General-purpose and special-purpose visual systems

The information that eyes supply supports a wide variety of functions, from the guidance systems that enable an animal to navigate successfully around the environment, to the detection and identification of predators, prey, and conspecifics. The eyes with which we are most familiar the single-chambered eyes of vertebrates and cephalopod molluscs, and the compound eyes of insects and higher crustaceans allow these animals to perform the full range of visual tasks. These eyes have evidently evolved in conjunction with brains that are capable of subjecting the raw visual information to many different kinds of analysis, depending on the nature of the task that the animal is engaged in. However, not all eyes evolved to provide such comprehensive information. For example, in bivalve molluscs we find eyes of very varied design (pinholes, concave mirrors, and apposition compound eyes) whose only function is to detect approaching predators and thereby allow the animal to protect itself by closing its shell. Thus, there are special-purpose eyes as well as eyes with multiple functions

Fairground rides and spatial updating

A simple experiment with a rotating office chair demonstrates that the extent of counter-rotation we experience when imposed rotation has stopped is the same as the angular inaccuracy of pointing to a previously fixated object. This suggests that our conscious percept of rotation and the updating signal for the egocentric model we use to guide motor actions are closely related

Ways of seeing Visual Ecology Tom Cronin, Sönke Johnsen, Justin Marshall and Eric Warrant (Princeton University Press, Princeton, NJ; 2014) ISBN: 978-1-400853-021

Unknow

Dispatch R955

During everyday activitiesdriving, making a sandwich or playing ping-pong -our eyes search ahead, trying to find the information that our hands and limbs need to carry out their tasks [1-4]. It has become clear in the last 20 years, since it became possible to monitor eye movements in freely moving people, that the eyemovement system does far more than respond reflexly to objects that catch the eye. In a skilled motor task, eye movement has a role that is different from the action itself, but thoroughly enmeshed with it [2]. For example, in driving on a winding road, one job of the eyes is to locate and track the inside lane edge (tangent point) of the next bend, as its location relative to the driver provides direct information about road curvature, and hence how much to turn the steering wheel Sailer, Flanagan and Johansson [6] devised a task which involved learning how to use a novel mouselike tool to control the position of a cursor on a screen, in order to hit a series of consecutively appearing target boxes. The tool consisted of a freely held box with a handle at each end. Applying opposite rotational torque to the two handles moved the cursor up and down the screen, whilst pushing the handles towards or away from each other moved the cursor laterally (in fact the system was isometric, and the handles did not move). Making oblique cursor movements with the tool was evidently quite difficult and took some time to learn. The gaze movements and cursor movements of the subjects were monitored as they learned how to use the tool, and measures of success such as hit rate and path length to target were also measured. The learning process took a total of about 20 minutes. The most interesting result was that, for most subjects, learning proceeded in three distinct stages: an exploratory phase in which the hit rate remained low; a skill acquisition stage in which the hit rate increased rapidly; and a skill refinement stage in which the rate increased more slowly. The three phases were characterised by very different patterns of both motor control (as shown by the cursor movements) and gaze movements. During the exploratory phase most cursor movements and gaze movements were either horizontal or vertical, as the subjects learned to cope with one or other control dimension of the tool ( During the skill acquisition stage, the subjects slowly learned to move the cursor obliquely, and the hit rate increased to about one target every two seconds ( During the skill refinement stage, gaze no longer tracked the cursor, but went straight to the next target, with either a single saccade, or with one large and one smaller saccade ( In many manual tasks, a specific repertoire of eye movements accompanies the actions. A new study has shown how this pattern changes as eye and hand become coordinated when learning a new skill

Juvenile Finfish and Blue Crab Stock Assessment Program Bottom Trawl Survey Annual Data Summary Report Series Volume 1988

The Virginia Institute of Marine Science (VIMS) has conducted a trawl survey of the Virginia tributaries to the Chesapeake Bay dating back to 1955. Over these forty years, methods and objectives have varied according to funding sources and state and/ or federal mandates. The present thrust of the program is to provide juvenile indices of relative abundance of recreationally, commercially, and ecologically important finfish and invertebrates. In 1988, the main area of focus was as a monitoring device of the resources of the Chesapeake Bay and its tributaries, as well as a way to create juvenile indices of key target species. These measures of juvenile abundance are widely used as a key element in the management of the Atlantic States\u27 coastal fishery resources and serve as early indicators of future year class strength. In addition to the river trawl survey, a comprehensive Bay-wide trawl survey of Virginia waters, which was performed in the past with varying sampling methods, was reintroduced in 1988 as a random stratified sampling design. This design was based on depth and three 20° latitudinal regions (top, middle and bottom). The design was altered slightly beginning in 1989 to create four regions (top, upper, lower and bottom). The purpose of this change was to associate each tributary with a mainstem Bay segment. Results are shown as this altered method. The Bay survey accounted for over 70 percent of the annual sampling and two-thirds of the overall 1988 catch. The bay anchovy in 1988 continued to be the most abundant species caught in the river trawl survey and was most abundant overall. The second most abundant species, spot, was captured at near historic high levels in 1988 (the highest since 1984 ). H.ogchoker, weakfish and Atlantic croaker complete the top five species caught overall

