125,007 research outputs found
Impacts of sperm competition on mating behaviour and life history traits in a simultaneous hermaphrodite
No full textEvolutionary theory suggests that post-copulatory sexual selection plays an important role in the evolution of reproductive traits of sexually reproducing animals. But despite its alleged universality empirical evidence is scarce for sexual selection operating in simultaneous hermaphrodites. I therefore investigated the potential for post-copulatory sexual selection in such an organism. Sexual selection can also act on phenotypic plasticity of traits. Flexible adjustments of an individual’s own sex allocation have been proposed to be a major advantage of hermaphrodites compared to separate-sexed organisms. The simultaneous hermaphrodite M. lignano flexibly adjusts its sex allocation to group size. I aimed to narrow down the cues on which this flatworm relies to make this adjustment, and I measured the costs of such phenotypically plastic responses to group size. I tested for mate limitation in a natural population of this outcrossing hermaphrodite as one possibile condition where simultaneous hermaphroditism is advantageous. In a double mating experiment I revealed genetic variation in paternity success and in five traits. One of them, mating rate, significantly predicted paternity success. This trait has recently been shown to be phenotypically plastic. I here demonstrate that it also exhibits genetic variation. Hence, it might be subjected to sexual selection. The findings of multiple paternity and genetic variation in paternity success clearly suggest that there is an opportunity for sexual selection in this simultaneous hermaphrodite. I discuss possible mechanisms of sexual selection (sperm competition, female bias in favour of one sperm donor) and random paternity skews that may underlie the paternity patterns observed in this species. Further results suggest that the well-documented phenotypically plastic response in sex allocation was based on indirect cues for sperm competition such as tactile cues of group size rather than direct cues such as assessment of the partner’s mating status. I also demonstrate that this response incurred significant production costs of phenotypic plasticity. However, since the magnitude of these costs was relatively low, I argue that flexible adjustments of sex allocation may still convey a net benefit to simultaneous hermaphrodites. Mate availability did not appear to seriously limit female fitness in a natural habitat of M. lignano. This is consistent with classical sexual selection theory, originally developed for separate-sexed species. Specifically, one aspect of Bateman’s principle states that female fecundity is not limited by the availability of mating partners but by resources available for egg production, which seems to apply to this simultaneous hermaphrodite. I conclude that sexual selection occurs in this simultaneous hermaphrodite. I rule out two presumptive cues for the phenotypically plastic response to group size and demonstrate production costs of this plasticity. Finally, I judge the significance of phenotypic plasticity and mate availability for the evolution of simultaneous hermaphroditism
Differences in Social Preferences - Are They Profitable for the Firm?
No full textThis paper analyzes the impact of heterogeneous (social) preferences on the weighting and combination of performance measures as well as on a firm’s profitability. We consider rivalry, egoism and altruism as extreme forms within the continuum of possible preferences and show that the principal can typically exploit both the altruistic and rivalistic behavior of his agents. Firm profits reach their maximum value if the agents are differentiated as much as possible in their individual characteristics. We provide further insight; namely, that in order to realize these gains in profitability, it is necessary to reallocate participation in performance measures such that competitive agents are privileged as compared to altruistic agents. In this context, stochastic interdependencies are of importance since they yield overlapping functions of the share parameters, causing additional adaptations in the optimal design of the wage compensation system.Social Preferences; Rivalry; Altruism; Egoism; Team Composition; Performance Measurement
Differences in Social Preferences - Are They Profitable for the Firm?
No full textThis paper analyzes the impact of heterogeneous (social) preferences on the weighting and combination of performance measures as well as on a firm’s profitability. We consider rivalry, egoism and altruism as extreme forms within the continuum of possible preferences and show that the principal can typically exploit both the altruistic and rivalistic behavior of his agents. Firm profits reach their maximum value if the agents are differentiated as much as possible in their individual characteristics. We provide further insight; namely, that in order to realize these gains in profitability, it is necessary to reallocate participation in performance measures such that competitive agents are privileged as compared to altruistic agents. In this context, stochastic interdependencies are of importance since they yield overlapping functions of the share parameters, causing additional adaptations in the optimal design of the wage compensation system
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Die "gute Mutter" revisited : genderkritische Anmerkungen zu Frühen Hilfen
No full textSandner E, Thiessen B. Die "gute Mutter" revisited : genderkritische Anmerkungen zu Frühen Hilfen. IzKK-Nachrichten / Informationszentrum Kindesmisshandlung Kindesvernachlässigung. 2010;2010(1):28-31
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Copolymerization and activation of peroxide decomposition with acrylic derivatives of tertiary aromatic amines
No full textThe reactivity parameters of the copolymerization of N,N-bis(2-methacryloyloxyethyl)-p-toluidine (BMAT) (M1) with methyl methacrylate (MMA) (M2) in 1,4-dioxane, i.e. r1 = 1.07 ± 0.20, and r2 = 0.11 ± 0.19, and with bisphenol-A bis(2-hydroxypropyl methacrylate) (Bis-GMA) (M2) in benzene, i.e. r1 = 0.58 ± 0.04, and r2 = 0.03 ± 0.03, were determined at 60°C at low concentration and low conversion (∼5%) of the monomers. Strongly delayed gelation occurred during the copolymerization of BMAT and MMA at monomer conversions of 20–30%, relatively independently of the composition of the monomer mixture. The efficiency of BMAT and N-acryloyl-N′-phenylpiperazine as activators in the redox initiated copolymerization of Bis-GMA in dental composites at ambient temperatures was found to be comparatively low. In the case where BMAT was used in equimolar proportions to benzoyl peroxide the former component was not detectable in the extract of the cured composit
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Familienleitbilder bei Professionellen : bei "Risikofamilien" besser weniger Diversität?
No full textThiessen B, Sandner E. Familienleitbilder bei Professionellen : bei "Risikofamilien" besser weniger Diversität? In: Effinger H, Borrmann S, Gahleitne SB, Köttig M, Kraus B, Stövesand S, eds. Diversität und Soziale Ungleichheit: analytische Zugänge und professionelles Handeln in der Sozialen Arbeit. Buchreihe Theorie, Forschung und Praxis der sozialen Arbeit. Vol 6. 2012: 142-152
Dr. Edwin Wright Collection: Author Unknown
No full textNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
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