1,721,524 research outputs found
Fine-tuned modulation of competitive behaviour according to kinship in barn swallow nestlings
No full textKin selection theory predicts that, in species where progeny members compete for limiting parental care, individual offspring should be more prone to monopolize parental resources as their genetic relatedness to brood competitors decreases. Mixed parentage among broodmates may arise as a consequence, for example, of extra-pair fertilization or brood parasitism events. In this experimental study of barn swallows (Hirundo rustica), we reciprocally partially cross-fostered hatchlings between broods and compared the behaviour of pairs of related and unrelated broodmates in a competitive context, both under normal food provisioning regime and after mild food deprivation. We found that scramble competition for food mediated by visual and vocal solicitation displays (begging) is inversely related to relatedness among competitors, independent of their level of satiation. Nestlings may modulate their competitive behaviour according to vocal cues that vary with their origin and allow kin recognition. We also uncover direct fitness costs to both parents and offspring arising from mixed parentage in a brood, in terms of increased parental workload and reduced survival of the nestlings. Such previously neglected costs may select for reduced frequency of extra-pair fertilizations and brood parasitism in species with extensive parental car
Feeding and anhydrobiosis in bdelloid rotifers: a preparatory study for an experiment aboard the International Space Station
No full textHere we report the effect of food concentration on the recovery from anhydrobiosis of a bdelloid rotifer Macrotrachela quadricornifera. Cohorts were either starved or fed high or low concentrations of food before being dried and their subsequent recovery rates determined. The rotifers starved for 3 days before anhydrobiosis recovered in significantly higher proportion, and those fed lower food concentration recovered better than those fed higher food concentration. In addition, starvation did not decrease the recovery of other bdelloid species (Philodina roseola and Adineta sp.1) which were either fed or starved before anhydrobiosis. These results suggest that a successful recovery from anhydrobiosis is not dependent on prior resource level supplied to the bdelloids. However, the lack of resources might not be the only factor in a successful recovery from anhydrobiosis. SEM observation of fed M. quadricornifera entering anhydrobiosis showed some food remains in the digestive tract. Thus, we propose that the negative effect of rich food may be due to a purely mechanical effect, maybe interfering with a proper folding of the rotifer body at the onset of anhydrobiosis. This contribution results from studies carried out in preparation for biological experiments scheduled on the International Space Station (ISS)
Stress and fitness in parthenogens: is dormancy a key feature for bdelloid rotifers?
Full text linkBackground: Bdelloid rotifers are the most common and abundant group of animals that reproduce by ameiotic parthenogenesis, only. They are common in temporally ephemeral habitats, and it is unclear if they dwell in unstable habitats because are excluded from better conditions by stronger competitors, or because they need unstable conditions for their success. We tested the hypothesis that bdelloids 'require' stressful conditions for their persistence by comparing fitness-related traits of stressed ( desiccated, D) and unstressed ( hydrated, H) lines of two species, Adineta ricciae and Macrotrachela quadricornifera.
Results: For both bdelloid species, fecundity was significantly lower in H than in parallel D line. Fitness components decreased with time progressively in the H line but not in the D line. Recovery rates of D lines were recorded after every desiccation and did not reveal any trend in time, suggesting that no selection was operating.
Conclusion: Stress in the form of reiterated desiccations seemed to help both bdelloid species to keep fitness stable; in contrast under stable conditions, like permanent hydration, these bdelloid species had poorer performances. Bdelloids, although aquatic animals, are not only efficient in tolerating desiccation, but seem somehow dependent on anhydrobiosis, a circumstance that might represent a key event in their life cycle. If this is true, life in unpredictable habitats should not be seen as the result of competitive exclusion from 'easier' habitats, but a requirement for long-term survival of these parthenogenetic animals
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Proteomic analysis and classification of metastatic melanoma by MALDI imaging mass spectrometry
No full textCHEMISTRY
PROTEOMIC ANALYSIS AND CLASSIFICATION OF METASTATIC MELANOMA BY MALDI IMAGING MASS SPECTROMETRY
WILLIAM MICHAEL HARDESTY
Dissertation under the direction of Professor Richard M. Caprioli
Classification of malignant melanoma from protein signatures is presented. Protein signals were acquired directly from thin sections of human melanoma, control lymph node, and skin biopsies using matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry. First, protein spectra collected from 62 fresh-frozen stage III melanomas are distinguished from cancer-free control lymph nodes and used to categorize patients into poor and favorable prognostic groups. Secondly, MALDI imaging is applied to two formalin-fixed tissue microarrays which showed trends in collagen and histone levels in progression from primary to metastatic disease. Proteins are identified by purification followed by enzymatic digestion as well as by direct fragmentation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Mass Spectrometry and High Resolution Mass Spectrometry: An Overview
No full textIn this chapter, a brief overview of fundamentals in mass spectrometry and some applications are presented. The main concepts in ionization techniques, classical techniques and ambient mass spectrometry are followed by an overview on analyzers. Particular attention has been paid to high resolution mass spectrometry and accurate mass measurements, highly debating topics in modern mass spectrometry, with some examples and applications. Finally tandem mass spectrometry, collision-induced dissociations (CID), interactions of ions with electrons (ECD, ETD), photons (IRMPD) and with surfaces (SID) are also briefly presented
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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