The segmentation of visual form

The argument of this work is that, despite the massive body of literature that has accumulated in the decades since the discovery of 'gestalt' as the ruling principle of perception, little genuine progress in solving the problem posed by the visual perception of form has been made. This state of affairs is attributed, moreover, to a fundementally inadequate formulation of this problem. It is not enough merely to revise this or that theory, or this or that experimental design, if the argument is correct; rather, it is necessary to revise the formulation of the form problem upon which theory and experimental design rest. Thus, the reformulation suggested is that (a) form is the unit which segments space, and consequently that (b) the problem posed by this unit is essentially that of its segmentation/formation of space, rather than that of its recognition/conservation through change in space; the former is the primary, the latter the secondary, (psycho-physical) problem posed by the visual perception of form. This work also contains a segmentation (spatial/holistic) theory of form, and five experiments designed to test this theory against current recognition (dimensional/analytic) theories of form (for example, see Corcoran, 1971); these experiments are all concerned with different facets of the role played by contour in visual perception, and they provide some evidence for the former, and against the latter, type of theory. It should be pointed out that both in the main body of the text, and in an appendix, it is argued that segmentation is primarily two-dimensional rather than three-dimensional: two-dimensional 'figure'form is primary over three-dimensional 'object' form in perceptual development, and indeed, the latter is constructed from the former. (This hypothesis is part of a more general point of view about cognition, namely that there is an a priori spatial system which is used to process perceptual input, and establish in it the spatial structure of perceptual experience, but one whose conceptual implications and properties become available for symbolisation and thinking when it is freed from the task of perceptual processing by being lifted out of perception into a visual form of representation which Bruner terms 'ikonic' (See Bruner et al., 1966).)<p

Investigating Disparities in High School Athletes’ Attitude Toward Concussion and Predictors of Continuing Play

Objective: Studies related to attitudes of concussion have been growing in athletic populations. While racial and socioeconomic disparities exist in knowledge and awareness of concussion, it remains unclear the effect of disparities on attitudes of concussion and reporting behaviors. The purpose of this study was to examine racial and socioeconomic disparities on attitudes towards concussion and the decision to remain in play with a suspected concussion. Design: This cross-sectional study included 577 athletes between the ages of 13-19 (16.0 ± 1.2) years from 14 high schools. Participants completed a knowledge and attitudes instrument assessing general attitudes of concussion using 7 Likert-scale attitude questions followed by 2 additional questions assessing the decision to continue play while symptomatic. Differences in attitudes of concussion between race and socioeconomic school type were examined using independent t-tests. A multivariable linear regression model was utilized to determine which demographic factors were associated with athletes’ attitude scores. Multivariable logistic regression models were utilized to determine what demographic variables were associated with athletes’ continuation of play in a practice or a game. Results: Differences in attitude scores between race were observed, with black athletes demonstrating lower scores than white athletes (pp=.04) and sex (OR: 0.59, 95% CI [0.36,0.96], p=.03) were, with females less likely to remain in a practice than males. Further, race and socioeconomic school type were not significantly associated with remaining in a game; however, attitude (OR: 0.97, 95% CI [0.95,0.99], p=.01) and sex (OR: 0.56 95% CI [0.35,0.90], p=.02) were, with females less likely to remain in a game than males. Conclusions: Disparities exist between race and socioeconomic school type on attitude of concussion. Black athletes and athletes attending Title I high schools had poorer attitude scores compared to white athletes and athletes attending non-Title I schools. Race was significantly associated with lower concussion attitude scores. The poorer, yet moderate concussion attitude scores suggest concussion education efforts be concentrated towards closing the disparity gap. Further, addressing concussion attitudes would likely also help to shift athletes’ decisions to remain in a practice or game while symptomatic

'They're battle scars, I wear them well': A phenomenological exploration of young women's experiences of building resilience following adversity in adolescence

