signaling is biased agonism, a phenomenon that occurs when a given ligand is able to preferentially activate one (or some) of the possible signaling pathways. In this review, we highlight the most recent findings about biased agonism, including an extension of this concept to intracellular signaling, allosterism, strategies for assessment and interpretation, and perspectives of therapeutic applications for biased agonists. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Accounting for Unobservable Exposure Time Bias Wh...

    Data.gov (United States)

    U.S. Department of Health & Human Services — Accounting for Unobservable Exposure Time Bias When Using Medicare Prescription Drug Data Unobservable exposure time is common among Medicare Part D beneficiaries,...

  13. Biased four-point probe resistance

    Science.gov (United States)

    Garcia-Vazquez, Valentin

    2017-11-01

    The implications of switching the current polarity in a four-point probe resistance measurement are presented. We demonstrate that, during the inversion of the applied current, any change in the voltage V produced by a continuous drop of the sample temperature T will induce a bias in the temperature-dependent DC resistance. The analytical expression for the bias is deduced and written in terms of the variations of the measured voltages with respect to T and by the variations of T with respect to time t. Experimental data measured on a superconducting Nb thin film confirm that the bias of the normal-state resistance monotonically increases with the cooling rate dT/dt while keeping fixed dV/dT; on the other hand, the bias increases with dV/dT, reaching values up to 13% with respect to the unbiased resistance obtained at room temperature.

  14. Agitated Honeybees Exhibit Pessimistic Cognitive Biases

    National Research Council Canada - National Science Library

    Bateson, Melissa; Desire, Suzanne; Gartside, Sarah E; Wright, Geraldine A

    2011-01-01

    ...]. In humans, negative feelings are reliably correlated with pessimistic cognitive biases, defined as the increased expectation of bad outcomes [9-11]. Recently, mammals [12-16] and birds [17-20...

  15. Students' gender bias in teaching evaluations

    Directory of Open Access Journals (Sweden)

    Narissra Punyanunt-Carter

    2015-09-01

    Full Text Available The goal of this study was to investigate if there is gender bias in student evaluations. Researchers administered a modified version of the teacher evaluation forms to 58 students (male=30; female=28 in a basic introductory communications class. Half the class was instructed to fill out the survey about a male professor, and the other half a female professor. Researchers broke down the evaluation results question by question in order to give a detailed account of the findings. Results revealed that there is certainly some gender bias at work when students evaluate their instructors. It was also found that gender bias does not significantly affect the evaluations. The results align with other findings in the available literature, which point to some sort of pattern regarding gender bias in evaluations, but it still seems to be inconsequential.  DOI: 10.18870/hlrc.v5i3.234

  16. Bias/Variance Analysis for Relational Domains

    National Research Council Canada - National Science Library

    Neville, Jennifer; Jensen, David

    2007-01-01

    .... To date, the impact of inference error on model performance has not been investigated. In this paper, we propose a new bias/variance framework that decomposes loss into errors due to both the learning and inference process...

  17. A Bias in the Diagnosis of Schizophrenia

    Science.gov (United States)

    Reade, William Kent; Wertheimer, Michael

    1976-01-01

    Research shows a relationship between diagnoses of schizophrenia among twins. It was studied whether information that a twin was schizophrenic would bias diagnoses. Such information almost doubled the rater's estimates of probability of schizophrenia in a hypothetical case history. (NG)

  18. Pseudo exchange bias due to rotational anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Ehrmann, A., E-mail: andrea.ehrmann@fh-bielefeld.de [Faculty of Engineering and Mathematics, Bielefeld University of Applied Sciences, 33619 Bielefeld (Germany); Komraus, S.; Blachowicz, T.; Domino, K. [Institute of Physics – Center for Science and Education, Silesian University of Technology, 44-100 Gliwice (Poland); Nees, M.K.; Jakobs, P.J.; Leiste, H. [Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Mathes, M.; Schaarschmidt, M. [ACCESS e. V., 57072 Aachen (Germany)

    2016-08-15

    Ferromagnetic nanostructure arrays with particle dimensions between 160 nm and 400 nm were created by electron-beam lithography. The permalloy structures consist of rectangular-shaped walls around a square open space. While measuring their magnetic properties using the Magneto-Optical Kerr Effect (MOKE), in some angular regions an exchange bias (EB) seemed to appear. This paper gives an overview of possible reasons for this “pseudo exchange bias” and shows experimentally and by means of micromagnetic simulations that this effect can be attributed to unintentionally measuring minor loops. - Highlights: • Pseudo exchange bias can be found in square Py nanorings of different dimensions. • Pseudo exchange bias stems from unintentionally measuring minor loops. • New approach in explaining “real” exchange bias effect in coupled FM/AFM systems. • Theoretical base to explain other measurements of a rotational anisotropy.

  19. Autobiographical memory bias in social anxiety.

    Science.gov (United States)

    Krans, Julie; de Bree, June; Bryant, Richard A

    2014-01-01

    In social anxiety the psychological self is closely related to the feared stimulus. Socially anxious individuals are, by definition, concerned about how the self is perceived and evaluated by others. As autobiographical memory is strongly related to views of the self it follows that biases in autobiographical memory play an important role in social anxiety. In the present study high (n = 19) and low (n = 29) socially anxious individuals were compared on autobiographical memory bias, current goals, and self-discrepancy. Individuals high in social anxiety showed a bias towards recalling more negative and more social anxiety-related autobiographical memories, reported more current goals related to overcoming social anxiety, and showed larger self-discrepancies. The pattern of results is largely in line with earlier research in individuals with PTSD and complicated grief. This suggests that the relation between autobiographical memory bias and the self is a potentially valuable trans-diagnostic factor.

  20. Ricean Bias Correction in Linear Polarization Observation

    OpenAIRE

    Bong Won Sohn

    2011-01-01

    I developed an enhanced correction method for Ricean bias which occurs in linear polarization measurement. Two known methods for Ricean bias correction are reviewed. In low signal-to-noise area, the method based on the mode of the equation gives better representation of the fractional polarization. But a caution should be given that the accurate estimation of noise level, i.e. σ of the polarized flux, is important. The maximum likelihood method is better choice for high signal-to-...

  1. Escalation Bias: Does It Extend to Marketing?

    OpenAIRE

    JS Armstrong; Nicole Coviello; Barbara Safranek

    2005-01-01

    Escalation bias implies that managers favor reinvestments in projects that are doing poorly over those doing well. We tested this implication in a marketing context by conducting experiments on advertising and product-design decisions. Each situation was varied to reflect either a long-term or a short-term decision. Besides these four conditions, we conducted three replications. We found little evidence of escalation bias by 365 subjects in the seven experimental comparisons.

  2. mb Bias and Regional Magnitude and Yield

    Science.gov (United States)

    2008-09-01

    events, but may indicate some complexity in bias in this region , perhaps controlled by crustal thickness or the distribution of recent volcanism. The...are relatively negative (Sichuan, Ordos, and Tarim basins). The lithosphere tends to be thick under these basins, possibly resulting in lower...mb BIAS AND REGIONAL MAGNITUDE AND YIELD Richard J. Stead, Hans E. Hartse, W. Scott Phillips, and George E. Randall Los Alamos National Laboratory

  3. THE NORMATIVE BIAS IN ENTREPRENEURIAL THEORY

    OpenAIRE

    KEITH JAKEE; HEATH SPONG

    2011-01-01

    This article highlights the normative bias in the entrepreneurial theories of Schumpeter and Kirzner. This bias, while significant, has remained largely implicit, and the approaches of both authors, we argue, entail "Panglossian" views of entrepreneurial processes. We trace these problems to each of the theories' teleological foundations and suggest that defining entrepreneurial "outcomes", and normatively judging those outcomes, will be more problematic than commonly admitted. We suggest ana...

  4. Biased trapping issue on weighted hierarchical networks

    Indian Academy of Sciences (India)

    edge's weight is used as local information by a random walker, we introduce a biased walk. The biased walk is that a ... because of its role in real situations such as transport in disordered media, neuron fir- ing, spread of .... consisting of the hub node of Gg and the local hub set, Hn(1 ≤ n

  5. Homophily explains perception biases in social networks

    OpenAIRE

    Lee, Eun; Karimi, Fariba; Jo, Hang-Hyun; Strohmaier, Markus; Wagner, Claudia

    2017-01-01

    Individual's perceptions about the prevalence of attributes in their social networks is commonly skewed by the limited information available to them. Filter bubbles -- being exposed to other like-minded people -- and majority illusion -- overestimation of minorities in social networks -- are two examples of how perception biases can manifest. In this paper, we show how homophily and disproportionate group sizes influence the emergence of perception biases in social networks. Using a generativ...

  6. Composite biasing in Monte Carlo radiative transfer

    Science.gov (United States)

    Baes, Maarten; Gordon, Karl D.; Lunttila, Tuomas; Bianchi, Simone; Camps, Peter; Juvela, Mika; Kuiper, Rolf

    2016-05-01

    Biasing or importance sampling is a powerful technique in Monte Carlo radiative transfer, and can be applied in different forms to increase the accuracy and efficiency of simulations. One of the drawbacks of the use of biasing is the potential introduction of large weight factors. We discuss a general strategy, composite biasing, to suppress the appearance of large weight factors. We use this composite biasing approach for two different problems faced by current state-of-the-art Monte Carlo radiative transfer codes: the generation of photon packages from multiple components, and the penetration of radiation through high optical depth barriers. In both cases, the implementation of the relevant algorithms is trivial and does not interfere with any other optimisation techniques. Through simple test models, we demonstrate the general applicability, accuracy and efficiency of the composite biasing approach. In particular, for the penetration of high optical depths, the gain in efficiency is spectacular for the specific problems that we consider: in simulations with composite path length stretching, high accuracy results are obtained even for simulations with modest numbers of photon packages, while simulations without biasing cannot reach convergence, even with a huge number of photon packages.

  7. Systematic biases in human heading estimation.

    Directory of Open Access Journals (Sweden)

    Luigi F Cuturi

    Full Text Available Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion.

  8. Implicit Racial Bias in Medical School Admissions.

    Science.gov (United States)

    Capers, Quinn; Clinchot, Daniel; McDougle, Leon; Greenwald, Anthony G

    2017-03-01

    Implicit white race preference has been associated with discrimination in the education, criminal justice, and health care systems and could impede the entry of African Americans into the medical profession, where they and other minorities remain underrepresented. Little is known about implicit racial bias in medical school admissions committees. To measure implicit racial bias, all 140 members of the Ohio State University College of Medicine (OSUCOM) admissions committee took the black-white implicit association test (IAT) prior to the 2012-2013 cycle. Results were collated by gender and student versus faculty status. To record their impressions of the impact of the IAT on the admissions process, members took a survey at the end of the cycle, which 100 (71%) completed. All groups (men, women, students, faculty) displayed significant levels of implicit white preference; men (d = 0.697) and faculty (d = 0.820) had the largest bias measures (P bias, 48% were conscious of their individual results when interviewing candidates in the next cycle, and 21% reported knowledge of their IAT results impacted their admissions decisions in the subsequent cycle. The class that matriculated following the IAT exercise was the most diverse in OSUCOM's history at that time. Future directions include preceding and following the IAT with more robust reflection and education on unconscious bias. The authors join others in calling for an examination of bias at all levels of academic medicine.

  9. Investigating bias in squared regression structure coefficients.

    Science.gov (United States)

    Nimon, Kim F; Zientek, Linda R; Thompson, Bruce

    2015-01-01

    The importance of structure coefficients and analogs of regression weights for analysis within the general linear model (GLM) has been well-documented. The purpose of this study was to investigate bias in squared structure coefficients in the context of multiple regression and to determine if a formula that had been shown to correct for bias in squared Pearson correlation coefficients and coefficients of determination could be used to correct for bias in squared regression structure coefficients. Using data from a Monte Carlo simulation, this study found that squared regression structure coefficients corrected with Pratt's formula produced less biased estimates and might be more accurate and stable estimates of population squared regression structure coefficients than estimates with no such corrections. While our findings are in line with prior literature that identified multicollinearity as a predictor of bias in squared regression structure coefficients but not coefficients of determination, the findings from this study are unique in that the level of predictive power, number of predictors, and sample size were also observed to contribute bias in squared regression structure coefficients.

  10. Melihat Bisnis Bias Kapital Media: Asumsi Aksiologi Dan Ontologis Sederhana

    OpenAIRE

    Kurnia, Septiawan Santana

    2003-01-01

    Idealnya, media massa menjadi pilar demokrasi, juga mencerahkan dan memberdayakan warga negara. Akan tetapi, di Indonesia, media massa seringkali mengalami bias: bias kapital, bias kekuasaan, bias kepentingan wartawan sendiri, dan bias-bias lainnya. Contoh sederhana, rubrik Advertorial di media cetak. Rubrik itu dikemas seperti berita, padahal ikLan. Sejalan dengan itu, muncul pula fenomena di mana iklan tidak dipagari oLeh fire wall, untuk membedakannya dengan teks berita. Pengemasan iklan i...

  11. Placebo effect studies are susceptible to response bias and to other types of biases

    DEFF Research Database (Denmark)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-01-01

    Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo.......Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo....

  12. Are attentional bias and memory bias for negative words causally related?

    Science.gov (United States)

    Blaut, Agata; Paulewicz, Borysław; Szastok, Marta; Prochwicz, Katarzyna; Koster, Ernst

    2013-09-01

    In cognitive theories of depression, processing biases are assumed to be partly responsible for the onset and maintenance of mood disorders. Despite a wealth of studies examining the relation between depression and individual biases (at the level of attention, interpretation, and memory), little is known about relationships between different biases. The purpose of the present study was to assess if attentional bias is causally related to memory bias. 71 participants were randomly assigned to a control (n = 37) or attentional training group (n = 34). The attentional manipulation was followed by an explicit, intentional memory task during which novel neutral, negative, and positive words were presented. It was found that individuals with elevated depression score trained to orient away from negative words did not display a memory bias for negative words (adjectives) whereas similar individuals displayed this memory bias in the control condition. Generalization of the findings is limited because of the short study time frame and specific nature of the memory task. These results indicate that altering attentional bias can influence elaborative processing of emotional material and that this bias could be one of the causes of mood congruent memory in depression. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Ontogenetic shifts in the diet of plains hog-nosed snakes (Heterodon nasicus) revealed by stable isotope analysis.

    Science.gov (United States)

    Durso, Andrew M; Mullin, Stephen J

    2017-02-01

    Wild snake diets are difficult to study using traditional methods, but stable isotopes offer several advantages, including integrating dietary information over time, providing data from individuals that have not fed recently, and avoiding bias towards slowly-digesting prey items. We used stable isotope signatures of carbon and nitrogen from scale tissue, red blood cells, and blood plasma to assess the diet of wild plains hog-nosed snakes (Heterodon nasicus) in Illinois. We developed Bayesian mixing models which, taken together, predicted that H. nasicus shifted from a juvenile diet predominantly (31-63%) composed of six-lined racerunners (Aspidoscelis sexlineatus) and their eggs to an adult diet predominantly (44-56%) composed of eggs of the aquatic turtles Chrysemys picta and Chelydra serpentina, with a contribution from toads (Anaxyrus sp.; 6-27%) during their adolescent years. These results agreed with sparse data from gut contents. Combining traditional and isotopic techniques for studying the diets of wild snakes can increase the utility of both types of data. Copyright © 2016 Elsevier GmbH. All rights reserved.

  14. Contextual modulation of biases in face recognition.

    Directory of Open Access Journals (Sweden)

    Fatima Maria Felisberti

    Full Text Available BACKGROUND: The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. METHODOLOGY AND FINDINGS: Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174. An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2. Such bias was eliminated or attenuated by making participants explicitly aware of "cooperative", "cheating" and "neutral/indifferent" behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3. Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4. CONCLUSION: The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context.

  15. Implicit Bias in Pediatric Academic Medicine.

    Science.gov (United States)

    Johnson, Tiffani J; Ellison, Angela M; Dalembert, George; Fowler, Jessica; Dhingra, Menaka; Shaw, Kathy; Ibrahim, Said

    2017-01-01

    Despite known benefits of diversity, certain racial/ethnic groups remain underrepresented in academic pediatrics. Little research exists regarding unconscious racial attitudes among pediatric faculty responsible for decisions on workforce recruitment and retention in academia. This study sought to describe levels of unconscious racial bias and perceived barriers to minority recruitment and retention among academic pediatric faculty leaders. Authors measured unconscious racial bias in a sample of pediatric faculty attending diversity workshops conducted at local and national meetings in 2015. A paper version of the validated Implicit Association Test (IAT) measured unconscious racial bias. Subjects also reported perceptions about minority recruitment and retention. Of 68 eligible subjects approached, 58 (85%) consented and completed the survey with IAT. Of participants, 83% had leadership roles and 93% were involved in recruitment. Participants had slight pro-white/anti-black bias on the IAT (M = 0.28, SD = 0.49). There were similar IAT scores among participants in leadership roles (M = 0.33, SD = 0.47) and involved in recruitment (M = 0.28, SD = 0.43). Results did not differ when comparing participants in local workshops to the national workshop (n = 36, M = 0.29, SD = 0.40 and n = 22, M = 0.27, SD = 0.49 respectively; p = 0.88). Perceived barriers to minority recruitment and retention included lack of minority mentors, poor recruitment efforts, and lack of qualified candidates. Unconscious pro-white/anti-black racial bias was identified in this sample of academic pediatric faculty and leaders. Further research is needed to examine how unconscious bias impacts decisions in academic pediatric workforce recruitment. Addressing unconscious bias and perceived barriers to minority recruitment and retention represent opportunities to improve diversity efforts. Copyright © 2017 National Medical Association. All rights reserved.

  16. Stimulus-driven attention, threat bias, and sad bias in youth with a history of an anxiety disorder or depression

    OpenAIRE

    Sylvester, Chad M.; Hudziak, James J.; Gaffrey, Michael S.; Barch, Deanna M.; Luby, Joan L.

    2016-01-01

    Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth ...

  17. Towards quantitative connectivity analysis: reducing tractography biases.

    Science.gov (United States)

    Girard, Gabriel; Whittingstall, Kevin; Deriche, Rachid; Descoteaux, Maxime

    2014-09-01

    Diffusion MRI tractography is often used to estimate structural connections between brain areas and there is a fast-growing interest in quantifying these connections based on their position, shape, size and length. However, a portion of the connections reconstructed with tractography is biased by their position, shape, size and length. Thus, connections reconstructed are not equally distributed in all white matter bundles. Quantitative measures of connectivity based on the streamline distribution in the brain such as streamline count (density), average length and spatial extent (volume) are biased by erroneous streamlines produced by tractography algorithms. In this paper, solutions are proposed to reduce biases in the streamline distribution. First, we propose to optimize tractography parameters in terms of connectivity. Then, we propose to relax the tractography stopping criterion with a novel probabilistic stopping criterion and a particle filtering method, both based on tissue partial volume estimation maps calculated from a T1-weighted image. We show that optimizing tractography parameters, stopping and seeding strategies can reduce the biases in position, shape, size and length of the streamline distribution. These tractography biases are quantitatively reported using in-vivo and synthetic data. This is a critical step towards producing tractography results for quantitative structural connectivity analysis. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. DNA replication induces compositional biases in yeast.

    Science.gov (United States)

    Marsolier-Kergoat, Marie-Claude; Goldar, Arach

    2012-03-01

    Asymmetries intrinsic to the process of DNA replication are expected to cause differences in the substitution patterns of the leading and the lagging strands and to induce compositional biases. These biases have been detected in the majority of eubacterial genomes but rarely in eukaryotes. Only in the human genome, the activity of a minority of replication origins seems to generate compositional biases. In this work, we provide evidence for replication-associated GC and TA skews in the genomes of two yeast species, Saccharomyces cerevisiae and Kluyveromyces lactis, whereas the data for the Schizosaccharomyces pombe genome are less conclusive. In contrast with the genomes of Homo sapiens and of the majority of eubacteria, the leading strand is enriched in cytosine and adenine in both S. cerevisiae and K. lactis. We observed significant variations across the interorigin intervals of several substitution rates in the S. cerevisiae lineage since its divergence from S. paradoxus. We also found that the S. cerevisiae genome is far from compositional equilibrium and that its present compositional biases are due to substitution rates operating before its divergence from S. paradoxus. Finally, we observed that replication and transcription tend to be cooriented in the S. cerevisiae genome, especially for genes encoding subunits of protein complexes. Taken together, our results suggest that replication-related compositional biases may be a feature of many eukaryotic genomes despite the stochastic nature of the firing of replication origins in these genomes.

  19. WFC3/UVIS: Bias Reference Files Analysis

    Science.gov (United States)

    McKay, M.; Baggett, S.

    2017-11-01

    We created and delivered new superbias reference files for the WFC3/UVIS channel and analyzed the data for temporal variation in the residual two-dimensional bias structure. Previously, the pipeline only provided superbias reference files for 2009 to 2010 in which the 2010 file was used for all the following years. We updated the 2009 and 2010 reference files and created new reference files for 2009 to 2016. The files were constructed from stacks of standard bias frames taken from 2009-2016. Statistics of the reference files were calculated and plotted as a function of time to display any significant changes in the data. The difference between the previous and current superbias files is 0.02 electrons for 2009 and 0.04 electrons for 2010. The analysis shows that the overall residual bias level gradually increased by 0.16 electrons from 2009 - 2016. In this report, we briefly discuss the process we used to generate the bias reference files, the process to check for significant changes in the biases and results of the analysis.

  20. Reducing environmental bias when measuring natural selection.

    Science.gov (United States)

    Scheiner, Samuel M; Donohue, Kathleen; Dorn, Lisa A; Mazer, Susan J; Wolfe, Lorne M

    2002-11-01

    Crucial to understanding the process of natural selection is characterizing phenotypic selection. Measures of phenotypic selection can be biased by environmental variation among individuals that causes a spurious correlation between a trait and fitness. One solution is analyzing genotypic data, rather than phenotypic data. Genotypic data, however, are difficult to gather, can be gathered from few species, and typically have low statistical power. Environmental correlations may act through traits other than through fitness itself. A path analytic framework, which includes measures of such traits, may reduce environmental bias in estimates of selection coefficients. We tested the efficacy of path analysis to reduce bias by re-analyzing three experiments where both phenotypic and genotypic data were available. All three consisted of plant species (Impatiens capensis, Arabidopsis thaliana, and Raphanus sativus) grown in experimental plots or the greenhouse. We found that selection coefficients estimated by path analysis using phenotypic data were highly correlated with those based on genotypic data with little systematic bias in estimating the strength of selection. Although not a panacea, using path analysis can substantially reduce environmental biases in estimates of selection coefficients. Such confidence in phenotypic selection estimates is critical for progress in the study of natural selection.

  1. Dinosaur census reveals abundant Tyrannosaurus and rare ontogenetic stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA.

