What are lightness illusions and why do we see them?

Lightness illusions are fundamental to human perception, and yet why we see them is still the focus of much research. Here we address the question by modelling not human physiology or perception directly as is typically the case but our natural visual world and the need for robust behaviour. Artificial neural networks were trained to predict the reflectance of surfaces in a synthetic ecology consisting of 3-D “dead-leaves” scenes under non-uniform illumination. The networks learned to solve this task accurately and robustly given only ambiguous sense data. In addition—and as a direct consequence of their experience—the networks also made systematic “errors” in their behaviour commensurate with human illusions, which includes brightness contrast and assimilation—although assimilation (specifically White's illusion) only emerged when the virtual ecology included 3-D, as opposed to 2-D scenes. Subtle variations in these illusions, also found in human perception, were observed, such as the asymmetry of brightness contrast. These data suggest that “illusions” arise in humans because (i) natural stimuli are ambiguous, and (ii) this ambiguity is resolved empirically by encoding the statistical relationship between images and scenes in past visual experience. Since resolving stimulus ambiguity is a challenge faced by all visual systems, a corollary of these findings is that human illusions must be experienced by all visual animals regardless of their particular neural machinery. The data also provide a more formal definition of illusion: the condition in which the true source of a stimulus differs from what is its most likely (and thus perceived) source. As such, illusions are not fundamentally different from non-illusory percepts, all being direct manifestations of the statistical relationship between images and scenes.     

Temporary forest pools: can we see the water for the trees?

Temporary waters, in general, are fascinating habitats in which to study the properties of species adapted to living in highly variable environments. Species display a remarkable array of strategies for dealing with the periodic loss of their primary medium that sets them apart from the inhabitants of permanent water bodies. Survival of individuals typically depends on exceptional physiological tolerance or effective migrational abilities, and communities have their own, distinctive hallmarks. This paper will broadly overview the biology of temporary ponds, but will emphasize those in temperate forests. In particular, links will be sought between aquatic community properties, the nature of the riparian vegetation, and forestry practices. Quite apart from their inherent biological interest, temporary waters are now in the limelight both from a conservation perspective, as these habitats come more into conflict with human activities, and a health-control perspective, as breeding habitats for vectors of arboviruses. Traditionally, many temporary waters, be they pools, streams or wetlands, have been considered to be ȁ8wastedȁ9 areas of land, potentially convertible to agriculture/silviculture once drained. In reality, they are natural features of the global landscape representing distinct and unique habitats for many species – some that are found nowhere else, others that reach their maximum abundance there. To be effective, conservation measures must preserve the full, hydroseral range of wetland types.     

CT angiography is here--are we expected to see a change of angiography referral pattern?

A 52-year-old asymptomatic man, with cardiac risk factors of hypertension, Type II diabetes, hypertriglyceridemia, low HDL, obesity, and positive family history for early coronary artery disease (CAD), was referred to nuclear stress test. He exercised for 14 minutes, achieved his target heart rate, without any symptoms or ECG changes. Nuclear images were entirely normal. However, the patient was still concerned and anxious so he underwent CT angiography that revealed coronary narrowings. Next, he underwent coronary angiography with similar findings. The lesions were treated with stents. We present a case report to illustrate how newer technology such as CT angiography alters the way in which we diagnose CAD and decide on whether to pursue further invasive therapy.     

New substrates for TonB-dependent transport: do we only see the 'tip of the iceberg'?

TonB-dependent transport is a mechanism for active uptake across the outer membrane of Gram-negative bacteria. The system promotes transport of rare nutrients and was thought to be restricted to iron complexes and vitamin B12. Recent experimental evidence of TonB-energized transport of nickel and different carbohydrates, in addition to bioinformatic-based predictions, challenges this notion and reveals that the number and variety of TonB-dependent substrates is underestimated. It is becoming clear that the chemical nature of the substrates, the energetic requirements for transport and the subsequent translocation across the cytoplasmic membrane can differ from those of the well-studied systems for iron complexes and vitamin B12. These findings question the understanding of TonB-dependent uptake and provide insights into the adaptation of bacteria to their environments.     

