168 research outputs found
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
Get PDFA new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
Global, regional, national, and selected subnational levels of stillbirths, neonatal, infant, and under-5 mortality, 1980�2015: a systematic analysis for the Global Burden of Disease Study 2015
Get PDFBackground Established in 2000, Millennium Development Goal 4 (MDG4) catalysed extraordinary political, financial, and social commitments to reduce under-5 mortality by two-thirds between 1990 and 2015. At the country level, the pace of progress in improving child survival has varied markedly, highlighting a crucial need to further examine potential drivers of accelerated or slowed decreases in child mortality. The Global Burden of Disease 2015 Study (GBD 2015) provides an analytical framework to comprehensively assess these trends for under-5 mortality, age-specific and cause-specific mortality among children under 5 years, and stillbirths by geography over time. Methods Drawing from analytical approaches developed and refined in previous iterations of the GBD study, we generated updated estimates of child mortality by age group (neonatal, post-neonatal, ages 1�4 years, and under 5) for 195 countries and territories and selected subnational geographies, from 1980�2015. We also estimated numbers and rates of stillbirths for these geographies and years. Gaussian process regression with data source adjustments for sampling and non-sampling bias was applied to synthesise input data for under-5 mortality for each geography. Age-specific mortality estimates were generated through a two-stage age�sex splitting process, and stillbirth estimates were produced with a mixed-effects model, which accounted for variable stillbirth definitions and data source-specific biases. For GBD 2015, we did a series of novel analyses to systematically quantify the drivers of trends in child mortality across geographies. First, we assessed observed and expected levels and annualised rates of decrease for under-5 mortality and stillbirths as they related to the Soci-demographic Index (SDI). Second, we examined the ratio of recorded and expected levels of child mortality, on the basis of SDI, across geographies, as well as differences in recorded and expected annualised rates of change for under-5 mortality. Third, we analysed levels and cause compositions of under-5 mortality, across time and geographies, as they related to rising SDI. Finally, we decomposed the changes in under-5 mortality to changes in SDI at the global level, as well as changes in leading causes of under-5 deaths for countries and territories. We documented each step of the GBD 2015 child mortality estimation process, as well as data sources, in accordance with the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). Findings Globally, 5·8 million (95 uncertainty interval UI 5·7�6·0) children younger than 5 years died in 2015, representing a 52·0% (95% UI 50·7�53·3) decrease in the number of under-5 deaths since 1990. Neonatal deaths and stillbirths fell at a slower pace since 1990, decreasing by 42·4% (41·3�43·6) to 2·6 million (2·6�2·7) neonatal deaths and 47·0% (35·1�57·0) to 2·1 million (1·8-2·5) stillbirths in 2015. Between 1990 and 2015, global under-5 mortality decreased at an annualised rate of decrease of 3·0% (2·6�3·3), falling short of the 4·4% annualised rate of decrease required to achieve MDG4. During this time, 58 countries met or exceeded the pace of progress required to meet MDG4. Between 2000, the year MDG4 was formally enacted, and 2015, 28 additional countries that did not achieve the 4·4% rate of decrease from 1990 met the MDG4 pace of decrease. However, absolute levels of under-5 mortality remained high in many countries, with 11 countries still recording rates exceeding 100 per 1000 livebirths in 2015. Marked decreases in under-5 deaths due to a number of communicable diseases, including lower respiratory infections, diarrhoeal diseases, measles, and malaria, accounted for much of the progress in lowering overall under-5 mortality in low-income countries. Compared with gains achieved for infectious diseases and nutritional deficiencies, the persisting toll of neonatal conditions and congenital anomalies on child survival became evident, especially in low-income and low-middle-income countries. We found sizeable heterogeneities in comparing observed and expected rates of under-5 mortality, as well as differences in observed and expected rates of change for under-5 mortality. At the global level, we recorded a divergence in observed and expected levels of under-5 mortality starting in 2000, with the observed trend falling much faster than what was expected based on SDI through 2015. Between 2000 and 2015, the world recorded 10·3 million fewer under-5 deaths than expected on the basis of improving SDI alone. Interpretation Gains in child survival have been large, widespread, and in many places in the world, faster than what was anticipated based on improving levels of development. Yet some countries, particularly in sub-Saharan Africa, still had high rates of under-5 mortality in 2015. Unless these countries are able to accelerate reductions in child deaths at an extraordinary pace, their achievement of proposed SDG targets is unlikely. Improving the evidence base on drivers that might hasten the pace of progress for child survival, ranging from cost-effective intervention packages to innovative financing mechanisms, is vital to charting the pathways for ultimately ending preventable child deaths by 2030. Funding Bill & Melinda Gates Foundation. © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license
Applied linguistic approach to discourse analysis
Get PDFThis study is intended as an exercise in applied
linguistics. Its purpose is to explore work done on the
description of language use for insights which might be
developed and exploited for the preparation of language
teaching materials, in particular for those learners of
English who need the language for the furtherance of their
specialist studies. Chapter 1 establishes this applied
linguistic perspective.