    Science.gov (United States)

    Horner, John R; Goodwin, Mark B; Myhrvold, Nathan

    2011-02-09

    A dinosaur census recorded during the Hell Creek Project (1999-2009) incorporates multiple lines of evidence from geography, taphohistory, stratigraphy, phylogeny and ontogeny to investigate the relative abundance of large dinosaurs preserved in the Upper Cretaceous Hell Creek Formation of northeastern Montana, USA. Overall, the dinosaur skeletal assemblages in the Hell Creek Formation (excluding lag-influenced records) consist primarily of subadult or small adult size individuals. Small juveniles and large adults are both extremely rare, whereas subadult individuals are relatively common. We propose that mature individuals of at least some dinosaur taxa either lived in a separate geographic locale analogous to younger individuals inhabiting an upland environment where sedimentation rates were relatively less, or these taxa experienced high mortality before reaching terminal size where late stage and often extreme cranial morphology is expressed. Tyrannosaurus skeletons are as abundant as Edmontosaurus, an herbivore, in the upper Hell Creek Formation and nearly twice as common in the lower third of the formation. Smaller, predatory dinosaurs (e.g., Troodon and dromaeosaurids) are primarily represented by teeth found in microvertebrate localities and their skeletons or identifiable lag specimens were conspicuously absent. This relative abundance suggests Tyrannosaurus was not a typical predator and likely benefited from much wider food choice opportunities than exclusively live prey and/or specific taxa. Tyrannosaurus adults may not have competed with Tyrannosaurus juveniles if the potential for selecting carrion increased with size during ontogeny. Triceratops is the most common dinosaur and isolated skulls contribute to a significant portion of this census. Associated specimens of Triceratops consisting of both cranial and postcranial elements remain relatively rare. This rarity may be explained by a historical collecting bias influenced by facies and taphonomic

  2. Spatial, seasonal and ontogenetic variation in the diet of Astyanax aff. fasciatus (Ostariophysi: Characidae in an Atlantic Forest river, Southern Brazil

    Directory of Open Access Journals (Sweden)

    Luciano Lazzarini Wolff

    Full Text Available This study described the feeding habits of the characin Astyanax aff. fasciatus. The diet compositions of specimens from two sites (A and B on a river in Southern Brazil were compared according to the size of individuals and seasonal period. The collections were performed monthly from March 2005 to February 2006, where the stomach contents of 290 specimens were assessed. Food items for A. aff. fasciatus were basically composed of plants and insects, especially leaf fragments, seeds, fruits, filamentous algae, aquatic and terrestrial insects and insect fragments. At site A, the most common items were insect and plant fragments. Conversely at site B, plant fragments were more representative. In general, all items of animal origin showed the highest feeding index values at site A, whereas at site B detritus and grass items were more abundant. The composition of items varied seasonally, with higher diversity of items being recorded during the spring at both sites. Smaller individuals preferred items of animal origin, while the larger ones consumed mainly items of plant origin. According to its size, A. aff. fasciatus in this study may be considered a species with insectivorous tendencies when immature or herbivorous tendencies when adult. Nevertheless, its feeding habits may be flexible according to resource availability, showing wide ontogenetic, besides spatial and temporal variation.

  3. Ontogenetic and temperature-dependent changes in tolerance to hypoxia and hydrogen sulfide during the early life stages of the Manila clam Ruditapes philippinarum.

    Science.gov (United States)

    Kodama, Keita; Waku, Mitsuyasu; Sone, Ryota; Miyawaki, Dai; Ishida, Toshiro; Akatsuka, Tetsuji; Horiguchi, Toshihiro

    2018-01-02

    Wind-induced upwelling of hypoxic waters containing hydrogen sulfide (H2S) sometimes causes mass mortalities of aquatic organisms inhabiting coastal areas, including the hypoxia-tolerant Manila clam Ruditapes philippinarum. We examined the tolerance of Manila clam to H2S under controlled laboratory conditions. Larvae and juveniles obtained by artificial fertilization or from a wild population were exposed to normoxic or to hypoxic water with or without un-ionized H2S (concentrations, 0.2-52.2 mg/L). Twenty-four-hour exposure experiments revealed ontogenetic changes in the clam's tolerance to H2S exposure: tolerance was enhanced from the larval stages to juveniles just after settlement but was attenuated as juveniles grew. Tolerance of larvae and juveniles to H2S exposure weakened as the water temperature rose from 20 to 28 °C. Prolonged 48-h exposure to H2S attenuated the tolerance of juveniles to H2S. Temporary suspension of H2S exposure by 24-h reoxygenation improved the ability of juveniles to withstand repeated H2S exposure. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. The role of spatial and ontogenetic morphological variation in the expansion of the geographic range of the tropical brown alga, Turbinaria ornata.

    Science.gov (United States)

    Stewart, Hannah L

    2008-12-01

    Like many reefs worldwide, reefs in French Polynesia are experiencing a shift from coral-dominated to algal-dominated systems. The macroalga Turbinaria ornata comprises the majority of the increasing algal biomass on the barrier reefs surrounding these islands, and its distribution is increasing throughout this region. Aspects of the ecomorphology of Turbinaria make it ideally suited to thrive under the physical conditions found across barrier reefs throughout French Polynesia. Spatial morphological variation allows Turbinaria to produce morphotypes that are suited either to the calm, unidirectional, slowly flowing water in the backreef or to the high-energy wave-driven flow of the forereef. Backreef plants are flexible and produce airbladders that make them buoyant, whereas forereef plants are not buoyant, but strong and stiff. Production of bladders and resulting buoyancy has been found to be a phenotypically plastic trait in response to movement of water and confers advantages to backreef plants and plays an important role in dispersal. Ontogenetic variation of buoyancy, material properties, and reproductive capacity is part of a dispersal strategy whereby fertile, buoyant fronds drift between oceanic islands and form new populations, thereby contributing to the recent expansion of range of T. ornata across French Polynesia.

  5. Observations on the ontogenetic and intraspecific changes in the radula of Polycera aurantiomarginata García and Bobo, 1984 (Gastropoda Opisthobranchia from Southern Spain

    Directory of Open Access Journals (Sweden)

    Inés Martínez-Pita

    2006-06-01

    Full Text Available Polycera aurantiomarginata García and Bobo 1984 has a stable population in the intertidal area of El Portil beach (Huelva, SW Spain. This fact allowed specimens of different sizes to be collected from March 2001 to December 2003. In this paper, the ontogenetic variations of the radula of P. aurantiomarginata are studied. The radulae of 141 specimens were examined, 138 from El Portil and 3 from La Herradura (Granada, SE Spain. Specimens of 1.5-2 mm in length lack the typical radula described for P. aurantiomarginata. They have the so called pre-radula whose teeth are different in size and shape from the typical radula of the adults. In the specimens of 3 and 4 mm the pre-radula coexists with the characteristic radula, which is the single structure present in the specimens larger than 4 mm. The following features of the radula are included in this study: radular length, number of teeth rows and length of the outer lateral teeth. According to the three measured variables, the affinities among specimens without a pre-radula were established through cluster analysis, which defined three different groups (4-10 mm, 11-22 mm and 23-48 mm. Correlations between specimen length and radula length, number of rows and mean length of outer lateral teeth were significant. Feeding strategies could be related to the different morphology of the radula established by the Cluster analysis.

  6. From crypsis to mimicry: changes in colour and the configuration of the visual system during ontogenetic habitat transitions in a coral reef fish.

    Science.gov (United States)

    Cortesi, Fabio; Musilová, Zuzana; Stieb, Sara M; Hart, Nathan S; Siebeck, Ulrike E; Cheney, Karen L; Salzburger, Walter; Marshall, N Justin

    2016-08-15

    Animals often change their habitat throughout ontogeny; yet, the triggers for habitat transitions and how these correlate with developmental changes - e.g. physiological, morphological and behavioural - remain largely unknown. Here, we investigated how ontogenetic changes in body coloration and of the visual system relate to habitat transitions in a coral reef fish. Adult dusky dottybacks, Pseudochromis fuscus, are aggressive mimics that change colour to imitate various fishes in their surroundings; however, little is known about the early life stages of this fish. Using a developmental time series in combination with the examination of wild-caught specimens, we revealed that dottybacks change colour twice during development: (i) nearly translucent cryptic pelagic larvae change to a grey camouflage coloration when settling on coral reefs; and (ii) juveniles change to mimic yellow- or brown-coloured fishes when reaching a size capable of consuming juvenile fish prey. Moreover, microspectrophotometric (MSP) and quantitative real-time PCR (qRT-PCR) experiments show developmental changes of the dottyback visual system, including the use of a novel adult-specific visual gene (RH2 opsin). This gene is likely to be co-expressed with other visual pigments to form broad spectral sensitivities that cover the medium-wavelength part of the visible spectrum. Surprisingly, the visual modifications precede changes in habitat and colour, possibly because dottybacks need to first acquire the appropriate visual performance before transitioning into novel life stages. © 2016. Published by The Company of Biologists Ltd.

  7. Attention bias modification training under working memory load increases the magnitude of change in attentional bias.

    Science.gov (United States)

    Clarke, Patrick J F; Branson, Sonya; Chen, Nigel T M; Van Bockstaele, Bram; Salemink, Elske; MacLeod, Colin; Notebaert, Lies

    2017-12-01

    Attention bias modification (ABM) procedures have shown promise as a therapeutic intervention, however current ABM procedures have proven inconsistent in their ability to reliably achieve the requisite change in attentional bias needed to produce emotional benefits. This highlights the need to better understand the precise task conditions that facilitate the intended change in attention bias in order to realise the therapeutic potential of ABM procedures. Based on the observation that change in attentional bias occurs largely outside conscious awareness, the aim of the current study was to determine if an ABM procedure delivered under conditions likely to preclude explicit awareness of the experimental contingency, via the addition of a working memory load, would contribute to greater change in attentional bias. Bias change was assessed among 122 participants in response to one of four ABM tasks given by the two experimental factors of ABM training procedure delivered either with or without working memory load, and training direction of either attend-negative or avoid-negative. Findings revealed that avoid-negative ABM procedure under working memory load resulted in significantly greater reductions in attentional bias compared to the equivalent no-load condition. The current findings will require replication with clinical samples to determine the utility of the current task for achieving emotional benefits. These present findings are consistent with the position that the addition of a working memory load may facilitate change in attentional bias in response to an ABM training procedure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Measurement bias and multidimensionality; an illustration of bias detection in multidimensonal measurement models

    NARCIS (Netherlands)

    Jak, S.; Oort, F.J.; Dolan, C.V.

    2010-01-01

    Restricted factor analysis can be used to investigate measurement bias. A prerequisite for the detection of measurement bias through factor analysis is the correct specification of the measurement model. We applied restricted factor analysis to two subtests of a Dutch cognitive ability test. These

  9. Expectancy biases in fear and anxiety and their link to biases in attention.

    Science.gov (United States)

    Aue, Tatjana; Okon-Singer, Hadas

    2015-12-01

    Healthy individuals often exhibit prioritized processing of aversive information, as manifested in enhanced orientation of attention to threatening stimuli compared with neutral items. In contrast to this adaptive behavior, anxious, fearful, and phobic individuals show exaggerated attention biases to threat. In addition, they overestimate the likelihood of encountering their feared stimulus and the severity of the consequences; both are examples of expectancy biases. The co-occurrence of attention and expectancy biases in fear and anxiety raises the question about causal influences. Herein, we summarize findings related to expectancy biases in fear and anxiety, and their association with attention biases. We suggest that evidence calls for more comprehensive research strategies in the investigation of mutual influences between expectancy and attention biases, as well as their combined effects on fear and anxiety. Moreover, both types of bias need to be related to other types of distorted information processing commonly observed in fear and anxiety (e.g., memory and interpretation biases). Finally, we propose new research directions that may be worth considering in developing more effective treatments for anxiety disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Research bias in judgement bias studies : A systematic review of valuation judgement literature

    NARCIS (Netherlands)

    Klamer, Pim; Bakker, C.; Gruis, Vincent

    2017-01-01

    Valuation judgement bias has been a research topic for several years due to its proclaimed effect on valuation accuracy. However, little is known on the emphasis of literature on judgement bias, with regard to, for instance, research methodologies, research context and robustness of research

  11. Research bias in judgement bias studies : a systematic review of valuation judgement literature

    NARCIS (Netherlands)

    Klamer, Pim; Bakker, Cok; Gruis, V.H.

    2017-01-01

    Valuation judgement bias has been a research topic for several years due to its proclaimed effect on valuation accuracy. However, little is known on the emphasis of literature on judgement bias, with regard to, for instance, research methodologies, research context and robustness of research

  12. Thinking in Black and White: Conscious thought increases racially biased judgments through biased face memory

    NARCIS (Netherlands)

    Strick, M.A.; Stoeckart, P.F.; Dijksterhuis, A.J.

    2015-01-01

    It is a common research finding that conscious thought helps people to avoid racial discrimination. These three experiments, however, illustrate that conscious thought may increase biased face memory, which leads to increased judgment bias (i.e., preferring White to Black individuals). In

  13. Cognitive Bias Modification Training in Adolescents: Effects on Interpretation Biases and Mood

    Science.gov (United States)

    Lothmann, Claudia; Holmes, Emily A.; Chan, Stella W. Y.; Lau, Jennifer Y. F.

    2011-01-01

    Background: Negative biases in the interpretation of ambiguous material have been linked to anxiety and mood problems. Accumulating data from adults show that positive and negative interpretation styles can be induced through cognitive bias modification (CBM) paradigms with accompanying changes in mood. Despite the therapeutic potential of…

  14. Placebo effect studies are susceptible to response bias and to other types of biases

    DEFF Research Database (Denmark)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-01-01

    Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo....

  15. Optimism Bias in Fans and Sports Reporters

    Science.gov (United States)

    Love, Bradley C.

    2015-01-01

    People are optimistic about their prospects relative to others. However, existing studies can be difficult to interpret because outcomes are not zero-sum. For example, one person avoiding cancer does not necessitate that another person develops cancer. Ideally, optimism bias would be evaluated within a closed formal system to establish with certainty the extent of the bias and the associated environmental factors, such that optimism bias is demonstrated when a population is internally inconsistent. Accordingly, we asked NFL fans to predict how many games teams they liked and disliked would win in the 2015 season. Fans, like ESPN reporters assigned to cover a team, were overly optimistic about their team’s prospects. The opposite pattern was found for teams that fans disliked. Optimism may flourish because year-to-year team results are marked by auto-correlation and regression to the group mean (i.e., good teams stay good, but bad teams improve). PMID:26352146

  16. Lateral bias in theatre-seat choice.

    Science.gov (United States)

    Harms, Victoria; Reese, Miriam; Elias, Lorin J

    2014-01-01

    Examples of behavioural asymmetries are common in the range of human behaviour; even when faced with a symmetrical environment people demonstrate reliable asymmetries in behaviours like gesturing, cradling, and even seating. One such asymmetry is the observation that participants tend to choose seats to the right of the screen when asked to select their preferred seating location in a movie theatre. However, these results are based on seat selection using a seating chart rather than examining real seat choice behaviour in the theatre context. This study investigated the real-world seating patterns of theatre patrons during actual film screenings. Analysis of bias scores calculated using photographs of theatre patrons revealed a significant bias to choose seats on the right side of the theatre. These findings are consistent with the prior research in the area and confirm that the seating bias observed when seats are selected from a chart accurately reflects real-world seating behaviour.

  17. Bias-voltage-controlled interlayer exchange coupling.

    Energy Technology Data Exchange (ETDEWEB)

    You, C.-Y.

    1999-03-29

    We propose a new system whose magnetization direction can be controlled by an applied bias voltage without an external magnetic field. The system consists of a four layered structure F{sub 1}/S/I/F{sub 2} (F{sub 1}, F{sub 2}: ferromagnets, S: spacer, I: insulator). An analytic expression for bias-voltage-controlled interlayer exchange coupling in this system is developed within a simple free-electron-like, one-dimensional approximation. According to the approach, the magnetic configurations of the two magnetic layers oscillate from antiferromagnetic to ferromagnetic with applied bias voltage. This implies that we can switch/rotate the magnetization direction without an external magnetic field. Possible applications of such a system are also discussed.

  18. Using Machine Learning to Predict MCNP Bias

    Energy Technology Data Exchange (ETDEWEB)

    Grechanuk, Pavel Aleksandrovi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-01-09

    For many real-world applications in radiation transport where simulations are compared to experimental measurements, like in nuclear criticality safety, the bias (simulated - experimental keff) in the calculation is an extremely important quantity used for code validation. The objective of this project is to accurately predict the bias of MCNP6 [1] criticality calculations using machine learning (ML) algorithms, with the intention of creating a tool that can complement the current nuclear criticality safety methods. In the latest release of MCNP6, the Whisper tool is available for criticality safety analysts and includes a large catalogue of experimental benchmarks, sensitivity profiles, and nuclear data covariance matrices. This data, coming from 1100+ benchmark cases, is used in this study of ML algorithms for criticality safety bias predictions.

  19. Recursive bias estimation for high dimensional smoothers

    Energy Technology Data Exchange (ETDEWEB)

    Hengartner, Nicolas W [Los Alamos National Laboratory; Matzner-lober, Eric [UHB, FRANCE; Cornillon, Pierre - Andre [INRA

    2008-01-01

    In multivariate nonparametric analysis, sparseness of the covariates also called curse of dimensionality, forces one to use large smoothing parameters. This leads to biased smoothers. Instead of focusing on optimally selecting the smoothing parameter, we fix it to some reasonably large value to ensure an over-smoothing of the data. The resulting smoother has a small variance but a substantial bias. In this paper, we propose to iteratively correct the bias initial estimator by an estimate of the latter obtained by smoothing the residuals. We examine in detail the convergence of the iterated procedure for classical smoothers and relate our procedure to L{sub 2}-Boosting. We apply our method to simulated and real data and show that our method compares favorably with existing procedures.

  20. Reappraisal modulates attentional bias to angry faces

    Directory of Open Access Journals (Sweden)

    Shin Ah Kim

    2016-11-01

    Full Text Available Heightened attentional bias to emotional information is one of the main characteristics of disorders related to emotion dysregulation such as anxiety, depression, and substance abuse. Although reappraisal, an emotion regulation strategy, is known to effectively modulate subjective experience of emotions, it remains unknown whether reappraisal can alter attentional biases to emotional information. In the current research, we investigated the influence of instruction-induced state reappraisal (Study 1 and trait reappraisal (Study 2 on attentional biases to happy and angry faces. In Study 1, healthy young women were recruited and randomly assigned to one of the three groups: up-, down-, and no-regulation. Participants were instructed to reappraise their emotions to increase and decrease emotional experience while viewing an emotionally negative film clip. Attentional bias was assessed with a dot-probe task with pictures of angry and happy facial expressions. In Study 2, a separate group of healthy young men and women participated. Participants’ trait reappraisal and suppression as well as state and trait anxiety were assessed. A dot-probe task was completed by all participants. Statistical tests in Study 1 revealed that participants who reappraised to decrease negative emotions while viewing an emotionally negative film clip had reduced attentional bias to subsequently presented angry faces compared to participants who reappraised to increase negative emotions. Multiple regression analyses in Study 2 revealed that trait reappraisal predicted slower orienting toward angry faces, whereas state anxiety predicted slower disengagement from angry faces. Interestingly, trait suppression predicted slower disengagement from happy faces. Taken together, these results suggest that both instruction-induced state reappraisal and trait reappraisal are linked to reduced attentional bias to negative information and contribute to better understanding of how

  1. Best Practices in Hiring: Addressing Unconscious Bias

    Science.gov (United States)

    Simpson, Caroline E.

    2012-01-01

    Research has shown that implementing certain hiring practices will increase diversity in the workplace while enhancing academic quality. All of these practices rely on addressing the issue of 'unconscious bias.' A brief overview of unconscious bias--what it is, how it works, and simple measures to counter it--will be presented. Successful strategies, actions, and recommendations for implementing best recruiting and hiring practices, which have been proven to enhance academic excellence by ensuring a deep and diverse applicant pool, will also be presented.

  2. Reducing hypothetical bias in choice experiments

    DEFF Research Database (Denmark)

    Ladenburg, Jacob; Olsen, Søren Bøye; Nielsen, Rasmus Christian Fejer

    eliminate some of the hypothetical bias. The present paper tests an addition to Cheap Talk, an Opt-Out Reminder. The Opt-Out Reminder is an objective short script presented prior to the choice sets, prompting the respondent to choose the opt-out alternative, if he/she finds the proposed policy generated...... alternatives in a choice set too expensive. The results suggest that adding an Opt-Out Reminder to Cheap Talk can in fact reduce hypothetical bias even further and reduces some of the ineffectiveness of CT in relation to the survey bid range and experienced respondents....

  3. Intergroup Bias in Parliamentary Rule Enforcement

    DEFF Research Database (Denmark)

    Hjorth, Frederik Georg

    2016-01-01

    Parliament chairmen drawn from parliamentary parties enforce speaking time. Analyzing 5,756 speeches scraped from online transcripts, I provide evidence that speech lengths are biased in favor of the presiding chairman’s party. On average, speakers of the same party as the presiding chairman give 5 percent...... longer speeches and are 5 percent more likely to exceed the speaking time limit. The paper contributes to the extant literature by demonstrating political intergroup bias in a natural setting, suggesting that group loyalties can supersede institutional obligations even in a “least likely” context...

  4. Biased liquid crystal infiltrated photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Scolari, Lara

    2009-01-01

    partial differential equations. From the liquid crystal alignment the full tensorial dielectric permittivity in the capillaries is derived. The transmission spectrum for the photonic crystal fiber is obtained by solving the generalized eigenvalue problem deriving from Maxwell’s equations using a vector......A simulation scheme for the transmission spectrum of a photonic crystal fiber infiltrated with a nematic liquid crystal and subject to an external bias is presented. The alignment of the biased liquid crystal is simulated using the finite element method to solve the relevant system of coupled...

  5. Heterogeneous Causal Effects and Sample Selection Bias

    DEFF Research Database (Denmark)

    Breen, Richard; Choi, Seongsoo; Holm, Anders

    2015-01-01

    causal effects might vary over individuals or groups. In this paper we point out one of the under-appreciated hazards of seeking to estimate heterogeneous causal effects: conventional selection bias (that is, selection on baseline differences) can easily be mistaken for heterogeneity of causal effects....... This might lead us to find heterogeneous effects when the true effect is homogenous, or to wrongly estimate not only the magnitude but also the sign of heterogeneous effects. We apply a test for the robustness of heterogeneous causal effects in the face of varying degrees and patterns of selection bias...

  6. Biased and g protein-independent signaling of chemokine receptors

    DEFF Research Database (Denmark)

    Steen, Anne; Larsen, Olav; Thiele, Stefanie

    2014-01-01

    Biased signaling or functional selectivity occurs when a 7TM-receptor preferentially activates one of several available pathways. It can be divided into three distinct forms: ligand bias, receptor bias, and tissue or cell bias, where it is mediated by different ligands (on the same receptor), dif...

