193 research outputs found

    Water Stress Strengthens Mutualism Among Ants, Trees, and Scale Insects

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    Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant–plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners\u27 investments in a widespread ant–plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism

    Effective Mass Dirac-Morse Problem with any kappa-value

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    The Dirac-Morse problem are investigated within the framework of an approximation to the term proportional to 1/r21/r^2 in the view of the position-dependent mass formalism. The energy eigenvalues and corresponding wave functions are obtained by using the parametric generalization of the Nikiforov-Uvarov method for any κ\kappa-value. It is also studied the approximate energy eigenvalues, and corresponding wave functions in the case of the constant-mass for pseudospin, and spin cases, respectively.Comment: 12 page

    Not by transmission alone : the role of invention in cultural evolution

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    We are grateful to the Templeton World Charity Foundation, Inc. for funding this work and to the Diverse Intelligences research community for valuable conversations around these themes. S. Nöbel acknowledges IAST funding from the French National Research Agency (ANR) under the Investissements d’Avenir program, grant ANR-17-EUR-0010 and support by the Laboratoires d’Excellence TULIP (ANR-10-LABX-41). EA and MS acknowledge support from the US Army Research Office (W911NF‐17‐1‐0017 to EA).Innovation—the combination of invention and social learning—can empower species to invade new niches via cultural adaptation. Social learning has typically been regarded as the fundamental driver for the emergence of traditions and thus culture. Consequently, invention has been relatively understudied outside the human lineage—despite being the source of new traditions. This neglect leaves basic questions unanswered: what factors promote the creation of new ideas and practices? What affects their spread or loss? We critically review the existing literature, focusing on four levels of investigation: traits (what sorts of behaviours are easiest to invent?), individuals (what factors make some individuals more likely to be inventors?), ecological contexts (what aspects of the environment make invention or transmission more likely?), and populations (what features of relationships and societies promote the rise and spread of new inventions?). We aim to inspire new research by highlighting theoretical and empirical gaps in the study of innovation, focusing primarily on inventions in non-humans. Understanding the role of invention and innovation in the history of life requires a well-developed theoretical framework (which embraces cognitive processes) and a taxonomically broad, cross-species dataset that explicitly investigates inventions and their transmission. We outline such an agenda here. This article is part of the theme issue ‘Foundations of cultural evolution’.Publisher PDFPeer reviewe

    The effect of bovine serum albumin and fetal calf serum on sperm quality, DNA fragmentation and lipid peroxidation of the liquid stored rabbit semen

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    The aim of the present study was to determine the effects of the bovine serum albumin (BSA) and fetal calf serum (FCS) on sperm quality, DNA fragmentation and lipid peroxidation of liquid stored rabbit semen stored up to 72 h at 5 C. Ejaculates were collected from five New Zealand male rabbits by artificial vagina and pooled at 37 C following evaluation. Each pooled ejaculate was split into three equal experimental groups and diluted to a final concentration of approximately 40 106 sperm/ml (single step dilution), in an Eppendorf tube, with the Tris based extender containing BSA (5 mg/ml), FCS (10%) or no additive (control) at 37 C, cooled to 5 C and stored for up to 72 h. The extender supplemented with BSA and FCS did not improve the percentages of motility and acrosomal abnormality during 48 h compared to the control. The additives BSA and FCS had a significant effect in the maintaining of plasma membrane integrity between 48 and 72 h storage period, compared to the control (P < 0.01). The supplementation of BSA and FCS had a protective effect on motility (P < 0.05), plasma membrane integrity (P < 0.01) and acrosomal integrity (P < 0.01) at 72 h compared to the control. The supplementations with BSA and FCS led to a reduction in DNA damage of rabbit sperm at 48 and 72 h during storage period, compared to the control (P < 0.001). Although supplementation of BSA and FCS caused significant (P < 0.01) decreases in malondialdehyde (MDA) level at 48 h and 72 h, they significantly (P < 0.01) increased the glutathione peroxidase (GPx) antioxidant activity up to 72 h when compared to the control group. In conclusion, BSA and FCS supplementation to liquid stored rabbit semen provide a protection for spermatozoa against cool storage-induced DNA damage and plasma membrane integrity by their antioxidative properties

    The Perfect Family: Decision Making in Biparental Care

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    Background Previous theoretical work on parental decisions in biparental care has emphasized the role of the conflict between evolutionary interests of parents in these decisions. A prominent prediction from this work is that parents should compensate for decreases in each other\u27s effort, but only partially so. However, experimental tests that manipulate parents and measure their responses fail to confirm this prediction. At the same time, the process of parental decision making has remained unexplored theoretically. We develop a model to address the discrepancy between experiments and the theoretical prediction, and explore how assuming different decision making processes changes the prediction from the theory. Model Description We assume that parents make decisions in behavioral time. They have a fixed time budget, and allocate it between two parental tasks: provisioning the offspring and defending the nest. The proximate determinant of the allocation decisions are parents\u27 behavioral objectives. We assume both parents aim to maximize the offspring production from the nest. Experimental manipulations change the shape of the nest production function. We consider two different scenarios for how parents make decisions: one where parents communicate with each other and act together (the perfect family), and one where they do not communicate, and act independently (the almost perfect family). Conclusions/Significance The perfect family model is able to generate all the types of responses seen in experimental studies. The kind of response predicted depends on the nest production function, i.e. how parents\u27 allocations affect offspring production, and the type of experimental manipulation. In particular, we find that complementarity of parents\u27 allocations promotes matching responses. In contrast, the relative responses do not depend on the type of manipulation in the almost perfect family model. These results highlight the importance of the interaction between nest production function and how parents make decisions, factors that have largely been overlooked in previous models

