2,382 research outputs found
Regional Patterns in the Achievement of the Lisbon Strategy: a Comparison Between Polycentric Regions and Monocentric Ones
Polycentrism is a common feature of European urban systems. Lately, the concept has assumed a more normative relevance and it has been often considered as a pre?requisite for a more sustainable and balanced development across Europe. However, the effects of polycentrism on other main European Strategies (such as the Lisbon Strategy, aimed at increasing European competitiveness and social cohesion) are not so clear. Therefore, the paper tries to highlight the relationships between a regional polycentric development and the achievement of the Lisbon Strategyâs targets. Referring to a sample of 75 regions belonging to France, Germany, Italy and Spain, we have first measured the extent of polycentrism, by estimating through OLS the slope of the rank-size distribution of cities within each region. Then, we have performed a principal component analysis (PCA) in order to highlight the main features characterising the performance of each region according to Lisbon Strategyâs targets. Looking at the correlations between the extent of polycentrism and the achievement of the Lisbon Strategyâs targets, we have found that the former is significantly correlated both with the spread of manufacture and with low investments in human capital and innovationthe Lisbon Strategy, polycentrism, rank-size distribution, PCA
Nesting ecology of a neotropical solitary wasp (Hymenoptera: Sphecidae) in PanamĂĄ
Cerceris is a very interesting genus, providing species living in all continents, in different climatic conditions, showing behaviors ranging from solitary to social. About the nesting habit of this genus, many authors described nest characteristics and prey, providing useful material for comparison. Yet, the majority of species studied so far live in temperate regions and we lack information about the tropical ones. The high number of species and their wide distribution suggest a phylogenetic adaptability that merit to be studied deeper. I investigated nest and prey of a tropical species, Cerceris binodis Spinola, on Barro Colorado Nature Monument in PanamĂĄ. The study was performed during three dry seasons, marking and excavating nests, observing individual's behavior and collecting prey. The nests, reused over the same season and in following years, are especially deep as observed only in another neotropical species, Cerceris lutzi Scullen . This result could be correlated with tropical soils depth and characteristics. In spite of the species being sexually dimorphic, the subterranean cells show no bimodality in size or content. Prey, identified from specimens carried by provisioning females, belongs to Clytrinae (Coleoptera: Chrysomelidae). Quantitative data on prey are analyzed comparing seasons and sites and differences emerged. Cerceris adaptability to ecological trait of the tropics is inferred to explain these differences as well as the ones observed in the nest structure. Cerceris Ă© um gĂȘnero bastante interessante, cujas espĂ©cies estĂŁo presentes em todos os continentes, em diferentes condiçÔes climĂĄticas, mostrando comportamentos variando do solitĂĄrio ao social. Com relação ao hĂĄbito de nidificação desse gĂȘnero, muitos autores descreveram as caracterĂsticas do ninho e das presas, provendo material Ăștil para comparaçÔes. AlĂ©m disso, a maioria das espĂ©cies estudadas atĂ© agora vivem em regiĂ”es temperadas e faltam informaçÔes sobre as tropicais. O grande nĂșmero de espĂ©cies e sua ampla distribuição sugerem uma adaptabilidade filogenĂ©tica que merece ser estudada mais profundamente. Neste trabalho foram investigados o ninho e a presa da espĂ©cie tropical Cerceris binodis Spinola, no Barro Colorado Natural Monument no PanamĂĄ. O estudo foi realizado durante trĂȘs estaçÔes secas, marcando e escavando os ninhos, observando o comportamento dos indivĂduos e coletando a presa. Os ninhos, reutilizados na mesma estação e nos anos seguintes, sĂŁo especialmente profundos, como observados somente em outra espĂ©cie neotropical, Cerceris lutzi Scullen. Esse resultado pode ser correlacionado com a profundidade de solos tropicais e suas caracterĂsticas. Apesar de as espĂ©cies apresentarem dimorfismo sexual, as celas subterrĂąneas nĂŁo mostram diferenças no tamanho ou no seu conteĂșdo. A presa, identificada dos espĂ©cimes carregados pelas fĂȘmeas provedoras, pertencem a Clytrinae (Coleoptera: Chrysomelidae). Os dados quantitativos sobre a presa foram analisados por comparação das estaçÔes e locais, evidenciando as diferenças. Infere-se que a adaptabilidade de Cerceris Ă s caracterĂsticas ecolĂłgicas dos trĂłpicos pode explicar essas diferenças assim como as observadas na estrutura do ninho
Life History Trade-offs Between Growth and Reproduction in Wild Yeast
Life history trade-offs are an organism\u27s balancing of energy allocations to necessary strategies of life: growth, reproduction, and survival. The success of a life history strategy depends on both the environment and the developmental constraints of an organism. The yeast Saccharomyces cerevisiae is an ideal organism to investigate microbial life history trade-offs. Since these yeast are found in a variety of environments with niche-specific strategies and the S. cerevisiae life cycle involves both sexual and asexual phases, I expected to see a life history trade-off between growth and reproduction within and between populations of yeast. A strain more efficient at mating should be a slower grower while a slow mater should proceed through the cell cycle quicker. To study this trade-off, I measured the relative rates of mating and asexual growth. I found a significant difference in both the speed of sexual and asexual reproduction within a single population as well as between populations from different environments. The results presented here are still preliminary, as the assays used to measure the relevant life history traits were prone to experimental error. Given that caveat, within the woodland population of yeast, which represents three distinct haplotypes, there appears to be an inverse relationship between the length of the cell cycle and the rate of mating, indicating a trade-off between the efficiency of each strategy. No pattern was found in strains of other ecotypes
Deposit formation and heat transfer in hydrocarbon rocket fuels
