461 research outputs found

    Minimal Holocene retreat of large tidewater glaciers in Køge Bugt, southeast Greenland

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    Abstract Køge Bugt, in southeast Greenland, hosts three of the largest glaciers of the Greenland Ice Sheet; these have been major contributors to ice loss in the last two decades. Despite its importance, the Holocene history of this area has not been investigated. We present a 9100 year sediment core record of glaciological and oceanographic changes from analysis of foraminiferal assemblages, the abundance of ice-rafted debris, and sortable silt grain size data. Results show that ice-rafted debris accumulated constantly throughout the core; this demonstrates that glaciers in Køge Bugt remained in tidewater settings throughout the last 9100 years. This observation constrains maximum Holocene glacier retreat here to less than 6 km from present-day positions. Retreat was minimal despite oceanic and climatic conditions during the early-Holocene that were at least as warm as the present-day. The limited Holocene retreat of glaciers in Køge Bugt was controlled by the subglacial topography of the area; the steeply sloping bed allowed glaciers here to stabilise during retreat. These findings underscore the need to account for individual glacier geometry when predicting future behaviour. We anticipate that glaciers in Køge Bugt will remain in stable configurations in the near-future, despite the predicted continuation of atmospheric and oceanic warming

    Is the qualitative research interview an acceptable medium for research with palliative care patients and carers?

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    <p>Abstract</p> <p>Background</p> <p>Contradictory evidence exists about the emotional burden of participating in qualitative research for palliative care patients and carers and this raises questions about whether this type of research is ethically justified in a vulnerable population. This study aimed to investigate palliative care patients' and carers' perceptions of the benefits and problems associated with open interviews and to understand what causes distress and what is helpful about participation in a research interview.</p> <p>Methods</p> <p>A descriptive qualitative study. The data were collected in the context of two studies exploring the experiences of care of palliative care patients and carers. The interviews ended with questions about patients' and carers' thoughts on participating in the studies and whether this had been a distressing or helpful event. We used a qualitative descriptive analysis strategy generated from the interviews and the observational and interactional data obtained in the course of the study.</p> <p>Results</p> <p>The interviews were considered helpful: sharing problems was therapeutic and being able to contribute to research was empowering. However, thinking about the future was reported to be the most challenging. Consent forms were sometimes read with apprehension and being physically unable to sign was experienced as upsetting. Interviewing patients and carers separately was sometimes difficult and not always possible.</p> <p>Conclusion</p> <p>The open interview enables the perspectives of patients and carers to be heard, unfettered from the structure of closed questions. It also enables those patients or carers to take part who would be unable to participate in other study designs. The context is at least as important as the format of the research interview taking into account the relational circumstances with carers and appropriate ways of obtaining informed consent. Retrospective consent could be a solution to enhancing participants control over the interview.</p

    Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us

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    Supernova remnants (SNRs) arise from the interaction between the ejecta of a supernova (SN) explosion and the surrounding circumstellar and interstellar medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However, to understand SNRs as a whole, large samples of SNRs must be assembled and studied. Here, we describe the radio, optical, and X-ray techniques which have been used to identify and characterize almost 300 Galactic SNRs and more than 1200 extragalactic SNRs. We then discuss which types of SNRs are being found and which are not. We examine the degree to which the luminosity functions, surface-brightness distributions and multi-wavelength comparisons of the samples can be interpreted to determine the class properties of SNRs and describe efforts to establish the type of SN explosion associated with a SNR. We conclude that in order to better understand the class properties of SNRs, it is more important to study (and obtain additional data on) the SNRs in galaxies with extant samples at multiple wavelength bands than it is to obtain samples of SNRs in other galaxiesComment: Final 2016 draft of a chapter in "Handbook of Supernovae" edited by Athem W. Alsabti and Paul Murdin. Final version available at https://doi.org/10.1007/978-3-319-20794-0_90-

    Classifying nursing organization in wards in Norwegian hospitals: self-identification versus observation