This is an Author's Accepted Manuscript of an article published in Journal of Youth Studies, 13(3), 273 - 290, 2010 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/13676260903520886.This phenomenological study explored young women's accounts of building resilience following chains of adverse life experiences in adolescence. Six participants were interviewed, aged 20–25 years. Most had, or were receiving, a university education. They described their recovery from adversity as starting with certain pivotal moments, followed by both short-term and longer-term strategies. Short-term strategies tended to offer respite from distress and emotional comfort, increased clarity about their experiences and social affirmation. Recovery involved gaining new perspectives on their adverse situation and recovering a positive self-image through three longer-term strategies. These involved making visible progress in their education, rebuilding relationships with family and friends, and participating in the ‘normalizing’ activities and developmental projects of adolescence. Participants believed that they were stronger and more compassionate although positive achievements co-existed with some regrets. Most perceived the adversity as catalyzing personal growth. These accounts of resilience revealed the complex psychosocial processes and resources available to some adolescents

Prolonged static stretching increases the magnitude and decreases the complexity of knee extensor muscle force fluctuations.

Static stretching decreases maximal muscle force generation in a dose-response manner, but its effects on the generation of task-relevant and precise levels of submaximal force, i.e. force control, is unclear. We investigated the effect of acute static stretching on knee extensor force control, quantified according to both the magnitude and complexity of force fluctuations. Twelve healthy participants performed a series of isometric knee extensor maximal voluntary contractions (MVCs) and targeted intermittent submaximal contractions at 25, 50 and 75% MVC (3 x 6 seconds contraction separated by 4 seconds rest, with 60 seconds rest between each intensity) prior to, and immediately after, one of four continuous static stretch conditions: 1) no stretch; 2) 30-second stretch; 3) 60-second stretch; 4) 120-second stretch. The magnitude of force fluctuations was quantified using the standard deviation (SD) and coefficient of variation (CV), while the complexity of fluctuations was quantified using approximate entropy (ApEn) and detrended fluctuation analysis (DFA) α. These measures were calculated using the steadiest 5 seconds of the targeted submaximal contractions at each intensity (i.e., that with the lowest SD). Significant decreases in MVC were evident following the 30, 60 and 120-second stretch conditions (all P < 0.001), with a significant correlation observed between stretch duration and the magnitude of decrease in MVC (r = -0.58, P < 0.001). The 120-second stretch resulted in significant increases in SD at 50% MVC (P = 0.007) and CV at 50% (P = 0.009) and 75% MVC (P = 0.005), and a significant decrease in ApEn at 75% MVC (P < 0.001). These results indicate that the negative effects of prolonged static stretching extend beyond maximal force generation tasks to those involving generation of precise levels of force during moderate- to high-intensity submaximal contractions

Population Impact & Efficiency of Benefit‐Targeted Versus Risk‐Targeted Statin Prescribing for Primary Prevention of Cardiovascular Disease

BACKGROUND: Benefit-targeted statin prescribing may be superior to risk-targeted statin prescribing (the current standard), but the impact and efficiency of this approach are unclear. METHODS AND RESULTS: We analyzed the National Health and Nutrition Examination Survey (NHANES) using an open-source model (the Prevention Impact and Efficiency Model) to compare targeting of statin therapy according to expected benefit (benefit-targeted) versus baseline risk (risk-targeted) in terms of projected population-level impact and efficiency. Impact was defined as relative % reduction in atherosclerotic cardiovascular disease in the US population for the given strategy compared to current statin treatment patterns; and efficiency as the number needed to treat over 10 years (NNT10, average and maximum) to prevent each atherosclerotic cardiovascular disease event. Benefit-targeted moderate-intensity statin therapy at a treatment threshold of 2.3% expected 10-year absolute risk reduction could produce a 5.7% impact (95% confidence interval, 4.8-6.7). This is approximately equivalent to the potential impact of risk-targeted therapy at a treatment threshold of 5% 10-year atherosclerotic cardiovascular disease risk (5.6% impact [4.7-6.6]). Whereas the estimated maximum NNT10 is much improved for benefit-targeted versus risk-targeted therapy at these equivalent-impact thresholds (43.5 vs 180), the average NNT10 is nearly equivalent (24.2 vs 24.6). Reaching 10% impact (half the Healthy People 2020 impact objective, loosely defined) is theoretically possible with benefit-targeted moderate-intensity statins of persons with expected absolute risk reduction >2.3% if we expand age eligibility and account for treatment of all persons with diabetes mellitus or with low-density lipoprotein >190 mg/dL (impact=12.4%; average NNT10=23.0). CONCLUSIONS: Benefit-based targeting of statin therapy provides modest gains in efficiency over risk-based prescribing and could theoretically help attain approximately half of the Healthy People 2020 impact goal with reasonable efficiency