An experimental research program was undertaken to investigate the thermal stability and heat transfer characteristics of several hydrocarbon fuels under conditions that simulate high-pressure, rocket engine cooling systems. The rates of carbon deposition in heated copper and nickel-plated copper tubes were determined for RP-1, propane, and natural gas using a continuous flow test apparatus which permitted independent variation and evaluation of the effect on deposit formation of wall temperature, fuel pressure, and fuel velocity. In addition, the effects of fuel additives and contaminants, cryogenic fuel temperatures, and extended duration testing with intermittent operation were examined. Parametric tests to map the thermal stability characteristics of RP-1, commercial-grade propane, and natural gas were conducted at pressures of 6.9 to 13.8 MPa, bulk fuel velocities of 30 to 90 m/s, and tube wall temperatures in the range of 230 to 810 K. Also, tests were run in which propane and natural gas fuels were chilled to 230 and 160 K, respectively. Corrosion of the copper tube surface was detected for all fuels tested. Plating the inside of the copper tubes with nickel reduced deposit formation and eliminated tube corrosion in most cases. The lowest rates of carbon deposition were obtained for natural gas, and the highest rates were obtained for propane. For all fuels tested, the forced-convection heat transfer film coefficients were satisfactorily correlated using a Nusselt-Reynolds-Prandtl number equation
A precision measurement of the lifetime of the positive muon
In an experiment performed at TRIUMF Laboratory, the time distribution of muon decay positrons arising from pions stopped in a water Cherenkov counter was measured with a high precision timing system. The pions served as a source of positive muons.;The data were used to determine a new value for the positive muon lifetime. This lifetime 2.19695 (+OR-) .00006 (sec) is slightly lower than previous measurements but still in fair agreement. The data were tested for the various systematic effects that typically occur in these measurements
Toward a Supernatural Biblical Hermeneutic
Many people who live and learn in the west, including Christian laity and scholars, inadvertently accept a materialistic cosmology in which the material world is all that exists, with the exception of God. This perspective is contrary to how the majority of ancient and modern people view the world. This essay seeks to analyze how this materialistic worldview is seen in biblical studies, and then proposes that biblical scholars should presuppose a supernatural worldview as a key aspect of their hermeneutics
First Steps Toward Change in Teacher Preparation for Elementary Science
Unless introductory undergraduate science classes for prospective elementary teachers actively incorporate the philosophy of inquiry-based learning called for in K-l2 science education refom little will change in elementary science education. Thus, at James Madison University, we have developed a new integrated science core curriculum called Understanding our World [1]. This course sequence was not only designed to fulïŹll general education science requirements. but also to focus on content areas our students will need to know as teachers. The objectives of these courses are based on the National Science Education Standards and Virginiaâs Science Standards of Learning, including earth and space science, chemistry, physics, life sciences, and environmental science [2,3]. As an integrated package, this course sequence addresses basic science content, calculation skills, the philosophy and history of science, the process of how science is done, the role of science in society, and applications of computers and technology in science. Keeping in mind that students tend to teach in the same way they were taught, Understanding our World core classes embrace the concepts associated with reform in elementary math and science
Adjustment of Refugees in Greece as a Social Identity Process: A Longitudinal Study
Many refugees moving into Greece and other European countries often struggle to adjust to their new life. Over and above other factors, social isolation seems to be a major contributor in their poor adjustment outcomes, yet the underlying psychological mechanisms of their links are not well understood. Based on the Social Identity Model of Identity Change, we conceptualized refugeesâ adjustment as a major life transition that depends on (i) the maintenance of existing pre-migratory group memberships (social identity continuity pathway), (ii) the development of new post-migratory social identities (social identity gain pathway), and (iii) the perceived compatibility between pre- and post-migratory identities. Belonging to multiple groups before displacement should facilitate both pathways. To test this idea, a longitudinal study with two measurement points over four months was conducted. The sample consisted of 60 asylum seekers in Greece. Using multilevel modeling, we found that social identity continuity and gain were positively related to socio-cultural adjustment, health-related adjustment, and well-being. Adjustment outcomes at Time 2 were predicted by the levels of social identity continuity at Time 1, and by group memberships before displacement through the two pathways at Time 1. Significant interactions also emerged between perceived compatibility and the two pathways. In general, the findings are consistent with SIMICâs theorizing suggesting that to understand refugeesâ adjustment in host countries, it is important to systematically consider the social identity processes that unfold over time
Self-supervised learning: When is fusion of the primary and secondary sensor cue useful?
Self-supervised learning (SSL) is a reliable learning mechanism in which a
robot enhances its perceptual capabilities. Typically, in SSL a trusted,
primary sensor cue provides supervised training data to a secondary sensor cue.
In this article, a theoretical analysis is performed on the fusion of the
primary and secondary cue in a minimal model of SSL. A proof is provided that
determines the specific conditions under which it is favorable to perform
fusion. In short, it is favorable when (i) the prior on the target value is
strong or (ii) the secondary cue is sufficiently accurate. The theoretical
findings are validated with computational experiments. Subsequently, a
real-world case study is performed to investigate if fusion in SSL is also
beneficial when assumptions of the minimal model are not met. In particular, a
flying robot learns to map pressure measurements to sonar height measurements
and then fuses the two, resulting in better height estimation. Fusion is also
beneficial in the opposite case, when pressure is the primary cue. The analysis
and results are encouraging to study SSL fusion also for other robots and
sensors
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