  7. Countering cognitive biases in minimising low value care.

    Science.gov (United States)

    Scott, Ian A; Soon, Jason; Elshaug, Adam G; Lindner, Robyn

    2017-05-15

    Cognitive biases in decision making may make it difficult for clinicians to reconcile evidence of overuse with highly ingrained prior beliefs and intuition. Such biases can predispose clinicians towards low value care and may limit the impact of recently launched campaigns aimed at reducing such care. Commonly encountered biases comprise commission bias, illusion of control, impact bias, availability bias, ambiguity bias, extrapolation bias, endowment effects, sunken cost bias and groupthink. Various strategies may be used to counter such biases, including cognitive huddles, narratives of patient harm, value considerations in clinical assessments, defining acceptable levels of risk of adverse outcomes, substitution, reflective practice and role modelling, normalisation of deviance, nudge techniques and shared decision making. These debiasing strategies have considerable face validity and, for some, effectiveness in reducing low value care has been shown in randomised trials.

  8. The influence of cognitive biases on psychophysiological vulnerability to stress

    OpenAIRE

    Randall, Kate

    2012-01-01

    Individuals who disproportionately attend to negative aspects of a situation (attention bias), or who unduly interpret ambiguity in a negative manner (interpretive bias) report more psychological ill-effects of stress than those with balanced or positively-skewed inclinations. Cognitive Bias Modification (CBM) techniques improve maladaptive biases through implicitly-based association learning, with induced positive biases buffering the future perception of stress. Six experimen...

  9. Global bias reliability in dogs (Canis familiaris).

    Science.gov (United States)

    Mongillo, Paolo; Pitteri, Elisa; Sambugaro, Pamela; Carnier, Paolo; Marinelli, Lieta

    2017-03-01

    Dogs enrolled in a previous study were assessed two years later for reliability of their local/global preference in a discrimination test with the same hierarchical stimuli used in the previous study (Experiment 1) and with a novel stimulus (Experiment 2). In Experiment 1, dogs easily re-learned to discriminate the positive stimulus; their individual global/local choices were stable compared to the previous study; and an overall clear global bias was found. In Experiment 2, dogs were slower in acquiring the initial discrimination task; the overall global bias disappeared; and, individually, dogs tended to make inverse choices compared to the original study. Spontaneous attention toward the test stimulus resembling the global features of the probe stimulus was the main factor affecting the likeliness of a global choice of our dogs, regardless of the type of experiment. However, attention to task-irrelevant elements increased at the expense of attention to the stimuli in the test phase of Experiment 2. Overall, the results suggest that the stability of global bias in dogs depends on the characteristics of the assessment contingencies, likely including the learning requirements of the tasks. Our results also clearly indicate that attention processes have a prominent role on dogs' global bias, in agreement with previous findings in humans and other species.

  10. Gender-Biased Communication in Physical Education

    Science.gov (United States)

    Valley, Julia A.; Graber, Kim C.

    2017-01-01

    Purpose: This study examined physical education teachers' awareness of gender equitable practices as well as the language and behaviors they employed in the physical education environment. The purpose of the study was to determine (a) what teachers know about gender equitable practices, (b) what types of gender bias are demonstrated, and (c) how…

  11. Biased allocation of faces to social categories

    NARCIS (Netherlands)

    Dotsch, R.; Wigboldus, D.H.J.; Knippenberg, A.F.M. van

    2011-01-01

    Three studies show that social categorization is biased at the level of category allocation. In all studies, participants categorized faces. In Studies 1 and 2, participants overallocated faces with criminal features-a stereotypical negative trait-to the stigmatized Moroccan category, especially if

  12. Apparent directional selection by biased pleiotropic mutation.

    Science.gov (United States)

    Tanaka, Yoshinari

    2010-07-01

    Pleiotropic effects of deleterious mutations are considered to be among the factors responsible for genetic constraints on evolution by long-term directional selection acting on a quantitative trait. If pleiotropic phenotypic effects are biased in a particular direction, mutations generate apparent directional selection, which refers to the covariance between fitness and the trait owing to a linear association between the number of mutations possessed by individuals and the genotypic values of the trait. The present analysis has shown how the equilibrium mean value of the trait is determined by a balance between directional selection and biased pleiotropic mutations. Assuming that genes act additively both on the trait and on fitness, the total variance-standardized directional selection gradient was decomposed into apparent and true components. Experimental data on mutation bias from the bristle traits of Drosophila and life history traits of Daphnia suggest that apparent selection explains a small but significant fraction of directional selection pressure that is observed in nature; the data suggest that changes induced in a trait by biased pleiotropic mutation (i.e., by apparent directional selection) are easily compensated for by (true) directional selection.

  13. Examining gender bias in studies of innovation

    OpenAIRE

    Crowden, N.

    2003-01-01

    This paper examines the presence of a gender bias in studies of innovation. Using the Innovation Systems Research Network (ISRN) and its interview guide as a case study, this research project examines how accurately and completely such innovation studies present gender differences in the innovation process.

  14. Test Bias and Ability Level Testing.

    Science.gov (United States)

    Silverman, Bernard

    1979-01-01

    The average grade equivalent reading comprehension scores of students in Black schools are compared to those of students in White schools under two forms of test administration. Concludes that use of grade level testing with the Iowa Tests of Basic Skills is biased in favor of low scoring subgroups. (Author)

  15. Bounding the bias of contrastive divergence learning

    DEFF Research Database (Denmark)

    Fischer, Anja; Igel, Christian

    2011-01-01

    , the number of variables in the RBM, and the maximum change in energy that can be produced by changing a single variable. The last reflects the dependence on the absolute values of the RBM parameters. The magnitude of the bias is also affected by the distance in variation between the modeled distribution...

  16. Biases for current FFTF calculational methods

    Energy Technology Data Exchange (ETDEWEB)

    Ombrellaro, P.A.; Bennett, R.A.; Daughtry, J.W.; Dobbin, K.D.; Harris, R.A.; Nelson, J.V.; Peterson, R.E.; Rothrock, R.B.

    1978-01-01

    Uncertainties in nuclear data and approximate calculational methods used in safety design, and operational support of a reactor yield biased as well as uncertain results. Experimentally based biases for use in Fast Flux Test Facility (FFTF) core calculations have been evaluated and are presented together with a description of calculational methods. Experimental data for these evaluations were obtained from an Engineering Mockup Critical (EMC) of the FFTF core built at the Argonne National Laboratory (ANL). The experiments were conceived and planned by the Hanford Engineering Development Laboratory (HEDL) in cooperation with the Westinghouse Advanced Reactors Division (WARD) and ANL personnel, and carried out by the ANL staff. All experiments were designed specifically to provide data for evaluation of current FFTF core calculational methods. These comprehensive experiments were designed to allow simultaneous evaluations of biases and uncertainties in calculated reactivities, fuel sub-assembly and material reactivity worths, small sample worths, absorber rod worths, spatial fission rate distributions, power tilting effects and spatial neutron spectra. Modified source multiplication and reactivity anomaly methods have also been evaluated. Uncertainties in the biases have been established and are sufficiently small to attain a high degree of confidence in the design, safety and operational aspects of the FFTF core.

  17. Administrative bias in South Africa | Nwauche | Potchefstroom ...

    African Journals Online (AJOL)

    ... the waiver of administrative bias, the curative mechanism of administrative appeal as well as some level of judicial review exemplified by the jurisprudence of article 6(1) of the European Convention of Human Rights, especially in the light of the contemplation of the South African Magistrate Court as a jurisdictional route of

  18. Agitated honeybees exhibit pessimistic cognitive biases.

    Science.gov (United States)

    Bateson, Melissa; Desire, Suzanne; Gartside, Sarah E; Wright, Geraldine A

    2011-06-21

    Whether animals experience human-like emotions is controversial and of immense societal concern [1-3]. Because animals cannot provide subjective reports of how they feel, emotional state can only be inferred using physiological, cognitive, and behavioral measures [4-8]. In humans, negative feelings are reliably correlated with pessimistic cognitive biases, defined as the increased expectation of bad outcomes [9-11]. Recently, mammals [12-16] and birds [17-20] with poor welfare have also been found to display pessimistic-like decision making, but cognitive biases have not thus far been explored in invertebrates. Here, we ask whether honeybees display a pessimistic cognitive bias when they are subjected to an anxiety-like state induced by vigorous shaking designed to simulate a predatory attack. We show for the first time that agitated bees are more likely to classify ambiguous stimuli as predicting punishment. Shaken bees also have lower levels of hemolymph dopamine, octopamine, and serotonin. In demonstrating state-dependent modulation of categorization in bees, and thereby a cognitive component of emotion, we show that the bees' response to a negatively valenced event has more in common with that of vertebrates than previously thought. This finding reinforces the use of cognitive bias as a measure of negative emotional states across species and suggests that honeybees could be regarded as exhibiting emotions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Nonresponse Bias in Student Evaluations of Teaching

    Science.gov (United States)

    Bacon, Donald R.; Johnson, Carol J.; Stewart, Kim A.

    2016-01-01

    Response rates in student evaluations of teaching (SET) surveys are often low, especially when conducted online. These lower response rates raise the question of nonresponse bias. This article examines a data set comprising student evaluations of 6,754 business courses occurring over an 11-year period to investigate whether response rate is…

  20. Students' Gender Bias in Teaching Evaluations

    Science.gov (United States)

    Punyanunt-Carter, Narissra; Carter, Stacy L.

    2015-01-01

    The goal of this study was to investigate if there is gender bias in student evaluations. Researchers administered a modified version of the teacher evaluation forms to 58 students (male = 30; female = 28) in a basic introductory communications class. Half the class was instructed to fill out the survey about a male professor, and the other half a…

  1. Do infants have the horizontal bias?

    NARCIS (Netherlands)

    van Renswoude, D.R.; Johnson, S.P.; Raijmakers, M.E.J.; Visser, I.

    2016-01-01

    A robust set of studies show that adults make more horizontal than vertical and oblique saccades, while scanning real-world scenes. In this paper we study the horizontal bias in infants. The directions of eye movements were calculated for 41 infants (M = 8.40 months, SD = 3.74, range = 3.48–15.47)

  2. Do infants have the horizontal bias?

    Science.gov (United States)

    Van Renswoude, D R; Johnson, S P; Raijmakers, M E J; Visser, I

    2016-08-01

    A robust set of studies show that adults make more horizontal than vertical and oblique saccades, while scanning real-world scenes. In this paper we study the horizontal bias in infants. The directions of eye movements were calculated for 41 infants (M=8.40 months, SD=3.74, range=3.48-15.47) and 47 adults (M=21.74 years, SD=4.54, range=17.89-39.84) while viewing 28 real-world scenes. Saccade directions were binned to study the proportion of saccades in the horizontal, vertical and oblique directions. In addition, saccade directions were also modeled using a mixture of Von Mises distributions, to account for the relatively large amount of variance in infants data. Horizontal bias was replicated in adults and also found in infants, using both the binning and Von Mises approach. Moreover, a developmental pattern was observed in which older infants are more precise in targeting their saccades than younger infants. That infants have a horizontal bias is important in understanding infants' eye movements. Future studies should account for the horizontal bias in their designs and analyses. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Assessing Projection Bias in Consumers' Food Preferences.

    Directory of Open Access Journals (Sweden)

    Tiziana de-Magistris

    Full Text Available The aim of this study is to test whether projection bias exists in consumers' purchasing decisions for food products. To achieve our aim, we used a non-hypothetical experiment (i.e., experimental auction, where hungry and non-hungry participants were incentivized to reveal their willingness to pay (WTP. The results confirm the existence of projection bias when consumers made their decisions on food products. In particular, projection bias existed because currently hungry participants were willing to pay a higher price premium for cheeses than satiated ones, both in hungry and satiated future states. Moreover, participants overvalued the food product more when they were delivered in the future hungry condition than in the satiated one. Our study provides clear, quantitative and meaningful evidence of projection bias because our findings are based on economic valuation of food preferences. Indeed, the strength of this study is that findings are expressed in terms of willingness to pay which is an interpretable amount of money.

  4. Does codon bias have an evolutionary origin?

    Directory of Open Access Journals (Sweden)

    Biro Jan C

    2008-07-01

    Full Text Available Abstract Background There is a 3-fold redundancy in the Genetic Code; most amino acids are encoded by more than one codon. These synonymous codons are not used equally; there is a Codon Usage Bias (CUB. This article will provide novel information about the origin and evolution of this bias. Results Codon Usage Bias (CUB, defined here as deviation from equal usage of synonymous codons was studied in 113 species. The average CUB was 29.3 ± 1.1% (S.E.M, n = 113 of the theoretical maximum and declined progressively with evolution and increasing genome complexity. A Pan-Genomic Codon Usage Frequency (CUF Table was constructed to describe genome-wide relationships among codons. Significant correlations were found between the number of synonymous codons and (i the frequency of the respective amino acids (ii the size of CUB. Numerous, statistically highly significant, internal correlations were found among codons and the nucleic acids they comprise. These strong correlations made it possible to predict missing synonymous codons (wobble bases reliably from the remaining codons or codon residues. Conclusion The results put the concept of "codon bias" into a novel perspective. The internal connectivity of codons indicates that all synonymous codons might be integrated parts of the Genetic Code with equal importance in maintaining its functional integrity.

  5. Bias in emerging biomarkers for bipolar disorder

    DEFF Research Database (Denmark)

    Carvalho, A F; Köhler, C A; Fernandes, B S

    2016-01-01

    BACKGROUND: To date no comprehensive evaluation has appraised the likelihood of bias or the strength of the evidence of peripheral biomarkers for bipolar disorder (BD). Here we performed an umbrella review of meta-analyses of peripheral non-genetic biomarkers for BD. METHOD: The Pubmed/Medline, E...

  6. Accounting for discovery bias in genomic prediction

    Science.gov (United States)

    Our objective was to evaluate an approach to mitigating discovery bias in genomic prediction. Accuracy may be improved by placing greater emphasis on regions of the genome expected to be more influential on a trait. Methods emphasizing regions result in a phenomenon known as “discovery bias” if info...

  7. Trained interpretive bias survives mood change

    NARCIS (Netherlands)

    Salemink, E.; van den Hout, M.A.

    2010-01-01

    Evidence is accumulating that interpretations can be trained using Cognitive Bias Modification procedures (CBM). The effects are replicable, stable over time and there is some evidence of generalizability. As a next step in determining the boundaries of the CBM model, the present experiment was

  8. Culturally Considerate School Counseling: Helping without Bias

    Science.gov (United States)

    Anderson, Kim L.

    2010-01-01

    The author brings her counseling expertise, personal experience, and compassionate perspective to this practical resource that cultivates "cultural competence"--essential for work with diverse populations. Expanding the definition of culture, this book addresses how biases have evolved in new and challenging ways, and provides strategies to help…

  9. The Psychological Price of Media Bias

    Science.gov (United States)

    Babad, Elisha

    2005-01-01

    Media bias was investigated through the effects of a TV interviewer's preferential behavior on the image of the interviewee in the eyes of the viewers. Judges viewed a political interview with either a friendly or a hostile interviewer then rated their impressions of the interviewed politician, whose behavior was identical in all conditions. The…

  10. Countering Gender Bias in the Media.

    Science.gov (United States)

    Lightbody, Mary

    2002-01-01

    Discusses gender bias created by media favoring males in science, mathematics, and technology and how female academic achievement and attitudes are effected negatively. Introduces an inquiry-based activity using media clippings in which students analyze the images in mass media and discuss their ideas on those images. (YDS)

  11. Vowel bias in Danish word-learning

    DEFF Research Database (Denmark)

    Højen, Anders; Nazzi, Thierry

    2016-01-01

    The present study explored whether the phonological bias favoring consonants found in French-learning infants and children when learning new words (Havy & Nazzi, 2009; Nazzi, 2005) is language-general, as proposed by Nespor, Peña and Mehler (2003), or varies across languages, perhaps as a functio...

  12. Cognitive bias measurement and social anxiety disorder: Correlating self-report data and attentional bias

    Directory of Open Access Journals (Sweden)

    Alexander Miloff

    2015-09-01

    Full Text Available Social anxiety disorder (SAD and attentional bias are theoretically connected in cognitive behavioral therapeutic models. In fact, there is an emerging field focusing on modifying attentional bias as a stand-alone treatment. However, it is unclear to what degree these attentional biases are present before commencing treatment. The purpose of this study was to measure pre-treatment attentional bias in 153 participants diagnosed with SAD using a home-based Internet version of the dot-probe paradigm. Results showed no significant correlation for attentional bias (towards or away from negative words or faces and the self-rated version of the Liebowitz Social Anxiety Scale (LSAS-SR. However, two positive correlations were found for the secondary measures Generalized Anxiety Disorder 7 (GAD-7 and Patient Health Questionnaire 9 (PHQ-9. These indicated that those with elevated levels of anxiety and depression had a higher bias towards negative faces in neutral–negative and positive–negative valence combinations, respectively. The unreliability of the dot-probe paradigm and home-based Internet delivery are discussed to explain the lack of correlations between LSAS-SR and attentional bias. Changes to the dot-probe task are suggested that could improve reliability.

  13. Quantifying Heuristic Bias: Anchoring, Availability, and Representativeness.

    Science.gov (United States)

    Richie, Megan; Josephson, S Andrew

    2018-01-01

    Construct: Authors examined whether a new vignette-based instrument could isolate and quantify heuristic bias. Heuristics are cognitive shortcuts that may introduce bias and contribute to error. There is no standardized instrument available to quantify heuristic bias in clinical decision making, limiting future study of educational interventions designed to improve calibration of medical decisions. This study presents validity data to support a vignette-based instrument quantifying bias due to the anchoring, availability, and representativeness heuristics. Participants completed questionnaires requiring assignment of probabilities to potential outcomes of medical and nonmedical scenarios. The instrument randomly presented scenarios in one of two versions: Version A, encouraging heuristic bias, and Version B, worded neutrally. The primary outcome was the difference in probability judgments for Version A versus Version B scenario options. Of 167 participants recruited, 139 enrolled. Participants assigned significantly higher mean probability values to Version A scenario options (M = 9.56, SD = 3.75) than Version B (M = 8.98, SD = 3.76), t(1801) = 3.27, p = .001. This result remained significant analyzing medical scenarios alone (Version A, M = 9.41, SD = 3.92; Version B, M = 8.86, SD = 4.09), t(1204) = 2.36, p = .02. Analyzing medical scenarios by heuristic revealed a significant difference between Version A and B for availability (Version A, M = 6.52, SD = 3.32; Version B, M = 5.52, SD = 3.05), t(404) = 3.04, p = .003, and representativeness (Version A, M = 11.45, SD = 3.12; Version B, M = 10.67, SD = 3.71), t(396) = 2.28, p = .02, but not anchoring. Stratifying by training level, students maintained a significant difference between Version A and B medical scenarios (Version A, M = 9.83, SD = 3.75; Version B, M = 9.00, SD = 3.98), t(465) = 2.29, p = .02, but not residents or attendings. Stratifying by heuristic and training level, availability maintained

  14. Disease fatality and bias in survival cohorts.

    Science.gov (United States)

    Barry, Vaughn; Klein, Mitchel; Winquist, Andrea; Darrow, Lyndsey A; Steenland, Kyle

    2015-07-01

    Simulate how the effect of exposure on disease occurrence and fatality influences the presence and magnitude of bias in survivor cohorts, motivated by an actual survivor cohort under study. We simulated a cohort of 50,000 subjects exposed to a disease-causing exposure over time and followed forty years, where disease incidence was the outcome of interest. We simulated this 'inception' cohort under different assumptions about the effect of exposure on disease occurrence and fatality after disease occurrence. We then created a corresponding 'survivor' (or 'cross-sectional') cohort, where cohort enrollment took place at a specific date after exposure began in the inception cohort; subjects dying prior to that enrollment date were excluded. The disease of interest caused all deaths in our simulations, but was not always fatal. In the survivor cohort, person-time at risk began before enrollment for all subjects who did not die prior to enrollment. We compared exposure-disease associations in each inception cohort to those in corresponding survivor cohorts to determine how different assumptions impacted bias in the survivor cohorts. All subjects in both inception and survivor cohorts were considered equally susceptible to the effect of exposure in causing disease. We used Cox proportional hazards regression to calculate effect measures. There was no bias in survivor cohort estimates when case fatality among diseased subjects was independent of exposure. This was true even when the disease was highly fatal and more highly exposed subjects were more likely to develop disease and die. Assuming a positive exposure-response in the inception cohort, survivor cohort rate ratios were biased downwards when case fatality was greater with higher exposure. Survivor cohort effect estimates for fatal outcomes are not always biased, although precision can decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Energy intake functions and energy budgets of ectotherms and endotherms derived from their ontogenetic growth in body mass and timing of sexual maturation.

    Science.gov (United States)

    Werner, Jan; Sfakianakis, Nikolaos; Rendall, Alan D; Griebeler, Eva Maria

    2018-05-07

    Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, reproduction, heat production and maintenance, with the latter subsuming any other additional task requiring energy) between ectothermic and endothermic vertebrates. With our model we calculated from the growth curves and ages at which species reached sexual maturity energy intake functions and energy partitioning for five ectothermic and seven endothermic vertebrate species. We show that our model produces energy intake patterns and distributions as observed in ectothermic and endothermic species. Our results comply consistently with some empirical studies that in endothermic species, like birds and mammals, energy is used for heat production instead of growth, and with a hypothesis on the evolution of endothermy in amniotes published by us before. Our model offers an explanation on known differences in absolute energy intake between ectothermic fish and reptiles and endothermic birds and mammals. From a mathematical perspective, the model comes in two equivalent formulations, a differential and an integral one. It is derived from a discrete level approach, and it is shown to be well-posed and to attain a unique solution for (almost) every parameter set. Numerically, the integral formulation of the model is considered as an inverse problem with unknown parameters that are estimated using a

  16. Ontogenetic behavior, migration, and social behavior of pallid sturgeon, Scaphirhynchus albus, and shovelnose sturgeon, S. platorynchus, with notes on the adaptive significance of body color

    Science.gov (United States)

    Kynard, B.; Henyey, E.; Horgan, M.

