35,151 research outputs found
The necessity of dark matter in MOND within galactic scales
To further test MOdified Newtonian Dynamics (MOND) on galactic scales -- originally proposed to explain the rotation curves of disk galaxies without dark matter -- we study a sample of six strong gravitational lensing early-type galaxies from the CASTLES database. To determine whether dark matter is present in these galaxies, we compare the total mass (from lensing) with the stellar mass content (from a comparison of photometry and stellar population synthesis). We find that strong gravitational lensing on galactic scales requires a significant amount of dark matter, even within MOND. On such scales a 2 eV neutrino cannot explain this excess matter -- in contrast with recent claims to explain the lensing data of the bullet cluster. The presence of dark matter is detected in regions with a higher acceleration than the characteristic MONDian scale of m/s. This is a serious challenge to MOND unless the proper treatment of lensing is qualitatively different (possibly to be developed within a consistent theory such as TeVeS)
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Heart rate and blood pressure monitoring in heart failure.
It has been long known that incessant tachycardia and severe hypertension can cause heart failure (HF). In recent years, it has also been recognized that more modest elevations in either heart rate (HR) or blood pressure (BP), if sustained, can be a risk factor both for the development of HF and for mortality in patients with established HF. Heart rate and BP are thus both modifiable risk factors in the setting of HF. What is less clear is the question whether routine systematic monitoring of these simple physiological parameters to a target value can offer clinical benefits. Measuring these parameters clinically during patient review is recommended in HF management in most HF guidelines, both in the acute and chronic phases of the disease. More sophisticated systems now allow long-term automatic or remote monitoring of HR and BP and whether this more detailed patient information can improve clinical outcomes will require prospective RCTs to evaluate. In addition, analysis of patterns of both HR and BP variability can give insights into autonomic function, which is also frequently abnormal in HF. This window into autonomic dysfunction in our HF patients can also provide further independent prognostic information and may in itself be target for future interventional therapies. This article, developed during a consensus meeting of the Heart Failure Association of the ESC concerning the role of physiological monitoring in the complex multi-morbid HF patient, highlights the importance of repeated assessment of HR and BP in HF, and reviews gaps in our knowledge and potential future directions
Bilingual distributed word representations from document-aligned comparable data
We propose a new model for learning bilingual word representations from non-parallel document-aligned data. Following the recent advances in word representation learning, our model learns dense real-valued word vectors, that is, bilingual word embeddings (BWEs). Unlike prior work on inducing BWEs which heavily relied on parallel sentence-aligned corpora and/or readily available translation resources such as dictionaries, the article reveals that BWEs may be learned solely on the basis of document-aligned comparable data without any additional lexical resources nor syntactic information. We present a comparison of our approach with previous state-of-the-art models for learning bilingual word representations from comparable data that rely on the framework of multilingual probabilistic topic modeling (MuPTM), as well as with distributional local context-counting models. We demonstrate the utility of the induced BWEs in two semantic tasks: (1) bilingual lexicon extraction, (2) suggesting word translations in context for polysemous words. Our simple yet effective BWE-based models significantly outperform the MuPTM-based and contextcounting representation models from comparable data as well as prior BWE-based models, and acquire the best reported results on both tasks for all three tested language pairs.This work was done while Ivan Vuli c was a postdoctoral researcher at Department of Computer Science, KU Leuven supported by the PDM Kort fellowship (PDMK/14/117). The work was also supported by the SCATE project (IWT-SBO 130041) and the ERC Consolidator Grant LEXICAL: Lexical Acquisition Across Languages (648909)
Radiocarbon dating of methane and carbon dioxide evaded from a temperate peatland stream
Streams draining peatlands export large quantities of carbon in different chemical forms and
are an important part of the carbon cycle. Radiocarbon (14C) analysis/dating provides unique
information on the source and rate that carbon is cycled through ecosystems, as has recently
been demonstrated at the air-water interface through analysis of carbon dioxide (CO2) lost
from peatland streams by evasion (degassing). Peatland streams also have the potential to
release large amounts of methane (CH4) and, though 14C analysis of CH4 emitted by ebullition
(bubbling) has been previously reported, diffusive emissions have not. We describe methods
that enable the 14C analysis of CH4 evaded from peatland streams. Using these methods, we
investigated the 14C age and stable carbon isotope composition of both CH4 and CO2 evaded
from a small peatland stream draining a temperate raised mire. Methane was aged between
1617-1987 years BP, and was much older than CO2 which had an age range of 303-521 years
BP. Isotope mass balance modelling of the results indicated that the CO2 and CH4 evaded
from the stream were derived from different source areas, with most evaded CO2 originating
from younger layers located nearer the peat surface compared to CH4. The study demonstrates
the insight that can be gained into peatland carbon cycling from a methodological