Chapter 2 examines what is involved in delimiting the
scope of grammatical statement and looks at the ontological
and heuristic validity of the langue/parole dichotomy.
This prepares the ground for a consideration, in the two
chapters which follow, of attempts to extend the scope of
linguistic description by redrawing the lines of idealization
to include variation and context. Chapter 3 surveys attempts
to characterize language varieties in terms of their formal
properties and introduces a distinction between usage, de¬
fined as the exemplification of linguistic forms, and use,
defined as the communicative function these forms are used
to fulfil. This distinction is developed further in
Chapter 4 in which text analysis is distinguished from dis¬
course analysis, the former having to do with cohesion, or
sentence linkage, and the latter with coherence, or the
manner in which utterances are related to each other as
communicative acts. This leads in to the discussion of the
relationship between sentences and utterances in Chapter 5,
which deals with the problems involved in attempting to
account for language use in grammatical terms, and which establishes discourse as a pragmatic rather than a semantic
matter.
Chapters 6-8 represent a development of the approach
to discourse which emerges from the preceding chapters.
Chapter 6 introduces the key notion of rhetorical value,
which is defined as the meaning which attaches to linguistic
forms when they occur mutually conditioned in contexts of
actual use. Value is contrasted with signification, which
is the meaning that linguistic forms have as elements of
the language code. The two notions are discussed in relation
to the sentence/utterance distinction and it is proposed
that both of these should be distinguished from the locution,
which is defined as the representation of a potential
utterance, as distinct from a sentence which is defined as
an exemplification of grammatical rules. Whereas Chapter 6
illustrates how value is realized with reference to lexical
items, Chapter 7 shows how it is realized through locutions
to create different illocutionary acts in a discourse, and
the illocutionary act of explanation is discussed in some
detail. The second half of this chapter is devoted to a
specimen analysis which is intended as an illustration of
the approach to discourse analysis that is being proposed.
In Chapter 6 the notion of value is applied to linguistic
elements corresponding to the terminal symbols of a
generative grammar and in Chapter 7 it is applied to those
corresponding to the initial symbol. Chapter 8 now relates
the notion to linguistic elements which correspond to the
non-terminal symbols representing sentence constituents which are subject to transformational operations. Trans¬
formational rules are shown as essentially rhetorical
devices for creating ambiguity by dissociating locutions
from specific deep structure sources and by thus providing
them with a freedom to take on whichever value is appropriate
in the context.
Chapter 9 is a restatement of the principles of dis¬
course analysis which this study has aimed at establishing
and suggests how the approach that has been outlined
corresponds to other approaches to discourse analysis in¬
formed by linguistic, sociological and sociolinguistic
orientations to the description of language use. The final
chapter is concerned with pedagogic application. It shows
how the signification/value distinction relates to
situational and notional approaches to language teaching.
It further shows how the insights discovered and developed
in this study might be exploited by providing examples of
exercises which are based on the same rhetorical principles
as those which, it has been argued, must be applied in a
satisfactory analysis of discourse
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