    Tuberculosis of the breast with erythema nodosum: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>There has been an increasing number of tuberculosis cases worldwide, but tuberculosis of the breast remains rare. In rare cases this is seen with a cutaneous manifestation of erythema nodosum.</p> <p>Case presentation</p> <p>We report the case of a 33-year-old Chinese woman with tuberculosis of the left breast accompanied by erythema nodosum on the anterior aspect of both lower legs. Due to her poor clinical response to conventional therapy, and the histopathological findings of fine needle aspiration cytology, there were strong indications of tuberculosis. Her clinical diagnosis was confirmed by molecular detection of <it>Mycobacterium tuberculosis </it>complex by polymerase chain reaction. The diagnosis was further confirmed by a second polymerase chain reaction test of erythema nodosum which tested positive for <it>Mycobacterium tuberculosis</it> complex. She received anti-tuberculous therapy for 18 months, and finally underwent residual lumpectomy. During her follow-up examination after 12 months, no evidence of either residual or recurrent disease was present.</p> <p>Conclusion</p> <p>Histopathological features and a high index of clinical suspicion are necessary to confirm a diagnosis of tuberculosis of the breast. Anti-tuberculous therapy with or without simple surgical intervention is the core treatment.</p

    Bilkent university at TRECVID 2006

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    We describe our third participation, that includes one high-level feature extraction run, and two manual and one interactive search runs, to the TRECVID video retrieval evaluation. All of these runs have used a system trained on the common development collection. Only visual and textual information were used where visual information consisted of color, texture and edge-based low-level features and textual information consisted of the speech transcript provided in the collection

    Giant primary adrenal hydatid cyst presenting with arterial hypertension: a case report and review of the literature

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    <p>Abstract</p> <p>Introduction</p> <p>A primary hydatid cyst of the adrenal gland is still an exceptional localization. The adrenal gland is an uncommon site even in Morocco, where echinococcal disease is endemic.</p> <p>Case presentation</p> <p>We report the case of a 64-year-old Moroccan man who presented with the unusual symptom of arterial hypertension associated with left flank pain. Computed tomography showed a cystic mass of his left adrenal gland with daughter cysts filing the lesion (Type III). Despite his negative serology tests, the diagnosis of a hydatid cyst was confirmed on surgical examination. Our patient underwent surgical excision of his left adrenal gland with normalization of blood pressure. No recurrence has occurred after 36 months of follow-up.</p> <p>Conclusion</p> <p>There are two remarkable characteristics of this case report; the first is the unusual location of the cyst, the second is the association of an adrenal hydatid cyst with arterial hypertension, which has rarely been reported in the literature.</p

    Context specificity of post-error and post-conflict cognitive control adjustments

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    There has been accumulating evidence that cognitive control can be adaptively regulated by monitoring for processing conflict as an index of online control demands. However, it is not yet known whether top-down control mechanisms respond to processing conflict in a manner specific to the operative task context or confer a more generalized benefit. While previous studies have examined the taskset-specificity of conflict adaptation effects, yielding inconsistent results, controlrelated performance adjustments following errors have been largely overlooked. This gap in the literature underscores recent debate as to whether post-error performance represents a strategic, control-mediated mechanism or a nonstrategic consequence of attentional orienting. In the present study, evidence of generalized control following both high conflict correct trials and errors was explored in a task-switching paradigm. Conflict adaptation effects were not found to generalize across tasksets, despite a shared response set. In contrast, post-error slowing effects were found to extend to the inactive taskset and were predictive of enhanced post-error accuracy. In addition, post-error performance adjustments were found to persist for several trials and across multiple task switches, a finding inconsistent with attentional orienting accounts of post-error slowing. These findings indicate that error-related control adjustments confer a generalized performance benefit and suggest dissociable mechanisms of post-conflict and post-error control. © 2014 Forster, Cho

    Declining extra-pair paternity with laying order associated with initial incubation behavior, but independent of final clutch size in the blue tit

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    Although functional explanations for female engagement in extra-pair copulation have been studied extensively in birds, little is known about how extra-pair paternity is linked to other fundamental aspects of avian reproduction. However, recent studies indicate that the occurrence of extra-pair offspring may generally decline with laying order, possibly because stimulation by eggs induces incubation, which may suppress female motivation to acquire extra-pair paternity. Here we tested whether experimental inhibition of incubation during the laying phase, induced by the temporary removal of eggs, resulted in increased extra-pair paternity, in concert with a later cessation of laying, in blue tits (Cyanistes caeruleus). As expected, experimental females showed a more gradual increase in nocturnal incubation duration over the laying phase and produced larger clutches than controls. Moreover, incubation duration on the night after the first egg was laid predicted how extra-pair paternity declined with laying order, with less incubation being associated with more extra-pair offspring among the earliest eggs in the clutch. However, incubation duration on this first night was unrelated to our experimental treatment and independent of final clutch size. Consequently, the observed decline in extra-pair paternity with laying order was unaffected by our manipulation and larger clutches included proportionally fewer extra-pair offspring. We suggest that female physiological state prior to laying, associated with incubation at the onset of laying, determines motivation to acquire extra-pair paternity independent of final clutch size. This decline in proportion of extra-pair offspring with clutch size may be a general pattern within bird species
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