    2002-01-01

    We conducted laboratory studies on the ontogenetic behavior of free embryos (first life interval after hatching) and larvae (first feeding interval) of pallid and shovelnose sturgeon. Migration styles of both species were similar for timing of migration (initiation by embryos on day 0 after hatching and cessation by larvae on days 12-13 at 236-243 cumulative temperature degree units), migration distance (about 13 km), life interval when most distance was moved (embryo), and diel behavior of embryos (diurnal). However, the species differed for two behaviors: movement characteristics of embryos (peak movement rate of pallid sturgeon was only one-half the peak rate of shovelnose sturgeon, but pallid sturgeon continued the lower rate for twice as long) and diel behavior of larvae (pallid sturgeon were diurnal and shovelnose sturgeon were nocturnal). Thus, the species used different methods to move the same distance. Migrating as poorly developed embryos suggests a migration style to avoid predation at the spawning site, but moving from spawning habitat to rearing habitat before first feeding could also be important. Migrants of both species preferred bright habitat (high illumination intensity and white substrate), a behavioral preference that may characterize the migrants of many species of sturgeon. Both species were remarkably similar for swimming height above the bottom by age, and day 7 and older migrants may swim far above the bottom and move far downstream. A migration of 12 or 13 days will probably not distribute larvae throughout the population's range, so an older life interval likely initiates a second longer downstream migration (2-step migration). By day 2, individuals of both species were a black-tail phenotype (light grey body with a black-tail that moved conspicuously during swimming). Aggregation behavior suggests that black-tail is a visual signal used for group cohesion.

  17. Preliminary indication of ontogenetic and spatial variations in the whole otolith isotopic and elemental signatures of Solea solea in the Gulf of Lions (NW Mediterranean

    Directory of Open Access Journals (Sweden)

    Fabien Morat

    2012-11-01

    Full Text Available Knowledge of fish life cycles is important for exploited species. In the Mediterranean Sea, catches of common sole (Solea solea have fluctuated widely since the 1970s. Solea solea displays an ontogenetic shift in habitat: sole larvae are marine, juveniles inhabit shallow marine waters and coastal lagoons and adults inhabit deeper marine waters. Although the results of this study were obtained using only a small set of individuals, the otolith elemental composition and isotopic ratios were investigated for the three life stages (post-larval, juvenile and adult in order to acquire a better knowledge of the variability in environmental conditions experienced by the common sole at each life stage in the NW Mediterranean. Moreover, this study provides the first evaluation of the potential of whole otolith microchemistry for investigating habitat connectivity in sole populations from the Gulf of Lions. The elemental and isotopic signatures of otoliths of post-larvae captured in various environments appear to show variations related to the River Rhône inputs (high Ba/Ca and low Sr/Ca ratios. Juveniles appear to show significant variations in otolith elemental and isotopic compositions depending not only on the physico-chemical properties of water in the nurseries they inhabit (Rhône River, Thau or Mauguio lagoons, but also as a result of variations in the chemical composition of their surrounding sediments and in their benthic prey. Adults exhibit otolith differences for isotopic ratios only, which is probably linked to the River Rhône inputs. Finally, several significant relationships were observed between otolith elemental composition and fish size in specimens captured at the River Rhône mouth. However, these variations seem to be an indication of the composition acquired in each environment rather than a sign of ontogeny.

  18. Early decrease in dietary protein:energy ratio by fat addition and ontogenetic changes in muscle growth mechanisms of rainbow trout: short- and long-term effects.

    Science.gov (United States)

    Alami-Durante, Hélène; Cluzeaud, Marianne; Duval, Carine; Maunas, Patrick; Girod-David, Virginia; Médale, Françoise

    2014-09-14

    As the understanding of the nutritional regulation of muscle growth mechanisms in fish is fragmentary, the present study aimed to (1) characterise ontogenetic changes in muscle growth-related genes in parallel to changes in muscle cellularity; (2) determine whether an early decrease in dietary protein:energy ratio by fat addition affects the muscle growth mechanisms of rainbow trout (Oncorhynchus mykiss) alevins; and (3) determine whether this early feeding of a high-fat (HF) diet to alevins had a long-term effect on muscle growth processes in juveniles fed a commercial diet. Developmental regulation of hyperplasia and hypertrophy was evidenced at the molecular (expression of myogenic regulatory factors, proliferating cell nuclear antigen and myosin heavy chains (MHC)) and cellular (number and diameter of white muscle fibres) levels. An early decrease in dietary protein:energy ratio by fat addition stimulated the body growth of alevins but led to a fatty phenotype, with accumulation of lipids in the anterior part, and less caudal muscle when compared at similar body weights, due to a decrease in both the white muscle hyperplasia and maximum hypertrophy of white muscle fibres. These HF diet-induced cellular changes were preceded by a very rapid down-regulation of the expression of fast-MHC. The present study also demonstrated that early dietary composition had a long-term effect on the subsequent muscle growth processes of juveniles fed a commercial diet for 3 months. When compared at similar body weights, initially HF diet-fed juveniles indeed had a lower mean diameter of white muscle fibres, a smaller number of large white muscle fibres, and lower expression levels of MyoD1 and myogenin. These findings demonstrated the strong effect of early feed composition on the muscle growth mechanisms of trout alevins and juveniles.

  19. Daily otolith growth and ontogenetic geochemical signatures of age-0 anchovy (Engraulis encrasicolus in the Gulf of Cádiz (SW Spain.

    Directory of Open Access Journals (Sweden)

    I. A. CATALÁN

    2014-12-01

    Full Text Available The European anchovy fishery in the Gulf of Cádiz (ICES Division IXa South is largely influenced by age-0 individuals. Knowledge of young of the year growth dynamics is crucial for management, yet data on daily growth are lacking in the area. Linking growth patterns to the environment requires information on habitat occupancy through ontogeny of the fish that reach the fishery, as anchovy use different areas of the Gulf and the Guadalquivir Estuary through development. We describe the growth dynamics of age-0 anchovy through otolith microstructure analysis, and couple these data with data on microchemical signals in the otoliths to shed light into habitat use and growth dynamics in the area. Age-0 anchovy captured in September, 2011 in the Gulf ranged from 3 to 6 months old for similar sizes, with average growth rates varying twofold. Individual non-linear growth curves showed that maximum otolith growth was positively correlated with the date of spawning, which in turn was negatively correlated with the time to reach maximum growth. There was no correlation between growth parameters and body length or condition (Fulton K at capture. The strontium:calcium (Sr/Ca and magnesium:calcium (Mg/Ca ratios were significantly lower at the edge of the otolith (approximately the age of capture than at ages corresponding to larval and early juveniles (<60 days old, but values fell within typical estuarine-dwelling species. The barium:calcium ratio (Ba/Ca increased significantly in the edge of the otolith, which possibly resulted from residency in highly productive coastal waters or from ontogenetic effects. The variance in otolith elemental ratios was larger at otolith back-calculated ages around 50 days old, age which coincides with the presumed closer dependence of estuarine waters. Our data are a first step towards understanding the contribution of the estuarine system to the fishery of anchovy in the Gulf. The limitations of the approach and future

  20. Modulation of fatty acid metabolism and immune suppression are features of in vitro tumour sphere formation in ontogenetically distinct dog cancers.

    Science.gov (United States)

    Kim, J-H; Frantz, A M; Sarver, A L; Gorden Klukas, B H; Lewellen, M; O'Brien, T D; Dickerson, E B; Modiano, J F

    2017-11-20

    Non-adherent, 3-dimensional sphere formation is used as an in vitro surrogate to evaluate cellular potential for tumour initiation and self-renewal. To determine if a shared molecular program underlies the capacity for sphere formation by cells originating from diverse tumour types, we characterized molecular and functional properties of 10 independent cell lines derived from 3 ontogenetically distinct dog cancers: hemangiosarcoma, osteosarcoma and glial brain tumours. Genome-wide gene expression profiling identified tumour-of-origin-dependent patterns of adjustment to sphere formation in a uniform culture condition. However, expression of the stem/progenitor markers CD34 and CD117, resistance to cytotoxic drugs and dye efflux (side population assays) showed no association with these gene expression profiles. Instead, primary sphere-forming capacity was inversely correlated with the ability to reform secondary spheres, regardless of tumour ontogeny. Primary sphere formation seemed to be proportional to the number of pre-existing cells with sphere-forming capacity in the cell lines. Cell lines where secondary sphere formation was more proficient than primary sphere formation showed enrichment of genes involved in fatty acid synthesis and immunosuppressive cytokines. In contrast, cell lines where secondary sphere formation was approximately equivalent to or less proficient than primary sphere formation showed upregulation of CD40 and enrichment of genes involved in fatty acid oxidation. Our data suggest that in vitro sphere formation is associated with upregulation of gene clusters involved in metabolic and immunosuppressive functions, which might be necessary for self-renewal and for tumour initiation and/or tumour propagation in vivo. © 2017 John Wiley & Sons Ltd.

  1. Ontogenetic behavior and migration of Dabry's sturgeon, Acipenser dabryanus, from the Yangtze River, with notes on body color and development rate

    Science.gov (United States)

    Kynard, B.; Zhuang, P.; Zhang, T.; Zhang, L.

    2003-01-01

    We conducted laboratory experiments with Dabry's sturgeon, Acipenser dabryanus, from the upper Yangtze River to develop a conceptual model of early behavior. We daily observed fish from day-0 (embryo, first life interval after hatching) to day-30 feeding larva for preference of bright habitat and cover, swimming distance above the bottom, up- and down-stream movement, and diel activity. Hatchling to day-12 embryos and days 13-24 larvae were similar for ontogenetic behavior, i.e., neither initiated a dispersal migration, both swam within 15 cm of the bottom, both preferred bright habitat, and neither strongly preferred cover or open habitat. Embryos and larvae were weakly active day and night. Days 72-76 juveniles had a weak nocturnal downstream migration, indicating wild juveniles disperse from a spawning site. In other sturgeon species yet studied representing three genera on three continents, Dabry's sturgeon is the first that does not disperse as an embryo or larva. Development of Dabry's sturgeon is slow, requiring more cumulative temperature degree days per millimeter of larvae TL than is required for other sturgeons to develop into larvae. Thus, a dispersal migration that diverts energy from development may not be adaptive. The available information suggests the initial dispersal of early life intervals is likely done by females, which spawn in a dispersed spawning style, not the usual aggregated spawning style. Juvenile migrants had a black body and tail with a light line along the lateral scutes. The color of juvenile migrants shows that a dark body and tail is characteristic of Acipenser that migrate downstream as larvae or juveniles.

  2. Not all stereotypic biases are created equal: Evidence for a Stereotype-disconfirming bias

    NARCIS (Netherlands)

    Wyer, N.A.

    2004-01-01

    Stereotype-confirming biases are well documented in the social psychological literature. However, motivations to disconfirm social stereotypes may be more influential for unprejudiced individuals. Three experiments are presented that test the hypothesis that extremely unprejudiced people exhibit a

  3. Thinking in Black and White: Conscious thought increases racially biased judgments through biased face memory.

    Science.gov (United States)

    Strick, Madelijn; Stoeckart, Peter F; Dijksterhuis, Ap

    2015-11-01

    It is a common research finding that conscious thought helps people to avoid racial discrimination. These three experiments, however, illustrate that conscious thought may increase biased face memory, which leads to increased judgment bias (i.e., preferring White to Black individuals). In Experiments 1 and 2, university students formed impressions of Black and White housemate candidates. They judged the candidates either immediately (immediate decision condition), thought about their judgments for a few minutes (conscious thought condition), or performed an unrelated task for a few minutes (unconscious thought condition). Conscious thinkers and immediate decision-makers showed a stronger face memory bias than unconscious thinkers, and this mediated increased judgment bias, although not all results were significant. Experiment 3 used a new, different paradigm and showed that a Black male was remembered as darker after a period of conscious thought than after a period of unconscious thought. Implications for racial prejudice are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Science mapping analysis characterizes 235 biases in biomedical research.

    Science.gov (United States)

    Chavalarias, David; Ioannidis, John P A

    2010-11-01

    Many different types of bias have been described. Some biases may tend to coexist or be associated with specific research settings, fields, and types of studies. We aimed to map systematically the terminology of bias across biomedical research. We used advanced text-mining and clustering techniques to evaluate 17,265,924 items from PubMed (1958-2008). We considered 235 bias terms and 103 other terms that appear commonly in articles dealing with bias. Forty bias terms were used in the title or abstract of more than 100 articles each. Pseudo-inclusion clustering identified 252 clusters of terms. The clusters were organized into macroscopic maps that cover a continuum of research fields. The resulting maps highlight which types of biases tend to co-occur and may need to be considered together and what biases are commonly encountered and discussed in specific fields. Most of the common bias terms have had continuous use over time since their introduction, and some (in particular confounding, selection bias, response bias, and publication bias) show increased usage through time. This systematic mapping offers a dynamic classification of biases in biomedical investigation and related fields and can offer insights for the multifaceted aspects of bias. Copyright © 2010. Published by Elsevier Inc.

  5. Mood-congruent free recall bias in anxious individuals is not a consequence of response bias

    OpenAIRE

    Russo, Riccardo; Whittuck, Dora; Roberson, Debi; Dutton, Kevin; Georgiou, George; Fox, Elaine

    2006-01-01

    The status of mood-congruent free recall bias in anxious individuals was evaluated following incidental encoding of target words. Individuals with high and low levels of trait anxiety completed a modified Stroop task, which revealed an attentional bias for threat-related stimuli in anxious individuals. This group was significantly slower in naming the colour in which threat-related words were displayed compared to neutral words. In a subsequent free recall test for the words used in the modif...

  6. Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling.

    Science.gov (United States)

    Biro, Peter A

    2013-02-01

    Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, 'hidden' trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

  7. Heuristics: The good, the bad, and the biased. What value can bias have for decision makers?

    OpenAIRE

    Curley, Lee J.; Murray, Jennifer.; MacLean, Rory.

    2017-01-01

    This discussion paper will look at heuristics (rule of thumb techniques for decision making), (Tversky & Kahneman, 1974) and their potential value. Typically, heuristics have been viewed negatively (Gigerenzer & Goldstein, 1996), with research suggesting that heuristics bias how individuals think, which may create sub-optimal performance (Tversky & Kahneman, 1974). However, researchers, such as Gigerenzer and Goldstein (1996), have highlighted that a bias in decision making may not necessaril...

  8. Placebo effect studies are susceptible to response bias and to other types of biases.

    Science.gov (United States)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-11-01

    Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyze and discuss typical types of bias in studies on placebo. A methodological analysis and discussion. The inherent nonblinded comparison between placebo and no-treatment is the best research design we have in estimating effects of placebo, both in a clinical and in an experimental setting, but the difference between placebo and no-treatment remains an approximate and fairly crude reflection of the true effect of placebo interventions. A main problem is response bias in trials with outcomes that are based on patients' reports. Other biases involve differential co-intervention and patient dropouts, publication bias, and outcome reporting bias. Furthermore, extrapolation of results to a clinical settings are challenging because of a lack of clear identification of the causal factors in many clinical trials, and the nonclinical setting and short duration of most laboratory experiments. Creative experimental efforts are needed to assess rigorously the clinical significance of placebo interventions and investigate the component elements that may contribute to the therapeutic benefit. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Is racial bias malleable? Whites' lay theories of racial bias predict divergent strategies for interracial interactions.

    Science.gov (United States)

    Neel, Rebecca; Shapiro, Jenessa R

    2012-07-01

    How do Whites approach interracial interactions? We argue that a previously unexamined factor-beliefs about the malleability of racial bias-guides Whites' strategies for difficult interracial interactions. We predicted and found that those who believe racial bias is malleable favor learning-oriented strategies such as taking the other person's perspective and trying to learn why an interaction is challenging, whereas those who believe racial bias is fixed favor performance-oriented strategies such as overcompensating in the interaction and trying to end the interaction as quickly as possible. Four studies support these predictions. Whether measured (Studies 1, 3, and 4) or manipulated (Study 2), beliefs that racial bias is fixed versus malleable yielded these divergent strategies for difficult interracial interactions. Furthermore, beliefs about the malleability of racial bias are distinct from related constructs (e.g., prejudice and motivations to respond without prejudice; Studies 1, 3, and 4) and influence self-reported (Studies 1-3) and actual (Study 4) strategies in imagined (Studies 1-2) and real (Studies 3-4) interracial interactions. Together, these findings demonstrate that beliefs about the malleability of racial bias influence Whites' approaches to and strategies within interracial interactions. PsycINFO Database Record (c) 2012 APA, all rights reserved

  10. Placebo effect studies are susceptible to response bias and to other types of biases

    Science.gov (United States)

    Hróbjartsson, Asbjørn; Kaptchuk, Ted J; Miller, Franklin G

    2011-01-01

    OBJECTIVE Investigations of the effect of placebo are often challenging to conduct and interpret. The history of placebo shows that assessment of its clinical significance has a real potential to be biased. We analyse and discuss typical types of bias in studies on placebo. STUDY DESIGN AND SETTING a methodological analysis and discussion. RESULTS The inherent nonblinded comparison between placebo and no-treatment is the best research design we have in estimating effects of placebo, both in a clinical and in an experimental setting, but the difference between placebo and no-treatment remains an approximate and fairly crude reflection of the true effect of placebo interventions. A main problem is response bias in trials with outcomes that are based on patients reports. Other biases involve differential co-intervention and patient drop-outs, publication bias, and outcome reporting bias. Furthermore, extrapolation of results to a clinical settings are challenging because of lack of clear identification of the causal factors in many clinical trials, and the non-clinical setting and short duration of most laboratory experiments. CONCLUSIONS Creative experimental efforts are needed to assess rigorously the clinical significance of placebo interventions and investigate the component elements that may contribute to therapeutic benefit. PMID:21524568

  11. Ricean Bias Correction in Linear Polarization Observation

    Directory of Open Access Journals (Sweden)

    Bong Won Sohn

    2011-12-01

    Full Text Available I developed an enhanced correction method for Ricean bias which occurs in linear polarization measurement. Two known methods for Ricean bias correction are reviewed. In low signal-to-noise area, the method based on the mode of the equation gives better representation of the fractional polarization. But a caution should be given that the accurate estimation of noise level, i.e. σ of the polarized flux, is important. The maximum likelihood method is better choice for high signal-to-noise area. I suggest a hybrid method which uses the mode of the equation at the low signal-to-noise area and takes the maximum likelihood method at the high signal-to-noise area. A modified correction coefficient for the mode solution is proposed. The impact on the depolarization measure analysis is discussed.

  12. Looming biases in monkey auditory cortex.

    Science.gov (United States)

    Maier, Joost X; Ghazanfar, Asif A

    2007-04-11

    Looming signals (signals that indicate the rapid approach of objects) are behaviorally relevant signals for all animals. Accordingly, studies in primates (including humans) reveal attentional biases for detecting and responding to looming versus receding signals in both the auditory and visual domains. We investigated the neural representation of these dynamic signals in the lateral belt auditory cortex of rhesus monkeys. By recording local field potential and multiunit spiking activity while the subjects were presented with auditory looming and receding signals, we show here that auditory cortical activity was biased in magnitude toward looming versus receding stimuli. This directional preference was not attributable to the absolute intensity of the sounds nor can it be attributed to simple adaptation, because white noise stimuli with identical amplitude envelopes did not elicit the same pattern of responses. This asymmetrical representation of looming versus receding sounds in the lateral belt auditory cortex suggests that it is an important node in the neural network correlate of looming perception.

  13. Optimistic biases in observational learning of value

    Science.gov (United States)

    Nicolle, A.; Symmonds, M.; Dolan, R.J.

    2011-01-01

    Action-outcome contingencies can be learnt either by active trial-and-error, or vicariously, by observing the outcomes of actions performed by others. The extant literature is ambiguous as to which of these modes of learning is more effective, as controlled comparisons of operant and observational learning are rare. Here, we contrasted human operant and observational value learning, assessing implicit and explicit measures of learning from positive and negative reinforcement. Compared to direct operant learning, we show observational learning is associated with an optimistic over-valuation of low-value options, a pattern apparent both in participants’ choice preferences and their explicit post-hoc estimates of value. Learning of higher value options showed no such bias. We suggest that such a bias can be explained as a tendency for optimistic underestimation of the chance of experiencing negative events, an optimism repressed when information is gathered through direct operant learning. PMID:21354558

  14. Biased galaxy formation with baryonic dark matter.

    Science.gov (United States)

    Morikawa, M.

    The author studies the possibility of baryonic dark matter associated with a galaxy/halo in the light of the biasing which segregates the luminous inner region and the dark outer region of a galaxy. He proposes a biasing mechanism based on the fact that stellar luminosity is highly sensitive to the strength of the gravitational force. He uses a nonconformal scalar field model in which the scalar field accumulates around the gravitational potential formed by the baryonic matter and yields a slight galactocentric gradient of the effective gravitational constant G. A small gradient (the value of G becomes half of the ordinary value at the distance about 100 kpc from the center of the galaxy) is sufficient to explain the smooth flat rotation curve of the spiral galaxies as well as a sharp cutoff of the luminosity profile. Several tests of this scenario are studied.

  15. Dynamic Nigrostriatal Dopamine Biases Action Selection.

    Science.gov (United States)

    Howard, Christopher D; Li, Hao; Geddes, Claire E; Jin, Xin

    2017-03-22

    Dopamine is thought to play a critical role in reinforcement learning and goal-directed behavior, but its function in action selection remains largely unknown. Here we demonstrate that nigrostriatal dopamine biases ongoing action selection. When mice were trained to dynamically switch the action selected at different time points, changes in firing rate of nigrostriatal dopamine neurons, as well as dopamine signaling in the dorsal striatum, were found to be associated with action selection. This dopamine profile is specific to behavioral choice, scalable with interval duration, and doesn't reflect reward prediction error, timing, or value as single factors alone. Genetic deletion of NMDA receptors on dopamine or striatal neurons or optogenetic manipulation of dopamine concentration alters dopamine signaling and biases action selection. These results unveil a crucial role of nigrostriatal dopamine in integrating diverse information for regulating upcoming actions, and they have important implications for neurological disorders, including Parkinson's disease and substance dependence. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Calibration biases in logical reasoning tasks

    Directory of Open Access Journals (Sweden)

    Guillermo Macbeth

    2013-08-01

    Full Text Available The aim of this contribution is to present an experimental study about calibration in deductive reasoning tasks. Calibration is defi ned as the empirical convergence or divergence between the objective and the subjective success. The underconfi dence bias is understood as the dominance of the former over the latter. The hypothesis of this study states that the form of the propositions presented in the experiment is critical for calibration phenomena. Affi rmative and negative propositions are distinguished in their cognitive processing. Results suggests that monotonous compound propositions are prone to underconfi dence. An heuristic approach to this phenomenon is proposed. The activation of a monotony heuristic would produce an illusion of simplicity that generates the calibration bias. These evidence is analysed in the context of the metacognitive modeling of calibration phenomena.

  17. Growth of oxide exchange bias layers

    Science.gov (United States)

    Chaiken, A.; Michel, R.P.

    1998-07-21

    An oxide (NiO, CoO, NiCoO) antiferromagnetic exchange bias layer produced by ion beam sputtering of an oxide target in pure argon (Ar) sputtering gas, with no oxygen gas introduced into the system. Antiferromagnetic oxide layers are used, for example, in magnetoresistive readback heads to shift the hysteresis loops of ferromagnetic films away from the zero field axis. For example, NiO exchange bias layers have been fabricated using ion beam sputtering of an NiO target using Ar ions, with the substrate temperature at 200 C, the ion beam voltage at 1000V and the beam current at 20 mA, with a deposition rate of about 0.2 {angstrom}/sec. The resulting NiO film was amorphous. 4 figs.

