Functional evidence for cone-specific connectivity in the human retina

NoPhysiological studies of colour vision have not yet resolved the controversial issue of how chromatic opponency is constructed at a neuronal level. Two competing theories, the cone-selective hypothesis and the random-wiring hypothesis, are currently equivocal to the architecture of the primate retina. In central vision, both schemes are capable of producing colour opponency due to the fact that receptive field centres receive input from a single bipolar cell ¿ the so called `private line arrangement¿. However, in peripheral vision this single-cone input to the receptive field centre is lost, so that any random cone connectivity would result in a predictable reduction in the quality of colour vision. Behavioural studies thus far have indeed suggested a selective loss of chromatic sensitivity in peripheral vision. We investigated chromatic sensitivity as a function of eccentricity for the cardinal chromatic (L/M and S/(L + M)) and achromatic (L + M) pathways, adopting stimulus size as the critical variable. Results show that performance can be equated across the visual field simply by a change of scale (size). In other words, there exists no qualitative loss of chromatic sensitivity across the visual field. Critically, however, the quantitative nature of size dependency for each of the cardinal chromatic and achromatic mechanisms is very specific, reinforcing their independence in terms of anatomy and genetics. Our data provide clear evidence for a physiological model of primate colour vision that retains chromatic quality in peripheral vision, thus supporting the cone-selective hypothesis

The Second World War\u27s impact on the progressive educational movement: Assessing its role

Evidence found in The New York Times from 1939 to 1945 and corroborating sources are used to demonstrate the impact of the Second World War on the progressive educational movement. We posit that December 7, 1941 initiated the waning of the progressive education movement in the secondary social studies curriculum. Progressive education emphasized a child-centered, experiential curriculum, an issues-centered approach to learning, and a critical analysis of society. Our findings indicate that the educational climate during the Second World War initiated a shift from questioning American institutions to celebrating them. Education became more centralized and many educational organizations were mobilized to support the war effort. Specifically, the secondary social studies curriculum became one of several propaganda vehicles in support of the war. In addition, colleges and universities became training grounds for teachers, defense workers, and soldiers. A war on the home front ensued. The progressive secondary social studies curriculum itself was viewed as placing the nation at risk. While other factors such as the Back-to-Basics movement and the Cold War contributed to the waning of the secondary progressive educational movement, World War Two (WWII) set the decline in motion

The Role of Social Capital in Natural Resource Policy Development

Social capital is used as a framework to focus on the nexus of society and natural resources in three case studies in the Texas Coastal Bend, USA. Social capital incorporates diverse social phenomena such as trust and reciprocity, engagement and cooperation, common rules and norms, and social networks. Capital exists in the relations among actors and the resources embedded in them (e.g. information and influence) that provide valuable assets that can be leveraged for individual or collective gain. I examined social capital as a resource for potential community involvement in whooping crane management using qualitative analysis of semi-structured interviews of 35 individuals. Community networks of reciprocity and trust formed bonding ties strengthened by active engagement; shared values and community identity; and institutions fostering leadership and service. Bridging ties offered opportunities for knowledge sharing and legitimacy. Social capital in this community provided a potential resource to save time and money in addressing ongoing efforts to protect this charismatic endangered species. A case study of collaborative modeling provided an opportunity for stakeholders to learn more about an estuarine system and strengthen network ties. Using Bloom’s Taxonomy, I demonstrated how this social learning process led to increased cognitive skills in understanding the estuarine system. Through engagement and networking, participants established social capital useful for addressing watershed issues. Affiliation network analysis of five water management groups over a ten-year period was based on meeting attendance records. I examined stakeholder heterogeneity within each group. Network density provided insight as to how actors are connected and the likelihood that groups function cohesively. Network measures of betweenness and eigenvector centrality indicated important individuals within the networks that serve as leaders within and bridges between groups. Important brokering roles within the networks, of connecting otherwise un-connected groups, were filled by regional water authorities and conservation organizations. Network visualization showed the differences and similarities, and integrity of all groups. Together, these studies demonstrated how social capital is an invaluable resource for successful management of natural resources in the Texas Coastal Bend

On the integrability of polynomial vector fields in the plane by means of Picard-Vessiot theory