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    <p>Abstract</p> <p>Background</p> <p>The organization of nursing services could be important to the quality of patient care and staff satisfaction. However, there is no universally accepted nomenclature for this organization. The objective of the current study was to classify general hospital wards based on data describing organizational practice reported by the ward nurse managers, and then to compare this classification with the name used in the wards to identify the organizational model (self-identification).</p> <p>Methods</p> <p>In a cross-sectional postal survey, 93 ward nurse managers in Norwegian hospitals responded to questions about nursing organization in their wards, and what they called their organizational models. K-means cluster analysis was used to classify the wards according to the pattern of activities attributed to the different nursing roles and discriminant analysis was used to interpret the solutions. Cross-tabulation was used to validate the solutions and to compare the classification obtained from the cluster analysis with that obtained by self-identification. The bootstrapping technique was used to assess the generalizability of the cluster solution.</p> <p>Results</p> <p>The cluster analyses produced two alternative solutions using two and three clusters, respectively. The three-cluster solution was considered to be the best representation of the organizational models: 32 team leader-dominated wards, 23 primary nurse-dominated wards and 38 wards with a hybrid or mixed organization. There was moderate correspondence between the three-cluster solution and the models obtained by self-identification. Cross-tabulation supported the empirical classification as being representative for variations in nursing service organization. Ninety-four per cent of the bootstrap replications showed the same pattern as the cluster solution in the study sample.</p> <p>Conclusions</p> <p>A meaningful classification of wards was achieved through an empirical cluster solution; this was, however, only moderately consistent with the self-identification. This empirical classification is an objective approach to variable construction and can be generally applied across Norwegian hospitals. The classification procedure used in the study could be developed into a standardized method for classifying hospital wards across health systems and over time.</p

    Lithic technological responses to Late Pleistocene glacial cycling at Pinnacle Point Site 5-6, South Africa

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    There are multiple hypotheses for human responses to glacial cycling in the Late Pleistocene, including changes in population size, interconnectedness, and mobility. Lithic technological analysis informs us of human responses to environmental change because lithic assemblage characteristics are a reflection of raw material transport, reduction, and discard behaviors that depend on hunter-gatherer social and economic decisions. Pinnacle Point Site 5-6 (PP5-6), Western Cape, South Africa is an ideal locality for examining the influence of glacial cycling on early modern human behaviors because it preserves a long sequence spanning marine isotope stages (MIS) 5, 4, and 3 and is associated with robust records of paleoenvironmental change. The analysis presented here addresses the question, what, if any, lithic assemblage traits at PP5-6 represent changing behavioral responses to the MIS 5-4-3 interglacial-glacial cycle? It statistically evaluates changes in 93 traits with no a priori assumptions about which traits may significantly associate with MIS. In contrast to other studies that claim that there is little relationship between broad-scale patterns of climate change and lithic technology, we identified the following characteristics that are associated with MIS 4: increased use of quartz, increased evidence for outcrop sources of quartzite and silcrete, increased evidence for earlier stages of reduction in silcrete, evidence for increased flaking efficiency in all raw material types, and changes in tool types and function for silcrete. Based on these results, we suggest that foragers responded to MIS 4 glacial environmental conditions at PP5-6 with increased population or group sizes, 'place provisioning', longer and/or more intense site occupations, and decreased residential mobility. Several other traits, including silcrete frequency, do not exhibit an association with MIS. Backed pieces, once they appear in the PP5-6 record during MIS 4, persist through MIS 3. Changing paleoenvironments explain some, but not all temporal technological variability at PP5-6.Social Science and Humanities Research Council of Canada; NORAM; American-Scandinavian Foundation; Fundacao para a Ciencia e Tecnologia [SFRH/BPD/73598/2010]; IGERT [DGE 0801634]; Hyde Family Foundations; Institute of Human Origins; National Science Foundation [BCS-9912465, BCS-0130713, BCS-0524087, BCS-1138073]; John Templeton Foundation to the Institute of Human Origins at Arizona State Universit

