2,169 research outputs found
Evidence for dark matter in the inner Milky Way
The ubiquitous presence of dark matter in the universe is today a central
tenet in modern cosmology and astrophysics. Ranging from the smallest galaxies
to the observable universe, the evidence for dark matter is compelling in
dwarfs, spiral galaxies, galaxy clusters as well as at cosmological scales.
However, it has been historically difficult to pin down the dark matter
contribution to the total mass density in the Milky Way, particularly in the
innermost regions of the Galaxy and in the solar neighbourhood. Here we present
an up-to-date compilation of Milky Way rotation curve measurements, and compare
it with state-of-the-art baryonic mass distribution models. We show that
current data strongly disfavour baryons as the sole contribution to the
galactic mass budget, even inside the solar circle. Our findings demonstrate
the existence of dark matter in the inner Galaxy while making no assumptions on
its distribution. We anticipate that this result will compel new
model-independent constraints on the dark matter local density and profile,
thus reducing uncertainties on direct and indirect dark matter searches, and
will shed new light on the structure and evolution of the Galaxy.Comment: First submitted version of letter published in Nature Physics on
Febuary 9, 2015:
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3237.htm
Assessment of a self-reported Drinks Diary for the estimation of drinks intake by care home residents: Fluid Intake Study in the Elderly (FISE)
Objectives: We evaluated the accuracy of a newly developed self-completed Drinks Diary in care home residents and compared it with direct observation and fluid intake charts. Design: Observational study. Setting: Residential care homes in Norfolk, UK. Participants: 22 elderly people (18 women, mean age 86.6 years SD 8.6, 12 with MMSE scores <27). Measurements: Participants recorded their own drinks intake over 24 hours using the Drinks Diary while care staff used the homes’ usual fluid intake chart to record drinks intake. These records were compared with drinks intake assessed by researcher direct observation (reference method), during waking hours (6am to 10pm), while drinks taken from 10pm to 6am were self-reported and checked with staff. Results: Drinks intake assessed by the Drinks Diary was highly correlated with researcher direct observation (Pearson correlation coefficient r=0.93, p<0.001, mean difference -163ml/day) while few staff-completed fluid charts were returned and correlation was low (r=0.122, p=0.818, mean difference 702ml/day). The Drinks Diary classified 19 of 22 participants correctly as drinking enough or not using both the European Food Safety Authority and US recommendations. Conclusion: The Drinks Diary estimate of drinks intake was comparable with direct observation and more accurate (and reliably completed) than staff records. The Drinks Diary can provide a reliable estimate of drinks intake in elderly care home residents physically and cognitively able to complete it. It may be useful for researchers, care staff and practitioners needing to monitor drinks intake of elderly people, to help them avoid dehydration
From a literature review to a conceptual framework for health sector websites’ assessment
Health sector institutions’ websites need to act as effective web resources of information and interactive communication mediums to address the versatile demands of their multiple stakeholders. Academic and practitioner interest in health sector website assessment has considerably risen in recent years. This can be seen by the number of papers published in journals. The purpose of this paper is twofold to further establish the field. First, it offers a literature re-view on hospitals’ websites assessment. Second, it offers a conceptual framework to address the website assessment issue in health sector. The proposed assessment framework focuses on four main criteria: content, technology, services, and participation being evaluated by the use of several indicators. Academics, hospital practitioners, public officials and users will find the review and the framework useful, as they outline major lines of research in the field and a method to assess health institution websites.This paper is a result of the project “SmartEGOV: Harnessing EGOV for Smart Governance (Foundations, methods, Tools) / NORTE-01-0145-FEDER-000037”, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (EFDR).info:eu-repo/semantics/publishedVersio
Ferritins: furnishing proteins with iron
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores and examine in detail how three selected ferritins oxidise Fe2+ in order to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins
Embodied identity as process: performativity through footwear in mid-Medieval (AD 800-1200) Northern Europe.