We study the integrability of polynomial vector fields using Galois theory of linear differential equations when the associated foliations is reduced to a Riccati type foliation. In particular we obtain integrability results for some families of quadratic vector fields, Liénard equations and equations related with special functions such as Hypergeometric and Heun ones. The Poincaré problem for some families is also approached

Socio-political dimensions of CCS deployment through the lens of social network analysis

AbstractThe Socio-Political Evaluation of Energy Deployment (SPEED) framework was proposed to improve understanding of energy technology deployment. It was intended to help energy policy-makers develop and implement more effective strategies to accelerate the deployment of emerging energy technologies. The theoretical underpinnings lie in the fields of sustainability science, political science, and risk perception. Part of the objectives of the SPEED framework are to identify the dominant socio-political influences on energy technology decisions and examine how policy can facilitate a societal response to climate change by contributing insights to stakeholders. The focus is at the state level because it is at the state level that emergent energy technologies are sited, permitted, and built. The purpose of this study was to examine the structure of communication about carbon capture and storage (CCS) technology from the perspective of individuals actively involved in decisions that affect deployment and diffusion. We use density of function-system networks to examine differences between states and categories stakeholders. The information is used to inform the discussion of the current structure of communication and how it might present either barriers or opportunities for CCS innovation. Five function systems are used, each divided into benefits (positive) or risks (negative) associated with CCS: Economic benefit (ECP), economic risk (ECN), environmental benefit (ENP), environmental risk (ENN), health and safety benefit (HLP), health and safety risk (HLN), political benefit (POP), political risk (PON), technical benefit (TEP), and technical risk (TEN). An additional category of CCS statements that could not be definitively assigned to one of these categories was included as an ‘other’ category (OTP and OTN). Networks were constructed for all stakeholders, each state, and each stakeholder type based on ties of shared intensity of communication about the particular frame. From these networks, density measurements were calculated and reported. In the case studies presented here, technical risk dominates communication about CCS at the state level. The economic, technical, and political system functions appear to present the greatest barrier due to largely negative communication. This study focuses on how the development of shared meaning creates ties between individuals in a CCS policy network

Influence of piping singularities on heat transfer in flow of surfactant solutions

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.Small amount of additives like e.g. surfactants can significantly suppress friction in turbulent flow of water. However the drag reduction is accompanied by a considerable decrease of heat transfer. Both drag reduction and good heat transfer are desired properties of systems employed in district heating systems. We investigated therefore the drag reduction properties of some surfactant mixtures with sodium salicylate. This contribution presents the results of drag reduction by three cationic surfactants. There was also investigated heat transfer effectiveness in these surfactants, particularly heat transfer behind singularities which were a valve and a tube bend. The singularities have negligible effect on heat transfer in water alone. They influence heat transfer coefficient only in the imminent part of the tube. The heat transfer enhancement is rather small.cs201

Live Imaging of Axolotl Digit Regeneration Reveals Spatiotemporal Choreography of Diverse Connective Tissue Progenitor Pools

Connective tissues—skeleton, dermis, pericytes, fascia—are a key cell source for regenerating the patterned skeleton during axolotl appendage regeneration. This complexity has made it difficult to identify the cells that regenerate skeletal tissue. Inability to identify these cells has impeded a mechanistic understanding of blastema formation. By tracing cells during digit tip regeneration using brainbow transgenic axolotls, we show that cells from each connective tissue compartment have distinct spatial and temporal profiles of proliferation, migration, and differentiation. Chondrocytes proliferate but do not migrate into the regenerate. In contrast, pericytes proliferate, then migrate into the blastema and give rise solely to pericytes. Periskeletal cells and fibroblasts contribute the bulk of digit blastema cells and acquire diverse fates according to successive waves of migration that choreograph their proximal-distal and tissue contributions. We further show that platelet-derived growth factor signaling is a potent inducer of fibroblast migration, which is required to form the blastema.Instituto de Física de Líquidos y Sistemas Biológico

Behavioral and antioxidant activity of a tosylbenz[g]indolamine derivative. A proposed better profile for a potential antipsychotic agent