    Flexible Dye-Sensitized Solar Cell Based on Vertical ZnO Nanowire Arrays

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    Flexible dye-sensitized solar cells are fabricated using vertically aligned ZnO nanowire arrays that are transferred onto ITO-coated poly(ethylene terephthalate) substrates using a simple peel-off process. The solar cells demonstrate an energy conversion efficiency of 0.44% with good bending tolerance. This technique paves a new route for building large-scale cost-effective flexible photovoltaic and optoelectronic devices

    Targeting pathogen metabolism without collateral damage to the host

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    The development of drugs that can inactivate disease-causing cells (e.g. cancer cells or parasites) without causing collateral damage to healthy or to host cells is complicated by the fact that many proteins are very similar between organisms. Nevertheless, due to subtle, quantitative differences between the biochemical reaction networks of target cell and host, a drug can limit the flux of the same essential process in one organism more than in another. We identified precise criteria for this â €network-based' drug selectivity, which can serve as an alternative or additive to structural differences. We combined computational and experimental approaches to compare energy metabolism in the causative agent of sleeping sickness, Trypanosoma brucei, with that of human erythrocytes, and identified glucose transport and glyceraldehyde-3-phosphate dehydrogenase as the most selective antiparasitic targets. Computational predictions were validated experimentally in a novel parasite-erythrocytes co-culture system. Glucose-transport inhibitors killed trypanosomes without killing erythrocytes, neurons or liver cells

    Improving a Mother to Child HIV Transmission Programme through Health System Redesign: Quality Improvement, Protocol Adjustment and Resource Addition

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    Health systems that deliver prevention of mother to child transmission (PMTCT) services in low and middle income countries continue to underperform, resulting in thousands of unnecessary HIV infections of newborns each year. We used a combination of approaches to health systems strengthening to reduce transmission of HIV from mother to infant in a multi-facility public health system in South Africa.All primary care sites and specialized birthing centers in a resource constrained sub-district of Cape Metro District, South Africa, were enrolled in a quality improvement (QI) programme. All pregnant women receiving antenatal, intrapartum and postnatal infant care in the sub-district between January 2006 and March 2009 were included in the intervention that had a prototype-innovation phase and a rapid spread phase. System changes were introduced to help frontline healthcare workers to identify and improve performance gaps at each step of the PMTCT pathway. Improvement was facilitated and spread through the use of a Breakthrough Series Collaborative that accelerated learning and the spread of successful changes. Protocol changes and additional resources were introduced by provincial and municipal government. The proportion of HIV-exposed infants testing positive declined from 7.6% to 5%. Key intermediate PMTCT processes improved (antenatal AZT increased from 74% to 86%, PMTCT clients on HAART at the time of labour increased from 10% to 25%, intrapartum AZT increased from 43% to 84%, and postnatal HIV testing from 79% to 95%) compared to baseline.System improvement methods, protocol changes and addition/reallocation of resources contributed to improved PMTCT processes and outcomes in a resource constrained setting. The intervention requires a clear design, leadership buy-in, building local capacity to use systems improvement methods, and a reliable data system. A systems improvement approach offers a much needed approach to rapidly improve under-performing PMTCT implementation programmes at scale in sub-Saharan Africa

    Self Assessment in Insects: Honeybee Queens Know Their Own Strength

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    Contests mediate access to reproductive opportunities in almost all species of animals. An important aspect of the evolution of contests is the reduction of the costs incurred during intra-specific encounters to a minimum. However, escalated fights are commonly lethal in some species like the honeybee, Apis mellifera. By experimentally reducing honeybee queens' fighting abilities, we demonstrate that they refrain from engaging in lethal contests that typically characterize their reproductive dominance behavior and coexist peacefully within a colony. This suggests that weak queens exploit an alternative reproductive strategy and provides an explanation for rare occurrences of queen cohabitation in nature. Our results further indicate that self-assessment, but not mutual assessment of fighting ability occurs prior to and during the agonistic encounters
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