Characterizing the role of disparity information in alleviating visual crowding

The ability to identify a target is reduced by the presence of nearby objects, a phenomenon known as visual crowding. The extent to which crowding impairs our perception is generally governed by the degree of similarity between a target stimulus and its surrounding flankers. Here we investigated the influence of disparity differences between target and flankers on crowding. Orientation discrimination thresholds for a parafoveal target were first measured when the target and flankers were presented at the same depth to establish a flanker separation that induced a significant elevation in threshold for each individual. Flankers were subsequently fixed at this spatial separation while the disparity of the flankers relative to the target was altered. For all participants, thresholds showed a systematic decrease as flanker-target disparity increased. The resulting tuning function was asymmetric: Crowding was lower when the target was perceived to be in front of the flankers rather than behind. A series of control experiments confirmed that these effects were driven by disparity, as opposed to other factors such as flanker-target separation in three-dimensional (3-D) space or monocular positional offsets used to create disparity. When flankers were distributed over a range of crossed and uncrossed disparities, such that the mean was in the plane of the target, there was an equivalent or greater release of crowding compared to when all flankers were presented at the maximum disparity of that range. Overall, our results suggest that depth cues can reduce the effects of visual crowding, and that this reduction is unlikely to be caused by grouping of flankers or positional shifts in the monocular image

Bioarchaeological and Climatological Evidence for the Fate of Norse Farmers in Medieval Greenland

Greenland, far north land of the Atlantic, has often been beyond the limit of European farming settlement. One of its Norse settlements, colonized just before AD 1000, is — astonishingly — not even at the southern tip, but a way up the west coast, the \u27Western Settlement\u27. Environmental studies show why its occupation came to an end within five centuries, leaving Greenland once more a place of Arctic-adapted hunters

Transport and optical gaps and energy band alignment at organic-inorganic interfaces

International audienc

Gásir in Eyjafjörđur: International Exchange and Local Economy in Medieval Iceland

The site of Gásir in Eyjafjörður in northeast Iceland was excavated from 2001–2006, revealing details of one of the larger seasonal trading centers of medieval Iceland. Interdisciplinary investigations of the site have shed light upon the organization of the site and provided confirmation of documentary accounts of both prestige items (gyrfalcons, walrus ivory) and bulk goods (sulphur) concentrated for export. Gásir was a major point of cultural contact as well as economic exchange between Icelanders and the world of medieval Europe, and the zooarchaeological analyses indicated a mix of foodways and the presence of exotic animals and a well-developed provisioning system, which supplied high-quality meat and fresh fish to the traders. The excavations demonstrated an unexpected regional-level economic impact of the seasonally occupied site on the surrounding rural countryside, and contribute to ongoing investigations of the extent and impact of overseas trade in medieval Iceland

Effect of single embryo transfer on the risk of preterm birth associated with in vitro fertilization

To determine whether elective single embryo transfer (eSET) reduces the risk of preterm delivery associated with in vitro fertilization (IVF). This is an observational study of 3125 eSET cycles performed from 2008 to 2009 and reported to the Society for Assisted Reproductive Technology (SART) database. Preterm delivery rates were compared to the overall preterm delivery rate among all patients undergoing IVF over the same time period. The 3125 eSET cycles resulted in 1507 live births (live birth rate 48.2 %) Among these deliveries were 27 twins (1.8 %) and one set of triplets (0.07 %). The overall preterm delivery rate (20-37 weeks gestation) following eSET was 17.6 % (269/1527). This is significantly greater than the preterm birth rate for all patients undergoing IVF over the same time period (12 %, P \u3c 0.001). Elective single embryo transfer does not reduce the risk of preterm delivery associated with in vitro fertilization (IVF)

Relative Attraction of the Mediterranean Fruit Fly (Diptera: Tephritidae) to the Eight Isomers of Trimedlure

ABSTRACT Relative attractiveness tests with the eight individual racemic isomers of trimedlure, teTt-butyl 4(and 5)-chloro-c1s-and tTans-2-methylcyclohexane-l-carboxylate (TML), showed that one of the four cis isomers, TML-Y (teTt-butyl c1s-5-chloro-cis-2-methylcyclohexane-I-carboxylate), was attractive to CeTatitis capitata (Wiedemann) and long lasting. The isomer is present in cis-TML in a concentration of about 5%. The three other cis isomers, which are present in about equal amounts, were unattractive. The relative attractiveness of the four tTans isomers was the same as reported previously. Possible structure-activity relationships are discussed. KEY WORDS Insecta, CeTatitis capitata, attractant, lure MALE MEDITERRANEAN FRUIT FLIES, CeTatitis capitata (Wiedemann) are strongly attracted to trimedlure, tert-butyl 4(and 5)-chloro-cis-and trans-2-methy Icyclohexane-l-carboxylate (TML), which consists of a blend of eight racemic isomers (Beroza et a!. 1961). Commercially synthesized TML contains 90-95% of the four possible trans isomers, which are designated TML-A

Neutron Beta Decay Studies with Nab

Precision measurements in neutron beta decay serve to determine the coupling constants of beta decay and allow for several stringent tests of the standard model. This paper discusses the design and the expected performance of the Nab spectrometer.Comment: Submitted to Proceedings of the Conference CIPANP12, St.Petersburg, Florida, May 201

Task-specific transfer of perceptual learning across sensory modalities

It is now widely accepted that primary cortical areas of the brain that were once thought to be sensory-specific undergo significant functional reorganisation following sensory deprivation. For instance, loss of vision or audition leads to the brain areas normally associated with these senses being recruited by the remaining sensory modalities [1]. Despite this, little is known about the rules governing crossmodal plasticity in people who experience typical sensory development, or the potential behavioural consequences. Here, we used a novel perceptual learning paradigm to assess whether the benefits associated with training on a task in one sense transfer to another sense. Participants were randomly assigned to a spatial or temporal task that could be performed visually or aurally, which they practiced for five days; before and after training, we measured discrimination thresholds on all four conditions and calculated the extent of transfer between them. Our results show a clear transfer of learning between sensory modalities; however, generalisation was limited to particular conditions. Specifically, learned improvements on the spatial task transferred from the visual domain to the auditory domain, but not vice versa. Conversely, benefits derived from training on the temporal task transferred from the auditory domain to visual domain, but not vice versa. These results suggest a unidirectional transfer of perceptual learning from dominant to non-dominant sensory modalities and place important constraints on models of multisensory processing and plasticity