A simple, fast and reproducible echocardiographic approach to grade left ventricular diastolic function

The American Society of Echocardiography and European Association of Echocardiography (ASE/EAE) have published an algorithm for the grading of diastolic function. However, the ability to use this algorithm effectively in daily clinical practice has not been investigated. We hypothesized that in some patients it may be difficult to grade diastolic dysfunction with this scheme, since there may be discrepancies in the assessed parameters. The aim of the current study was to test the feasibility of the ASE/EAE algorithm and to compare this with a new Thoraxcenter (TXC) algorithm. The ASE/EAE and TXC algorithms were applied to 200 patients. The ASE/EAE algorithm starts with assessment of diastolic myocardial wall velocities and left atrial (LA) volumes with subsequent assessment of E/A ratio, E-wave deceleration time and pulmonary venous flow. The TXC algorithm reverses these steps, uses LA dimension instead of volume and does not include a Valsalva manoeuvre and pulmonary venous flow. Due to inconsistencies between diastolic myocardial wall velocities and LA volumes and a not covered E/A ratio in the range of 1.5–2 it was not possible to classify 48 % of patients with the ASE/EAE algorithm, as opposed to only 10 % by the TXC algorithm. LA volume was always needed in the ASE/EAE algorithm. In only 64 % of patients LA size was necessary by the TXC algorithm. When LA volume would have been used instead of LA dimension, grading of LV diastolic function would have been different in only 2 % of patients without apparent improvement. Assessment of LA dimension was considerably faster than LA volume. The TXC algorithm to grade LV diastolic dysfunction was compared to the ASE/EAE algorithm simpler, faster, better reproducible and yields a higher diagnostic outcome

Magneto-rotational overstability in accretion disks

We present analytical and numerical studies of magnetorotational instabilities occuring in magnetized accretion disks. In these studies we make use of the linearised compressible MHD equations. These calculations are performed for general radially stratified disks in the cylindrical limit. In particular, we investigate the influence of nonvanishing toroidal magnetic field component on the growth rate and oscillation frequency of magnetorotational instabilities in Keplerian disks. We find the persistence of these instabilities in accretion disks close to equipartition. Our calculations show that these eigenmodes become overstable (complex eigenvalue), due to the presence of a toroidal magnetic field component, while their growth rate reduces slightly. Furthermore, we demonstrate the presence of magneto-rotational overstabilities in weakly magnetized sub-Keplerian rotating disks. We show that the growth rate scales with the rotation frequency of the disk. These eigenmodes also have a nonzero oscillation frequency, due to the presence of the dominant toroidal magnetic field component. The overstable character of the MRI increases as the rotation frequency of the disk decreases.Comment: 11 pager, 18 Postscript figures, accepted for publication in Astronomy & Astrophysic

A simple, fast and reproducible echocardiographic approach to grade left ventricular diastolic function

The American Society of Echocardiography and European Association of Echocardiography (ASE/EAE) have published an algorithm for the grading of diastolic function. However, the ability to use this algorithm effectively in daily clinical practice has not been investigated. We hypothesized that in some patients it may be difficult to grade diastolic dysfunction with this scheme, since there may be discrepancies in the assessed parameters. The aim of the current study was to test the feasibility of the ASE/EAE algorithm and to compare this with a new Thoraxcenter (TXC) algorithm. The ASE/EAE and TXC algorithms were applied to 200 patients. The ASE/EAE algorithm starts with assessment of diastolic myocardial wall velocities and left atrial (LA) volumes with subsequent assessment of E/A ratio, E-wave deceleration time and pulmonary venous flow. The TXC algorithm reverses these steps, uses LA dimension instead of volume and does not include a Valsalva manoeuvre and pulmonary venous flow. Due to inconsistencies between diastolic myocardial wall velocities and LA volumes and a not covered E/A ratio in the range of 1.5–2 it was not possible to classify 48 % of patients with the ASE/EAE algorithm, as opposed to only 10 % by the TXC algorithm. LA volume was always needed in the ASE/EAE algorithm. In only 64 % of patients LA size was necessary by the TXC algorithm. When LA volume would have been used instead of LA dimension, grading of LV diastolic function would have been different in only 2 % of patients without apparent improvement. Assessment of LA dimension was considerably faster than LA volume. The TXC algorithm to grade LV diastolic dysfunction was compared to the ASE/EAE algorithm simpler, faster, better reproducible and yields a higher diagnostic outcome