Juvenile Finfish and Blue Crab Stock Assessment Program Bottom Trawl Survey Annual Data Summary Report Series Volume 1994

The Virginia Institute of Marine Science (VIMS) has conducted a trawl survey dating back to 1955. Over these forty years methods and objectives have varied according to funding sources and state and/or federal mandates. The present thrust of the program is to provide juvenile indices of relative abundance for recreationally, commercially, and ecologically important finfish and invertebrates. These measures of juvenile abundance are widely used as a key element in the management of the Atlantic States\u27 coastal fishery resources. Estimates of juveniles (age-0) have proven to be a reliable and early indicator of future year-class strength. A review of previously available indices of juvenile abundance for important fishery resource species of the Chesapeake Bay by the Chesapeake Bay Stock Assessment Committee (CBSAC), a federal/ state committee sponsored and funded by the National Oceanic and Atmospheric Administration (NOAA), resulted in the recommendation that, a unified, consistent trawl program should be one of the primary monitoring tools for finfish and crab stock assessment. (Chesapeake Bay Program Stock Assessment Plan, Chesapeake Executive Council 1988). There were several notable survey results for this year. Catch information for 1994 indicated a continuing decline in the blue crab population, although not as pronounced as in recent years. However, the 1994 spawning stock (adult females) was half that of 1993. Juvenile white perch and striped bass catches continued to increase. Summer flounder indices doubled over the disastrous 1992 and 1993 year classes. Atmosperically, winter temperatures were normal with the exception of two extremely cold periods (air temperatures less than 4° C). Summer temperatures were relatively mild compared to 1993 values. The purpose of this summary is to provide an accurate account of trawl survey sampling performed during the calendar year 1994. Previous volumes of this series have served as excellent reference guides to resource managers, scientists, academics, as well as the general public. Since there are other venues which presently detail specific results of these data (Geer et al., 1993), conclusions are kept at a minimum in order to provide the most information in the available space

Growth characteristics in individuals with osteogenesis imperfecta in North America: results from a multicenter study.

PurposeOsteogenesis imperfecta (OI) predisposes people to recurrent fractures, bone deformities, and short stature. There is a lack of large-scale systematic studies that have investigated growth parameters in OI.MethodsUsing data from the Linked Clinical Research Centers, we compared height, growth velocity, weight, and body mass index (BMI) in 552 individuals with OI. Height, weight, and BMI were plotted on Centers for Disease Control and Prevention normative curves.ResultsIn children, the median z-scores for height in OI types I, III, and IV were -0.66, -6.91, and -2.79, respectively. Growth velocity was diminished in OI types III and IV. The median z-score for weight in children with OI type III was -4.55. The median z-scores for BMI in children with OI types I, III, and IV were 0.10, 0.91, and 0.67, respectively. Generalized linear model analyses demonstrated that the height z-score was positively correlated with the severity of the OI subtype (P < 0.001), age, bisphosphonate use, and rodding (P < 0.05).ConclusionFrom the largest cohort of individuals with OI, we provide median values for height, weight, and BMI z-scores that can aid the evaluation of overall growth in the clinic setting. This study is an important first step in the generation of OI-specific growth curves

Fossilized Biophotonic Nanostructures Reveal the Original Colors of 47-Million-Year-Old Moths

Original structural colors reconstructed in fossil moths had a dual defensive function and illuminate the evolution of communication strategies in insects

The Genome of Deep-Sea Vent Chemolithoautotroph Thiomicrospira crunogena XCL-2

Presented here is the complete genome sequence of Thiomicrospira crunogena XCL-2, representative of ubiquitous chemolithoautotrophic sulfur-oxidizing bacteria isolated from deep-sea hydrothermal vents. This gammaproteobacterium has a single chromosome (2,427,734 base pairs), and its genome illustrates many of the adaptations that have enabled it to thrive at vents globally. It has 14 methyl-accepting chemotaxis protein genes, including four that may assist in positioning it in the redoxcline. A relative abundance of coding sequences (CDSs) encoding regulatory proteins likely control the expression of genes encoding carboxysomes, multiple dissolved inorganic nitrogen and phosphate transporters, as well as a phosphonate operon, which provide this species with a variety of options for acquiring these substrates from the environment. Thiom. crunogena XCL-2 is unusual among obligate sulfur-oxidizing bacteria in relying on the Sox system for the oxidation of reduced sulfur compounds. The genome has characteristics consistent with an obligately chemolithoautotrophic lifestyle, including few transporters predicted to have organic allocrits, and Calvin-Benson-Bassham cycle CDSs scattered throughout the genome