development which enables dual isotope (14C and 13C) analysis of both CH4 and CO2 collected
at the same time and in the same way
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Development and validation of the Spanish hazard perception test
Objective: The aim of the current study is to develop and obtain validity evidence for a Hazard Perception test suitable for the Spanish driving population. To obtain validity evidence to support the use of the test, the effect of hazardous and quasi-hazardous situations on the participantsâ Hazard Prediction is analysed and the pattern of results of drivers of different driving experience: learner, novice and expert drivers and re-offender vs. non-offender drivers, is compared. Potentially hazardous situations are those that develop without involving any real hazard (i.e., the driver didnât actually have to decelerate or make any evasive manoeuvre to avoid a potential collision). The current study analysed multiple offender drivers attending compulsory re-education programmes as a result of reaching the maximum number of penalty points on their driving licence, due to repeated violations of traffic laws. Method: A new video-based hazard perception test was developed, using a total of 20 hazardous situation videos plus 8 quasi-hazardous situation videos. They were selected from 167 recordings of natural hazards in real Spanish driving settings
The Development and Use of A Piloted Flight Simulation Environment for Rotary-Wing Operation to the Queen Elizabeth Class Aircraft Carriers
Flight simulation is being used to inform the First of Class Flight Trials for the UKâs new Queen Elizabeth Class (QEC) aircraft carriers. The carriers will operate with the Lockheed Martin F-35B Lightning II fighter aircraft, i.e. the Advanced Short Take-Off and Vertical Landing variant of the F-35. The rotary wing assets that are expected to operate with QEC include Merlin, Wildcat, Chinook and Apache helicopters. An F-35B flight simulator has been developed and is operated by BAE Systems at Warton Aerodrome. The University of Liverpool is supporting this project by using Computational Fluid Dynamics (CFD) to provide the unsteady air flow field that is required in a realistic flight simulation environment. This paper is concerned with a research project that is being conducted using the Universityâs research simulator, HELIFLIGHT-R, to create a simulation environment for helicopter operations to the QEC. The paper briefly describes how CFD has been used to model the unsteady airflow over the 280m long aircraft carrier and how this is used to create a realistic flight simulation environment. Results are presented from an initial simulation trial in which test pilots have used the HELIFLIGHT-R simulator to conduct simulated helicopter landings to two landing spots on the carrier, one in a disturbed air flow and the other in clean air. As expected, the landing to the spot in disturbed air flow requires a greater pilot workload, shows greater deviation in its positional accuracy and requires more control activity. This initial trial is the first of a planned series of simulated helicopter deck landings for different wind angles and magnitudes
Uncommon Multicystic Lesion of the Interventricular Septum in a 7-Year-Old Boy: Unusual Presentation of an Intracardiac Teratoma
Intracardiac teratomas are very rare primary cardiac tumors; only a few cases have been reported. We present the case of a 7-year-old boy who early in life showed pulmonary stenosis and needed percutaneous and surgical procedures, including sectioning of the right ventricular bands and reconstruction of the right ventricular outflow tract. At the age of 7 years the patient received a diagnosis of a multilobular cystic mass in the right ventricle adherent to the interventricular septum, which was not present at birth. Successful surgical resection was performed. Histologic examination revealed a mature teratoma. We emphasize the differential diagnosis of teratomas in cystic lesions of the interventricular septum
Simulations of mid infrared emission of InAsN semiconductors
This paper delivers an approximation to the complex many body problem of luminescence in semiconductors to the case of mid infrared luminescence of dilute nitrides. The results are compared with recent experimental data for InAsN semiconductors
The Queen Elizabeth Class Aircraft Carriers: Airwake Modelling and Validation for ASTOVL Flight Simulation
This paper outlines progress towards the development of a high-fidelity piloted flight simulation environment for the UKâs Queen Elizabeth Class (QEC) aircraft carriers which are currently under construction. It is intended that flight simulation will be used to de-risk the clearance of the F-35B Lightning-II to the ship, helping to identify potential wind-speeds/directions requiring high pilot workload or control margin limitations prior to First of Class Flight Trials. Simulated helicopter launch & recovery trials are also planned for the future. The paper details the work that has been undertaken at the University of Liverpool to support this activity, and which draws upon Liverpoolâs considerable research experience into simulated launch and recovery of maritime helicopters to single-spot combat ships. Predicting the unsteady air flow over and around the QEC is essential for the simulation environment; the very large and complex flow field has been modelled using Computational Fluid Dynamics (CFD) and will be incorporated into the flight simulators at the University of Liverpool and BAE Systems Warton for use in future piloted simulation trials. The challenges faced when developing airwake models for such a large ship are presented together with details of the experimental setup being prepared to validate the CFD predictions. Finally, the paper describes experimental results produced to date for CFD validation purposes and looks ahead to the piloted simulation trials of aircraft launch and recovery operations to the carrier
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