The distribution of important forest trees of the United States

Information on the range and distribution of forest trees has far-reaching practical usefulness in addition to its value to botanists, naturalists, teachers, and others whose work or interests are with trees. It is a valuable tool for the forester, the lumberman, and the manufacturer in search of raw materials. It is an essential element in erosion and flood control operations, and in land-use planning. Indeed, present trends toward better planning and integration of land use are directing increased attention to forest cover, the species represented in it, and the possibilities of enlarging the contribution of forest land to community welfare. In some cases the occurrence of certain species in a region may assume major importance in such planning. It is the purpose of this publication to make readily accessible the information available in the Forest Service on the distribution of important forest trees.Gerald W. Williams Collectio

N-learners problem: Fusion of concepts

We are given N learners each capable of learning concepts (subsets) of a domain set X in the sense of Valiant, i.e. for any c {element of} C {improper subset} 2{sup X}, given a finite set of examples of the form ; ;...; generated according to an unknown probability distribution P{sub X} on X, each learner produces a close approximation to c with a high probability. We are interested in combining the N learners using a single fuser or consolidator. We consider the paradigm of passive fusion, where each learner is first trained with the sample without the influence of the consolidator. The composite system is constituted by the fuser and the individual learners. We consider two cases: open and closed fusion. In open fusion the fuser is given the sample and the hypotheses of the individual learners; we show that the fusion rule can be obtained by formulating this problem as another learning problem. For the case all individual learners are trained with the same sample, we show sufficiency conditions that ensure the composite system to be better than the best of the individual: the hypothesis space of the consolidator (a) satisfies the isolation property of degree at least N, and (b) has Vapnik-Chervonenkis dimension less than or equal to that of every individual learner. If individual learners are trained by independently generated samples, we obtain a much weaker bound on the VC-dimension of the hypothesis space of the fuser. Second, in closed fusion the fuser does not have an access to either the training sample or the hypotheses of the individual learners. By suitable designing a linear threshold function of the outputs of individual learners, we show that the composite system can be made better than the best of the learners

Duration and urgency of transfer in births planned at home and in freestanding midwifery units in England: secondary analysis of the Birthplace national prospective cohort study

Background: In England, there is a policy of offering healthy women with straightforward pregnancies a choice of birth setting. Options may include home or a freestanding midwifery unit (FMU). Transfer rates from these settings are around 20%, and higher for nulliparous women. The duration of transfer is of interest because of the potential for delay in access to specialist care and is also of concern to women. We aimed to estimate the duration of transfer in births planned at home and in FMUs and explore the effects of distance and urgency on duration. Methods: This was a secondary analysis of data collected in a national prospective cohort study including 27,842 ‘low risk’ women with singleton, term, ‘booked’ pregnancies, planning birth in FMUs or at home in England from April 2008 to April 2010. We described transfer duration using the median and interquartile range, for all transfers and those for reasons defined as potentially urgent or non-urgent, and used cumulative distribution curves to compare transfer duration by urgency. We explored the effect of distance for transfers from FMUs and described outcomes in women giving birth within 60 minutes of transfer. Results: The median overall transfer time, from decision to transfer to first OU assessment, was shorter in transfers from home compared with transfers from FMUs (49 vs 60 minutes; p < 0.001). The median duration of transfers before birth for potentially urgent reasons (home 42 minutes, FMU 50 minutes) was 8–10 minutes shorter compared with transfers for non-urgent reasons. In transfers for potentially urgent reasons, the median overall transfer time from FMUs within 20 km of an OU was 47 minutes, increasing to 55 minutes from FMUs 20-40 km away and 61 minutes in more remote FMUs. In women who gave birth within 60 minutes after transfer, adverse neonatal outcomes occurred in 1-2% of transfers. Conclusions: Transfers from home or FMU commonly take up to 60 minutes from decision to transfer, to first assessment in an OU, even for transfers for potentially urgent reasons. Most transfers are not urgent and emergencies and adverse outcomes are uncommon, but urgent transfer is more likely for nulliparous women

How should beta-diversity inform biodiversity conservation?

To design robust protected area networks, accurately measure species losses, or understand the processes that maintain species diversity, conservation science must consider the organization of biodiversity in space. Central is beta-diversity - the component of regional diversity that accumulates from compositional differences between local species assemblages. We review how beta-diversity is impacted by human activities, including farming, selective logging, urbanization, species invasions, overhunting, and climate change. Beta-diversity increases, decreases, or remains unchanged by these impacts, depending on the balance of processes that cause species composition to become more different (biotic heterogenization) or more similar (biotic homogenization) between sites. While maintaining high beta-diversity is not always a desirable conservation outcome, understanding beta-diversity is essential for protecting regional diversity and can directly assist conservation planning. Beta-diversity reveals the spatial scaling of diversity loss.Beta-diversity illuminates mechanisms of regional diversity maintenance.Human activities cause beta-diversity to increase, decrease, or remain unchanged.Conservation significance of beta-diversity shift depends on local diversity dynamics

How effective are on-farm conservation land management strategies for preserving ecosystem services in developing countries? A systematic map protocol

Background An extensive body of literature in the field of agro-ecology claims to show the positive effects that maintenance of ecosystem services can have on sustainably meeting future food demand, by making farms more productive and resilient, and contributing to better nutrition and livelihoods of farmers. In Africa alone, some research has estimated a two-fold yield increase if food producers capitalize on new and existing knowledge from science and technology. Site-specific strategies adopted with the aim of improving ecosystem services may incorporate principles of multifunctional agriculture, sustainable intensification and conservation agriculture. However, a coherent synthesis and review of the evidence of these claims is largely absent, and the quality of much of this literature is questionable. Moreover, inconsistent effects have commonly been reported, while empirical evidence to support assumed improvements is largely lacking. Objectives This systematic map is stimulated by an interest to (1) collate evidence on the effectiveness of on-farm conservation land management for preserving and enhancing ecosystem services in agricultural landscapes, by drawing together the currently fragmented and multidisciplinary literature base, and (2) geographically map what indicators have been used to assess on-farm conservation land management. For both questions, we will focus on 74 low-income and developing countries, where much of the world’s agricultural expansion is occurring, yet 80% of arable land is already used and croplands are yielding well below their potential. Methods/Design To this end, reviewers will systematically search bibliographic databases for peer-reviewed research from Web of Science, SCOPUS, AGRICOLA, AGRIS databases and CAB abstracts, and grey literature from Google Scholar, and 22 subject-specific or institutional websites. Boolean search operators will be used to create search strings where applicable. Ecosystem services included in the study are pollination services; pest-, carbon-, soil-, and water-regulation; nutrient cycling; medicinal and aromatic plants; fuel wood and cultural services. Outputs of the systematic map will include a database, technical report and an online interactive map, searchable by topic. The results of this map are expected to provide clarity about synergistic outcomes of conservation land management, which will help support local decision-making

Ultrafast laser micro-nano structuring of transparent materials with high aspect ratio

Ultrafast lasers are ideal tools to process transparent materials because they spatially confine the deposition of laser energy within the material's bulk via nonlinear photoionization processes. Nonlinear propagation and filamentation were initially regarded as deleterious effects. But in the last decade, they turned out to be benefits to control energy deposition over long distances. These effects create very high aspect ratio structures which have found a number of important applications, particularly for glass separation with non-ablative techniques. This chapter reviews the developments of in-volume ultrafast laser processing of transparent materials. We discuss the basic physics of the processes, characterization means, filamentation of Gaussian and Bessel beams and provide an overview of present applications