Convective magneto-rotational instabilities in accretion disks

We present a study of instabilities occuring in thick magnetized accretion disks. We calculate the growth rates of these instabilities and characterise precisely the contribution of the magneto-rotational and the convective mechanism. All our calculations are performed in radially stratified disks in the cylindrical limit. The numerical calculations are performed using the appropriate local dispersion equation solver discussed in Blokland et al. (2005). A comparison with recent results by Narayan et al. (2002) shows excellent agreement with their approximate growth rates only if the disks are weakly magnetized. However, for disks close to equipartition, the dispersion equation from Narayan et al. (2002) loses its validity. Our calculations allow for a quantitative determination of the increase of the growth rate due to the magneto-rotational mechanism. We find that the increase of the growth rate for long wavelength convective modes caused by this mechanism is almost neglible. On the other hand, the growth rate of short wavelength instabilities can be significantly increased by this mechanism, reaching values up to 60%.Comment: 10 pages, 9 figures, Accepted for publication in Astronomy & Astrophysic

The effects of spin-down on the structure and evolution of pulsar wind nebulae

We present high resolution spherically symmetric relativistic magnetohydrodynamical simulations of the evolution of a pulsar wind nebula inside the free expanding ejecta of the supernova progenitor. The evolution is followed starting from a few years after the supernova explosion and up to an age of the remnant of 1500 years. We consider different values of the pulsar wind magnetization parameter and also different braking indices for the spin-down process. We compare the numerical results with those derived through an approximate semi-analytical approach that allows us to trace the time evolution of the positions of both the pulsar wind termination shock and the contact discontinuity between the nebula and the supernova ejecta. We also discuss, whenever a comparison is possible, to what extent our numerical results agree with former self-similar models, and how these models could be adapted to take into account the temporal evolution of the system. The inferred magnetization of the pulsar wind could be an order of magnitude lower than that derived from time independent analytic models.Comment: 11 pages, 7 figures, Accepted for publication on A&

Unstable magnetohydrodynamical continuous spectrum of accretion disks. A new route to magnetohydrodynamical turbulence in accretion disks

We present a detailed study of localised magnetohydrodynamical (MHD) instabilities occuring in two--dimensional magnetized accretion disks. We model axisymmetric MHD disk tori, and solve the equations governing a two--dimensional magnetized accretion disk equilibrium and linear wave modes about this equilibrium. We show the existence of novel MHD instabilities in these two--dimensional equilibria which do not occur in an accretion disk in the cylindrical limit. The disk equilibria are numerically computed by the FINESSE code. The stability of accretion disks is investigated analytically as well as numerically. We use the PHOENIX code to compute all the waves and instabilities accessible to the computed disk equilibrium. We concentrate on strongly magnetized disks and sub--Keplerian rotation in a large part of the disk. These disk equilibria show that the thermal pressure of the disk can only decrease outwards if there is a strong gravitational potential. Our theoretical stability analysis shows that convective continuum instabilities can only appear if the density contours coincide with the poloidal magnetic flux contours. Our numerical results confirm and complement this theoretical analysis. Furthermore, these results show that the influence of gravity can either be stabilizing or destabilizing on this new kind of MHD instability. In the likely case of a non--constant density, the height of the disk should exceed a threshold before this type of instability can play a role. This localised MHD instability provides an ideal, linear route to MHD turbulence in strongly magnetized accretion disk tori.Comment: 20 pages, 10 figures, accepted for publication in Astronomy & Astrophysic