  18. The development of comparative bias index

    Science.gov (United States)

    Aimran, Ahmad Nazim; Ahmad, Sabri; Afthanorhan, Asyraf; Awang, Zainudin

    2017-08-01

    Structural Equation Modeling (SEM) is a second generation statistical analysis techniques developed for analyzing the inter-relationships among multiple variables in a model simultaneously. There are two most common used methods in SEM namely Covariance-Based Structural Equation Modeling (CB-SEM) and Partial Least Square Path Modeling (PLS-PM). There have been continuous debates among researchers in the use of PLS-PM over CB-SEM. While there is few studies were conducted to test the performance of CB-SEM and PLS-PM bias in estimating simulation data. This study intends to patch this problem by a) developing the Comparative Bias Index and b) testing the performance of CB-SEM and PLS-PM using developed index. Based on balanced experimental design, two multivariate normal simulation data with of distinct specifications of size 50, 100, 200 and 500 are generated and analyzed using CB-SEM and PLS-PM.

  19. Model selection bias and Freedman's paradox

    Science.gov (United States)

    Lukacs, P.M.; Burnham, K.P.; Anderson, D.R.

    2010-01-01

    In situations where limited knowledge of a system exists and the ratio of data points to variables is small, variable selection methods can often be misleading. Freedman (Am Stat 37:152-155, 1983) demonstrated how common it is to select completely unrelated variables as highly "significant" when the number of data points is similar in magnitude to the number of variables. A new type of model averaging estimator based on model selection with Akaike's AIC is used with linear regression to investigate the problems of likely inclusion of spurious effects and model selection bias, the bias introduced while using the data to select a single seemingly "best" model from a (often large) set of models employing many predictor variables. The new model averaging estimator helps reduce these problems and provides confidence interval coverage at the nominal level while traditional stepwise selection has poor inferential properties. ?? The Institute of Statistical Mathematics, Tokyo 2009.

  20. Edge biasing in the WEGA stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Lischtschenko, Oliver

    2009-02-27

    The WEGA stellarator is used to confine low temperature, overdense (densities exceeding the cut-off density of the heating wave) plasmas by magnetic fields in the range of B=50-500 mT. Microwave heating systems are used to ignite gas discharges using hydrogen, helium, neon or argon as working gases. The produced plasmas have been analyzed using Langmuir and emissive probes, a single-channel interferometer and ultra-high resolution Doppler spectroscopy. For a typical argon discharge in the low field operation, B=56 mT, the maximum electron density is n{sub e}{proportional_to}10{sup 18} m{sup -3} with temperatures in the range of T=4-12 eV. The plasma parameters are determined by using Langmuir probes and are cross-checked with interferometry. It is demonstrated within this work that the joint use of emissive probes and ultra-high resolution Doppler spectroscopy allows a precise measurement of the radial electric field. The focus of this work is on demonstrating the ability to modify the existing radial electric field in a plasma by using the biasing probe. This work commences with a basic approach and first establishes the diagnostic tools in a well-known discharge. Then the perturbation caused by the biasing probe is assessed. Following the characterization of the unperturbed plasmas, plasma states altered by the operation of the energized biasing probe are characterized. During biasing the plasma two different stable plasma states have been found. The two observed plasma states differ in plasma parameter profiles, such as density, temperature, electric field and confined energy. (orig.)

  1. Heuristics and Biases in Retirement Savings Behavior

    OpenAIRE

    Shlomo Benartzi; Richard Thaler

    2007-01-01

    Standard economic theories of saving implicitly assume that households have the cognitive ability to solve the relevant optimization problem and the willpower to execute the optimal plan. Both of the implicit assumptions are suspect. Even among economists, few spend much time calculating a personal optimal savings rate. Instead, most people cope by adopting simple heuristics, or rules of thumb. In this paper, we investigate both the heuristics and the biases that emerge in the area of retirem...

  2. Avoiding bias in safety testing design

    DEFF Research Database (Denmark)

    Calow, Peter

    2011-01-01

    All scientists are biased, no matter what their backgrounds or affiliations, so what is it about the scientific method that overcomes this and which makes science so successful? Key features are transparency and critical peer scrutiny. These general issues will be will be considered in terms of t...... of the scientific basis of risk assessment, including the design of safety testing procedures, particularly as applied to industrial chemicals....

  3. Biases in Cometary Catalogues and Planet X

    OpenAIRE

    Horner, J.; Evans, N. W.

    2002-01-01

    Two sets of investigators -- Murray (1999) and Matese, Whitman & Whitmire (1999) -- have recently claimed evidence for an undiscovered Solar System planet from possible great circle alignments in the aphelia directions of the long period comets. However, comet discoveries are bedevilled by selection effects. These include anomalies caused by the excess of observers in the northern as against the southern hemisphere, seasonal and diurnal biases, directional effects which make it harder to disc...

  4. Heuristics and Biases in Military Decision Making

    Science.gov (United States)

    2010-10-01

    critical com- ponents increases, we find mathematically that the probability of event (or system) failure increases. However, we again find that...Uncertainty: Heuristics and Biases, ed. Daniel Kahneman and Amos Tversky (New York, Cambridge University Press, 1982), 156-57. It is similar to a quiz I...gave during my Game Theory class at West Point. 38. Mathematically , this problem can be solved using Bayesian inference. 39. Some may feel that the

  5. Limiter biasing experiments on the tokamak ISTTOK

    Czech Academy of Sciences Publication Activity Database

    Silva, C.; Nedzelskiy, I.; Figueiredo, H.; Cabral, J. A. C.; Varandas, C. A. F.; Stöckel, Jan

    2003-01-01

    Roč. 53, č. 10 (2003), s. 937-944 ISSN 0011-4626. [Workshop "Electric Fields Structures and Relaxation in Edge Plasmas"/6th./. St. Petersburg, 13.06.2003-14.06.2003] Institutional research plan: CEZ:AV0Z2043910 Keywords : biasing, edge plasma, particle confinement Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.263, year: 2003

  6. Students' gender bias in teaching evaluations

    OpenAIRE

    Narissra Punyanunt-Carter; Carter, Stacy L.

    2015-01-01

    The goal of this study was to investigate if there is gender bias in student evaluations. Researchers administered a modified version of the teacher evaluation forms to 58 students (male=30; female=28) in a basic introductory communications class. Half the class was instructed to fill out the survey about a male professor, and the other half a female professor. Researchers broke down the evaluation results question by question in order to give a detailed account of the findings. Results revea...

  7. Measures of Equity Home Bias Puzzle

    OpenAIRE

    Mishra, Anil V

    2014-01-01

    The paper develops measures of home bias for 48 countries over the period 2001 to 2011 by employing various models: International Capital Asset Pricing Model (ICAPM), Mean-Variance, Minimum-Variance, Bayes-Stein, Bayesian and Multi-Prior. ICAPM country portfolio weights are computed relative to world market capitalization. Bayesian models allow for various degrees of mis-trust in the ICAPM model. Multi-Prior restricts the expected return for each asset to lie within specified confidence inter...

  8. Automation bias: empirical results assessing influencing factors.

    Science.gov (United States)

    Goddard, Kate; Roudsari, Abdul; Wyatt, Jeremy C

    2014-05-01

    To investigate the rate of automation bias - the propensity of people to over rely on automated advice and the factors associated with it. Tested factors were attitudinal - trust and confidence, non-attitudinal - decision support experience and clinical experience, and environmental - task difficulty. The paradigm of simulated decision support advice within a prescribing context was used. The study employed within participant before-after design, whereby 26 UK NHS General Practitioners were shown 20 hypothetical prescribing scenarios with prevalidated correct and incorrect answers - advice was incorrect in 6 scenarios. They were asked to prescribe for each case, followed by being shown simulated advice. Participants were then asked whether they wished to change their prescription, and the post-advice prescription was recorded. Rate of overall decision switching was captured. Automation bias was measured by negative consultations - correct to incorrect prescription switching. Participants changed prescriptions in 22.5% of scenarios. The pre-advice accuracy rate of the clinicians was 50.38%, which improved to 58.27% post-advice. The CDSS improved the decision accuracy in 13.1% of prescribing cases. The rate of automation bias, as measured by decision switches from correct pre-advice, to incorrect post-advice was 5.2% of all cases - a net improvement of 8%. More immediate factors such as trust in the specific CDSS, decision confidence, and task difficulty influenced rate of decision switching. Lower clinical experience was associated with more decision switching. Age, DSS experience and trust in CDSS generally were not significantly associated with decision switching. This study adds to the literature surrounding automation bias in terms of its potential frequency and influencing factors. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  9. Gender bias and the female brain drain

    OpenAIRE

    Aniruddha Mitra; James T. Bang

    2010-01-01

    This paper contributes to the emerging literature on gender differences in the causes and consequences of brain drain. Differentiating between gender bias in the access to economic opportunities and gender differentials in economic outcomes, we find that differences in access have a significant impact on the emigration of highly-skilled women relative to that of men. However, differentials in outcomes do not have a significant impact. Additionally, the structure of political institutions in t...

  10. Alleviating Media Bias Through Intelligent Agent Blogging

    OpenAIRE

    Diaz-Aviles, Ernesto

    2009-01-01

    Consumers of mass media must have a comprehensive, balanced and plural selection of news to get an unbiased perspective; but achieving this goal can be very challenging, laborious and time consuming. News stories development over time, its (in)consistency, and different level of coverage across the media outlets are challenges that a conscientious reader has to overcome in order to alleviate bias. In this paper we present an intelligent agent framework currently facilitating analysis of the m...

  11. Bias temperature instability for devices and circuits

    CERN Document Server

    2014-01-01

    This book provides a single-source reference to one of the more challenging reliability issues plaguing modern semiconductor technologies, negative bias temperature instability.  Readers will benefit from state-of-the art coverage of research in topics such as time dependent defect spectroscopy, anomalous defect behavior, stochastic modeling with additional metastable states, multiphonon theory, compact modeling with RC ladders and implications on device reliability and lifetime.  ·         Enables readers to understand and model negative bias temperature instability, with an emphasis on dynamics; ·         Includes coverage of DC vs. AC stress, duty factor dependence and bias dependence; ·         Explains time dependent defect spectroscopy, as a measurement method that operates on nanoscale MOSFETs; ·         Introduces new defect model for metastable defect states, nonradiative multiphonon theory and stochastic behavior.

  12. Sampling of temporal networks: Methods and biases

    Science.gov (United States)

    Rocha, Luis E. C.; Masuda, Naoki; Holme, Petter

    2017-11-01

    Temporal networks have been increasingly used to model a diversity of systems that evolve in time; for example, human contact structures over which dynamic processes such as epidemics take place. A fundamental aspect of real-life networks is that they are sampled within temporal and spatial frames. Furthermore, one might wish to subsample networks to reduce their size for better visualization or to perform computationally intensive simulations. The sampling method may affect the network structure and thus caution is necessary to generalize results based on samples. In this paper, we study four sampling strategies applied to a variety of real-life temporal networks. We quantify the biases generated by each sampling strategy on a number of relevant statistics such as link activity, temporal paths and epidemic spread. We find that some biases are common in a variety of networks and statistics, but one strategy, uniform sampling of nodes, shows improved performance in most scenarios. Given the particularities of temporal network data and the variety of network structures, we recommend that the choice of sampling methods be problem oriented to minimize the potential biases for the specific research questions on hand. Our results help researchers to better design network data collection protocols and to understand the limitations of sampled temporal network data.

  13. Learning biases predict a word order universal.

    Science.gov (United States)

    Culbertson, Jennifer; Smolensky, Paul; Legendre, Géraldine

    2012-03-01

    How recurrent typological patterns, or universals, emerge from the extensive diversity found across the world's languages constitutes a central question for linguistics and cognitive science. Recent challenges to a fundamental assumption of generative linguistics-that universal properties of the human language acquisition faculty constrain the types of grammatical systems which can occur-suggest the need for new types of empirical evidence connecting typology to biases of learners. Using an artificial language learning paradigm in which adult subjects are exposed to a mix of grammatical systems (similar to a period of linguistic change), we show that learners' biases mirror a word-order universal, first proposed by Joseph Greenberg, which constrains typological patterns of adjective, numeral, and noun ordering. We briefly summarize the results of a probabilistic model of the hypothesized biases and their effect on learning, and discuss the broader implications of the results for current theories of the origins of cross-linguistic word-order preferences. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Cognitive Reflection, Decision Biases, and Response Times

    Directory of Open Access Journals (Sweden)

    Carlos Alos-Ferrer

    2016-09-01

    Full Text Available We present novel evidence on decision times and personality traits in standard questions from the decision-making literature where responses are relatively slow (medians around half a minute or above. To this end, we measured decision times in a number of incentivized, framed items (decisions from description including the Cognitive Reflection Test, two additional questions following the same logic, and a number of classic questions used to study decision biases in probability judgments (base-rate neglect, the conjunction fallacy, and the ratio bias. All questions create a conflict between an intuitive process and more deliberative thinking. For each item, we then created a non-conflict version by either making the intuitive impulse correct (resulting in an alignment question, shutting it down (creating a neutral question, or making it dominant (creating a heuristic question. For CRT questions, the differences in decision times are as predicted by dual-process theories, with alignment and heuristic variants leading to faster responses and neutral questions to slower responses than the original, conflict questions. For decision biases (where responses are slower, evidence is mixed. To explore the possible influence of personality factors on both choices and decision times, we used standard personality scales including the Rational-Experiential Inventory and the Big Five, and used the mas controls in regression analysis.

  15. Biases in small RNA deep sequencing data.

    Science.gov (United States)

    Raabe, Carsten A; Tang, Thean-Hock; Brosius, Juergen; Rozhdestvensky, Timofey S

    2014-02-01

    High-throughput RNA sequencing (RNA-seq) is considered a powerful tool for novel gene discovery and fine-tuned transcriptional profiling. The digital nature of RNA-seq is also believed to simplify meta-analysis and to reduce background noise associated with hybridization-based approaches. The development of multiplex sequencing enables efficient and economic parallel analysis of gene expression. In addition, RNA-seq is of particular value when low RNA expression or modest changes between samples are monitored. However, recent data uncovered severe bias in the sequencing of small non-protein coding RNA (small RNA-seq or sRNA-seq), such that the expression levels of some RNAs appeared to be artificially enhanced and others diminished or even undetectable. The use of different adapters and barcodes during ligation as well as complex RNA structures and modifications drastically influence cDNA synthesis efficacies and exemplify sources of bias in deep sequencing. In addition, variable specific RNA G/C-content is associated with unequal polymerase chain reaction amplification efficiencies. Given the central importance of RNA-seq to molecular biology and personalized medicine, we review recent findings that challenge small non-protein coding RNA-seq data and suggest approaches and precautions to overcome or minimize bias.

  16. Assembly bias and splashback in galaxy clusters

    Science.gov (United States)

    Busch, Philipp; White, Simon D. M.

    2017-10-01

    We use publicly available data for the Millennium Simulation to explore the implications of the recent detection of assembly bias and splashback signatures in a large sample of galaxy clusters. These were identified in the Sloan Digital Sky Survey/Data Release 8 (SDSS/DR8) photometric data by the redMaPPer algorithm and split into high- and low-concentration subsamples based on the projected positions of cluster members. We use simplified versions of these procedures to build cluster samples of similar size from the simulation data. These match the observed samples quite well and show similar assembly bias and splashback signals. Previous theoretical work has found the logarithmic slope of halo density profiles to have a well-defined minimum whose depth decreases and whose radius increases with halo concentration. Projected profiles for the observed and simulated cluster samples show trends with concentration which are opposite to these predictions. In addition, for high-concentration clusters the minimum slope occurs at significantly smaller radius than predicted. We show that these discrepancies all reflect confusion between splashback features and features imposed on the profiles by the cluster identification and concentration estimation procedures. The strong apparent assembly bias is not reflected in the three-dimensional distribution of matter around clusters. Rather it is a consequence of the preferential contamination of low-concentration clusters by foreground or background groups.

  17. Bias and ignorance in demographic perception.

    Science.gov (United States)

    Landy, D; Guay, B; Marghetis, T

    2017-08-31

    When it comes to knowledge of demographic facts, misinformation appears to be the norm. Americans massively overestimate the proportions of their fellow citizens who are immigrants, Muslim, LGBTQ, and Latino, but underestimate those who are White or Christian. Previous explanations of these estimation errors have invoked topic-specific mechanisms such as xenophobia or media bias. We reconsidered this pattern of errors in the light of more than 30 years of research on the psychological processes involved in proportion estimation and decision-making under uncertainty. In two publicly available datasets featuring demographic estimates from 14 countries, we found that proportion estimates of national demographics correspond closely to what is found in laboratory studies of quantitative estimates more generally. Biases in demographic estimation, therefore, are part of a very general pattern of human psychology-independent of the particular topic or demographic under consideration-that explains most of the error in estimates of the size of politically salient populations. By situating demographic estimates within a broader understanding of general quantity estimation, these results demand reevaluation of both topic-specific misinformation about demographic facts and topic-specific explanations of demographic ignorance, such as media bias and xenophobia.

  18. Fandom Biases Retrospective Judgments Not Perception.

    Science.gov (United States)

    Huff, Markus; Papenmeier, Frank; Maurer, Annika E; Meitz, Tino G K; Garsoffky, Bärbel; Schwan, Stephan

    2017-02-24

    Attitudes and motivations have been shown to affect the processing of visual input, indicating that observers may see a given situation each literally in a different way. Yet, in real-life, processing information in an unbiased manner is considered to be of high adaptive value. Attitudinal and motivational effects were found for attention, characterization, categorization, and memory. On the other hand, for dynamic real-life events, visual processing has been found to be highly synchronous among viewers. Thus, while in a seminal study fandom as a particularly strong case of attitudes did bias judgments of a sports event, it left the question open whether attitudes do bias prior processing stages. Here, we investigated influences of fandom during the live TV broadcasting of the 2013 UEFA-Champions-League Final regarding attention, event segmentation, immediate and delayed cued recall, as well as affect, memory confidence, and retrospective judgments. Even though we replicated biased retrospective judgments, we found that eye-movements, event segmentation, and cued recall were largely similar across both groups of fans. Our findings demonstrate that, while highly involving sports events are interpreted in a fan dependent way, at initial stages they are processed in an unbiased manner.

  19. Perceptive biases in major depressive episode.

    Science.gov (United States)

    Naudin, Marine; Carl, Tatiana; Surguladze, Simon; Guillen, Catherine; Gaillard, Philippe; Belzung, Catherine; El-Hage, Wissam; Atanasova, Boriana

    2014-01-01

    Alterations in emotional processing occur during a major depressive episode (MDE), and olfaction and facial expressions have implications in emotional and social interactions. To gain a better understanding of these processes, we characterized the perceptive sensorial biases, potential links, and potential remission after antidepressant treatment of MDE. We recruited 22 patients with acute MDE, both before and after three months of antidepressant treatment, and 41 healthy volunteers matched by age and smoking status. The participants underwent a clinical assessment (Mini International Neuropsychiatry Interview, Montgomery-Åsberg Depression Rating Scale, State-Trait Anxiety Inventory, Physical and Social Anhedonia scales, Pleasure-Displeasure Scale), an olfactory evaluation (hedonic aspect, familiarity and emotional impact of odors), and a computerized Facial Affect Recognition task. MDE was associated with an olfactory bias concerning hedonic and emotional aspects, including negative olfactory alliesthesia (unpleasant odorants perceived as more unpleasant), facial emotion expression recognition (happy facial expressions), and in part olfactory anhedonia (pleasant odorants perceived as less pleasant). In addition, the results revealed that these impairments represent state markers of MDE, suggesting that the patients recovered the same sensory processing as healthy subjects after antidepressant treatment. This study demonstrated that MDE is associated with negative biases toward olfactory perception and the recognition of facial emotional expressions. The link between these two sensory parameters suggests common underlying processes.

  20. Perceptive biases in major depressive episode.

    Directory of Open Access Journals (Sweden)

    Marine Naudin

    Full Text Available INTRODUCTION: Alterations in emotional processing occur during a major depressive episode (MDE, and olfaction and facial expressions have implications in emotional and social interactions. To gain a better understanding of these processes, we characterized the perceptive sensorial biases, potential links, and potential remission after antidepressant treatment of MDE. METHODS: We recruited 22 patients with acute MDE, both before and after three months of antidepressant treatment, and 41 healthy volunteers matched by age and smoking status. The participants underwent a clinical assessment (Mini International Neuropsychiatry Interview, Montgomery-Åsberg Depression Rating Scale, State-Trait Anxiety Inventory, Physical and Social Anhedonia scales, Pleasure-Displeasure Scale, an olfactory evaluation (hedonic aspect, familiarity and emotional impact of odors, and a computerized Facial Affect Recognition task. RESULTS: MDE was associated with an olfactory bias concerning hedonic and emotional aspects, including negative olfactory alliesthesia (unpleasant odorants perceived as more unpleasant, facial emotion expression recognition (happy facial expressions, and in part olfactory anhedonia (pleasant odorants perceived as less pleasant. In addition, the results revealed that these impairments represent state markers of MDE, suggesting that the patients recovered the same sensory processing as healthy subjects after antidepressant treatment. DISCUSSION: This study demonstrated that MDE is associated with negative biases toward olfactory perception and the recognition of facial emotional expressions. The link between these two sensory parameters suggests common underlying processes.

  1. Interpretive bias, repressive coping, and trait anxiety.

    Science.gov (United States)

    Walsh, James J; McNally, Maria A; Skariah, Ancy; Butt, Ayesha A; Eysenck, Michael W

    2015-01-01

    According to vigilance-avoidance theory, repressors have an avoidant interpretive bias, i.e., they interpret ambiguous self-relevant situations in a nonthreatening fashion. This study sought to demarcate the range of situations associated with avoidant interpretive bias in repressors. Four groups of participants, representing the four combinations of low- and high-trait anxiety and defensiveness, were identified. Those low in trait anxiety and high in defensiveness were categorized as repressors. Participants (N = 163) rated their likelihood of making both threatening and nonthreatening interpretations of 32 ambiguous scenarios over four domains: social, intellectual, physical, and health. Half the scenarios were self-relevant and half were other relevant. Brief measures of state anxiety were taken after each likelihood rating. Repressors displayed an avoidant interpretive bias for ambiguous threats in the social and intellectual domains but not the health or physical domains. This was due to repressors' low level of trait anxiety rather than their high defensiveness. Individuals high in trait anxiety are especially sensitive to situations involving social evaluation but not those characterized by danger to their health or physical well-being.