A strong case is made for the re-thinking of identity as a dynamic and
performative process, rather than a label. Using ideas from Wiessner and others,
the relationship between material culture and interactive processes of emulation
and rejection is refined, in a framework derived from Bourdieu (particularly
Bodily Hexis) and Goffinan (particularly Impression Management). These ideas
are explored through a rigorous study of stylistic variability in footwear from
Mid-Medieval Northern Europe. It is argued that the large amounts of footwear,
which is shaped to and marked by the wearers' bodies, are potentially rich
sources of information about the active `impression management' of the people
of the time. That the period defined for this project tends to be seen by historians
as one of timeless continuity for all but the elite, and a time when `identity' is
primordial and its substance almost archetypal, makes, it is argued, the variability
particularly worth pursuing.
18 archives are sampled and the footwear recorded in a systematic manner. These
primary sources are extended through the use of secondary sources, and
contextualised (within the limits of iconographic conventions) through the careful
and systematic quarrying of the iconography of the human body in contemporary
representations. The outcomes suggest a complex situation of change over time,
from distinct regional patterns in the 9U' century through convergence in the 10th
century which culminates in relative homogeneity in the 11th century, with
marked regional contrasts returning in the 12th century. Within this, there are
similarities and differences in preferences, which raise important questions about
links between, for example, York, Dublin and London in the 10th century, and the
interplay of consumer preference and artisan practice at the time. Timeless
continuity and primordial identity are not affirmed through the footwear, except
in particular significant contexts. In keeping with the firmly hermeneutic
approach used throughout the project, the thesis concludes with a summary of
new directions suggested by the research
Biodiversity Loss and the Taxonomic Bottleneck: Emerging Biodiversity Science
Human domination of the Earth has resulted in dramatic changes to global and local patterns of biodiversity. Biodiversity is critical to human sustainability because it drives the ecosystem services that provide the core of our life-support system. As we, the human species, are the primary factor leading to the decline in biodiversity, we need detailed information about the biodiversity and species composition of specific locations in order to understand how different species contribute to ecosystem services and how humans can sustainably conserve and manage biodiversity. Taxonomy and ecology, two fundamental sciences that generate the knowledge about biodiversity, are associated with a number of limitations that prevent them from providing the information needed to fully understand the relevance of biodiversity in its entirety for human sustainability: (1) biodiversity conservation strategies that tend to be overly focused on research and policy on a global scale with little impact on local biodiversity; (2) the small knowledge base of extant global biodiversity; (3) a lack of much-needed site-specific data on the species composition of communities in human-dominated landscapes, which hinders ecosystem management and biodiversity conservation; (4) biodiversity studies with a lack of taxonomic precision; (5) a lack of taxonomic expertise and trained taxonomists; (6) a taxonomic bottleneck in biodiversity inventory and assessment; and (7) neglect of taxonomic resources and a lack of taxonomic service infrastructure for biodiversity science. These limitations are directly related to contemporary trends in research, conservation strategies, environmental stewardship, environmental education, sustainable development, and local site-specific conservation. Today’s biological knowledge is built on the known global biodiversity, which represents barely 20% of what is currently extant (commonly accepted estimate of 10 million species) on planet Earth. Much remains unexplored and unknown, particularly in hotspots regions of Africa, South Eastern Asia, and South and Central America, including many developing or underdeveloped countries, where localized biodiversity is scarcely studied or described. ‘‘Backyard biodiversity’’, defined as local biodiversity near human habitation, refers to the natural resources and capital for ecosystem services at the grassroots level, which urgently needs to be explored, documented, and conserved as it is the backbone of sustainable economic development in these countries. Beginning with early identification and documentation of local flora and fauna, taxonomy has documented global biodiversity and natural history based on the collection of ‘‘backyard biodiversity’’ specimens worldwide. However, this branch of science suffered a continuous decline in the latter half of the twentieth century, and has now reached a point of potential demise. At present there are very few professional taxonomists and trained local parataxonomists worldwide, while the need for, and demands on, taxonomic services by conservation and resource management communities are rapidly increasing. Systematic collections, the material basis of biodiversity information, have been neglected and abandoned, particularly at institutions of higher learning. Considering the rapid increase in the human population and urbanization, human sustainability requires new conceptual and practical approaches to refocusing and energizing the study of the biodiversity that is the core of natural resources for sustainable development and biotic capital for sustaining our life-support system. In this paper we aim to document and extrapolate the essence of biodiversity, discuss the state and nature of taxonomic demise, the trends of recent biodiversity studies, and suggest reasonable approaches to a biodiversity science to facilitate the expansion of global biodiversity knowledge and to create useful data on backyard biodiversity worldwide towards human sustainability
The possibility of critical realist randomised controlled trials.