Proper Motion Measurements of Pulsar B1951+32 in the Supernova Remnant CTB 80

Using the Very Large Array and the Pie Town antenna, we have measured the position of the radio pulsar B1951+32 relative to nearby background radio sources at four epochs between 1989 and 2000. These data show a clear motion for the pulsar of (25 +/- 4) milliarcsec/yr at a position angle (252 +/- 7) degrees (north through east), corresponding to a transverse velocity (240 +/- 40) km/s for a distance to the source of 2 kpc. The measured direction of motion confirms that the pulsar is moving away from the center of its associated supernova remnant, the first time that such a result has been demonstrated. Independent of assumptions made about the pulsar birth-place, we show that the measured proper motion implies an age for the pulsar of (64 +/- 18) kyr, somewhat less than its characteristic age of 107 kyr. This discrepancy can be explained if the initial spin period of the pulsar was (27 +/- 6) ms

Grootschalige concentratie- en depositiekaarten Nederland : Rapportage 2014

Nieuwe concentratie- en depositiekaarten voor NSL en PAS Het RIVM heeft kaarten opgesteld waarop staat aangegeven wat in 2013 in Nederland de concentraties in de lucht waren van onder andere stikstofdioxide en fijn stof. Ook is op een kaart aangegeven in welke mate stikstof op de bodem neerslaat. Daarnaast zijn toekomstberekeningen voor deze stoffen gemaakt voor de periode 2015- 2030. De kaarten worden gebruikt voor de monitoring van het Nationaal Samenwerkingsprogramma Luchtkwaliteit (NSL) en de Programmatische Aanpak Stikstof (PAS). Hiermee worden onder andere de effecten van ruimtelijke plannen getoetst Stikstofdioxideconcentraties voor 2015 veelal lager De gemeten concentraties stikstofdioxide waren in 2013 lager dan in 2012. De concentraties die voor 2015 zijn berekend, zijn op de meeste locaties lager dan vorig jaar was geraamd. Toch blijven er een aantal probleemgebieden bestaan waarin de verwachte concentraties hoger zijn dan vorig jaar geraamd, vooral in de regio's Rotterdam en Den Haag. Wat de verwachte overschrijdingen van de normen in 2015 betreft, zal dat in Amsterdam en Utrecht op minder locaties aan de orde zijn dan eerder was ingeschat, en in Rotterdam op meer locaties Drie oorzaken voor deze aangepaste verwachting zijn het belangrijkst. Als eerste is bij de ramingen een correctie aangebracht voor systematische verschillen tussen gemeten en berekende stikstofdioxideconcentraties. Ten tweede stoten de nieuwste modellen vrachtauto's minder stikstofoxiden uit dan eerder was ingeschat. Ten derde zijn effecten meegenomen van het SER-energieakkoord uit 2013. Hierin zijn afspraken gemaakt om energie te besparen bij huishoudens, industrie en landbouw en het aandeel alternatieve energiebronnen als wind- en zonne-energie te vergroten Roetconcentraties dalen naar verwachting verder Steeds meer dieselauto's hebben een filter, waarmee roet effectief wordt afgevangen. Op basis van het huidige beleid wordt geschat dat de roetconcentratie de komende jaren verder daalt, en in 2020 bijna zal zijn gehalveerd ten opzicht van het huidige niveau Daling stikstofdepositie onveranderd De neerslag van stikstof op de bodem in Nederland daalt naar verwachting de komende jaren in ongeveer dezelfde mate als vorig jaar was geraamd. Een dalende stikstofdepositie is een voorwaarde voor natuurbehoudNew maps of concentrations and depositions for NSL and PAS In this report, the National Institute for Public Health and the Environment (RIVM) presents the latest maps of air concentrations in the Netherlands for several substances, including nitrogen dioxide and particulate matter for 2013. It also presents the maps for the deposition of nitrogen compounds to the soil for that year. Calculations for the future (2015-2030) have also been made. The maps are being used in the national air quality collaboration programme (NSL) and for the programmatic approach to nitrogen (PAS) for monitoring new spatial planning projects Nitrogen dioxide concentrations mostly lower for 2015 The measured concentrations of nitrogen dioxide were in 2013 lower than in 2012. Concentrations calculated for 2015 are at most locations below last year's estimates. Yet, there remain a number of areas where the expected concentrations are higher than last year's estimates, especially in the vicinity of Rotterdam and The Hague. The limit value for the nitrogen dioxide concentration will probably be exceeded in fewer locations in Amsterdam and Utrecht than was estimated earlier and in more locations in Rotterdam in 2015 There are three main reasons for these adjusted expectations of future concentrations. First, a correction is applied to projections of nitrogen dioxide concentrations for systematic differences between measured and calculated concentrations. Second, the latest truck models emit less nitrogen oxides than was previously expected. Third, the effects of the SER energy agreement from 2013 have been taken into account. Arrangements have been made in the agreement to save energy in households, industry and agriculture, and to increase the share of alternative energy sources, such as, wind and solar energy Soot concentrations are expected to decrease further More and more diesel cars have a filter, which is effective in capturing soot. It is expected that, based on the current policies, the soot concentrations will continue to decrease in the coming years and will be reduced by almost 50 percent by 2020 compared to current levels Decrease in nitrogen deposition unchanged The deposition of nitrogen to the soil in the Netherlands is expected to decrease in the coming years by approximately the same amount as was estimated last year. A reduction in nitrogen deposition is a prerequisite for nature conservationMinisterie van I&