  2. Information bias in health research: definition, pitfalls, and adjustment methods

    Directory of Open Access Journals (Sweden)

    Althubaiti A

    2016-05-01

    Full Text Available Alaa Althubaiti Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia Abstract: As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassification, is one of the most common sources of bias that affects the validity of health research. It originates from the approach that is utilized to obtain or confirm study measurements. This paper seeks to raise awareness of information bias in observational and experimental research study designs as well as to enrich discussions concerning bias problems. Specifying the types of bias can be essential to limit its effects and, the use of adjustment methods might serve to improve clinical evaluation and health care practice. Keywords: self-report bias, social desirability bias, recall bias, misclassification, measurement error bias, confirmation bias 

  3. Cognitive sophistication does not attenuate the bias blind spot.

    Science.gov (United States)

    West, Richard F; Meserve, Russell J; Stanovich, Keith E

    2012-09-01

    The so-called bias blind spot arises when people report that thinking biases are more prevalent in others than in themselves. Bias turns out to be relatively easy to recognize in the behaviors of others, but often difficult to detect in one's own judgments. Most previous research on the bias blind spot has focused on bias in the social domain. In 2 studies, we found replicable bias blind spots with respect to many of the classic cognitive biases studied in the heuristics and biases literature (e.g., Tversky & Kahneman, 1974). Further, we found that none of these bias blind spots were attenuated by measures of cognitive sophistication such as cognitive ability or thinking dispositions related to bias. If anything, a larger bias blind spot was associated with higher cognitive ability. Additional analyses indicated that being free of the bias blind spot does not help a person avoid the actual classic cognitive biases. We discuss these findings in terms of a generic dual-process theory of cognition.

  4. The reactive collision mechanism evinced: stereodynamical control of the elementary Br + H2 → H + HBr reaction.

    Science.gov (United States)

    Herráez-Aguilar, D; Jambrina, P G; Aldegunde, J; Sáez-Rábanos, Vicente; de Miranda, M P; Aoiz, F J

    2013-08-28

    From a kinetics standpoint, reactive molecular collisions are the building blocks of the mechanisms of chemical reactions. In contrast, a dynamics standpoint reveals molecular collisions to have their own internal mechanisms, which are not mere theoretical abstractions: through suitable preparation of the reactants internal and stereochemical states, features of the mechanisms of a reactive molecular collision can be made evident and used as "handles" to control the reaction outcome. Using time-independent quantum dynamical calculations, we demonstrate this for the Br + H2(v = 0-1, j = 2) → H + HBr reaction in the 1.0-1.6 eV range of total energies. Despite its pronounced effect on reactivity, which is in agreement with the predictions from Polanyi rules, reactant vibration is found to have little effect on the mechanism of this endoergic, late-barrier reaction. Analysis of the correlations between directional reaction properties shows that the collision stereochemistry strongly depends on the total energy, but not on how this energy is partitioned between reactant translation and vibration. The stereodynamical preferences implied by the collision mechanisms determine how and to what extent one can control the reaction. Regarding the overall reaction, the extent of control is found to be large near the reaction threshold but not when the total energy is high. Regarding state-to-state reactions, the effect of reactant stereochemistry on the product rotational state distribution is found to be nontrivial and energy dependent.

  5. Cross-situational consistency in recognition memory response bias.

    Science.gov (United States)

    Kantner, Justin; Lindsay, D Stephen

    2014-10-01

    Individuals taking an old-new recognition memory test differ widely in their bias to respond "old," ranging from strongly conservative to strongly liberal, even without any manipulation intended to affect bias. Kantner and Lindsay (2012) found stability of bias across study-test cycles, suggesting that bias is a cognitive trait. That consistency, however, could have arisen because participants perceived the two tests as being part of the same experiment in the same context. In the present study, we tested for stability across two recognition study-test procedures embedded in markedly different experiments, held weeks apart, that participants did not know were connected. Bias showed substantial cross-situational stability. Moreover, bias weakly predicted identifications on an eyewitness memory task and accuracy on a go-no-go task. Although we found little in the way of relationships between bias and five personality measures, these findings suggest that response bias is a stable and broadly influential characteristic of recognizers.

  6. A selected history of expectation bias in physics

    OpenAIRE

    Jeng, Monwhea

    2005-01-01

    The beliefs of physicists can bias their results towards their expectations in a number of ways. We survey a variety of historical cases of expectation bias in observations, experiments, and calculations.

  7. Impact of Continued Biased Disenrollment from the Medic...

    Data.gov (United States)

    U.S. Department of Health & Human Services — Impact of Continued Biased Disenrollment from the Medicare Advantage Program to Fee-for-Service As reported in Impact of Continued Biased Disenrollment from the...

  8. Towards process-informed bias correction of climate change simulations

    Science.gov (United States)

    Maraun, Douglas; Shepherd, Theodore G.; Widmann, Martin; Zappa, Giuseppe; Walton, Daniel; Gutiérrez, José M.; Hagemann, Stefan; Richter, Ingo; Soares, Pedro M. M.; Hall, Alex; Mearns, Linda O.

    2017-11-01

    Biases in climate model simulations introduce biases in subsequent impact simulations. Therefore, bias correction methods are operationally used to post-process regional climate projections. However, many problems have been identified, and some researchers question the very basis of the approach. Here we demonstrate that a typical cross-validation is unable to identify improper use of bias correction. Several examples show the limited ability of bias correction to correct and to downscale variability, and demonstrate that bias correction can cause implausible climate change signals. Bias correction cannot overcome major model errors, and naive application might result in ill-informed adaptation decisions. We conclude with a list of recommendations and suggestions for future research to reduce, post-process, and cope with climate model biases.

  9. Stimulus-Driven Attention, Threat Bias, and Sad Bias in Youth with a History of an Anxiety Disorder or Depression.

    Science.gov (United States)

    Sylvester, Chad M; Hudziak, James J; Gaffrey, Michael S; Barch, Deanna M; Luby, Joan L

    2016-02-01

    Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth with a history of an anxiety disorder and/or depression (ANX/DEP; n = 40) as well as healthy controls (HC; n = 33). Stimulus-driven attention was measured with a non-emotional spatial orienting task, while threat bias and sad bias were measured at a short time interval (150 ms) with a spatial orienting task using emotional faces and at a longer time interval (500 ms) using a dot-probe task. In ANX/DEP but not HC, early attention bias towards threat was negatively correlated with later attention bias to threat, suggesting that early threat vigilance was associated with later threat avoidance. Across all subjects, stimulus-driven orienting was not correlated with early threat bias but was negatively correlated with later threat bias, indicating that rapid stimulus-driven orienting is linked to later threat avoidance. No parallel relationships were detected for sad bias. Current symptoms of depression but not anxiety were related to decreased stimulus-driven attention. Together, these results are consistent with the hypothesis that threat bias but not sad bias relies on stimulus-driven attention. These results inform the design of attention bias modification programs that aim to reverse threat biases and reduce symptoms associated with pediatric anxiety and depression.

  10. Information bias in health research: definition, pitfalls, and adjustment methods

    OpenAIRE

    Althubaiti A

    2016-01-01

    Alaa Althubaiti Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia Abstract: As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassific...

  11. Multiple Factors Drive Replicating Strand Composition Bias in Bacterial Genomes

    OpenAIRE

    Hai-Long Zhao; Zhong-Kui Xia; Fa-Zhan Zhang; Yuan-Nong Ye; Feng-Biao Guo

    2015-01-01

    Composition bias from Chargaff’s second parity rule (PR2) has long been found in sequenced genomes, and is believed to relate strongly with the replication process in microbial genomes. However, some disagreement on the underlying reason for strand composition bias remains. We performed an integrative analysis of various genomic features that might influence composition bias using a large-scale dataset of 1111 genomes. Our results indicate (1) the bias was stronger in obligate intracellular b...

  12. Dwalingen in de methodologie. II. Bias door vragenlijsten

    DEFF Research Database (Denmark)

    Pouwer, F; Van Der Ploeg, Henk M; Bramsen, I

    1998-01-01

    Some characteristics of self-report questionnaires can result in bias in responding. When a test item or a questionnaire is biased, the observed scores form an imprecise measurement of reality as a consequence of systematic errors of measurement. Causes of such bias are: unclear instructions, vag...... wording of the test items, culture-bound item content, suggestive questions, framing of questions, social desirability of certain answers, faking good, faking bad and the recall bias....

  13. Modifying Threat-Related Interpretive Bias in Adolescents

    Science.gov (United States)

    Salemink, Elske; Wiers, Reinout W.

    2011-01-01

    Socially anxious feelings sharply increase during adolescence and such feelings have been associated with interpretive biases. Studies in adults have shown that interpretive biases can be modified using Cognitive Bias Modification procedures (CBM-I) and subsequent effects on anxiety have been observed. The current study was designed to examine…

  14. Decomposing Bias in Different Types of Simple Decisions

    Science.gov (United States)

    White, Corey N.; Poldrack, Russell A.

    2014-01-01

    The ability to adjust bias, or preference for an option, allows for great behavioral flexibility. Decision bias is also important for understanding cognition as it can provide useful information about underlying cognitive processes. Previous work suggests that bias can be adjusted in 2 primary ways: by adjusting how the stimulus under…

  15. Development of Heuristic Bias Detection in Elementary School

    Science.gov (United States)

    De Neys, Wim; Feremans, Vicky

    2013-01-01

    Although human reasoning is often biased by intuitive heuristics, recent studies have shown that adults and adolescents detect the biased nature of their judgments. The present study focused on the development of this critical bias sensitivity by examining the detection skills of young children in elementary school. Third and 6th graders were…

  16. Scale dependent bias from primordial non-Gaussianity with trispectrum

    CERN Document Server

    Gong, Jinn-Ouk

    2011-01-01

    We study the scale dependent bias of the halo power spectrum arising from primordial non-Gaussianity. We present an analytic result of the halo bias including up to the trispectrum contributions. We find the scale dependent bias opens a new possibility of probing the relation between the non-linearity parameters $\\fnl$ and $\\tnl$.

  17. Motivational mechanisms underlying the approach bias to cigarettes

    NARCIS (Netherlands)

    Watson, P.; de Wit, S.; Cousijn, J.; Hommel, B.; Wiers, R.W.

    2013-01-01

    Approach Avoidance tasks measure approach bias, a behavioral tendency to be faster at approaching rather than avoiding drug cues. Approach bias has been measured in a number of different drug-using populations and there is evidence to suggest that approach bias measurements correlate with drug use.

  18. An Experimental Examination of Readers' Perceptions of Media Bias.

    Science.gov (United States)

    D'Alessio, Dave

    2003-01-01

    Explores perceptions of media bias by manipulating expectations of bias and news topic. Explains that university students read dummy newspaper articles and then responded to a survey. Concludes that readers were more likely to designate material opposing their own views as biased. (PM)

  19. Bias in Examination Test Banks that Accompany Cost Accounting Texts.

    Science.gov (United States)

    Clute, Ronald C.; McGrail, George R.

    1989-01-01

    Eight text banks that accompany cost accounting textbooks were evaluated for the presence of bias in the distribution of correct responses. All but one were found to have considerable bias, and three of eight were found to have significant choice bias. (SK)

  20. Observational biases in flux magnification measurements

    Science.gov (United States)

    Hildebrandt, H.

    2016-02-01

    Flux magnification is an interesting complement to shear-based lensing measurements, especially at high redshift where sources are harder to resolve. One measures either changes in the source density (magnification bias) or in the shape of the flux distribution (e.g. magnitude shift). The interpretation of these measurements relies on theoretical estimates of how the observables change under magnification. Here, we present simulations to create multiband photometric mock catalogues of Lyman-break galaxies in a CFHTLenS (Canada France Hawaii Telescope Lensing Survey)-like survey that include several observational effects that can change these relations, making simple theoretical estimates unusable. In particular, we show how the magnification bias can be affected by photometric noise, colour selection, and dust extinction. We find that a simple measurement of the slope of the number-counts is not sufficient for the precise interpretation of virtually all observations of magnification bias. We also explore how sensitive the shift in the mean magnitude of a source sample in different photometric bands is to magnification including the same observational effects. Again we find significant deviations from simple analytical estimates. We also discover a wavelength-dependence of the magnitude-shift effect when applied to a colour-selected noisy source sample. Such an effect can mimic the reddening by dust in the lens. It has to be disentangled from the dust extinction before the magnitude shift/colour-excess can be used to measure the distribution of either dark matter or extragalactic dust. Using simulations like the ones presented here these observational effects can be studied and eventually removed from observations making precise measurements of flux magnification possible.

  1. Heuristics and bias in rectal surgery.

    Science.gov (United States)

    MacDermid, Ewan; Young, Christopher J; Moug, Susan J; Anderson, Robert G; Shepherd, Heather L

    2017-08-01

    Deciding to defunction after anterior resection can be difficult, requiring cognitive tools or heuristics. From our previous work, increasing age and risk-taking propensity were identified as heuristic biases for surgeons in Australia and New Zealand (CSSANZ), and inversely proportional to the likelihood of creating defunctioning stomas. We aimed to assess these factors for colorectal surgeons in the British Isles, and identify other potential biases. The Association of Coloproctology of Great Britain and Ireland (ACPGBI) was invited to complete an online survey. Questions included demographics, risk-taking propensity, sensitivity to professional criticism, self-perception of anastomotic leak rate and propensity for creating defunctioning stomas. Chi-squared testing was used to assess differences between ACPGBI and CSSANZ respondents. Multiple regression analysis identified independent surgeon predictors of stoma formation. One hundred fifty (19.2%) eligible members of the ACPGBI replied. Demographics between ACPGBI and CSSANZ groups were well-matched. Significantly more ACPGBI surgeons admitted to anastomotic leak in the last year (p < 0.001). ACPGBI surgeon age over 50 (p = 0.02), higher risk-taking propensity across several domains (p = 0.044), self-belief in a lower-than-average anastomotic leak rate (p = 0.02) and belief that the average risk of leak after anterior resection is 8% or lower (p = 0.007) were all independent predictors of less frequent stoma formation. Sensitivity to criticism from colleagues was not a predictor of stoma formation. Unrecognised surgeon factors including age, everyday risk-taking, self-belief in surgical ability and lower probability bias of anastomotic leak appear to exert an effect on decision-making in rectal surgery.

  2. Bias During the Evaluation of Animal Studies?

    Science.gov (United States)

    Knight, Andrew

    2012-01-01

    Simple Summary Animal experimentation evokes strong emotional responses in people on both sides of the debate surrounding its ethical status. However, the true level of its usefulness to society may only be discerned by careful examination of reliable scientific evidence. My recent book, The Costs and Benefits of Animal Experiments, reviewed more than 500 relevant scientific publications. Recently in this journal, however, a reviewer essentially accused me of bias. Yet the conclusions of my book are based on sound reasoning and strong evidence, and no critic has yet provided any substantive evidence to refute them. Abstract My recent book entitled The Costs and Benefits of Animal Experiments seeks to answer a key question within animal ethics, namely: is animal experimentation ethically justifiable? Or, more precisely, is it justifiable within the utilitarian cost:benefit framework that fundamentally underpins most regulations governing animal experimentation? To answer this question I reviewed more than 500 scientific publications describing animal studies, animal welfare impacts, and alternative research, toxicity testing and educational methodologies. To minimise bias I focused primarily on large-scale systematic reviews that had examined the human clinical and toxicological utility of animal studies. Despite this, Dr. Susanne Prankel recently reviewed my book in this journal, essentially accusing me of bias. However, she failed to provide any substantive evidence to refute my conclusions, let alone evidence of similar weight to that on which they are based. Those conclusions are, in fact, firmly based on utilitarian ethical reasoning, informed by scientific evidence of considerable strength, and I believe they are robust. PMID:26486779

  3. Codon Bias and Mutability in HIV Sequences

    CERN Document Server

    Waelbroeck, H

    1997-01-01

    A survey of the patterns of synonymous codon preferences in the HIV env gene reveals a relation between the codon bias and the mutability requirements in different regions in the protein. At hypervariable regions in $gp120$, one finds a greater proportion of codons that tend to mutate non-synonymously, but to a target that is similar in hydrophobicity and volume. We argue that this strategy results from a compromise between the selective pressure placed on the virus by the induced immune response, which favours amino acid substitutions in the complementarity determining regions, and the negative selection against missense mutations that violate structural constraints of the env protein.

  4. Leveraging position bias to improve peer recommendation.

    Directory of Open Access Journals (Sweden)

    Kristina Lerman

    Full Text Available With the advent of social media and peer production, the amount of new online content has grown dramatically. To identify interesting items in the vast stream of new content, providers must rely on peer recommendation to aggregate opinions of their many users. Due to human cognitive biases, the presentation order strongly affects how people allocate attention to the available content. Moreover, we can manipulate attention through the presentation order of items to change the way peer recommendation works. We experimentally evaluate this effect using Amazon Mechanical Turk. We find that different policies for ordering content can steer user attention so as to improve the outcomes of peer recommendation.

  5. Spectral response measurements with white light bias

    Science.gov (United States)

    Devaney, W.; Lorenz, S.; Meakin, J. D.

    1976-01-01

    The spectral response of solar cells such as the CdS/Cu2S cell is non-linear with distinct quenching and enhancement bands. One possible technique to produce standardized solar efficiencies is to fold in spectral response with a standard solar spectrum. The spectral response of a cell was measured in a way which matched cell behavior under white light illumination. A technique was developed to measure the response of a cell to low intensity chopped monochromatic light while the cell is also illuminated with a white light bias corresponding to AMI.

  6. Biases in Visual, Auditory, and Audiovisual Perception of Space.

    Directory of Open Access Journals (Sweden)

    Brian Odegaard

    2015-12-01

    Full Text Available Localization of objects and events in the environment is critical for survival, as many perceptual and motor tasks rely on estimation of spatial location. Therefore, it seems reasonable to assume that spatial localizations should generally be accurate. Curiously, some previous studies have reported biases in visual and auditory localizations, but these studies have used small sample sizes and the results have been mixed. Therefore, it is not clear (1 if the reported biases in localization responses are real (or due to outliers, sampling bias, or other factors, and (2 whether these putative biases reflect a bias in sensory representations of space or a priori expectations (which may be due to the experimental setup, instructions, or distribution of stimuli. Here, to address these questions, a dataset of unprecedented size (obtained from 384 observers was analyzed to examine presence, direction, and magnitude of sensory biases, and quantitative computational modeling was used to probe the underlying mechanism(s driving these effects. Data revealed that, on average, observers were biased towards the center when localizing visual stimuli, and biased towards the periphery when localizing auditory stimuli. Moreover, quantitative analysis using a Bayesian Causal Inference framework suggests that while pre-existing spatial biases for central locations exert some influence, biases in the sensory representations of both visual and auditory space are necessary to fully explain the behavioral data. How are these opposing visual and auditory biases reconciled in conditions in which both auditory and visual stimuli are produced by a single event? Potentially, the bias in one modality could dominate, or the biases could interact/cancel out. The data revealed that when integration occurred in these conditions, the visual bias dominated, but the magnitude of this bias was reduced compared to unisensory conditions. Therefore, multisensory integration not only

  7. The immitigable nature of assembly bias: the impact of halo definition on assembly bias

    Science.gov (United States)

    Villarreal, Antonio S.; Zentner, Andrew R.; Mao, Yao-Yuan; Purcell, Chris W.; van den Bosch, Frank C.; Diemer, Benedikt; Lange, Johannes U.; Wang, Kuan; Campbell, Duncan

    2017-11-01

    Dark matter halo clustering depends not only on halo mass, but also on other properties such as concentration and shape. This phenomenon is known broadly as assembly bias. We explore the dependence of assembly bias on halo definition, parametrized by spherical overdensity parameter, Δ. We summarize the strength of concentration-, shape-, and spin-dependent halo clustering as a function of halo mass and halo definition. Concentration-dependent clustering depends strongly on mass at all Δ. For conventional halo definitions (Δ ˜ 200 - 600 m), concentration-dependent clustering at low mass is driven by a population of haloes that is altered through interactions with neighbouring haloes. Concentration-dependent clustering can be greatly reduced through a mass-dependent halo definition with Δ ˜ 20 - 40 m for haloes with M200 m ≲ 1012 h-1M⊙. Smaller Δ implies larger radii and mitigates assembly bias at low mass by subsuming altered, so-called backsplash haloes into now larger host haloes. At higher masses (M200 m ≳ 1013 h-1M⊙) larger overdensities, Δ ≳ 600 m, are necessary. Shape- and spin-dependent clustering are significant for all halo definitions that we explore and exhibit a relatively weaker mass dependence. Generally, both the strength and the sense of assembly bias depend on halo definition, varying significantly even among common definitions. We identify no halo definition that mitigates all manifestations of assembly bias. A halo definition that mitigates assembly bias based on one halo property (e.g. concentration) must be mass dependent. The halo definitions that best mitigate concentration-dependent halo clustering do not coincide with the expected average splashback radii at fixed halo mass.

  8. An Evaluation of Depletion Bias and Bias Uncertainty of the GBC cask with PLUS7 Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyungju; Park, Kwangheon; Hong, Ser Gi [Kyung Hee Univ., Yongin (Korea, Republic of)

    2016-10-15

    A nuclear criticality safety evaluation that applies burnup credit (BUC) to a DSC is performed mainly through a two-step process: (1) the determination of isotopic compositions within UNFs to be loaded into a DSC by a depletion analysis and (2) the determination of the k{sub eff} value with respect to the DSC by a criticality analysis. In particular, the isotopic compositions by a depletion analysis should be estimated accurately because the concentrations of the nuclides contained in a UNF have a significant influence on the accuracies of depletion analysis and its subsequent criticality analysis. However, since no depletion computer code can calculate exactly nuclide compositions contained in a used nuclear fuel assembly (UNFA), it requires bias and bias uncertainty in terms of a reactivity difference, Δk{sub eff}, by a depletion code for burnup credit criticality safety analyses. In this work, the bias and bias uncertainty in k{sub eff} resulting from biases and bias uncertainties in the calculated nuclide concentrations were determined for the GBC-32 DSC system with 32 PLUS7 16X16 UNFAs. First, the new one-group cross section libraries of the ORIGEN code were generated with respect to the PLUS7 16X16 NFA using the SCALE 6.1/TRITON code. Second, the appropriate initial enrichment values for which the k{sub eff}-REF value of the DSC system was to be 0.94 were searched as a function of specific burnup using the SCALE 6.1/STARBUCS code.

  9. Gender Bias in Engineering: Does More Contact with Female Engineers Reduce Bias?

    OpenAIRE

    Hoeffel, Elizabeth Marie

    2007-01-01

    Status Characteristics Theory and Contact Theory are tested to measure gender bias in engineering students, and to determine if contact with female engineers helps reduce gender bias. To assess this, two versions of a resume, one with a femaleâ s name and one with a maleâ s name, were given to senior mechanical engineering students (n=225) to establish if they would rate the male applicant better than the female applicant. Respondents were asked how qualified they thought the respondent w...

  10. Residual bias in a multiphase flow model calibration and prediction

    Science.gov (United States)

    Poeter, E.P.; Johnson, R.H.

