1,131 research outputs found
Overview of the lithium problem in metal-poor stars and new results on 6Li
Two problems are discussed here. The first one is the 0.4 dex discrepancy
between the 7Li abundance derived from the spectra of metal-poor halo stars on
the one hand, and from Big Bang nucleosynthesis, based on the cosmological
parameters constrained by the WMAP measurements, on the other hand. Lithium,
indeed, can be depleted in the convection zone of unevolved stars. The
understanding of the hydrodynamics of the crucial zone near the bottom of the
convective envelope in dwarfs or turn-off stars of solar metallicity has
recently made enormous progress with the inclusion of internal gravity waves.
However, similar work for metal-poor stars is still lacking. Therefore it is
not yet clear whether the depletion occurring in the metal-poor stars
themselves is adequate to produce a 7Li plateau. The second problem pertains to
the large amount of 6Li recently found in metal-poor halo stars. The
convection-related asymmetry of the 7Li line could mimic the signal attributed
so far to the weak blend of 6Li in the red wing of the 7Li line. Theoretical
computations show that the signal generated by the asymmetry of 7Li is 2.0,
2.1, and 3.7 per cent for [Fe/H]= -3.0, -2.0, -1.0, respectively (Teff =6250 K
and log g=4.0 [cgs]). In addition we re-investigate the statistical properties
of the 6Li plateau and show that previous analyses were biased. Our conclusion
is that the 6Li plateau can be reinterpreted in terms of intrinsic line
asymmetry, without the need to invoke a contribution of 6Li. (abridged)Comment: Invited talk at the 10th Symposium on Nuclei in the Cosmos - July 27
- August 1 2008 - Mackinac Island, Michigan, USA, Accepted version. Minor
changes following referee's suggestion
The need for improved management of the subsurface
The subsurface is used intensively to support economic stability and growth. Human interaction with
the shallow subsurface ranges from exploitation of resources, accommodation of utilities, harnessing
of energy (ground source heat pumps) and storage of waste. Current practice of managing these
shallow subsurface zones is far from ideal. Many subsurface interventions are preceded by feasibility
studies, predictive models or investigative measures to mitigate risks or predict the impacts of the
work. However, the complex interactions between the anthropogenic structures and natural processes
mean that a holistic impact assessment is often not achievable. By integrating these subsurface
infrastructures within three dimensional framework models, a comprehensive assessment of the
potential hazards in these shallow subsurface environments may be made. Some Geological Survey
Organizations (GSOs) are currently developing subsurface management systems that will aid decision
making in the shallow subsurface [1]. The British Geological Survey (BGS) is developing an open
Environmental Modeling Platform [2] to provide the data standards and applications to link models,
numerical simulations and ultimately socio-economic models so as to generate predictive responses to
questions concerning sustainable us of the subsurface
Solar abundances and 3D model atmospheres
We present solar photospheric abundances for 12 elements from optical and
near-infrared spectroscopy. The abundance analysis was conducted employing 3D
hydrodynamical (CO5BOLD) as well as standard 1D hydrostatic model atmospheres.
We compare our results to others with emphasis on discrepancies and still
lingering problems, in particular exemplified by the pivotal abundance of
oxygen. We argue that the thermal structure of the lower solar photosphere is
very well represented by our 3D model. We obtain an excellent match of the
observed center-to-limb variation of the line-blanketed continuum intensity,
also at wavelengths shortward of the Balmer jump.Comment: Contributed paper, to be published in the proceedings of IAU
Symposium 265, eds. K. Cunha, M. Spite, and B. Barbuy, Cambridge University
Press (CUP). 2 figures, 4 page
Elm Farm Research Centre Bulletin 79 July 2005
Regular newletter from Elm Farm Research Centre (EFRC)covering research, technical and policy articles, views and comment
Acoustics in water: synergies with marine biology
This paper presents some of the bioacoustics related analysis that was performed on the ANTARES data, focussing on the year 2014. The data was processed for sperm whale, dolphin and shipping presence and grouped by hour of the day. It seemed that dolphins were more socially active during the day and foraging during the night. Sperm whales were mostly foraging during the day, but they may have been moving to other areas during the night. The most intense shipping noise came from a ferry that passed the platform twice a day. Although beaked whales were expected to be present in the area, so far their biosonar signal has not been conclusively found.Postprint (published version
Prophylactic Insertion of Optional Vena Cava Filters in High-Risk Trauma Patients
Background:: Vena cava interruption is a form of pulmonary embolism prophylaxis that is being used in high-risk patients who do not tolerate pharmacologic prophylaxis. Retrievable prophylactic vena cava filters (VCFs) are of particular interest for severely injured patients where the necessity for VCF is often only temporary. Methods:: In a single-institution case series of consecutive patients who received prophylactic VCFs after polytrauma, between 04/1998 and 07/2004, the demographic data, injury pattern and complications were analysed. Results:: Ninety-five prophylactic VCFs were placed in polytrauma patients (median ISS of 38). Median age was 38 years (range 16-80 years). Median delay between trauma and filter placement was 1 day (range 0-31 days). No complication was seen related to filter insertion or retrieval. Sixty-five VCFs (68.4%) were retrieved after 4-25 days (median 13 days). One filter migration (1.1%) was observed. Retrieval failed in two patients (3.0%). A total of 30 VCFs (31.6%) were left permanently. One non-fatal PE (1.1%) occurred 21 days after filter retrieval despite prophylaxis with LMWH. DVT developed in two patients (2.1%) including one vena caval occlusion (1.1%). Overall mortality was 7.4%. Conclusions:: Early prophylactic placement of VCF in a high-risk trauma patient should be considered when anticoagulation is contraindicated. Filter insertion and retrieval is safe with a low complication rat
