The vergence eye movements induced by radial optic flow: Some fundamental properties of the underlying local-motion detectors

AbstractRadial optic flow applied to large random dot patterns is known to elicit horizontal vergence eye movements at short latency, expansion causing convergence and contraction causing divergence: the Radial Flow Vergence Response (RFVR). We elicited RFVRs in human subjects by applying radial motion to concentric circular patterns whose radial luminance modulation was that of a square wave lacking the fundamental: the missing fundamental (mf) stimulus. The radial motion consisted of successive ¼–wavelength steps, so that the overall pattern and the 4n+1 harmonics (where n =integer) underwent radial expansion (or contraction), whereas the 4n−1 harmonics—including the strongest Fourier component (the 3rd harmonic)—underwent the opposite radial motion. Radial motion commenced only after the subject had fixated the center of the pattern. The initial RFVRs were always in the direction of the 3rd harmonic, e.g., expansion of the mf pattern causing divergence. Thus, the earliest RFVRs were strongly dependent on the motion of the major Fourier component, consistent with early spatio-temporal filtering prior to motion detection, as in the well-known energy model of motion analysis. If the radial mf stimulus was reduced to just two competing harmonics—the 3rd and 5th—the initial RFVRs showed a nonlinear dependence on their relative contrasts: when the two harmonics differed in contrast by more than about an octave then the one with the higher contrast completely dominated the RFVRs and the one with lower contrast lost its influence: winner-take-all. We suggest that these nonlinear interactions result from mutual inhibition between the mechanisms sensing the motion of the different competing harmonics. If single radial-flow steps were used, a brief inter-stimulus interval resulted in reversed RFVRs, consistent with the idea that the motion detectors mediating these responses receive a visual input whose temporal impulse response function is strongly biphasic. Lastly, all of these characteristics of the RFVR, which we attribute to the early cortical processing of visual motion, are known to be shared by the Ocular Following Response (OFR)—a conjugate tracking (version) response elicited at short-latency by linear motion—and even the quantitative details are generally very similar. Thus, although the RFVR and OFR respond to very different patterns of global motion—radial vs. linear—they have very similar local spatiotemporal properties as though mediated by the same low-level, local-motion detectors, which we suggest are in the striate cortex

Predicting university performance in psychology: the role of previous performance and discipline-specific knowledge

Recent initiatives to enhance retention and widen participation ensure it is crucial to understand the factors that predict students' performance during their undergraduate degree. The present research used Structural Equation Modeling (SEM) to test three separate models that examined the extent to which British Psychology students' A-level entry qualifications predicted: (1) their performance in years 1-3 of their Psychology degree, and (2) their overall degree performance. Students' overall A-level entry qualifications positively predicted performance during their first year and overall degree performance, but negatively predicted their performance during their third year. Additionally, and more specifically, students' A-level entry qualifications in Psychology positively predicted performance in the first year only. Such findings have implications for admissions tutors, as well as for students who have not studied Psychology before but who are considering applying to do so at university

Persistent disparities over time in the distribution of sugar-sweetened beverage intake among children in the United States

Background Recent research suggests that sugar-sweetened beverage (SSB) consumption has been declining among US children aged 2-18 y. However, most studies focused on changes in mean intake, ignore high SSB consumers and do not examine intake among vulnerable groups and, including adolescents, low-income households, and several racial/ethnic minorities. Objective The aim was to estimate usual SSB intake from NHANES surveys from 2003-2004 to 2013-2014 to examine shifts at both the median and 90th percentile among US children, evaluating the extent to which intake disparities in total SSBs and subtypes have persisted. Design Children 2-18 y from NHANES 2003, 2005, 2007, 2009, 2011 and 2013. SSBs were all non-diet beverages sweetened with sugars including revising all beverages to as consumed status and excluding soy and dairy based beverages. The NCI usual intake method was used to estimate usual intake from two 24-hour recalls. A 2-part correlated model accounted for nonconsumers. Quantile regression was then used to examine differences in SSB usual intakes at the 50th and 90th percentiles by race-ethnicity, and examine interactions indicating whether racial-ethnic disparities in intake were modified by income. Results Despite considerable declines, children's SSB intake remains high, particularly among heavy consumers. Among adolescents, median SSB intake in 2013-2014 was on the order of 150-200 kcal/d, and heavy intake at the 90th percentile was on the order of 250-300 kcal/d. There were important disparities in intake that persisted over time. Although high household income was associated with lower SSB intake in non-Hispanic white (NHW) children, intakes of non-Hispanic black (NHB) and Mexican-American (MA) children from these households were similar to or higher than those from poor households. There were also large racial/ethnic differences in the types of SSBs consumed. The consumption of regular sodas by NHB children was somewhat lower than among MA and NHW children, whereas fruit drink intake was markedly higher. Conclusions Overall, these findings suggest that, despite recent declines, strategies are needed to further reduce SSB consumption, and particularly heavy intake, especially among NHB children where fruit drinks also are key source of SSBs