    2002-01-01

    When calibrated models produce biased residuals, we assume it is due to an inaccurate conceptual model and revise the model, choosing the most representative model as the one with the best-fit and least biased residuals. However, if the calibration data are biased, we may fail to identify an acceptable model or choose an incorrect model. Conceptual model revision could not eliminate biased residuals during inversion of simulated DNAPL migration under controlled conditions at the Borden Site near Ontario Canada. This paper delineates hypotheses for the source of bias, and explains the evolution of the calibration and resulting model predictions.

  11. Visual signals bias auditory targets in azimuth and depth.

    Science.gov (United States)

    Bowen, Amanda L; Ramachandran, Ramnarayan; Muday, Jeffrey A; Schirillo, James A

    2011-10-01

    In the psychophysical phenomenon visual bias, an accurately localized irrelevant signal, such as a light, impairs localization of a spatially discrepant target, such as a sound, when the two stimuli are perceived as unified. Many studies have demonstrated visual bias in azimuth, but none have tested directly or found this effect in depth. The current study was able to produce over 90% bias in azimuth and somewhat less (83%) bias in depth. A maximum likelihood estimate can predict bias by the variance in the localization of each unimodal signal in each dimension in space.

  12. Cognitive biases can affect moral intuitions about cognitive enhancement

    Directory of Open Access Journals (Sweden)

    Lucius eCaviola

    2014-10-01

    Full Text Available Research into cognitive biases that impair human judgment has mostly been applied to the area of economic decision-making. Ethical decision-making has been comparatively neglected. Since ethical decisions often involve very high individual as well as collective stakes, analyzing how cognitive biases affect them can be expected to yield important results. In this theoretical article, we consider the ethical debate about cognitive enhancement (CE and suggest a number of cognitive biases that are likely to affect moral intuitions and judgments about CE: status quo bias, loss aversion, risk aversion, omission bias, scope insensitivity, nature bias, and optimistic bias. We find that there are more well-documented biases that are likely to cause irrational aversion to CE than biases in the opposite direction. This suggests that common attitudes about CE are predominantly negatively biased. Within this new perspective, we hope that subsequent research will be able to elaborate this hypothesis and develop effective de-biasing techniques that can help increase the rationality of the public CE debate and thus improve our ethical decision-making.

  13. Biased allocation of faces to social categories.

    Science.gov (United States)

    Dotsch, Ron; Wigboldus, Daniël H J; van Knippenberg, Ad

    2011-06-01

    Three studies show that social categorization is biased at the level of category allocation. In all studies, participants categorized faces. In Studies 1 and 2, participants overallocated faces with criminal features--a stereotypical negative trait--to the stigmatized Moroccan category, especially if they were prejudiced. On the contrary, the stereotype-irrelevant negative trait stupid did not lead to overallocation to the Moroccan category. In Study 3, using the stigmatized category homosexual, the previously used negative trait criminal--irrelevant to the homosexual stereotype--did not lead to overallocation, but the stereotype-relevant positive trait femininity did. These results demonstrate that normative fit is higher for faces with stereotype-relevant features regardless of valence. Moreover, individual differences in implicit prejudice predicted the extent to which stereotype-relevant traits elicited overallocation: Whereas more negatively prejudiced people showed greater overallocation of faces associated with negative stereotype-relevant traits, they showed less overallocation of faces associated with positive stereotype-relevant traits. These results support our normative fit hypothesis: In general, normative fit is better for faces with stereotypical features. Moreover, normative fit is enhanced for prejudiced individuals when these features are evaluatively congruent. Social categorization thus may be biased in itself. 2011 APA, all rights reserved

  14. Two success-biased social learning strategies.

    Science.gov (United States)

    Baldini, Ryan

    2013-06-01

    I compare the evolutionary dynamics of two success-biased social learning strategies, which, by definition, use the success of others to inform one's social learning decisions. The first, "Compare Means", causes a learner to adopt cultural variants with highest mean payoff in her sample. The second, "Imitate the Best", causes a learner to imitate the single most successful individual in her sample. I summarize conditions under which each strategy performs well or poorly, and investigate their evolution via a gene-culture coevolutionary model. Despite the adaptive appeal of these strategies, both encounter conditions under which they systematically perform worse than simply imitating at random. Compare Means performs worst when the optimal cultural variant is usually at high frequency, while Imitate the Best performs worst when suboptimal variants sometimes produce high payoffs. The extent to which it is optimal to use success-biased social learning depends strongly on the payoff distributions and environmental conditions that human social learners face. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Social influence bias: a randomized experiment.

    Science.gov (United States)

    Muchnik, Lev; Aral, Sinan; Taylor, Sean J

    2013-08-09

    Our society is increasingly relying on the digitized, aggregated opinions of others to make decisions. We therefore designed and analyzed a large-scale randomized experiment on a social news aggregation Web site to investigate whether knowledge of such aggregates distorts decision-making. Prior ratings created significant bias in individual rating behavior, and positive and negative social influences created asymmetric herding effects. Whereas negative social influence inspired users to correct manipulated ratings, positive social influence increased the likelihood of positive ratings by 32% and created accumulating positive herding that increased final ratings by 25% on average. This positive herding was topic-dependent and affected by whether individuals were viewing the opinions of friends or enemies. A mixture of changing opinion and greater turnout under both manipulations together with a natural tendency to up-vote on the site combined to create the herding effects. Such findings will help interpret collective judgment accurately and avoid social influence bias in collective intelligence in the future.

  16. Ombud’s Corner: defeating unconscious bias

    CERN Multimedia

    Sudeshna Datta-Cockerill

    2016-01-01

    Do you have a tendency to switch off at meetings every time a particular colleague starts to speak? Is it obvious to you that your colleagues will never accept a peer as a project leader? And doesn’t that candidate from your own alma mater clearly have a definite edge over the others?   How do we come to these conclusions and what can we do to ensure that our decisions are based on objective criteria alone? Can we always be sure that we are not influenced by pre-conceived notions or prejudices that may unconsciously bias our thinking? Unconscious bias is a part of everyday life – it refers to the insidious influences that our backgrounds, cultural environments or personal experiences exert on the way in which we judge or assess people or situations. In the workplace, it has a negative impact on our goals and interactions when it causes us to make decisions based on generalisations or mental associations that we are not even aware of, and that have little or no bearing on the o...

  17. Simultaneous quaternion estimation (QUEST) and bias determination

    Science.gov (United States)

    Markley, F. Landis

    1989-01-01

    Tests of a new method for the simultaneous estimation of spacecraft attitude and sensor biases, based on a quaternion estimation algorithm minimizing Wahba's loss function are presented. The new method is compared with a conventional batch least-squares differential correction algorithm. The estimates are based on data from strapdown gyros and star trackers, simulated with varying levels of Gaussian noise for both inertially-fixed and Earth-pointing reference attitudes. Both algorithms solve for the spacecraft attitude and the gyro drift rate biases. They converge to the same estimates at the same rate for inertially-fixed attitude, but the new algorithm converges more slowly than the differential correction for Earth-pointing attitude. The slower convergence of the new method for non-zero attitude rates is believed to be due to the use of an inadequate approximation for a partial derivative matrix. The new method requires about twice the computational effort of the differential correction. Improving the approximation for the partial derivative matrix in the new method is expected to improve its convergence at the cost of increased computational effort.

  18. Linguistic intergroup bias in political communication.

    Science.gov (United States)

    Anolli, Luigi; Zurloni, Valentino; Riva, Giuseppe

    2006-07-01

    The Linguistic Intergroup Bias (LIB) illustrates the disposition to communicate positive in-group and negative out-group behaviors more abstractly than negative in-group and positive out-group behaviors. The present research examined the function of language in reinforcing this bias in political communication. To illustrate the LIB, the Linguistic Category Model (LCM) was used, including a nouns category. Because social stereotypes are usually conveyed by nominal terms, the aim was to observe the relationship between stereotypes and language in political communication. Moreover, we were interested in analyzing the psychological processes that drive the LIB. Therefore, we verified whether the LIB is more related to language abstractness than to agent-patient causality. Several political debates and interviews, which took place before the latest Italian provincial elections, were analyzed. Results suggested that the language politicians use in communicating about political groups are conceptualized as stereotypes rather than as trait-based categories. Moreover, it seems that the LIB could not be explained only at a lexical level. Social implications of the present findings in interpersonal relations and causal attribution were discussed.

  19. Bias During the Evaluation of Animal Studies?

    Directory of Open Access Journals (Sweden)

    Andrew Knight

    2012-02-01

    Full Text Available My recent book entitled The Costs and Benefits of Animal Experiments seeks to answer a key question within animal ethics, namely: is animal experimentation ethically justifiable? Or, more precisely, is it justifiable within the utilitarian cost:benefit framework that fundamentally underpins most regulations governing animal experimentation? To answer this question I reviewed more than 500 scientific publications describing animal studies, animal welfare impacts, and alternative research, toxicity testing and educational methodologies. To minimise bias I focused primarily on large-scale systematic reviews that had examined the human clinical and toxicological utility of animal studies. Despite this, Dr. Susanne Prankel recently reviewed my book in this journal, essentially accusing me of bias. However, she failed to provide any substantive evidence to refute my conclusions, let alone evidence of similar weight to that on which they are based. Those conclusions are, in fact, firmly based on utilitarian ethical reasoning, informed by scientific evidence of considerable strength, and I believe they are robust.

  20. Mindful attention reduces linguistic intergroup bias.

    Science.gov (United States)

    Tincher, Moses M; Lebois, Lauren A M; Barsalou, Lawrence W

    2016-04-01

    A brief mindfulness intervention diminished bias in favor of one's in-group and against one's out-group. In the linguistic intergroup bias (LIB), individuals expect in-group members to behave positively, and out-group members to behave negatively. Consequently, individuals choose abstract language beset with character inferences to describe these expected behaviors, and in contrast, choose concrete, objective language to describe unexpected behaviors. Eighty-four participants received either mindful attention instructions (observe their thoughts as fleeting mental states) or immersion instructions (become absorbed in the vivid details of thoughts). After instruction, participants viewed visual depictions of an imagined in-group or out-group member's positive or negative behavior, selecting the best linguistic description from a set of four descriptions that varied in abstractness. Immersion groups demonstrated a robust LIB. Mindful attention groups, however, exhibited a markedly tempered LIB, suggesting that even a brief mindfulness-related instruction can implicitly reduce the propensity to perpetuate stereotypical thinking through language. These results contribute to understanding the mechanisms that facilitate unprejudiced thinking.

  1. Emotions in context : Anger causes ethnic bias but not gender bias in men but not women

    NARCIS (Netherlands)

    Kuppens, Toon; Pollet, Thomas V.; Teixeira, Catia P.; Demoulin, Stephanie; Roberts, S. Craig; Little, Anthony C.

    Emotions influence information processing because they are assumed to carry valuable information. We predict that induced anger will increase ethnic but not gender intergroup bias because anger is related to conflicts for resources, and ethnic groups typically compete for resources, whereas gender

  2. Mood-congruent free recall bias in anxious individuals is not a consequence of response bias.

    Science.gov (United States)

    Russo, Riccardo; Whittuck, Dora; Roberson, Debi; Dutton, Kevin; Georgiou, George; Fox, Elaine

    2006-05-01

    The status of mood-congruent free recall bias in anxious individuals was evaluated following incidental encoding of target words. Individuals with high and low levels of trait anxiety completed a modified Stroop task, which revealed an attentional bias for threat-related stimuli in anxious individuals. This group was significantly slower in naming the colour in which threat-related words were displayed compared to neutral words. In a subsequent free recall test for the words used in the modified Stroop task, anxious individuals recalled more threat-related words compared to low-anxious people. This difference was significant even when controlling for the false recall of items that had not been presented during study. These results support the view put forward by Russo, Fox, Bellinger, and Nguyen-Van-Tam (2001) that mood-congruent free recall bias in anxious individuals can be observed if the target material is encoded at a relatively shallow level. Moreover, contrary to Dowens and Calvo (2003), the current results show that the memory advantage for threat-related information in anxious individuals is not a consequence of response bias.

  3. FractBias: a graphical tool for assessing fractionation bias following polyploidy.

    Science.gov (United States)

    Joyce, Blake L; Haug-Baltzell, Asher; Davey, Sean; Bomhoff, Matthew; Schnable, James C; Lyons, Eric

    2017-02-15

    Following polyploidy events, genomes undergo massive reduction in gene content through a process known as fractionation. Importantly, the fractionation process is not always random, and a bias as to which homeologous chromosome retains or loses more genes can be observed in some species. The process of characterizing whole genome fractionation requires identifying syntenic regions across genomes followed by post-processing of those syntenic datasets to identify and plot gene retention patterns. We have developed a tool, FractBias, to calculate and visualize gene retention and fractionation patterns across whole genomes. Through integration with SynMap and its parent platform CoGe, assembled genomes are pre-loaded and available for analysis, as well as letting researchers integrate their own data with security options to keep them private or make them publicly available. FractBias is freely available as a web application at https://genomevolution.org/CoGe/SynMap.pl . The software is open source (MIT license) and executable with Python 2.7 or iPython notebook, and available on GitHub ( https://goo.gl/PaAtqy ). Documentation for FractBias is available on CoGepedia ( https://goo.gl/ou9dt6 ). ericlyons@email.arizona.edu. Supplementary data are available at Bioinformatics online.

  4. Vowel Bias in Danish Word-Learning: Processing Biases Are Language-Specific

    Science.gov (United States)

    Højen, Anders; Nazzi, Thierry

    2016-01-01

    The present study explored whether the phonological bias favoring consonants found in French-learning infants and children when learning new words (Havy & Nazzi, 2009; Nazzi, 2005) is language-general, as proposed by Nespor, Peña and Mehler (2003), or varies across languages, perhaps as a function of the phonological or lexical properties of…

  5. Formal definitions of measurement bias and explanation bias clarify measurement and conceptual perspectives on response shift

    NARCIS (Netherlands)

    Oort, F.J.; Visser, M.R.M.; Sprangers, M.A.G.

    2009-01-01

    Objective: Response shift is generally associated with a change in the meaning of test scores, impeding the comparison of repeated measurements. Still, different researchers have different views of response shift. From a measurement perspective, response shift can be considered as bias in the

  6. Afrikaans and the Ontogenetic Myth.

    Science.gov (United States)

    Roberge, Paul T.

    1992-01-01

    Argues that politicians have evoked and reinforced mythic views held by linguistically naive Afrikaaners regarding the origin and elaboration of Afrikaans, focusing on the merits of claims regarding certain linguistic attitudes that reflect an underlying cultural assumption that has remained deeply embedded in public consciousness. (60 references)…

  7. Spatial Clustering of Dark Matter Haloes: Secondary Bias, Neighbour Bias, and the Influence of Massive Neighbours on Halo Properties

    Science.gov (United States)

    Salcedo, Andrés N.; Maller, Ariyeh H.; Berlind, Andreas A.; Sinha, Manodeep; McBride, Cameron K.; Behroozi, Peter S.; Wechsler, Risa H.; Weinberg, David H.

    2018-01-01

    We explore the phenomenon commonly known as halo assembly bias, whereby dark matter haloes of the same mass are found to be more or less clustered when a second halo property is considered, for haloes in the mass range 3.7 × 1011 h-1 M⊙ - 5.0 × 1013 h-1 M⊙. Using the Large Suite of Dark Matter Simulations (LasDamas) we consider nine commonly used halo properties and find that a clustering bias exists if haloes are binned by mass or by any other halo property. This secondary bias implies that no single halo property encompasses all the spatial clustering information of the halo population. The mean values of some halo properties depend on their halo's distance to a more massive neighbour. Halo samples selected by having high values of one of these properties therefore inherit a neighbour bias such that they are much more likely to be close to a much more massive neighbour. This neighbour bias largely accounts for the secondary bias seen in haloes binned by mass and split by concentration or age. However, haloes binned by other mass-like properties still show a secondary bias even when the neighbour bias is removed. The secondary bias of haloes selected by their spin behaves differently than that for other halo properties, suggesting that the origin of the spin bias is different than of other secondary biases.

  8. Cognitive bias in forensic anthropology: visual assessment of skeletal remains is susceptible to confirmation bias.

    Science.gov (United States)

    Nakhaeizadeh, Sherry; Dror, Itiel E; Morgan, Ruth M

    2014-05-01

    An experimental study was designed to examine cognitive biases within forensic anthropological non-metric methods in assessing sex, ancestry and age at death. To investigate examiner interpretation, forty-one non-novice participants were semi randomly divided into three groups. Prior to conducting the assessment of the skeletal remains, two of the groups were given different extraneous contextual information regarding the sex, ancestry and age at death of the individual. The third group acted as a control group with no extraneous contextual information. The experiment was designed to investigate if the interpretation and conclusions of the skeletal remains would differ amongst participants within the three groups, and to assess whether the examiners would confirm or disagree with the given extraneous context when establishing a biological profile. The results revealed a significant biasing effect within the three groups, demonstrating a strong confirmation bias in the assessment of sex, ancestry and age at death. In assessment of sex, 31% of the participants in the control group concluded that the skeleton remains were male. In contrast, in the group that received contextual information that the remains were male, 72% concluded that the remains were male, and in the participant group where the context was that the remains were of a female, 0% of the participants concluded that the remains were male. Comparable results showing bias were found in assessing ancestry and age at death. These data demonstrate that cognitive bias can impact forensic anthropological non-metric methods on skeletal remains and affects the interpretation and conclusions of the forensic scientists. This empirical study is a step in establishing an evidence base approach for dealing with cognitive issues in forensic anthropological assessments, so as to enhance this valuable forensic science discipline. Copyright © 2013 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights

  9. Does anxiety-linked attentional bias to threatening information reflect bias in the setting of attentional goals, or bias in the execution of attentional goals?

    Science.gov (United States)

    Basanovic, Julian; MacLeod, Colin

    2017-04-01

    Heightened anxiety vulnerability is characterised by an attentional bias that favours the processing of negative information. However, this anxiety-linked attentional bias is amenable to two quite different explanations. One possibility is that it reflects anxiety-linked bias in the setting of attentional goals that favours setting the goal of attending towards negative information over the alternative goal of attending away from such information. Another possibility is that it reflects anxiety-linked bias in the execution of attentional goals that enhances the execution of the former attentional goal compared to the latter. The present study introduces a novel methodology designed to discriminate the validity of these competing hypotheses, by examining anxiety-linked attentional bias under two conditions. One condition left attentional goals unconstrained. The other condition imposed the attentional goal of either attending towards more negative or more benign emotional stimuli. The finding that anxiety-linked attentional bias was observed only under the former condition supported the hypothesis that anxiety is characterised by a bias favouring the setting attentional goals involving vigilance rather than avoidance of negative information, while giving no support to the hypothesis that anxiety is characterised by a bias reflecting enhanced execution of the former attentional goal compared to the latter.

  10. Measuring individual differences in decision biases: methodological considerations

    Directory of Open Access Journals (Sweden)

    Balazs eAczel

    2015-11-01

    Full Text Available Individual differences in people’s susceptibility to heuristics and biases (HB are often measured by multiple-bias questionnaires consisting of one or a few items for each bias. This research approach relies on the assumptions that (1 different versions of a decision bias task measure are interchangeable as they measure the same cognitive failure; and (2 that some combination of these tasks measures the same underlying construct. Based on these assumptions, in Study 1 we developed two versions of a new decision bias survey for which we modified 13 HB tasks to increase their comparability, construct validity, and the participants’ motivation. The analysis of the responses (N = 1279 showed weak internal consistency within the surveys and a great level of discrepancy between the extracted patterns of the underlying factors. To explore these inconsistencies, in Study 2 we used three original examples of HB tasks for each of seven biases. We created three decision bias surveys by allocating one version of each HB task to each survey. The participants’ responses (N = 527 showed a similar pattern as in Study 1, questioning the assumption that the different examples of the HB tasks are interchangeable and that they measure the same underlying construct. These results emphasize the need to understand the domain-specificity of cognitive biases as well as the effect of the wording of the cover story and the response mode on bias susceptibility before employing them in multiple-bias questionnaires.

  11. Measuring Individual Differences in Decision Biases: Methodological Considerations.

    Science.gov (United States)

    Aczel, Balazs; Bago, Bence; Szollosi, Aba; Foldes, Andrei; Lukacs, Bence

    2015-01-01

    Individual differences in people's susceptibility to heuristics and biases (HB) are often measured by multiple-bias questionnaires consisting of one or a few items for each bias. This research approach relies on the assumptions that (1) different versions of a decision bias task measure are interchangeable as they measure the same cognitive failure; and (2) that some combination of these tasks measures the same underlying construct. Based on these assumptions, in Study 1 we developed two versions of a new decision bias survey for which we modified 13 HB tasks to increase their comparability, construct validity, and the participants' motivation. The analysis of the responses (N = 1279) showed weak internal consistency within the surveys and a great level of discrepancy between the extracted patterns of the underlying factors. To explore these inconsistencies, in Study 2 we used three original examples of HB tasks for each of seven biases. We created three decision bias surveys by allocating one version of each HB task to each survey. The participants' responses (N = 527) showed a similar pattern as in Study 1, questioning the assumption that the different examples of the HB tasks are interchangeable and that they measure the same underlying construct. These results emphasize the need to understand the domain-specificity of cognitive biases as well as the effect of the wording of the cover story and the response mode on bias susceptibility before employing them in multiple-bias questionnaires.

  12. Measuring Individual Differences in Decision Biases: Methodological Considerations

    Science.gov (United States)

    Aczel, Balazs; Bago, Bence; Szollosi, Aba; Foldes, Andrei; Lukacs, Bence

    2015-01-01

    Individual differences in people's susceptibility to heuristics and biases (HB) are often measured by multiple-bias questionnaires consisting of one or a few items for each bias. This research approach relies on the assumptions that (1) different versions of a decision bias task measure are interchangeable as they measure the same cognitive failure; and (2) that some combination of these tasks measures the same underlying construct. Based on these assumptions, in Study 1 we developed two versions of a new decision bias survey for which we modified 13 HB tasks to increase their comparability, construct validity, and the participants' motivation. The analysis of the responses (N = 1279) showed weak internal consistency within the surveys and a great level of discrepancy between the extracted patterns of the underlying factors. To explore these inconsistencies, in Study 2 we used three original examples of HB tasks for each of seven biases. We created three decision bias surveys by allocating one version of each HB task to each survey. The participants' responses (N = 527) showed a similar pattern as in Study 1, questioning the assumption that the different examples of the HB tasks are interchangeable and that they measure the same underlying construct. These results emphasize the need to understand the domain-specificity of cognitive biases as well as the effect of the wording of the cover story and the response mode on bias susceptibility before employing them in multiple-bias questionnaires. PMID:26635677

  13. Self-perpetuating development of encoding biases.

    Science.gov (United States)

    Lewicki, P; Hill, T; Sasaki, I

    1989-12-01

    The process of encoding new information involves the imposition of preexisting interpretive categories on newly encountered stimuli, even if the categories do not match perfectly those stimuli. We hypothesized that such encoding of stimuli as supportive of preexisting encoding dispositions may become a source of a perceiver's subjective experiences that support these dispositions. Through this nonconsciously operating mechanism, encoding rules may gradually develop in a self-perpetuating manner, even in the absence of any objectively supportive evidence. Results demonstrated this self-perpetuating process in three studies involving different stimulus materials and experimental tasks (matrix-scanning paradigm and two "intuitive judgment" tasks). The self-perpetuating development of encoding biases is discussed as one of the elementary mechanisms involved in the development of interpretive categories and other individually differentiated cognitive dispositions.

