1,868 research outputs found
Proximate factors underpinning receiver responses to deceptive false alarm calls in wild tufted capuchin monkeys: is it counterdeception?
Previous research demonstrates that tufted capuchin monkeys use terrestrial predator alarm calls in a functionally deceptive manner to distract conspecifics when feeding on contestable resources, although the success of this tactic is limited because listeners frequently ignore these calls when given in such situations. While this decreased response rate is suggestive of a counterstrategy to deception by receivers, the proximate factors underpinning the behavior are unclear. The current study aims to test if the decreased response rate to alarm calls in competitive contexts is better explained by the perception of subtle acoustic differences between predator-elicited and deceptive false alarms, or by receivers varying their responses based on the context in which the signal is received. This was tested by first examining the acoustic structure of predator-elicited and deceptive false alarms for any potentially perceptible acoustic differences, and second by comparing the responses of capuchins to playbacks of each of predator-elicited and false alarms, played back in noncompetitive contexts. The results indicate that deceptive false alarms and predator-elicited alarms show, at best, minimal acoustic differences based on the structural features measured. Likewise, playbacks of deceptive false alarms elicited antipredator reactions at the same rate as did predator-elicited alarms, although there was a nonsignificant tendency for false alarms to be more likely to elicit escape reactions. The lack of robust acoustic differences together with the high response rate to false alarms in noncompetitive contexts suggests that the context in which the signal is received best explains receiver responses. It remains unclear, however, if listeners ascribe different meanings to the calls based on context, or if they generally ignore all signals in competitive contexts. Whether or not the decreased response rate of receivers directly stems from the deceptive use of the calls cannot be determined until these latter possibilities are rigorously tested
Expression of Protease-Activated Receptor 1 and 2 and Anti-Tubulogenic Activity of Protease-Activated Receptor 1 in Human Endothelial Colony-Forming Cells
Endothelial colony-forming cells (ECFCs) are obtained from the culture of human peripheral blood mononuclear cell (hPBMNC) fractions and are characterised by high proliferative and pro-vasculogenic potential, which makes them of great interest for cell therapy. Here, we describe the detection of protease-activated receptor (PAR) 1 and 2 amongst the surface proteins expressed in ECFCs. Both receptors are functionally coupled to extracellular signal-regulated kinase (ERK) 1 and 2, which become activated and phosphorylated in response to selective PAR1- or PAR2-activating peptides. Specific stimulation of PAR1, but not PAR2, significantly inhibits capillary-like tube formation by ECFCs in vitro, suggesting that tubulogenesis is negatively regulated by proteases able to stimulate PAR1 (e.g. thrombin). The activation of ERKs is not involved in the regulation of tubulogenesis in vitro, as suggested by use of the MEK inhibitor PD98059 and by the fact that PAR2 stimulation activates ERKs without affecting capillary tube formation. Both qPCR and immunoblotting showed a significant downregulation of vascular endothelial growth factor 2 (VEGFR2) in response to PAR1 stimulation. Moreover, the addition of VEGF (50–100 ng/ml) but not basic Fibroblast Growth Factor (FGF) (25–100 ng/ml) rescued tube formation by ECFCs treated with PAR1-activating peptide. Therefore, we propose that reduction of VEGF responsiveness resulting from down-regulation of VEGFR2 is underlying the anti-tubulogenic effect of PAR1 activation. Although the role of PAR2 remains elusive, this study sheds new light on the regulation of the vasculogenic activity of ECFCs and suggests a potential link between adult vasculogenesis and the coagulation cascade
Causality in AdS/CFT and Lovelock theory
We explore the constraints imposed on higher curvature corrections of the
Lovelock type due to causality restrictions in the boundary of asymptotically
AdS space-time. In the framework of AdS/CFT, this is related to positivity of
the energy constraints that arise in conformal collider physics. We present
explicit analytic results that fully address these issues for cubic Lovelock
gravity in arbitrary dimensions and give the formal analytic results that
comprehend general Lovelock theory. The computations can be performed in two
ways, both by considering a thermal setup in a black hole background and by
studying the scattering of gravitons with a shock wave in AdS. We show that
both computations coincide in Lovelock theory. The different helicities, as
expected, provide the boundaries defining the region of allowed couplings. We
generalize these results to arbitrary higher dimensions and discuss their
consequences on the shear viscosity to energy density ratio of CFT plasmas, the
possible existence of Boulware-Deser instabilities in Lovelock theory and the
extent to which the AdS/CFT correspondence might be valid for arbitrary
dimensions.Comment: 35 pages, 20 figures; v2: minor amendments and clarifications
include
Recognition memory, self-other source memory, and theory-of-mind in children with autism spectrum disorder.
