385 research outputs found
Galactic Outflows and the pollution of the Galactic Environment by Supernovae
We here explore the effects of the SN explosions into the environment of
star-forming galaxies like the Milky Way. Successive randomly distributed and
clustered SNe explosions cause the formation of hot superbubbles that drive
either fountains or galactic winds above the galactic disk, depending on the
amount and concentration of energy that is injected by the SNe. In a galactic
fountain, the ejected gas is re-captured by the gravitational potential and
falls back onto the disk. From 3D nonequilibrium radiative cooling
hydrodynamical simulations of these fountains, we find that they may reach
altitudes up to about 5 kpc in the halo and thus allow for the formation of the
so called intermediate-velocity-clouds (IVCs) which are often observed in the
halos of disk galaxies. The high-velocity-clouds that are also observed but at
higher altitudes (of up to 12 kpc) require another mechanism to explain their
production. We argue that they could be formed either by the capture of gas
from the intergalactic medium and/or by the action of magnetic fields that are
carried to the halo with the gas in the fountains. Due to angular momentum
losses to the halo, we find that the fountain material falls back to smaller
radii and is not largely spread over the galactic disk. Instead, the SNe ejecta
fall nearby the region where the fountain was produced, a result which is
consistent with recent chemical models of the galaxy. The fall back material
leads to the formation of new generations of molecular clouds and to supersonic
turbulence feedback in the disk.Comment: 10 pages, 5 figures; paper of invited talk for the Procs. of the 2007
WISER Workshop (World Space Environment Forum), Alexandria, Egypt, October
2007, Spa. Sci. Rev
Recommended from our members
ESICM LIVES 2017 : 30th ESICM Annual Congress. September 23-27, 2017.
INTRODUCTION. Unplanned readmission to intensive care is highly
undesirable in that it contributes to increased variance in care,
disruption, difficulty in resource allocation and may increase length
of stay and mortality particularly if subject to delays. Unlike the ICU
admission from the ward, readmission prediction has received
relatively little attention, perhaps in part because at the point of ICU
discharge, full physiological information is systematically available to
the clinician and so it is expected that readmission should be largely
due to unpredictable factors. However it may be that there are
multidimensional trends that are difficult for the clinician to perceive
that may nevertheless be predictive of readmission.
OBJECTIVES. We investigated whether machine learning (ML)
techniques could be used to improve on the simple published SWIFT
score [1] for the prediction of unplanned readmission to ICU within
48 hours.
METHODS. We extracted systolic BP, pulse pressure, heart and
respiration rate, temperature, SpO2, bilirubin, creatinine, INR, lactate,
white cell count, platelet count, pH, FiO2, and total Glasgow Coma
Score from ICU stays of over 2000 adult patients from our hospital
electronic patient record system. We trained our own custom
multidimensional / time-sensitive algorithmic ML system to predict
failed discharges defined as either readmission or unexpected death
within 48 hours of discharge. We used 10-fold cross validation to assess performance. We also assessed the effect of augmenting our
system by transfer learning (TL) with 44,000 additional cases from
the MIMIC III database.
RESULTS. The SWIFT score performed relatively poorly with an
AUROC of around 0.6 which our ML system trained on local data was
also able to match. However when augmented with an additional
dataset by TL, the AUROC for the ML system improved statistically
and clinically significantly to over 0.7.
CONCLUSIONS. Machine learning is able to improve on predictors
based on simple multiple logistic regression. Thus there is likely to
be information in the trends and in combinations of variables. A
disadvantage with this technique is that ML approaches require large
amounts of data for training. However, ML approaches can be
improved by TL. Basing prediction models on locally derived data
augmented by TL is a potentially novel approach to generating tools
that customised to the institution yet can exploit the potential power
of ML algorithms.
REFERENCES
[1] Gajic O, Malinchoc M, Comfere TB, et al. The Stability and
Workload Index for Transfer score predicts unplanned intensive care
unit patient readmission: initial development and validation. Crit Care
Med. 2008;36(3):676–82.