Disaggregated N2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology

Acknowledgements This work was funded by Chinese Ministry of Agriculture and the United Kingdom Department for Environment, Food and Rural Affairs (DEFRA), UK under the UK-China Sustainable Agriculture Innovation Network (SAIN; Project DC09-06). Rothamsted Research receives strategic funding by the Biotechnology and Biological Sciences Research Council (BBSRC).Peer reviewedPublisher PD

Fast-Speed Compared to Slow-Speed Eccentric Muscle Actions are Detrimental to Jump Performance in Elite Soccer Players In-Season

Purpose: To examine the effect of fast-speed vs. slow-speed eccentric muscle actions resistance training on lower-body strength, vertical jump height, sprint speed and COD performance in elite soccer players during a competitive season. Methods: Twenty-two elite soccer players, from a single team, were randomly selected to groups that undertook either 1 s (fast speed [1S]) or 4 s (slow speed [4S]) eccentric resistance training during the in-season period. A five-week programme was conducted during an elite top division European League soccer season. Performance measures, including predicted one repetition maximum (1RM) back squat, countermovement jump (CMJ), 20 m sprint and change of direction (COD) were tested before and after the intervention period. Total match and training running distance and muscle soreness were also recorded during each week of the intervention. Results: An ANCOVA showed significant group effects (P = 0.01) for CMJ with a greater jump height in the 1S group post-intervention (95% CI [1.1 to 6.9 cm]). Despite an overall increase in 1RM pre- to post-training (95% CI [10.0 kg to 15.3 Kg], ES: 0.69), there were no significant differences (P > 0.05) between groups after the intervention. Similarly, there were no differences between groups for COD, 20 m sprint or muscle soreness. Conclusion: Faster eccentric muscle actions may be superior for increasing jumping movements in elite soccer players in-season

Tissue-engineered valved conduits in the pulmonary circulation

AbstractObjective: Bioprosthetic and mechanical valves and valved conduits are unable to grow, repair, or remodel. In an attempt to overcome these shortcomings, we have evaluated the feasibility of creating 3-leaflet, valved, pulmonary conduits from autologous ovine vascular cells and biodegradable polymers with tissue-engineering techniques. Methods: Endothelial cells and vascular medial cells were harvested from ovine carotid arteries. Composite scaffolds of polyglycolic acid and polyhydroxyoctanoates were formed into a conduit, and 3 leaflets (polyhydroxyoctanoates) were sewn into the conduit. These constructs were seeded with autologous medial cells on 4 consecutive days and coated once with autologous endothelial cells. Thirty-one days (±3 days) after cell harvesting, 8 seeded and 1 unseeded control constructs were implanted to replace the pulmonary valve and main pulmonary artery on cardiopulmonary bypass. No postoperative anticoagulation was given. Valve function was assessed by means of echocardiography. The constructs were explanted after 1, 2, 4, 6, 8, 12, 16, and 24 weeks and evaluated macroscopically, histologically, and biochemically. Results: Postoperative echocardiography of the seeded constructs demonstrated no thrombus formation with mild, nonprogressive, valvular regurgitation up to 24 weeks after implantation. Histologic examination showed organized and viable tissue without thrombus. Biochemical assays revealed increasing cellular and extracellular matrix contents. The unseeded construct developed thrombus formation on all 3 leaflets after 4 weeks. Conclusion: This experimental study showed that valved conduits constructed from autologous cells and biodegradable matrix can function in the pulmonary circulation. The progressive cellular and extracellular matrix formation indicates that the remodeling of the tissue-engineered structure continues for at least 6 months. (J Thorac Cardiovasc Surg 2000;119:732-40