Primary structure and functional expression of a cyclic nucleotidegated channel from rabbit aorta
Sequences specific for cyclic nucleotide-gated channels (CNG channels) have been amplified by PCR from cDNA of heart, aorta, sinoatrial node, cerebellum, C-cells and kidney. The complete amino acid sequence of a CNG channel from rabbit aorta has been deduced by cloning and sequence analysis of the cDNA. Synthetic RNA derived from this cDNA induces the formation of a functional CNG channel in Xenopus oocytes
Perceiving text and image in Apollinaire's calligrammes
Literary scholars have recently become increasingly interested in the perceptual and cognitive mechanisms involved in reading, and have incorporated scientific research in this area into their critical approaches to texts. This article argues that such an approach is particularly appropriate when authors explicitly engage with the way in which their texts are visually taken in and processed. This is the case with Guillaume Apollinaire, whose calligrammes are informed by a theory of visual-verbal simultaneity stipulating that the reader should be simultaneously aware of both textual and pictorial aspects of the poem. Experimental research in the psychology of reading and picture perception is used to assess this theory of simultaneity, and specifically to challenge Michel Foucault's claim that reading and viewing are mutually exclusive processes. The article concludes by considering further applications of psychological research to word and image studies
Characteristics and outcomes of medical emergency team calls in a Swiss tertiary centre - a retrospective observational study.
AIMS OF THE STUDY
To describe reasons for medical emergency team (MET) activation over time, to analyse outcomes, and to describe the circadian distribution of MET calls and Intensive Care Unit (ICU) admissions following MET activation.
METHODS
Monocentric retrospective observational study of prospectively collected data on all MET calls between 1st of January 2012 until 31st of May 2019. We analysed data on baselines, referring wards, and disposition of all MET patients. In addition, we allocated all MET calls to the hourly intervals over the 24-hour cycle of the day in order to identify peak times of team activation.
RESULTS
A total of 4068 calls in 3277 patients (37% female, n = 1210) were analysed. The mean age was 65.9 years (± 15.7). The MET dose (defined as MET calls/1000 hospital admissions) remained relatively stable over the years with a median of 8.0 calls/1000 hospitalisations (interquartile range [IQR] 7.0-10.0). A total of 2526 calls (62%) occurred out of hours (17:00 to 8:00). The hourly rate of MET activations was greatest during the evening shift (33.8% of calls in seven hours), followed by the day shift (35.8% calls in nine hours) and night shift (30.4% in eight hours). Over the years, staff concern was the main reason for a MET call (n = 1192, 34%), followed by low peripheral oxygen saturation (SpO2) not responding to oxygen therapy (n = 776, 22%). Abnormal respiratory rate was a trigger to call the MET in 44 cases (1.3%), and was not documented prior to 2017. Overall, in-hospital mortality was 22%.
CONCLUSION
While most common reasons for MET calls over the years were staff concern and low SpO2, abnormal respiratory rate was the least frequent, but increased after the introduction of the quick sequential organ failure assessment (qSOFA) in 2016. Most MET calls occurred out of hours with peak hours during the evening shift, highlighting the importance of resource allocation during this shift when planning to introduce a MET system in a hospital. In-hospital mortality after a MET call was 22%
Active mitral ring for post-surgical remote correction of residual mitral regurgitation on the beating heartâ€
OBJECTIVES Residual mitral regurgitation after valve repair worsens patients' clinical outcome. Postimplant adjustable mitral rings potentially address this issue, allowing the reshaping of the annulus on the beating heart under echocardiography control. We developed an original mitral ring allowing valve geometry remodelling after the implantation and designed an animal study to assess device effectiveness in correcting residual mitral regurgitation. METHODS The device consists of two concentric rings: one internal and flexible, sutured to the mitral annulus and a second external and rigid. A third conic element slides between the two rings, modifying the shape of the flexible ring. This sliding element is remotely activated with a rotating tool. Animal model: in adult swine, under cardio pulmonary bypass and cardiac arrest, we shortened the primary chordae of P2 segment to reproduce Type III regurgitation and implanted the active ring. We used intracardiac ultrasound to assess mitral regurgitation and the efficacy of the active ring to correct it. RESULTS Severe mitral regurgitation (3+ and 4+) was induced in eight animals, 54 ± 6 kg in weight. Vena contracta width decreased from 0.8 ± 0.2 to 0.1 cm; proximal isovelocity surface area radius decreased from 0.8 ± 0.2 to 0.1 cm and effective regurgitant orifice area decreased from 0.50 ± 0.1 to 0.1 ± 0.1 cm2. Six animals had a reversal of systolic pulmonary flow that normalized following the activation of the device. All corrections were reversible. CONCLUSIONS Postimplant adjustable mitral ring corrects severe mitral regurgitation through the reversible modification of the annulus geometry on the beating heart. It addresses the frequent and morbid issue of recurrent mitral valve regurgitatio
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