Grant Acknowledgement
This work was internally funded
Minced Umbilical Cord Fragments as a Source of Cells for Orthopaedic Tissue Engineering: An In Vitro Study
A promising approach for musculoskeletal repair and regeneration is mesenchymal-stem-cell- (MSC-)based tissue engineering. The aim of the study was to apply a simple protocol based on mincing the umbilical cord (UC), without removing any blood vessels or using any enzymatic digestion, to rapidly obtain an adequate number of multipotent UC-MSCs. We obtained, at passage 1 (P1), a mean value of 4, 2 × 106 cells (SD 0,4) from each UC. At immunophenotypic characterization, cells were positive for CD73, CD90, CD105, CD44, CD29, and HLA-I and negative for CD34 and HLA-class II, with a subpopulation negative for both HLA-I and HLA-II. Newborn origin and multilineage potential toward bone, fat, cartilage, and muscle was demonstrated. Telomere length was similar to that of bone-marrow (BM) MSCs from young donors. The results suggest that simply collecting UC-MSCs at P1 from minced umbilical cord fragments allows to achieve a valuable population of cells suitable for orthopaedic tissue engineering
Incidence of chronic subdural haematoma: a single-centre exploration of the effects of an ageing population with a review of the literature
Abstract: Background: Chronic subdural haematoma (cSDH) is a common neurosurgical pathology frequently occurring in older patients. The impact of population ageing on cSDH caseload has not been examined, despite relevance for health system planning. Methods: This is a single-centre study from the UK. Operated cases of cSDH (n = 446) for 2015–2018 were identified. Crude and directly standardised incidence rates were calculated. Medline and EMBASE were systematically searched to identify studies reporting on the incidence of cSDH by year, so an estimate of rate of incidence change could be determined. Local incidence rates were then applied to population projections for local catchment area to estimate operated cSDH numbers at 5 yearly intervals due to shifting demographics. Results: We identified nine studies presenting incidence estimates. Crude estimates for operative cases ranged from 1.3/100,000/year (1.4–2.2) to 5.3/100,000/year (4.3–6.6). When non-operated cases were included, incidence was higher: 8.2/100,000/year (6.0–11.2) to 48/100,000/year (37.7–61.1). Four pairs of studies demonstrated incidence rate increases of 200–600% over the last 50 years, but data was deemed too heterogeneous to generate formal estimate of incidence change. Local crude incidence of operated cSDH was 3.50/100,000/year (3.19–3.85). Directly standardised incidence was 1.58/100,000/year (1.26–1.90). After applying local incidence rates to population projections, case numbers were predicted to increase by 53% over the next 20 years. Conclusions: The incidence of cSDH is increasing. We project a 53% increase in operative caseload within our region by 2040. These are important findings for guiding future healthcare planning
Descriptors of Sepsis Using the Sepsis-3 Criteria: A Cohort Study in Critical Care Units Within the U.K. National Institute for Health Research Critical Care Health Informatics Collaborative
OBJECTIVES: To describe the epidemiology of sepsis in critical care by applying the Sepsis-3 criteria to electronic health records. DESIGN: Retrospective cohort study using electronic health records. SETTING: Ten ICUs from four U.K. National Health Service hospital trusts contributing to the National Institute for Health Research Critical Care Health Informatics Collaborative. PATIENTS: A total of 28,456 critical care admissions (14,332 emergency medical, 4,585 emergency surgical, and 9,539 elective surgical). MEASUREMENTS AND MAIN RESULTS: Twenty-nine thousand three hundred forty-three episodes of clinical deterioration were identified with a rise in Sequential Organ Failure Assessment score of at least 2 points, of which 14,869 (50.7%) were associated with antibiotic escalation and thereby met the Sepsis-3 criteria for sepsis. A total of 4,100 episodes of sepsis (27.6%) were associated with vasopressor use and lactate greater than 2.0 mmol/L, and therefore met the Sepsis-3 criteria for septic shock. ICU mortality by source of sepsis was highest for ICU-acquired sepsis (23.7%; 95% CI, 21.9-25.6%), followed by hospital-acquired sepsis (18.6%; 95% CI, 17.5-19.9%), and community-acquired sepsis (12.9%; 95% CI, 12.1-13.6%) (p for comparison less than 0.0001). CONCLUSIONS: We successfully operationalized the Sepsis-3 criteria to an electronic health record dataset to describe the characteristics of critical care patients with sepsis. This may facilitate sepsis research using electronic health record data at scale without relying on human coding
Conserving plant diversity in Europe: outcomes, criticisms and perspectives of the Habitats Directive application in Italy
