Conformal group with two observer independent scales

The Poincar\'e sector of a recently deformed conformal algebra is proposed to describe, after the identification of the deformation parameter with the Planck length, the symmetries of a new relativistic theory with two observer-independent scales (or DSR theory). Also a new non-commutative space-time is proposed. It is found that momentum space exhibits the same features of the DSR proposals preserving Lorentz invariance in a deformed way. The space-time sector is a generalization of the well known non-commutative $\kappa$-Minkowski space-time which however does not preserve Lorentz invariance, not even in the deformed sense. It is shown that this behavior could be expected in some attempts to construct DSR theories starting from the Poincar\'e sector of a deformed symmetry larger than Poincar\'e symmetry, unless one takes a variable Planck length. It is also shown that the formalism can be useful in analyzing the role of quantum deformations in the ``AdS-CFT correspondence".Comment: 3 pages, brief summary of a talk given at the Tenth Marcel Grossmann Meeting, Rio de Janeiro, 2003, based on results previously obtained in hep-th/0306089 and hep-th/030503

Secular Milenarism and the Perception of Risk

According to the Carter-Leslie "doomsday argument", the probability of the world ending soon is larger than people think. The argument exploits Bayesian reasoning to compute the posterior probability of the world ending at some near point in the future, given the rank of our generation in the human race, and given assumptions about the prior probability of the world ending at that point. The doomsday argument appears flawed both in its logical structure and in its assumptions about millenaristic beliefs (or lack thereof). In fact, a correct application of Bayeasian reasoning to the doom problem demonstrates that the posterior probability of doom at any point in the future depends continously on the choice of priors. Thus, the posterior can take any value and the argument becomes essentially meaningless. Moreover, when people are asked to rate the probability of the world ending at some point in the future, they assign probabilities in accord with known principles of the psychology of reasoning: risk perception depends on familiarity and degree of perceived control. Thus, people can think that the probability of the world ending soon can be of almost any size, depending on how you frame the question

Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy

While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding starbursts. Recently, we have shown that long-slit spectroscopy provides a valuable alternative approach to probe the size in terms of AGN photoionisation. Moreover, several parameters of the NLR can be directly accessed. We here apply the same methods developed and described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation of the NLR and thus, its ``real'' size using diagnostic line-ratio diagrams.We derive physical properties of the NLR such as reddening, ionisation parameter, electron density, and velocity as a function of distance from the nucleus. For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius. Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample. We discuss our findings in detail for each object.Comment: 23 pages, 41 figures, accepted for publication in A&

Women in Mongol Iran: The Khatuns, 1206-1335

The book investigates the development of women’s status in the Mongol Empire from its original homeland in Mongolia up to the end of the Ilkhanate of Iran in 1335. Taking a thematic approach, the chapters show a coherent progression of this development and contextualise the evolution of the role of women in medieval Mongol society. The arrangement serves as a starting point from where to draw comparison with the status of Mongol women in the later period. Exploring patterns of continuity and transformation in the status of these women in different periods of the Mongol Empire as it expanded westwards into the Islamic world, the book offers a view on the transformation of a nomadic-shamanist society from its original homeland in Mongolia to its settlement in the mostly sedentary-Muslim Iran in the mid-13th century

The great excuse: how Renzi could exploit the UK’s EU deal

The conclusion of the UK’s renegotiation has obvious implications for British party politics, but what impact has the deal had on domestic politics in other EU countries? Bruno Marino and Nicola Martocchia Diodati write on reactions to the deal in Italy. They state that while the response has been mixed among Italian parties, Matteo Renzi is likely to view the deal as an opportunity to push for European concessions over the ongoing migration crisis

How Does One Become an Artist? A Copying Task Provides No Support for the "Upside-Down Drawing" Technique

According to a technique widely used in art schools, everyone can make more realistic drawings by copying upside-down originals. We tested if this is true by asking 40 artistically untrained participants to copy either upright or upside-down drawings of a face or a car. Our results indicate that participants were faster when copying the car in comparison to the face, but not when copying upside-down in comparison to upright images. In addition, they were more accurate in capturing the global proportions of the image in comparison to the local proportions of its parts. However, neither the face nor the car were copied more accurately when presented upside-down. Overall, we observed no significant difference in accuracy between the upright and upside-down conditions, with most measures showing a pattern consistent with greater accuracy in the upright orientation especially for the face. These results provide no evidence that copying upside-down images promotes greater resemblance to the original stimulus image. Implications for the cognitive psychology of drawing and for the pedagogy of the visual arts are discusse

A ilusão do quadrado flexível

We report a new illusion of elasticity in a rigid surface. A square frame is presented behind a concentric occluding cross. When the two surfaces are rotated rigidly, the square frame appears "rubbery", that is, it appears to contract or expand during the rotation. The rubber square illusion is related to a number of other illusory phenomena involving motion and surface stratification. It is generally believed that these phenomena are due to suppression of potentially veridical motion signals at t-junctions signalling occlusions. However, in all previously reported phenomena the effect of t-junctions was confounded with effects due to surface relative motion, spatial integration, or relative contrast. Given that none of these potential confounds applies to our demonstration, the rubber square illusion provides critical evidence that t-junctions are sufficient to cause suppression of the corresponding motion signals. Nós relatamos uma nova ilusão de elasticidade de uma superfície rígida. Uma moldura quadrada é apresentada atrás de uma cruz concêntrica ocludente. Quando as duas superfícies são rotacionadas rigidamente, a moldura quadrada aparenta flexibilidade, qual seja, ela parece contrair e expandir durante a rotação. A ilusão do quadrado flexível é relatada em inúmeras outros fenômenos ilusórios envolvendo estratificação de movimento e de superfícies. Acredita-se que estes fenômenos são devido à supressão de sinais de movimento potencialmente verídicos nas junções em T sinalizando oclusões. Entretanto, em todos os fenômenos previamente relatados, o efeito das junções em T foram confundidos com os efeitos relacionados ao movimento relativo, integração espacial, ou contraste relativo. Dado que nenhuma destas potenciais confusões se aplica à nossa demonstração, a ilusão do quadrado flexível fornece evidência crítica em favor de que as junções em T são suficientes para gerar a supressão dos sinais de movimento correspondentes

Nonverbal communication in selfies posted on Instagram: Another look at the effect of gender on vertical camera angle

Background Selfies are a novel social phenomenon that is gradually beginning to receive attention within the cognitive sciences. Several studies have documented biases that may be related to nonverbal communicative intentions. For instance, in selfies posted on the dating platform Tinder males but not females prefer camera views from below (Sedgewick, Flath & Elias, 2017). We re-examined this study to assess whether this bias is confined to dating selection contexts and to compare variability between individuals and between genders. Methods Three raters evaluated vertical camera position in 2000 selfies– 1000 by males and 1000 by females—posted in Instagram. Results We found that the choices of camera angle do seem to vary depending on the context under which the selfies were uploaded. On Tinder, females appear more likely to choose neutral, frontal presentations than they do on Instagram, whereas males on Tinder appear more likely to opt for camera angles from below than on Instagram. Conclusions This result confirms that the composition of selfies is constrained by factors affecting nonverbal communicative intentions