Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate

Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for determining mean planetary climate. Here we investigate this idea using a three-dimensional general circulation model with a sophisticated cloud scheme. We find that slowly rotating planets (like Venus) can maintain an Earth-like climate at nearly twice the stellar flux as rapidly rotating planets (like Earth). This suggests that many exoplanets previously believed to be too hot may actually be habitable, depending on their rotation rate. The explanation for this behavior is that slowly rotating planets have a weak Coriolis force and long daytime illumination, which promotes strong convergence and convection in the substellar region. This produces a large area of optically thick clouds, which greatly increases the planetary albedo. In contrast, on rapidly rotating planets a much narrower belt of clouds form in the deep tropics, leading to a relatively low albedo. A particularly striking example of the importance of rotation rate suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time.Comment: 7 pages, 4 figures, accepted at Astrophysical Journal Letter

Asymptotic freedom in a scalar field theory on the lattice

An alternative model to the trivial $\phi^4$-theory of the standard model of weak interactions is suggested, which embodies the Higgs-mechanism, but is free of the conceptual problems of standard $\phi ^4$-theory. We propose a N-component, O(N)-symmetric scalar field theory, which is originally defined on the lattice. The model can be motivated from SU(2) gauge theory. Thereby the scalar field arises as a gauge invariant degree of freedom. The scalar lattice model is analytically solved in the large N limit. The continuum limit is approached via an asymptotically free scaling. The renormalized theory evades triviality, and furthermore gives rise to a dynamically formed mass of the scalar particle.Comment: 10 pages, LaTeX, one figure and a motivation for the particular type of action adde

Environmental Group and Legal expertise: Shaping the Brexit Process

Environmental Groups and Legal Expertise explores the use and understanding of law and legal expertise by environmental groups. Rather than the usual focus on the court room, it scrutinises environmental NGO advocacy during the extraordinarily dramatic Brexit process, from the referendum on leaving the EU in June 2016 to the debate around the new Environment Bill in the first half of 2020. There is generally a weak understanding of both the complexity and the potential of legal expertise in the environmental NGO community. Legal expertise can be more than a tool for campaigners, and more than litigation: it provides distinctive ways of both seeing the world and changing the world. The available legal resource in the sector is not just a practical limit on what can be done, but spills into the very understanding of what should be done, and what resource is needed. Mutually reinforcing links between capacity, understanding, culture and investment affect legal expertise across the board. There are, however, pockets of sophisticated legal expertise in the community, and legal expertise was heavily and often effectively used in the anomalously law-heavy Brexit-environment debate. The ability to call on thinly spread legal expertise in a crisis was in part due to effective NGO collaboration around Brexit-environment

Exact Baryon, Strangeness and Charge Conservation in Hadronic Gas Models

Relativistic heavy ion collisions are studied assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The exact conservation of baryon number, strangeness and charge are explicitly taken into account. For heavy ions the effect arising from the neutron surplus becomes important and leads to a substantial increase in e.g. the $\pi^-/\pi^+$ ratio. A method is developed which is very well suited for the study of small systems.Comment: 5 pages, 5 Postscript figure

Training Custom Light Curve Models of SN Ia Sub-Populations Selected According to Host Galaxy Properties

Type Ia supernova (SN Ia) cosmology analyses include a luminosity step function in their distance standardization process to account for an observed yet unexplained difference in the post-standardization luminosities of SNe Ia originating from different host galaxy populations (e.g., high-mass ($M \gtrsim 10^{10} M_{\odot}$) versus low-mass galaxies). We present a novel method for including host-mass correlations in the SALT3 light curve model used for standardising SN Ia distances. We split the SALT3 training sample according to host-mass, training independent models for the low- and high-host-mass samples. Our models indicate that there are different average Si II spectral feature strengths between the two populations, and that the average SED of SNe from low-mass galaxies is bluer than the high-mass counterpart. We then use our trained models to perform a SN cosmology analysis on the 3-year spectroscopically confirmed Dark Energy Survey SN sample, treating SNe from low- and high-mass host galaxies as separate populations throughout. We find that our mass-split models reduce the Hubble residual scatter in the sample, albeit at a low statistical significance. We do find a reduction in the mass-correlated luminosity step but conclude that this arises from the model-dependent re-definition of the fiducial SN absolute magnitude rather than the models themselves. Our results stress the importance of adopting a standard definition of the SN parameters ($x_0, x_1, c$) in order to extract the most value out of the light curve modelling tools that are currently available and to correctly interpret results that are fit with different models.Comment: 15 pages, accepted by MNRA

Concerning the Relationship of the Didactic and the Plastic in the Visual Arts

The problem of the position and nature of didactic content may arise from within the effort of painting itself. We cannot truly know the whys and hows of creation, and misgivings may invade our attempts at visual communication. How are we involved with didacticism, and what are its forms and possibilities? We find differences between the child and the adult in the desires and conditioning to expression. The didactic is found herein. Within the multiple forms and ages of visual art didactic exists on numerous levels. The author hypothesizes that in its basic and immediate nature didacticism relates closely to the nature of pure communication itself. The beliefs of some recent artists, as they pertain to the problem, are presented and discussed, as are certain observations on &ldquo;primitive art.&rdquo; The conclusion is drawn that a purely visual language exists and is indeed, at the present, the foundation and structure of painting. Within this the didactic may also be implied in its fitting sense.</p

First upper limit analysis and results from LIGO science data: stochastic background

I describe analysis of correlations in the outputs of the three LIGO interferometers from LIGO's first science run, held over 17 days in August and September of 2002, and the resulting upper limit set on a stochastic background of gravitational waves. By searching for cross-correlations between the LIGO detectors in Livingston, LA and Hanford, WA, we are able to set a 90% confidence level upper limit of h_{100}^2 Omega_0 < 23 +/- 4.6.Comment: 7 pages; 1 eps figures; proceeding from 2003 Edoardo Amaldi Meeting on Gravitational Wave

High-CO2 Cloud Radiative Forcing Feedback Over Both Land and Ocean in a Global Climate Model

A positive feedback on high-latitude winter marine climate change involving convective clouds has recently been proposed using simple models. This feedback could help explain data from equable climates, e.g., the Eocene, and might be relevant for future climate. Here this convective cloud feedback is shown to be active in an atmospheric GCM in modern configuration (CAM) at CO2 = 2240 ppm and in a coupled GCM in Eocene configuration (CCSM) at CO2 = 560 ppm. Changes in boundary conditions that increase surface temperature have a similar effect as increases in CO2 concentration. It is also found that the high-latitude winter cloud radiative forcing over land increases with increases in surface temperature due to either increased CO2 or changes in boundary conditions, which could represent an important part of the explanation for warm continental interior winter surface temperatures during equable climates. This is due to increased low-level layered clouds caused by increased relative humidity

Towards an evidence-based approach to fostering collaborative conversation in mainstream primary classrooms: Response to commentators

The ability to engage with ease in collaborative conversation is critical for child well-being and development. While key underpinning skills are biologically enabled, children require appropriate scaffolding and practice opportunities to develop proficient social conversational ability. Teaching conversation skills is a statutory requirement of the English primary (and many other) curricula. However, currently most upper primary mainstream teachers are not trained to teach conversation skills and do not teach them in the classroom or provide time for children to practice. We argue for first steps towards an evidence-based approach for a universal/Tier 1 programme, while fully acknowledging an ongoing need for Tier 2 and Tier 3 support as well as for further research into the strategies which are most effective in Tier 2/3 contexts. Further research is also needed to explore cultural variation in social conversation and to develop reliable, valid and brief teacher measures of child social conversational ability