This study investigated semantic and episodic memory in autism spectrum disorder (ASD), using a task which assessed recognition and self-other source memory. Children with ASD showed undiminished recognition memory but significantly diminished source memory, relative to age- and verbal ability-matched comparison children. Both children with and without ASD showed an “enactment effect”, demonstrating significantly better recognition and source memory for self-performed actions than other-person-performed actions. Within the comparison group, theory-of-mind (ToM) task performance was significantly correlated with source memory, specifically for other-person-performed actions (after statistically controlling for verbal ability). Within the ASD group, ToM task performance was not significantly correlated with source memory (after controlling for verbal ability). Possible explanations for these relations between source memory and ToM are considered
HPV testing in routine cervical screening: cross sectional data from the ARTISTIC trial
To evaluate the effectiveness of human papillomavirus (HPV) testing in primary cervical screening. This was a cross-sectional study from the recruitment phase of a prospective randomised trial. Women were screened for HPV in addition to routine cervical cytology testing. Greater Manchester, attendees at routine NHS Cervical Screening Programme. In all, 24 510 women aged 20–64 screened with liquid-based cytology (LBC) and HPV testing at entry. HPV testing in primary cervical screening. Type-specific HPV prevalence rates are presented in relation to age as well as cytological and histological findings at entry. In all, 24 510 women had adequate cytology and HPV results. Cytology results at entry were: 87% normal, 11% borderline or mild, 1.1% moderate and 0.6% severe dyskaryosis or worse. Prevalence of HPV decreased sharply with age, from 40% at age 20–24 to 12% at 35–39 and 7% or less above age 50. It increased with cytological grade, from 10% of normal cytology and 31% of borderline to 70% mild, 86% moderate, and 96% of severe dyskaryosis or worse. HPV 16 or HPV 18 accounted for 64% of infections in women with severe or worse cytology, and one or both were found in 61% of women with severe dyskaryosis but in only 2.2% of those with normal cytology. The majority of young women in Greater Manchester have been infected with a high-risk HPV by the age of 30. HPV testing is practicable as a primary routine screening test, but in women aged under 30 years, this would lead to a substantial increase in retesting and referral rates. HPV 16 and HPV 18 are more predictive of underlying disease, but other HPV types account for 30% of high-grade disease
Experimental delayed-choice entanglement swapping
Motivated by the question, which kind of physical interactions and processes
are needed for the production of quantum entanglement, Peres has put forward
the radical idea of delayed-choice entanglement swapping. There, entanglement
can be "produced a posteriori, after the entangled particles have been measured
and may no longer exist". In this work we report the first realization of
Peres' gedanken experiment. Using four photons, we can actively delay the
choice of measurement-implemented via a high-speed tunable bipartite state
analyzer and a quantum random number generator-on two of the photons into the
time-like future of the registration of the other two photons. This effectively
projects the two already registered photons onto one definite of two mutually
exclusive quantum states in which either the photons are entangled (quantum
correlations) or separable (classical correlations). This can also be viewed as
"quantum steering into the past"
An inhomogeneous toy-model of the quantum gravity with explicitly evolvable observables
An inhomogeneous (1+1)-dimensional model of the quantum gravity is
considered. It is found, that this model corresponds to a string propagating
against some curved background space. The quantization scheme including the
Wheeler-DeWitt equation and the "particle on a sphere" type of the gauge
condition is suggested. In the quantization scheme considered, the "problem of
time" is solved by building of the quasi-Heisenberg operators acting in a space
of solutions of the Wheeler-DeWitt equation and the normalization of the wave
