2,351 research outputs found
Till death (or an intruder) do us part: intrasexual-competition in a monogamous Primate
Polygynous animals are often highly dimorphic, and show large sex-differences in the degree of intra-sexual competition and aggression, which is associated with biased operational sex ratios (OSR). For socially monogamous, sexually monomorphic species, this relationship is less clear. Among mammals, pair-living has sometimes been assumed to imply equal OSR and low frequency, low intensity intra-sexual competition; even when high rates of intra-sexual competition and selection, in both sexes, have been theoretically predicted and described for various taxa. Owl monkeys are one of a few socially monogamous primates. Using long-term demographic and morphological data from 18 groups, we show that male and female owl monkeys experience intense intra-sexual competition and aggression from solitary floaters. Pair-mates are regularly replaced by intruding floaters (27 female and 23 male replacements in 149 group-years), with negative effects on the reproductive success of both partners. Individuals with only one partner during their life produced 25% more offspring per decade of tenure than those with two or more partners. The termination of the pair-bond is initiated by the floater, and sometimes has fatal consequences for the expelled adult. The existence of floaters and the sporadic, but intense aggression between them and residents suggest that it can be misleading to assume an equal OSR in socially monogamous species based solely on group composition. Instead, we suggest that sexual selection models must assume not equal, but flexible, context-specific, OSR in monogamous species.Wenner-Gren Foundation, L.S.B. Leakey Foundation, the National Geographic Society, National
Science Foundation (BCS- 0621020), the University of Pennsylvania Research Foundation and the Zoological Society of San Diego, German
Science Foundation (HU 1746-2/1
Revisiting protein aggregation as pathogenic in sporadic Parkinson and Alzheimer diseases.
The gold standard for a definitive diagnosis of Parkinson disease (PD) is the pathologic finding of aggregated α-synuclein into Lewy bodies and for Alzheimer disease (AD) aggregated amyloid into plaques and hyperphosphorylated tau into tangles. Implicit in this clinicopathologic-based nosology is the assumption that pathologic protein aggregation at autopsy reflects pathogenesis at disease onset. While these aggregates may in exceptional cases be on a causal pathway in humans (e.g., aggregated α-synuclein in SNCA gene multiplication or aggregated ÎČ-amyloid in APP mutations), their near universality at postmortem in sporadic PD and AD suggests they may alternatively represent common outcomes from upstream mechanisms or compensatory responses to cellular stress in order to delay cell death. These 3 conceptual frameworks of protein aggregation (pathogenic, epiphenomenon, protective) are difficult to resolve because of the inability to probe brain tissue in real time. Whereas animal models, in which neither PD nor AD occur in natural states, consistently support a pathogenic role of protein aggregation, indirect evidence from human studies does not. We hypothesize that (1) current biomarkers of protein aggregates may be relevant to common pathology but not to subgroup pathogenesis and (2) disease-modifying treatments targeting oligomers or fibrils might be futile or deleterious because these proteins are epiphenomena or protective in the human brain under molecular stress. Future precision medicine efforts for molecular targeting of neurodegenerative diseases may require analyses not anchored on current clinicopathologic criteria but instead on biological signals generated from large deeply phenotyped aging populations or from smaller but well-defined genetic-molecular cohorts
Evaluation of the impact of the GRACE risk score on the management and outcome of patients hospitalised with non-ST elevation acute coronary syndrome in the UK: protocol of the UKGRIS cluster-randomised registry-based trial
Introduction
For non-ST-segment elevation acute coronary syndrome (NSTEACS) there is a gap between the use of class 1 guideline recommended therapies and clinical practice. The GRACE risk score is recommended in international guidelines for the risk stratification of NSTEACS, but its impact on adherence to guideline-indicated treatments and reducing adverse clinical outcomes is unknown. The objective of the UKGRIS trial is to assess the effectiveness of the GRACE risk score tool and associated treatment recommendations on the use of guideline-indicated care and clinical outcomes.
Methods and Analysis
The UK GRACE Risk Score Intervention Study (UKGRIS), a parallel-group cluster randomised registry-based controlled trial, will allocate hospitals in a 1:1 ratio to manage NSTEACS by standard care or according to the GRACE risk score and associated international guidelines. UKGRIS will recruit a minimum of 3000 patients from at least 30 English National Health Service hospitals and collect healthcare data from national electronic health records. The co-primary endpoints are the use of guideline-indicated therapies, and the composite of cardiovascular death, non-fatal myocardial infarction, new onset heart failure hospitalisation or cardiovascular readmission at 12 months. Secondary endpoints include duration of inpatient hospital stay over 12 months, EQ-5D-5L responses and utilities, unscheduled revascularisation and the components of the composite endpoint over 12 months follow-up.
Ethics and Dissemination
The study has ethical approval (North East - Tyne & Wear South Research Ethics Committee ref: 4/NE/1180). Findings will be announced at relevant conferences and published in peer-reviewed journals in line with the funderâs open access policy.
Registration
ISRCTN29731761, registered 12th January 2017
Trophic resource partitioning drives fine-scale coexistence in cryptic bat species
This is the final version. Available on open access from Wiley via the DOI in this recordUnderstanding the processes that enable species coexistence has important implications for assessing
how ecological systems will respond to global change. Morphology and functional similarity increase
the potential for competition, and therefore, co-occurring morphologically similar but genetically
unique species are a good model system for testing coexistence mechanisms. We used DNA
metabarcoding and High Throughput Sequencing to characterise for the first time the trophic ecology
of two recently-described cryptic bat species with parapatric ranges, Myotis escalerai and Myotis
crypticus. We collected faecal samples from allopatric and sympatric regions and from syntopic and
allotopic locations within the sympatric region to describe the diets both taxonomically and
functionally and compare prey consumption with prey availability. The two bat species had highly
similar diets characterised by high arthropod diversity, particularly Lepidoptera, Diptera and Araneae,
and a high proportion of prey that is not volant at night, which points to extensive use of gleaning.
