509 research outputs found
Persistence of contrasting traditions in cultural evolution: Unpredictable payoffs generate slower rates of cultural change
We report an experimental test of the hypothesis that contrasting traditions will persist for longer, maintaining cultural differences between otherwise similar groups, under conditions of uncertainty about payoffs from individual learning. We studied the persistence of two alternative, experimentally-introduced, task solutions in chains of human participants. In some chains, participants were led to believe that final payoffs would be difficult to predict for an innovative solution, and in others, participants were aware that their final payoff would be directly linked to their immediate solution. Although the difference between the conditions was illusory (only participants' impressions were manipulated, not actual payoffs) clear differences were found between the conditions. Consistent with predictions, in the chains that were less certain about final payoffs, the distinctive variants endured over several replacement "generations" of participants. In contrast, in the other chains, the influence of the experimentally-introduced solutions was rapidly diluted by participants' exploration of alternative approaches. The finding provides support for the notion that rates of cultural change are likely to be slower for behaviors for which the relationship between performance and payoff may be hard to predict
Analysing the one-to-one tutorial: A conversation analysis approach
Tutor: So, essay writing… Student: Yeah. How do you do that? This workshop sheds light on what happens behind the closed door of the academic skills tutorial. Using Conversation Analysis (see Drew and Heritage, 1992), we identify defining characteristics of tutorial dialogues; in particular we investigate how talk is used to establish goals, reflect power relations, confirm roles/identities, achieve neutrality and offer correction/repair. Arising from discussions within the Learning Development community around the lack of CPD opportunities and resources for new entrants to the profession, this project provides empirical research in this area and will be of value for the professional development of learning developers. Interactive workshop After a brief introduction to the project, participants will have the opportunity to analyse dialogue extracts from authentic academic skills one-to-one tutorials in terms of the organisation of the tutorial conversation, the establishing of relationships and identities and how learning occurs. There will also be opportunity to reflect on aspects of academic tutorial conversation and consider how the dialogue extracts may be exploited for further use in the CPD of LD practitioners. This interactive workshop will provide insights into features of productive (or otherwise) individual tutorials and as a result be a useful training resource for learning development professionals. This in turn will impact on the student experience by contributing to the development of a reflective community of practitioners and evidence-informed practice
Causes of Higher Climate Sensitivity in CMIP6 Models
Equilibrium climate sensitivity, the global surface temperature response to CO urn:x-wiley:grl:media:grl60047:grl60047-math-0001 doubling, has been persistently uncertain. Recent consensus places it likely within 1.5–4.5 K. Global climate models (GCMs), which attempt to represent all relevant physical processes, provide the most direct means of estimating climate sensitivity via CO urn:x-wiley:grl:media:grl60047:grl60047-math-0002 quadrupling experiments. Here we show that the closely related effective climate sensitivity has increased substantially in Coupled Model Intercomparison Project phase 6 (CMIP6), with values spanning 1.8–5.6 K across 27 GCMs and exceeding 4.5 K in 10 of them. This (statistically insignificant) increase is primarily due to stronger positive cloud feedbacks from decreasing extratropical low cloud coverage and albedo. Both of these are tied to the physical representation of clouds which in CMIP6 models lead to weaker responses of extratropical low cloud cover and water content to unforced variations in surface temperature. Establishing the plausibility of these higher sensitivity models is imperative given their implied societal ramifications
Reconstructing holographic quintessence
The holographic dark energy model is an attempt for probing the nature of
dark energy within the framework of quantum gravity. The dimensionless
parameter determines the main property of the holographic dark energy. With
the choice of , the holographic dark energy can be described
completely by a quintessence scalar field. In this paper, we show this
quintessential description of the holographic dark energy with and
reconstruct the potential of the quintessence as well as the dynamics of the
scalar field.Comment: 8 pages, 4 figures; version published in Phys. Lett.
Non-minimally coupled canonical, phantom and quintom models of holographic dark energy
We investigate canonical, phantom and quintom models, with the various fields
being non-minimally coupled to gravity, in the framework of holographic dark
energy. We classify them and we discuss their cosmological implications. In
particular, we examine the present value of the dark energy equation-of-state
parameter and the crossing through the phantom divide, and we extract the
conditions for a future cosmological singularity. The combined scenarios are in
agreement with observations and reveal interesting cosmological behaviors.Comment: 9 pages, 5 figures, version published in Phys. Lett.
Holographic tachyon model
We propose in this Letter a holographic model of tachyon dark energy. A
connection between the tachyon scalar-field and the holographic dark energy is
established, and accordingly, the potential of the holographic tachyon field is
constructed. We show that the holographic evolution of the universe with
can be described completely by the resulting tachyon model in a
certain way.Comment: 5 pages, 2 figures; version to appear in Phys. Lett.
Image polaritons in boron nitride for extreme polariton confinement with low losses
Polaritons in two-dimensional materials provide extreme light confinement
that is difficult to achieve with metal plasmonics. However, such tight
confinement inevitably increases optical losses through various damping
channels. Here we demonstrate that hyperbolic phonon polaritons in hexagonal
boron nitride can overcome this fundamental trade-off. Among two observed
polariton modes, featuring a symmetric and antisymmetric charge distribution,
the latter exhibits lower optical losses and tighter polariton confinement.
Far-field excitation and detection of this high-momenta mode becomes possible
with our resonator design that can boost the coupling efficiency via virtual
polariton modes with image charges that we dub image polaritons. Using these
image polaritons, we experimentally observe a record-high effective index of up
to 132 and quality factors as high as 501. Further, our phenomenological theory
suggests an important role of hyperbolic surface scattering in the damping
process of hyperbolic phonon polaritons
Awe and Wonder in Scientific Practice: Implications for the Relationship Between Science and Religion
This paper examines the role of awe and wonder in scientific practice.
Drawing on evidence from psychological research and the writings of scientists and science communicators, I argue that awe and wonder play a crucial role in scientific discovery. They focus our attention on the natural world, encourage open-mindedness, diminish the self (particularly feelings of self-importance), help to accord value to the objects that are being studied, and provide a mode of understanding in the absence of full knowledge. I will flesh out implications of the role of awe and wonder in scientific discovery for debates on the relationship between science and religion. Abraham Heschel argued that awe and wonder are religious emotions because they reduce our feelings of self-importance, and thereby help to cultivate the proper reverent attitude towards God. Yet metaphysical naturalists such as Richard Dawkins insist that awe and wonder need not lead to any theistic commitments for scientists. The awe some scientists experience can be regarded as a form of non-theistic spirituality, which is neither a reductive naturalism nor theism. I will attempt to resolve the tension between these views by identifying some common ground
Constraints on holographic dark energy from X-ray gas mass fraction of galaxy clusters
We use the Chandra measurements of the X-ray gas mass fraction of 26 rich
clusters released by Allen et al. to perform constraints on the holographic
dark energy model. The constraints are consistent with those from other
cosmological tests, especially with the results of a joint analysis of
supernovae, cosmic microwave background, and large scale structure data. From
this test, the holographic dark energy also tends to behave as a quintom-type
dark energy.Comment: 5 pages, 3 figures; to appear in Phys. Lett.
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