function corresponds to the Klein-Gordon type. To analyze the physical
consequences of the scheme, a (1+1)-dimensional background space is considered
for which a classical solution is found and quantized. The obtained estimations
show the way to solution of the cosmological constant problem, which consists
in compensation of the zero-point oscillations of the matter fields by the
quantum oscillations of the scale factor. Along with such a compensation, a
slow global evolution of a background corresponding to an universe expansion
exists.Comment: 18 page
Lovelock theories, holography and the fate of the viscosity bound
We consider Lovelock theories of gravity in the context of AdS/CFT. We show
that, for these theories, causality violation on a black hole background can
occur well in the interior of the geometry, thus posing more stringent
constraints than were previously found in the literature. Also, we find that
instabilities of the geometry can appear for certain parameter values at any
point in the geometry, as well in the bulk as close to the horizon. These new
sources of causality violation and instability should be related to CFT
features that do not depend on the UV behavior. They solve a puzzle found
previously concerning unphysical negative values for the shear viscosity that
are not ruled out solely by causality restrictions. We find that, contrary to
previous expectations, causality violation is not always related to positivity
of energy. Furthermore, we compute the bound for the shear viscosity to entropy
density ratio of supersymmetric conformal field theories from d=4 till d=10 -
i.e., up to quartic Lovelock theory -, and find that it behaves smoothly as a
function of d. We propose an approximate formula that nicely fits these values
and has a nice asymptotic behavior when d goes to infinity for any Lovelock
gravity. We discuss in some detail the latter limit. We finally argue that it
is possible to obtain increasingly lower values for the shear viscosity to
entropy density ratio by the inclusion of more Lovelock terms.Comment: 42 pages, 17 figures, JHEP3.cls. v2: reference adde
Reduced H+ channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH
Coccolithophores are major producers of ocean biogenic calcite, but this process is predicted to be negatively affected by future ocean acidification scenarios. Since coccolithophores calcify intracellularly, the mechanisms through which changes in seawater carbonate chemistry affect calcification remain unclear. Here we show that voltage-gated H+ channels in the plasma membrane of Coccolithus braarudii serve to regulate pH and maintain calcification under normal conditions but have greatly reduced activity in cells acclimated to low pH. This disrupts intracellular pH homeostasis and impairs the ability of C. braarudii to remove H+ generated by the calcification process, leading to specific coccolith malformations. These coccolith malformations can be reproduced by pharmacological inhibition of H+ channels. Heavily calcified coccolithophore species such as C. braarudii, which make the major contribution to carbonate export to the deep ocean, have a large intracellular H+ load and are likely to be most vulnerable to future decreases in ocean pH
Higher Derivative Corrections to R-charged Black Holes: Boundary Counterterms and the Mass-Charge Relation
We carry out the holographic renormalization of Einstein-Maxwell theory with
curvature-squared corrections. In particular, we demonstrate how to construct
the generalized Gibbons-Hawking surface term needed to ensure a perturbatively
well-defined variational principle. This treatment ensures the absence of ghost
degrees of freedom at the linearized perturbative order in the
higher-derivative corrections. We use the holographically renormalized action
to study the thermodynamics of R-charged black holes with higher derivatives
and to investigate their mass to charge ratio in the extremal limit. In five
dimensions, there seems to be a connection between the sign of the higher
derivative couplings required to satisfy the weak gravity conjecture and that
violating the shear viscosity to entropy bound. This is in turn related to
possible constraints on the central charges of the dual CFT, in particular to
the sign of c-a.Comment: 30 pages. v2: references added, some equations simplifie
- …