Diet overlap at the prey-item level was lower in syntopic populations, supporting trophic shift under
fine-scale co-occurrence. Furthermore, the diet of M. escalerai had a marginally lower proportion of
not nocturnally volant prey in syntopic populations, suggesting that the shift in diet may be driven by
a change in foraging mode. Our findings suggest that fine-scale coexistence mechanisms can have
implications for maintaining broad-scale diversity patterns. This study highlights the importance of
including both allopatric and sympatric populations and choosing meaningful spatial scales for
detecting ecological patterns. We conclude that a combination of high taxonomic resolution with a
functional approach helps identify patterns of niche shift.Natural Environment Research Council (NERC
The Rich Structure of Gauss-Bonnet Holographic Superconductors
We study fully backreacting, Gauss-Bonnet (GB) holographic superconductors in
5 bulk spacetime dimensions. We explore the system's dependence on the scalar
mass for both positive and negative GB coupling, . We find that when
the mass approaches the Breitenlohner-Freedman (BF) bound and
the effect of backreaction is to increase the
critical temperature, , of the system: the opposite of its effect in the
rest of parameter space. We also find that reducing below zero
increases and that the effect of backreaction is diminished. We study the
zero temperature limit, proving that this system does not permit regular
solutions for a non-trivial, tachyonic scalar field and constrain possible
solutions for fields with positive masses. We investigate singular, zero
temperature solutions in the Einstein limit but find them to be incompatible
with the concept of GB gravity being a perturbative expansion of Einstein
gravity. We study the conductivity of the system, finding that the inclusion of
backreaction hinders the development of poles in the conductivity that are
associated with quasi-normal modes approaching the real axis from elsewhere in
the complex plane.Comment: 26 pages, 11 figures, V3, Added discussion of non-tachyonic scalars,
alterations to figures and tex
On cytoadhesion of Plasmodium vivax: raison d'ĂȘtre?
It is generally accepted that Plasmodium vivax, the most widely distributed human malaria parasite, causes mild disease and that this species does not sequester in the deep capillaries of internal organs. Recent evidence, however, has demonstrated that there is severe disease, sometimes resulting in death, exclusively associated with P. vivax and that P. vivax-infected reticulocytes are able to cytoadhere in vitro to different endothelial cells and placental cryosections. Here, we review the scarce and preliminary data on cytoadherence in P. vivax, reinforcing the importance of this phenomenon in this species and highlighting the avenues that it opens for our understanding of the pathology of this neglected human malaria parasite.798
A scalar field instability of rotating and charged black holes in (4+1)-dimensional Anti-de Sitter space-time
We study the stability of static as well as of rotating and charged black
holes in (4+1)-dimensional Anti-de Sitter space-time which possess spherical
horizon topology. We observe a non-linear instability related to the
condensation of a charged, tachyonic scalar field and construct "hairy" black
hole solutions of the full system of coupled Einstein, Maxwell and scalar field
equations. We observe that the limiting solution for small horizon radius is
either a hairy soliton solution or a singular solution that is not a regular
extremal solution. Within the context of the gauge/gravity duality the
condensation of the scalar field describes a holographic
conductor/superconductor phase transition on the surface of a sphere.Comment: 16 pages including 8 figures, v2: discussion on soliton solutions
extended; v3: matches version accepted for publication in JHE
Pathomechanisms of ulnar ligament lesions of the wrist in a cadaveric distal radius fracture model
Background and purpose: Mechanisms of injury to ulnar sided ligaments, stabilizing the distal radioulnar joint and the ulna to the carpus, associated with dorsally displaced distal radius fractures are poorly described. We investigated the injury patterns in a human cadaver fracture model. Methods: Fresh frozen human cadaver arms were used. A dorsal open wedge osteotomy was made in the distal radius. In 8 specimens pressure was applied to the palm with the wrist in dorsiflexion and ulnar sided stabilizing structures subsequently severed. Dorsal angulation was measured on digitized radiographs. In 8 more specimens the triangular fibrocartilage complex was forced into rupture by axially loading the forearm with the wrist in dorsiflexion. The ulnar side was dissected and injuries were recorded. Results: Intact ulnar soft tissues limited the dorsal angulation of the distal radius fragment to a median of 32o (16-34o). A combination of bending and shearing of the distal radius fragment was needed to create TFCC injuries. Both palmar and dorsal injuries were observed simultaneously in 6/8 specimens. Interpretation: A TFCC injury can be expected when dorsal angulation of a distal radius fracture exceeds 32o. The extensor carpi ulnaris subsheath may be a functionally integral part of the TFCC. Both dorsal and palmar structures can tear simultaneously. These findings may have implications for reconstruction of ulnar sided soft tissue injuries
Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin
Background: In inland water systems, it is important to characterize the trophic links in order to identify the âtrophic speciesâ and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours.
Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs.
Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro- and microfauna.Fil: Williner, VerĂłnica. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: de Azevedo Carvalho, Debora. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; Argentina. Universidad Nacional del Litoral. Facultad de BioquĂmica y Ciencias BiolĂłgicas; Argentin
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