BACKGROUND: Some realists have criticised randomised controlled trials for their inability to explain the causal relations that they identify; to take into account the influence of the social context of the interventions they evaluate; and to account for individual difference. However, among realists, there is controversy over whether it is possible to improve trials by making them realist, or whether realism and the philosophical assumptions underlying trials are incompatible. This paper contributes to the debate in Trials on this issue. The debate thus far has concentrated on the possibility of combining trial methodology with that of realist evaluation. MAIN BODY: We concur with the contention that it is not feasible to combine randomised controlled trial design with the realist evaluation approach. However, we argue that a different variant of realism, critical realism, provides a more appropriate theoretical grounding for realist trials. In contrast to realist evaluation, which regards social mechanisms as an amalgam of social resources and people's reasoning, critical realism insists on their distinction. It does so on the basis of its assertion of the need to distinguish between social structures (in which resources lie) and human agency (which is at least partly guided by reasoning). From this perspective, conceiving of social mechanisms as external to participants can be seen as a valid methodological strategy for supplementing the exclusive concentration of trials on outcomes. While accepting realist evaluation's insistence that causality in open systems involves a configuration of multiple generative mechanisms, we adopt the critical realist interpretation of the experimental method, which sees it as creating artificial closure in order to identify the effects of specific causal mechanisms. If randomised controlled trials can be regarded as epidemiological proxies that substitute probabilistic controls over extraneous factors for closed experiments, their examination of the powers of discrete mechanisms through observation of the variation of outcomes is appropriate. CONCLUSION: While there are still issues to be resolved, critical realist randomised controlled trials are possible and have the potential to overcome some of the difficulties faced by traditional trial designs in accounting for the influence of social context and individual interpretation
Distances and ages of globular clusters using Hipparcos parallaxes of local subdwarfs
We discuss the impact of Population II and Globular Cluster (GCs) stars on
the derivation of the age of the Universe, and on the study of the formation
and early evolution of galaxies, our own in particular. The long-standing
problem of the actual distance scale to Population II stars and GCs is
addressed, and a variety of different methods commonly used to derive distances
to Population II stars are briefly reviewed. Emphasis is given to the
discussion of distances and ages for GCs derived using Hipparcos parallaxes of
local subdwarfs. Results obtained by different authors are slightly different,
depending on different assumptions about metallicity scale, reddenings, and
corrections for undetected binaries. These and other uncertainties present in
the method are discussed. Finally, we outline progress expected in the near
future.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles',
A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 22
pages including 3 tables and 2 postscript figures, uses Kluwer's crckapb.sty
LaTeX style file, enclose
Immune-Complex Mimics as a Molecular Platform for Adjuvant-Free Vaccine Delivery
Protein-based vaccine development faces the difficult challenge of finding robust yet non-toxic adjuvants suitable for humans. Here, using a molecular engineering approach, we have developed a molecular platform for generating self-adjuvanting immunogens that do not depend on exogenous adjuvants for induction of immune responses. These are based on the concept of Immune Complex Mimics (ICM), structures that are formed between an oligomeric antigen and a monoclonal antibody (mAb) to that antigen. In this way, the roles of antigens and antibodies within the structure of immune complexes are reversed, so that a single monoclonal antibody, rather than polyclonal sera or expensive mAb cocktails can be used. We tested this approach in the context of Mycobacterium tuberculosis (MTB) infection by linking the highly immunogenic and potentially protective Ag85B with the oligomeric Acr (alpha crystallin, HspX) antigen. When combined with an anti-Acr monoclonal antibody, the fusion protein formed ICM which bound to C1q component of the complement system and were readily taken up by antigen-presenting cells in vitro. ICM induced a strong Th1/Th2 mixed type antibody response, which was comparable to cholera toxin adjuvanted antigen, but only moderate levels of T cell proliferation and IFN-γ secretion. Unfortunately, the systemic administration of ICM did not confer statistically significant protection against intranasal MTB challenge, although a small BCG-boosting effect was observed. We conclude that ICM are capable of inducing strong humoral responses to incorporated antigens and may be a suitable vaccination approach for pathogens other than MTB, where antibody-based immunity may play a more protective role
TRY plant trait database - enhanced coverage and open access
Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
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