In the shadow of the Moon,what type of solar eclipse will we see?

Solar eclipses occur several times a year, but most people will be lucky if they see one total solar eclipse in their lifetime. There are two upcoming total solar eclipses that can be seen from different parts of the United States (August 21, 2017 and April 8, 2024), and they provide teachers with an amazing opportunity to engage students with a remarkable astronomical event. We summarize the science behind eclipses and describe an inexpensive activity for students from third grade up through middle school that will let them use models to see the differences between total, annular, and partial solar eclipses. The activity lets students explore why, during a solar eclipse, people in different areas will see different types of eclipses. The activity can be used as a way to get students excited about astronomy and the upcoming eclipses. We also give ideas for ways that teachers can engage their students during the eclipses.     

To see or not to see: explaining intolerance against the “Burqa” in European public space

ABSTRACT

Why has the face veil become the centre of political debates about Islam in urban contexts? What kinds of experiences and ideas have animated its framing as a practice in need of regulation? Focusing on Spain, we argue that space and emotion are the key categories for explaining the micro-politics of face veil conflicts and that constitute face veiling as an object of contention “on the ground”. We suggest the notion of regimes of public space and highlight three central components: (1) understandings of ideal public space; (2) regimes of urban visibility; (3) emotional regimes. Taken together, these dimensions filter forms of inclusion and exclusion that emerge from regulatory practices and feed into graduated forms of urban citizenship and frame people’s sensibilities. The article also illustrates how the spatial analysis complicates the secular-religious dichotomy.     

What do family physicians see in practice?

Health care problems dealt with in their practices were recorded by seven family physicians over a period of 1 year (two others recorded for 3 months), each diagnosis being coded according to the Canuck Disease Classification Index. Problems were classified into four types: physical, psychosocial, diseases of choice (or lifestyle) and diseases of social impact. More than 85% of the 23 108 problems recorded were physical in origin and had physical manifestations. More time was spent on routine checkups and treatment of respiratory disease than on any other activity. Venereal disease and alcoholism were infrequent problems. The family physician is in a favourable position to act as health educator and counsellor and must be throughly trained in the physical aspects of disease.     

Cutting the forest to see a single tree?

The development of single-molecule tools has significantly impacted the way we think about biochemical processes. Watching a single protein in action allows us to observe kinetic details and rare subpopulations that are hidden in ensemble-averaging techniques. I will discuss here the pros and cons of the single-molecule approach in studying ligand binding in macromolecular systems and how these techniques can be applied to characterize the behavior of large multicomponent biochemical systems.     

Can we see a cohort effect on survival of Steller sea lions (Eumetopias jubatus) at Kozlova Cape rookery (eastern Kamchatka,Russia)?

Steller sea lions ( Eumetopias jubatus ) have experienced a decline in Russia as well as the United States. The causes for the decline of the Russian population may or may not overlap the causes of the decline in Alaska. The demographics of the Russian population are not well understood and are an area of interest for scientists wishing to compare and contrast the Alaskan and Russian stocks. This study uses a unique observational system to assess survival by age at a small rookery on the Kamchatka Peninsula, Kozlova Cape. We proceeded under the hypothesis that changes in environmental conditions between years would produce noticeable differences in survival of pups born in those years. We found no evidence to support our hypothesis, but did find some differences from the Alaskan population in estimated survival for the juvenile stage class. This study also provides some of the history of Steller sea lions in Russia for context.     

Can you still see the cochlea for the molecules?

It is now established that the mammalian cochlea uses active amplification of incoming sound to achieve sensitivity. Cellular details are emerging slowly. Recent studies of sensory hair cells have highlighted the possible molecular bases for amplification and the components of sensitivity regulation within the cochlea: a synthesis is likely to depend on effective and physiologically informed modelling.