  14. Reference List About Implicit and Unconscious Bias

    DEFF Research Database (Denmark)

    Munar, Ana Maria; Villeseche, Florence; Weidemann, Cecilie Dam

    ” (Equality Challenge Unit, 2013) and expands and updates it with other references – including literature published up to July 2016. The list aims to be used as a working document for employees or students at Copenhagen Business School. Therefore, besides the references, it includes direct links......The compilation of this reference list is one of the initiatives of the action plan developed by the Council for Diversity and Inclusion at Copenhagen Business School (CBS). This reference list is the first in a series of efforts initiated by this Council to develop an academic resource pool......, everyday human thought and activity” (Hardin and Banaji, 2013, pp. 13-14). Research also indicates that it is possible to implement procedures and strategic actions that help reduce implicit biases (Devine, Forscher, Austin, & Cox, 2012). Although extensive, this list does not include all existing academic...

  15. Information filtering via biased heat conduction

    CERN Document Server

    Liu, Jian-Guo; Guo, Qiang

    2011-01-01

    Heat conduction process has recently found its application in personalized recommendation [T. Zhou \\emph{et al.}, PNAS 107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction (BHC), which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix and Delicious datasets could be improved by 43.5%, 55.4% and 19.2% compared with the standard heat conduction algorithm, and the diversity is also increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering.

  16. Information filtering via biased heat conduction

    Science.gov (United States)

    Liu, Jian-Guo; Zhou, Tao; Guo, Qiang

    2011-09-01

    The process of heat conduction has recently found application in personalized recommendation [Zhou , Proc. Natl. Acad. Sci. USA PNASA60027-842410.1073/pnas.1000488107107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction, which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix, and Delicious datasets could be improved by 43.5%, 55.4% and 19.2%, respectively, compared with the standard heat conduction algorithm and also the diversity is increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering.

  17. Bias effects in implicit memory tasks.

    Science.gov (United States)

    Ratcliff, R; McKoon, G

    1996-12-01

    A major focus of recent research in memory has been performance on implicit tasks. The phenomenon of most interest has been repetition priming, the effect that prior exposure to a stimulus has on later perception of the stimulus or on a later decision about the stimulus. Picture naming, word identification, and word production in stem- and fragment-completion tasks all show repetition priming effects. The separation of implicit from explicit memory systems provides one account of this data, but a different theoretical view is proposed here: Repetition-priming effects come about because the processes that perform a task are biased products, temporary modifications of the processes, which influence later processing. The aim of this article is to demonstrate the potential of this view for developing new theories and for prompting new empirical questions.

  18. Measurement of Minimum Bias Observables with ATLAS

    CERN Document Server

    Kvita, Jiri; The ATLAS collaboration

    2017-01-01

    The modelling of Minimum Bias (MB) is a crucial ingredient to learn about the description of soft QCD processes. It has also a significant relevance for the simulation of the environment at the LHC with many concurrent pp interactions (“pileup”). The ATLAS collaboration has provided new measurements of the inclusive charged particle multiplicity and its dependence on transverse momentum and pseudorapidity in special data sets with low LHC beam currents, recorded at center of mass energies of 8 TeV and 13 TeV. The measurements cover a wide spectrum using charged particle selections with minimum transverse momentum of both 100 MeV and 500 MeV and in various phase space regions of low and high charged particle multiplicities.

  19. Cultural capital, teacher bias, and educational success

    DEFF Research Database (Denmark)

    Jæger, Mads Meier; Møllegaard, Stine

    2017-01-01

    In this paper we use new data on Danish monozygotic (MZ) twins to analyze the effect of cultural capital on educational success. We report three main findings. First, cultural capital has a positive direct effect on the likelihood of completing the college-bound track in Danish secondary education....... Second, cultural capital leads teachers to form upwardly biased perceptions of children's academic ability, but only when their exposure to children's cultural capital is brief (as in oral and written exams) rather than long (as in grades awarded at the end of the school year). Third, we find...... that the positive direct effect of cultural capital on educational success is higher for children from high-socioeconomic status (SES) backgrounds than for those from low-SES backgrounds. This result suggests that high-SES children are more likely to be in schooling contexts that enable them to convert cultural...

  20. Implicit and explicit memory bias in anxiety.

    Science.gov (United States)

    Mathews, A; Mogg, K; May, J; Eysenck, M

    1989-08-01

    Previous investigations of recall and recognition for threatening information in clinically anxious subjects have yielded equivocal results. The present study contrasts implicit (word completion) with explicit (cued recall) memory and shows that indices of bias for emotional material derived from the two types of memory are independent of one another. The explicit measure was correlated with trait anxiety scores, but did not clearly distinguish between subjects with clinical anxiety states and normal control subjects. On the implicit memory measure, clinically anxious subjects produced more threat word completions, but only from a set to which they had recently been exposed. These results are taken as evidence that internal representations of threat words are more readily or more persistently activated in anxiety states, although they are not necessarily better elaborated.

  1. A Self-Biasing Pulsed Depressed Collector

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Mark A.; Jensen, Aaron; Neilson, Jeff; /SLAC

    2014-05-29

    Depressed collectors have been utilized successfully for many years to improve the electrical efficiency of vacuum electron devices. Increasingly, pulsed, high-peak power accelerator applications are placing a premium on electrical efficiency. As RF systems are responsible for a large percentage of the overall energy usage at accelerator laboratories, methods to improve upon the state-of-the-art in pulsed high-power sources are desired. This paper presents a technique for self-biasing the stages in a multistage depressed collector. With this technique, the energy lost during the rise and fall times of the pulse can be recovered, separate power supplies are not needed, and existing modulators can be retrofitted. Calculations show that significant cost savings can be realized with the implementation of this device in high-power systems. In this paper, the technique is described along with experimental demonstration. (auth)

  2. Do abnormal responses show utilitarian bias?

    Science.gov (United States)

    Kahane, Guy; Shackel, Nicholas

    2008-03-20

    Neuroscience has recently turned to the study of utilitarian and non-utilitarian moral judgement. Koenigs et al. examine the responses of normal subjects and those with ventromedial-prefrontal-cortex (VMPC) damage to moral scenarios drawn from functional magnetic resonance imaging studies by Greene et al., and claim that patients with VMPC damage have an abnormally "utilitarian" pattern of moral judgement. It is crucial to the claims of Koenigs et al. that the scenarios of Greene et al. pose a conflict between utilitarian consequence and duty: however, many of them do not meet this condition. Because of this methodological problem, it is too early to claim that VMPC patients have a utilitarian bias.

  3. SURVIVAL ANALYSIS AND LENGTH-BIASED SAMPLING

    Directory of Open Access Journals (Sweden)

    Masoud Asgharian

    2010-12-01

    Full Text Available When survival data are colleted as part of a prevalent cohort study, the recruited cases have already experienced their initiating event. These prevalent cases are then followed for a fixed period of time at the end of which the subjects will either have failed or have been censored. When interests lies in estimating the survival distribution, from onset, of subjects with the disease, one must take into account that the survival times of the cases in a prevalent cohort study are left truncated. When it is possible to assume that there has not been any epidemic of the disease over the past period of time that covers the onset times of the subjects, one may assume that the underlying incidence process that generates the initiating event times is a stationary Poisson process. Under such assumption, the survival times of the recruited subjects are called “lengthbiased”. I discuss the challenges one is faced with in analyzing these type of data. To address the theoretical aspects of the work, I present asymptotic results for the NPMLE of the length-biased as well as the unbiased survival distribution. I also discuss estimating the unbiased survival function using only the follow-up time. This addresses the case that the onset times are either unknown or known with uncertainty. Some of our most recent work and open questions will be presented. These include some aspects of analysis of covariates, strong approximation, functional LIL and density estimation under length-biased sampling with right censoring. The results will be illustrated with survival data from patients with dementia, collected as part of the Canadian Study of Health and Aging (CSHA.

  4. Selection bias and the perils of benchmarking.

    Science.gov (United States)

    Denrell, Jerker

    2005-04-01

    To find the secrets of business success, what could be more natural than studying successful businesses? In fact, nothing could be more dangerous, warns this Stanford professor. Generalizing from the examples of successful companies is like generalizing about New England weather from data taken only in the summer. That's essentially what businesspeople do when they learn from good examples and what consultants, authors, and researchers do when they study only existing companies or--worse yet--only high-performing companies. They reach conclusions from unrepresentative data samples, falling into the classic statistical trap of selection bias. Drawing on a wealth of case studies, for instance, one researcher concluded that great leaders share two key traits: They persist, often despite initial failures, and they are able to persuade others to join them. But those traits are also the hallmarks of spectacularly unsuccessful entrepreneurs, who must persist in the face of failure to incur large losses and must be able to persuade others to pour their money down the drain. To discover what makes a business successful, then, managers should look at both successes and failures. Otherwise, they will overvalue risky business practices, seeing only those companies that won big and not the ones that lost dismally. They will not be able to tell if their current good fortune stems from smart business practices or if they are actually coasting on past accomplishments or good luck. Fortunately, economists have developed relatively simple tools that can correct for selection bias even when data about failed companies are hard to come by. Success may be inspirational, but managers are more likely to find the secrets of high performance if they give the stories of their competitors'failures as full a hearing as they do the stories of dazzling successes.

  5. Effect of salinity on the metabolism and osmoregulation of selected ontogenetic stages of an amazon population of Macrobrachium amazonicum shrimp (Decapoda, Palaemonidae

    Directory of Open Access Journals (Sweden)

    CCM. Mazzarelli

    acids gets diminished and oxygen consumption elevated, probably due to greater energy expenditure with the active transportation of salts through epithelial membranes. Osmotic challenges also seem to alter throughout development, given that in zoeae II oxygen consumption is elevated on brackish water of 18, but in zoeae V it happens in fresh water. After M. amazonicum metamorphosis, free amino acids begin to play an important role as intracellular osmolytes, because we verified an increase of up to 40% in post-larvae exposed to brackish water of 18. The main free amino acids involved in cell volume regulation of ontogenetic stages evaluated were the non essential ones: glutamic acid, glycine, alanine, arginine, and proline. Interestingly, larvae from estuarine population studied here survived until the zoeae V stage in fresh water, but in some populations far from the sea, zoeae die right after eclosion in fresh water or they do not reach zoeae III stage. In addition, given that in favorable conditions caridean shrimp larvae shorten their development, we may infer that the cultivation environment, in which larvae developed in the present work, was appropriate, because almost all zoeae VIII kept on brackish water underwent metamorphosis directly to post-larvae and did not go through zoeae IX stage.

  6. Effect of salinity on the metabolism and osmoregulation of selected ontogenetic stages of an Amazon population of Macrobrachium amazonicum shrimp (Decapoda, Palaemonidae).

    Science.gov (United States)

    Mazzarelli, C C M; Santos, M R; Amorim, R V; Augusto, A

    2015-05-01

    diminished and oxygen consumption elevated, probably due to greater energy expenditure with the active transportation of salts through epithelial membranes. Osmotic challenges also seem to alter throughout development, given that in zoeae II oxygen consumption is elevated on brackish water of 18, but in zoeae V it happens in fresh water. After M. amazonicum metamorphosis, free amino acids begin to play an important role as intracellular osmolytes, because we verified an increase of up to 40% in post-larvae exposed to brackish water of 18. The main free amino acids involved in cell volume regulation of ontogenetic stages evaluated were the non essential ones: glutamic acid, glycine, alanine, arginine, and proline. Interestingly, larvae from estuarine population studied here survived until the zoeae V stage in fresh water, but in some populations far from the sea, zoeae die right after eclosion in fresh water or they do not reach zoeae III stage. In addition, given that in favorable conditions caridean shrimp larvae shorten their development, we may infer that the cultivation environment, in which larvae developed in the present work, was appropriate, because almost all zoeae VIII kept on brackish water underwent metamorphosis directly to post-larvae and did not go through zoeae IX stage.

  7. Self-perpetuating development of encoding biases in person perception.

    Science.gov (United States)

    Hill, T; Lewicki, P; Czyzewska, M; Boss, A

    1989-09-01

    It was hypothesized that encoding (interpretive) biases may develop in a self-perpetuating manner through biased, self-supportive encoding (even in the absence of any objectively supportive evidence). This process was investigated in 3 experiments with different stimulus materials (matrices of digits, silhouettes of persons, descriptions of personal problems). In the learning phase of each study, Ss nonconsciously acquired some encoding bias. In the testing phase, Ss' encoding of new material was predictably biased, and, consistent with the self-perpetuation hypothesis, the strength of the bias gradually increased over the segments of the material, even though the material did not contain any evidence supportive of the bias. Given the ambiguity of many (particularly social) stimuli, the self-perpetuation process may play a ubiquitous role in the development of interpretive categories and other individually differentiated cognitive dispositions.

  8. Children’s Beliefs in Reciprocation of Biases and Flexibility

    Science.gov (United States)

    Rennels, Jennifer L.

    2015-01-01

    Children display positive and negative biases based on peers’ attractiveness, gender, and race, but it is unclear whether children who associate positive attributes with certain peers also believe those peers think positively of them. In each domain (attractiveness, gender, race), we measured 3- to 11-year-olds’ (N=102) biases and flexibility and their beliefs in reciprocity of bias and flexibility by asking who would think positively of them. Children could choose one of two unfamiliar peers (forced choice assessment) or had the additional options of choosing both or neither peer (non-forced choice assessment). We found children often displayed beliefs in reciprocation, with beliefs in positive bias reciprocation from attractive girls showing the largest effect sizes. These beliefs significantly correlated with and were predictive of children’s positive and negative biases and flexibility. The duality of children’s beliefs may contribute to strengthening their biases and segregating social groups. PMID:25918015

  9. Developing the Bias Blind Spot: Increasing Skepticism towards Others.

    Directory of Open Access Journals (Sweden)

    Fadwa B Elashi

    Full Text Available Two experiments with eighty-eight 7- to 10-year-olds examined the bias blind spot in children. Both younger and older children rated themselves as less likely than a specific other (Experiment 1 or an average child (Experiment 2 to commit various biases. These self-other differences were also more extreme for biased behaviors than for other behaviors. At times, older children demonstrated stronger self-other differences than younger children, which seemed primarily driven by older children's judgments about bias in others. These findings suggest that, although the bias blind spot exists as soon as children recognize other-committed biases, what changes over development is how skeptical children are towards others.

  10. Modifying Threat-related Interpretive Bias in Adolescents

    OpenAIRE

    Salemink, E.; Wiers, R.W.

    2011-01-01

    Socially anxious feelings sharply increase during adolescence and such feelings have been associated with interpretive biases. Studies in adults have shown that interpretive biases can be modified using Cognitive Bias Modification procedures (CBM-I) and subsequent effects on anxiety have been observed. The current study was designed to examine whether the CBM-I procedure has similar effects in adolescents. Unselected adolescents were randomly allocated to either a positive interpretation trai...

  11. Cognitive bias modification training in adolescents: persistence of training effects

    OpenAIRE

    Belli, Stefano R.; Lau, Jennifer Y.F.

    2014-01-01

    Negative biases in the interpretation of social information are associated with anxious symptoms in adolescents. Previous studies have attempted to modify interpretive biases to alleviate anxious mood responses but the longevity of such training effects has not been established. A cognitive bias modification of interpretations (CBM-I) paradigm was administered to sixty-nine 15–17 year-olds. Participants were either trained to interpret ambiguous social situations positively, or received contr...

  12. ExoPriors: Accounting for observational bias of transiting exoplanets

    Science.gov (United States)

    Kipping, David M.; Sandford, Emily

    2016-03-01

    ExoPriors calculates a log-likelihood penalty for an input set of transit parameters to account for observational bias (geometric and signal-to-noise ratio detection bias) of transiting exoplanets. Written in Python, the code calculates this log-likelihood penalty in one of seven user-specified cases specified with Boolean input parameters for geometric and/or SNR bias, grazing or non-grazing events, and occultation events.

  13. Observation bias correction with an ensemble Kalman filter

    OpenAIRE

    Fertig, Elana J.; Baek, Seung-Jong; Hunt, Brian R.; Ott, Edward; Szunyogh, Istvan; Aravéquia, José A.; Kalnay, Eugenia; Li, Hong; Liu, Junjie

    2009-01-01

    This paper considers the use of an ensemble Kalman filter to correct satellite radiance observations for state dependent biases. Our approach is to use state-space augmentation to estimate satellite biases as part of the ensemble data assimilation procedure. We illustrate our approach by applying it to a particular ensemble scheme—the local ensemble transform Kalman filter (LETKF)—to assimilate simulated biased atmospheric infrared sounder brightness temperature observations from 15 channels ...

  14. Weight bias: Prejudice and discrimination toward overweight and obese people

    OpenAIRE

    Diedrichs, P. C.; Puhl, R.

    2016-01-01

    Weight bias refers to prejudice and discrimination towards overweight and obese individuals, and is argued to be one of the last socially acceptable forms of discrimination. Multi-country studies document its widespread prevalence. Children, adults, health professionals, employers, and the media are sources of weight bias. Fifty years of research consistently documents the significant detrimental consequences of weight bias for targets’ psychological and physical health, employment opportunit...

  15. Phase Retrieval with Signal Bias. Section 7.3

    Science.gov (United States)

    Thurman, Samuel T.; Fienup, James R.

    2009-01-01

    The effect of a uniform measurement bias, due to background light, stray light, detector dark current, or detector offset, on phase retrieval wavefront sensing algorithms is analyzed. Simulation results indicate that the root-mean-square error of the retrieved phase can be more sensitive to an unaccounted-for signal bias than to random noise in practical scenarios. Three methods for reducing the impact of signal bias are presented

  16. 'He's got his father's bias': Parental influence on weight bias in young children.

    Science.gov (United States)

    Spiel, Emma C; Rodgers, Rachel F; Paxton, Susan J; Wertheim, Eleanor H; Damiano, Stephanie R; Gregg, Karen J; McLean, Siân A

    2016-06-01

    Our aim was to explore the role of parents in the transmission of stereotypical body size attitudes and awareness of weight loss strategies to preschool children. Participants were 279 3-year-old children and their parents, who provided data at baseline and 1 year later. Parents completed self-report body size attitude and dieting measures. Child weight bias and awareness of weight loss strategies were assessed through interview. Over time, negative associations with large bodies and awareness of weight loss strategies increased. Fathers' attitudes prospectively predicted boys' weight bias and awareness of weight loss strategies. Among girls, parental attitudes were less predictive. Findings confirm the importance of fathers in the development of boys' body attitudes and inform prevention programmes. © 2015 The British Psychological Society.

  17. What is pharmacological 'affinity'? Relevance to biased agonism and antagonism.

    Science.gov (United States)

    Kenakin, Terry

    2014-09-01

    The differences between affinity measurements made in binding studies and those relevant to receptor function are described. There are theoretical and practical reasons for not utilizing binding data and, in terms of the quantification of signaling bias, it is unnecessary to do so. Finally, the allosteric control of ligand affinity through receptor-signaling protein interaction is discussed within the context of biased antagonism. In this regard, it is shown that both the bias and relative efficacy of a ligand are essential data for fully predicting biased effects in vivo. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Seed sexing revealed female bias in two Rumex species

    Directory of Open Access Journals (Sweden)

    Dagmara Kwolek

    2011-07-01

    Full Text Available Sex-ratio bias in seeds of dioecious Rumex species with sex chromosomes is an interesting and still unsettled issue. To resolve gender among seeds of R. acetosa and R. thyrsiflorus (two species with an XX/XY1Y2 sex chromosome system, this work applied a PCR-based method involving DNA markers located on Y chromosomes. Both species showed female-biased primary sex ratios, with female bias greater in R. acetosa than in R. thyrsiflorus. The observed predominance of female seeds is consistent with the view that the female biased sex ratios in Rumex are conditioned not only postzygotically but also prezygotically.

  19. Modeling Temporal Bias of Uplift Events in Recommender Systems

    KAUST Repository

    Altaf, Basmah

    2013-05-08

    Today, commercial industry spends huge amount of resources in advertisement campaigns, new marketing strategies, and promotional deals to introduce their product to public and attract a large number of customers. These massive investments by a company are worthwhile because marketing tactics greatly influence the consumer behavior. Alternatively, these advertising campaigns have a discernible impact on recommendation systems which tend to promote popular items by ranking them at the top, resulting in biased and unfair decision making and loss of customers’ trust. The biasing impact of popularity of items on recommendations, however, is not fixed, and varies with time. Therefore, it is important to build a bias-aware recommendation system that can rank or predict items based on their true merit at given time frame. This thesis proposes a framework that can model the temporal bias of individual items defined by their characteristic contents, and provides a simple process for bias correction. Bias correction is done either by cleaning the bias from historical training data that is used for building predictive model, or by ignoring the estimated bias from the predictions of a standard predictor. Evaluated on two real world datasets, NetFlix and MovieLens, our framework is shown to be able to estimate and remove the bias as a result of adopted marketing techniques from the predicted popularity of items at a given time.

  20. Extreme and acquiescence bias in a bi-ethnic population.

    Science.gov (United States)

    Baron-Epel, Orna; Kaplan, Giora; Weinstein, Ruth; Green, Manfred S

    2010-10-01

    Extreme and acquiescence biases are the tendency to give a positive or extreme answer regardless of the 'true' answer. These biases may compromise comparisons of attitudes regarding health between population groups. The aim of the study was to measure the extent of extreme and acquiescence biases and identify factors associated with them in two ethnic groups: Jews and Arabs in Israel. A random telephone survey was conducted during 2006, interviewing 2322 Jews and 809 Arabs. Three attitude questions were presented twice with opposite wording to measure extreme and acquiescence biases in these two groups. Extreme bias ranged from 2 to 14% among Jews and from 6 to 29% among Arabs, depending on the question. Acquiescence bias ranged from 2 to 10% among Jews and 5-19% among Arabs. The less educated respondents gave more extreme biased responses for all items. The older respondents gave more extreme answers for two out of the three questions tested. After adjusting for age and education the odds ratio (OR) of giving more extreme biased answers was higher among Arabs compared with Jews for all three questions [OR = 2.49, confidence interval (CI) = 1.87, 3.31; OR = 2.33, CI = 1.75, 3.10; and OR = 2.94, CI = 1.83-4.71, respectively, for each question]. Levels of response biases are higher in the Arab minority population compared with the majority Jewish population and depended on the subject, age and education.