Development of a food composition database to monitor changes in packaged foods and beverages

In order to monitor nutritional changes in the US food supply and assess potential impact on individual dietary intake, an approach was developed to enhance existing standard food composition tables with time-varying product- and brand-specific information for barcoded packaged foods. A “Crosswalk” was formed between barcoded products and USDA foodcodes in a time-specific manner, such that sales-weighted average nutritional profiles were generated for each foodcode based on corresponding products (275,000–350,000 per 2-year cycle). This Crosswalk-enhanced food composition table was applied to dietary intake data from the National Health and Nutrition Examination Survey (cycles 2007–2008, 2009–2010, and 2011–2012). Total energy density of foods consumed by Americans from stores/vending was stable over time and differed by <5 kcal/100 g using the Crosswalk-enhanced vs standard database. However, changes in the energy density of food groups were found utilizing the Crosswalk that were not detected using the standard database. Likewise, significant declines in energy intake from beverages among children (288 ± 7.3 to 258 ± 6.8 kcal/d) were found using the Crosswalk-enhanced database but were non-significant using the standard database. The Crosswalk approach can potentially augment national nutrition surveys by utilizing commercial food purchase and nutrient databases to capture changes in the nutrient content of packaged foods

A recepção da família na hospitalização de crianças

Fundamentando-se em estudos que discutem a participação de familiares na hospitalização de seus filhos, este trabalho pretende estudar como os familiares de crianças hospitalizadas vivenciam o momento da recepção, que profissional da equipe os acompanha durante os procedimentos iniciais, que informações recebem e quem encarrega-se de informá-los, logo que a criança é admitida no hospital em razão de uma doença que necessita de cuidados hospitalares. Os participantes foram 40 pais e se utilizou entrevistas semi-estruturadas para a coleta de dados. Estes foram analisados segundo métodos de análise de conteúdo. Os resultados mostraram que os pais vivenciam um estado de ansiedade generalizado, não sabem nomear que profissional os acompanhou, além de lembrarem-se de informações esporádicas que dizem respeito, exclusivamente, às suas necessidades imediatas

Formability of similar and dissimilar friction stir welded AA 5182-H111 and AA 6016-T4 tailored blanks

http://www.sciencedirect.com/science/article/B6TX5-4V4KPJ7-6/2/69e70bca89227102937e48ad003fff3

Human vergence eye movements initiated by competing disparities: Evidence for a winner-take-all mechanism

AbstractVergence eye movements were elicited in human subjects at short latencies (∼70ms) by applying binocular disparities briefly (200ms) to large grating patterns (46° wide, 35° high). The positions of both eyes were recorded with the electromagnetic search coil technique. Using a dichoptic viewing arrangement (Wheatstone stereoscope), each eye viewed two overlapping 1-D sine waves that had the same orientation but different spatial frequencies. These two sine waves each had a binocular disparity that was 1/4 of its wavelength and the effect of varying their relative contrasts was examined (15 contrast ratios ranging from 0.125 to 8). The first experiment used horizontal gratings and recorded the vertical vergence responses when the two sine waves had spatial frequencies in the ratio 3:5 and vertical disparities of opposite sign. Initial vergence responses showed a highly nonlinear dependence on the contrast ratio. On average, when the contrast of one sine wave exceeded that of the other by a factor of >2.2, the sine wave with the higher contrast dominated responses and the sine wave with the lower contrast had almost no influence: winner-take-all. A second experiment, which used vertical gratings and recorded the horizontal vergence responses when the two sine waves had spatial frequencies in the ratio 3:5 and horizontal disparities of opposite sign, also uncovered nonlinear interactions but these were much more variable from one subject to another and, on average, one sine wave did not achieve complete dominance until its contrast exceeded that of the other by a factor of >4.5. When these two experiments were repeated with grating patterns in which the two sine waves had spatial frequencies in the ratio 3:7 and disparities of the same sign, similar nonlinear interactions were apparent. We attribute the nonlinear dependence on relative contrast to mutual inhibition between the neural elements processing the disparities of the two sine waves. We further suggest that this interaction will help to maintain binocular alignment on the objects in the plane of regard because the retinal images of those objects will tend to be better focused—and hence tend to have higher contrasts—than the images of objects in other depth planes