New Constraints on the Structure and Evolution of the Pulsar Wind Nebula 3C 58

We present an investigation of the spectral and spatial structure of the X-ray emission from 3C 58 based on a 350 ks observation with the Chandra X-ray Observatory. This deep image, obtained as part of the Chandra Large Project program, reveals new information on nearly all spatial scales in the pulsar wind nebula (PWN). On the smallest scales we derive an improved limit of T < 1.02 X 10^6 K for blackbody emission from the entire surface of the central neutron star (NS), confirming the need for rapid, nonstandard cooling in the stellar interior. Furthermore, we show that the data are consistent with emission from a light element atmosphere with a similar temperature. Surrounding the NS, a toroidal structure with a jet is resolved, consistent with earlier measurements and indicative of an east-west orientation for the projected rotation axis of the pulsar. A complex of loop-like X-ray filaments fills the nebula interior, and corresponds well with structures seen in the radio band. Several of the structures coincide with optical filaments as well. The emission from the interior of the PWN, including the pulsar, jet, and filaments, is primarily nonthermal in nature. The power law index steepens with radius, but appears to also show small azimuthal variations. The outermost regions of the nebula require a thermal emission component, confirming the presence of an ejecta-rich swept up shell.Comment: 12 pages, 9 figures. Accepted for Publication in ApJ. Fixed several incorrect east/west designations and revised treatment of column density. The latter results in minor changes to some derived spectral parameter

Discovery of a New Pulsar Wind Nebula in the Large Magellanic Cloud

We present new high-resolution radio and X-ray observations of the supernova remnant (SNR) B0453-685 in the Large Magellanic Cloud, carried out with the Australia Telescope Compact Array and the Chandra X-ray Observatory respectively. Embedded in the SNR shell is a compact central nebula producing both flat-spectrum polarized radio emission and non-thermal X-rays; we identify this source as a pulsar wind nebula (PWN) powered by an unseen central neutron star. We present a new approach by which the properties of a SNR and PWN can be used to infer upper limits on the initial spin period and surface magnetic field of the unseen pulsar, and conclude that this star was an initial rapid rotator with current properties similar to those of the Vela pulsar. As is the case for other similarly-aged sources, there is currently an interaction taking place between the PWN and the SNR's reverse shock.Comment: 4 pages of text plus 2 embedded EPS figures. Minor changes following referee's report. ApJ Letters, in pres