Habitat Directive is the core strategy of nature conservation in Europe aiming at halting biodiversity loss. In this study the results of the third Italian assessment regarding the conservation status (CS) of plants listed in the Habitat Directive (Flora of community interest—FCI) was presented. Data was collected from several sources related to plant distribution, population data, habitats and pressures. Following the official European procedure, all parameters were evaluated and combined to give the CS of each taxon in each biogeographical region of presence. A comparison between the recent Italian IUCN and Reporting assessments was performed in order to evaluate the consistency between these two assessments. The official EU checklist comprises 113 Italian plant taxa, 107 of which were examined in this study. Our results showed a critical situation with only 34% of favourable CS, while 50% were unfavourable (40% inadequate plus 10% bad) and 16% unknown, in particular in the Mediterranean bioregion, where the unfavourable assessments reach the 65%. The results of the Report were consistent with those of the IUCN assessment, in which 41.9% of plants were threatened with extinction. This report highlighted some benefits and criticisms at national level, but it may have a wider significance. Although a general advance of knowledge, a great effort is needed to reach the Habitats Directive goals. Despite the limited resources, monitoring activities needs to be improved in order to close information gaps for several plants. A positive outcome was the development of a specific national project funded by the Italian Ministry of Environment, with the ambitious target to set future monitoring activities for FCI and optimize monitoring efforts
Modeling heat transport in crystals and glasses from a unified lattice-dynamical approach
We introduce a novel approach to model heat transport in solids, based on the Green-Kubo theory of linear response. It naturally bridges the Boltzmann kinetic approach in crystals and the Allen-Feldman model in glasses, leveraging interatomic force constants and normal-mode linewidths computed at mechanical equilibrium. At variance with molecular dynamics, our approach naturally and easily accounts for quantum mechanical effects in energy transport. Our methodology is carefully validated against results for crystalline and amorphous silicon from equilibrium molecular dynamics and, in the former case, from the Boltzmann transport equation
Concomitant CIS on TURBT does not impact oncological outcomes in patients treated with neoadjuvant or induction chemotherapy followed by radical cystectomy
© Springer-Verlag GmbH Germany, part of Springer Nature 2018Background: Cisplatin-based neoadjuvant chemotherapy (NAC) for muscle invasive bladder cancer improves all-cause and cancer specific survival. We aimed to evaluate whether the detection of carcinoma in situ (CIS) at the time of initial transurethral resection of bladder tumor (TURBT) has an oncological impact on the response to NAC prior to radical cystectomy. Patients and methods: Patients were identified retrospectively from 19 centers who received at least three cycles of NAC or induction chemotherapy for cT2-T4aN0-3M0 urothelial carcinoma of the bladder followed by radical cystectomy between 2000 and 2013. The primary and secondary outcomes were pathological response and overall survival, respectively. Multivariable analysis was performed to determine the independent predictive value of CIS on these outcomes. Results: Of 1213 patients included in the analysis, 21.8% had concomitant CIS. Baseline clinical and pathologic characteristics of the ‘CIS’ versus ‘no-CIS’ groups were similar. The pathological response did not differ between the two arms when response was defined as pT0N0 (17.9% with CIS vs 21.9% without CIS; p = 0.16) which may indicate that patients with CIS may be less sensitive to NAC or ≤ pT1N0 (42.8% with CIS vs 37.8% without CIS; p = 0.15). On Cox regression model for overall survival for the cN0 cohort, the presence of CIS was not associated with survival (HR 0.86 (95% CI 0.63–1.18; p = 0.35). The presence of LVI (HR 1.41, 95% CI 1.01–1.96; p = 0.04), hydronephrosis (HR 1.63, 95% CI 1.23–2.16; p = 0.001) and use of chemotherapy other than ddMVAC (HR 0.57, 95% CI 0.34–0.94; p = 0.03) were associated with shorter overall survival. For the whole cohort, the presence of CIS was also not associated with survival (HR 1.05 (95% CI 0.82–1.35; p = 0.70). Conclusion: In this multicenter, real-world cohort, CIS status at TURBT did not affect pathologic response to neoadjuvant or induction chemotherapy. This study is limited by its retrospective nature as well as variability in chemotherapy regimens and surveillance regimens.Peer reviewedFinal Accepted Versio
The species-specific monitoring protocols for plant species of Community interest in Italy.
The results of a project for the identification of species-specific monitoring protocols for the Italian plant species protected under the Habitats Directive (Annexes II/IV/V) are presented. The project led to the development of 118 monitoring factsheets, providing an operational guidance for 107 vascular taxa, 10 bryophytes and 1 lichen taxon. Each factsheet includes information on the species (distribution, biology, ecology, conservation status, threats, etc.) and the description of field methodologies for the detection of the two main reporting parameters, i.e. population size and habitat quality. Practical information to plan field activities are also given. Protocols were designed to address the requirements of the European reporting system with the aim to standardize future monitoring activities, optimize efforts at national scale and overcome some current problems related to data heterogeneity and discrepancies from the EC standards. More than 60 botanists collaborated to identify the best practices and to design an operational field survey format through several stages of discussion and sharing. The protocols, developed by ISPRA and Scientific Societies and shared with the Italian institutions responsible for the Directive application, were published in a dedicated National handbook. The work provides a first uniform technical basis for future national monitoring plans
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