1,138 research outputs found
Fine-sediment dispersal in the Gulf of San Miguel, western Gulf of Panama: A reconnaissance
The Gulf of San Miguel, 30 km wide at its mouth and extending 40 km inland, is the estuary of river systems that drain eastern Panama. The Gulf consists of a central scour channel up to 36 m deep, flanked by semicircular bays. The tide has a range of up to 7 m, and maximum surface tidal currents average 200 cm/sec on the flood tide and 230 cm/sec on the ebb tide...
On the influence of tree size on the climate–growth relationship of New Zealand kauri (Agathis australis): insights from annual, monthly and daily growth patterns
Many tree-ring-based climate reconstructions are based on the assumption that the climate reaction of trees is independent of their size. Here, we test this assumption for New Zealand kauri (Agathis australis), one of the longest tree ring-based proxies for the El Niño-Southern Oscillation (ENSO). The most recent kauri chronology contains a large amount of archaeological material, e.g. timber for which the original tree size is often unknown. We analyzed the climate–growth relationship of different-sized kauri in a pristine forest using different temporal scales, i.e. annually, monthly and daily data on tree growth and climate conditions. Trees of different life stages exhibited approximately the same seasonal growth peaks during austral spring (October and November). The dormancy period overlaps with the period where weekly air temperature maxima are below ca. 17–18 °C, and where the corresponding daily minima are below ca. 8 °C. However, both correlation functions between annual growth and seasonal climate as well as Kalman filter regressions between daily growth and climate conditions suggest an influence of tree size on the climate–growth relationship for kauri. Smaller trees (DBH < 40 cm) contain weaker climate signals than larger trees. Therefore, the precautionary stripping of near-pith material (first 20 cm) from kauri chronologies may result in more uniform responses to climate forcing and thus enhance the reliability of long-term climate reconstructions
Population, sexual and reproductive health, rights and sustainable development: forging a common agenda.
This article suggests that sexual and reproductive health and rights activists seeking to influence the post-2015 international development paradigm must work with sustainable development advocates concerned with a range of issues, including climate change, environmental issues, and food and water security, and that a way of building bridges with these communities is to demonstrate how sexual and reproductive health and rights are relevant for these issues. An understanding of population dynamics, including urbanization and migration, as well as population growth, can help to clarify these links. This article therefore suggests that whether or not sexual and reproductive health and rights activists can overcome resistance to discussing "population", become more knowledgeable about other sustainable development issues, and work with others in those fields to advance the global sustainable development agenda are crucial questions for the coming months. The article also contends that it is possible to care about population dynamics (including ageing and problems faced by countries with a high proportion of young people) and care about human rights at the same time. It expresses concern that, if sexual and reproductive health and rights advocates do not participate in the population dynamics discourse, the field will be left free for those for whom respecting and protecting rights may be less of a priority
Effect of increasing fruit and vegetable intake by dietary intervention on nutritional biomarkers and attitudes to dietary change : a randomised trial
This work was funded by The Scottish Government Rural and Environmental Science and Analytical Sciences Division (RESAS) and supported by the Rank Prize Funds.Peer reviewedPublisher PD
Annonaceae substitution rates - a codon model perspective
The Annonaceae includes cultivated species of economic interest and represents an important source of information for better understanding the evolution of tropical rainforests. In phylogenetic analyses of DNA sequence data that are used to address evolutionary questions, it is imperative to use appropriate statistical models. Annonaceae are cases in point: Two sister clades, the subfamilies Annonoideae and Malmeoideae, contain the majority of Annonaceae species diversity. The Annonoideae generally show a greater degree of sequence divergence compared to the Malmeoideae, resulting in stark differences in branch lengths in phylogenetic trees. Uncertainty in how to interpret and analyse these differences has led to inconsistent results when estimating the ages of clades in Annonaceae using molecular dating techniques. We ask whether these differences may be attributed to inappropriate modelling assumptions in the phylogenetic analyses. Specifically, we test for (clade-specific) differences in rates of non-synonymous and synonymous substitutions. A high ratio of nonsynonymous to synonymous substitutions may lead to similarity of DNA sequences due to convergence instead of common ancestry, and as a result confound phylogenetic analyses. We use a dataset of three chloroplast genes (rbcL, matK, ndhF) for 129 species representative of the family. We find that differences in branch lengths between major clades are not attributable to different rates of non-synonymous and synonymous substitutions. The differences in evolutionary rate between the major clades of Annonaceae pose a challenge for current molecular dating techniques that should be seen as a warning for the interpretation of such results in other organisms
Uninterested youth? Young people's attitudes towards party politics in Britain
Following the outcome of the 2001 and 2005 General Elections, when the numbers of abstainers outweighed the numbers of Labour voters on both occasions, much attention has focused upon the state of British democracy and how to enthuse the electorate, especially young people. While the government is exploring ways to make the whole process of voting easier, it may be failing to tackle the real problem - that youth appear to find the business of politics uninviting and irrelevant. This paper examines data derived from a nationwide survey of over 700 young people in order to shed light on what lies at the heart of young people's apparent disengagement from formal politics in Britain - political apathy or a sense of political alienation. The findings reveal that they support the democratic process, but are sceptical of the way the British political system is organised and led, and are turned off by politicians and the political parties. However, there is no uniform youth orientation to politics, and the data indicate that views differ according to social class, educational history, and also gender. However both ethnicity and region of the country in which young people live seem to have little influence in structuring political attitudes and behaviour
Justifications-on-demand as a device to promote shifts of attention associated with relational thinking in elementary arithmetic
Student responses to arithmetical questions that can be solved by using arithmetical structure can serve to reveal the extent and nature of relational, as opposed to computational thinking. Here, student responses to probes which require them to justify-on-demand are analysed using a conceptual framework which highlights distinctions between different forms of attention. We analyse a number of actions observed in students in terms of forms of attention and shifts between them: in the short-term (in the moment), medium-term (over several tasks), and long-term (over a year). The main factors conditioning students´ attention and its movement are identified and some didactical consequences are proposed
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