BACKGROUND: Tardive dyskinesia (TD) is a major limitation of older antipsychotics. Newer antipsychotics have various other side effects such as weight gain, hyperglycemia, etc. In a previous study we have shown that an indolamine molecule expresses a moderate binding affinity at the dopamine D(2 )and serotonin 5-HT(1A )receptors in in vitro competition binding assays. In the present work, we tested its p-toluenesulfonyl derivative (TPBIA) for behavioral effects in rats, related to interactions with central dopamine receptors and its antioxidant activity. METHODS: Adult male Fischer-344 rats grouped as: i) Untreated rats: TPBIA was administered i.p. in various doses ii) Apomorphine-treated rats: were treated with apomorphine (1 mg kg(-1), i.p.) 10 min after the administration of TPBIA. Afterwards the rats were placed individually in the activity cage and their motor behaviour was recorded for the next 30 min The antioxidant potential of TPBIA was investigated in the model of in vitro non enzymatic lipid peroxidation. RESULTS: i) In non-pretreated rats, TPBIA reduces the activity by 39 and 82% respectively, ii) In apomorphine pretreated rats, TPBIA reverses the hyperactivity and stereotype behaviour induced by apomorphine. Also TPBIA completely inhibits the peroxidation of rat liver microsome preparations at concentrations of 0.5, 0.25 and 0.1 mM. CONCLUSION: TPBIA exerts dopamine antagonistic activity in the central nervous system. In addition, its antioxidant effect is a desirable property, since TD has been partially attributed, to oxidative stress. Further research is needed to test whether TPBIA may be used as an antipsychotic agent

The Picard-Fuchs equations for complete hyperelliptic integrals of even order curves, and the actions of the generalized Neumann system

We consider a family of genus 2 hyperelliptic curves of even order and obtain explicitly the systems of 5 linear ordinary differential equations for periods of the corresponding Abelian integrals of first, second, and third kind, as functions of some parameters of the curves. The systems can be regarded as extensions of the well-studied Picard-Fuchs equations for periods of complete integrals of first and second kind on odd hyperelliptic curves. The periods we consider are linear combinations of the action variables of several integrable systems, in particular the generalized Neumann system with polynomial separable potentials. Thus the solutions of the extended Picard-Fuchs equations can be used to study various properties of the actions. (C) 2014 AIP Publishing LLC.Peer ReviewedPostprint (published version

Kinetics of Extracellular ATP from Goldfish Hepatocytes: A Lesson from Mathematical Modeling

In goldfish hepatocytes, hypotonic exposure leads to cell swelling, followed by a compensatory shrinkage termed RVD. It has been previously shown that ATP is accumulated in the extracellular medium of swollen cells in a non-linear fashion, and that extracellular ATP (ATPe) is an essential intermediate to trigger RVD. Thus, to understand how RVD proceeds in goldfish hepatocytes, we developed two mathematical models accounting for the experimental ATPe kinetics reported recently by Pafundo et al. in Am. J. Physiol. 294, R220–R233, 2008. Four different equations for ATPe fluxes were built to account for the release of ATP by lytic (JL) and nonlytic mechanisms (JNL), ATPe diffusion (JD), and ATPe consumption by ectonucleotidases (JV). Particular focus was given to JNL, defined as the product of a time function (JR) and a positive feedback mechanism whereby ATPe amplifies JNL. Several JR functions (Constant, Step, Impulse, Gaussian, and Lognormal) were studied. Models were tested without (model 1) or with (model 2) diffusion of ATPe. Mathematical analysis allowed us to get a general expression for each of the models. Subsequently, by using model dependent fit (simulations) as well as model analysis at infinite time, we observed that: – use of JD does not lead to improvements of the models. – Constant and Step time functions are only applicable when JR = 0 (and thus, JNL = 0), so that the only source of ATPe would be JL, a result incompatible with experimental data. – use of impulse, Gaussian, and lognormal JRs in the models led to reasonable good fits to experimental data, with the lognormal function in model 1 providing the best option. Finally, the predictive nature of model 1 loaded with a lognormal JR was tested by simulating different putative in vivo scenarios where JV; and JNL; were varied over ample ranges.Facultad de Ciencias ExactasInstituto de Física de Líquidos y Sistemas Biológico