652 research outputs found
Case Series of Triathletes with Takotsubo Cardiomyopathy Presenting with Swimming-Induced Pulmonary Edema
OBJECTIVES:
To report three cases of triathletes who presented with swimming-induced pulmonary edema (SIPE) following water immersion. They were subsequently diagnosed with Takotsubo cardiomyopathy (TCM).
DESIGN:
Retrospective case series.
METHOD:
All cases were recreational athletes competing in mass participation triathlons between June 2018 and 2019. They were initially managed by the event medical team and subsequently at the local tertiary level hospital. Written consent was gained from all the subjects.
RESULTS:
The three triathletes were aged between 50 and 60 years, two were females, and all presented with acute dyspnoea on exiting the water. Two also presented with chest pain and haemoptysis. A diagnosis of SIPE was suspected by the medical event team on initial presentation of low oxygen saturations and clinical signs of pulmonary oedema. All were transferred to the local emergency department and had signs of pulmonary oedema on chest radiographs. Further investigations led to a diagnosis of TCM with findings of T wave inversion in anterolateral electrocardiogram leads and apical hypokinesia on transthoracic echocardiogram and unobstructed coronary arteries.
CONCLUSIONS:
This case series presents triathletes diagnosed with SIPE and TCM following the open water swim phase. It is unclear whether the myocardial dysfunction contributed to causation of SIPE or was the result of SIPE. Mass participation race organizers must be prepared that both SIPE and TCM can present in this population. Those presenting with an episode of SIPE require prompt evaluation of their cardiac and pulmonary physiology. Further research is required to ascertain the exact nature of the relationship between TCM and SIPE
The new very small angle neutron scattering spectrometer at Laboratoire Leon Brillouin
The design and characteristics of the new very small angle neutron scattering
spectrometer under construction at the Laboratoire Leon Brillouin is described.
Its goal is to extend the range of scattering vectors magnitudes towards
2x10{-4} /A. The unique feature of this new spectrometer is a high resolution
two dimensional image plate detector sensitive to neutrons. The wavelength
selection is achieved by a double reflection supermirror monochromator and the
collimator uses a novel multibeam design
Cladoceran birth and death rates estimates
I. Birth and death rates of natural cladoceran populations cannot be measured directly. Estimates of these population parameters must be calculated using methods that make assumptions about the form of population growth. These methods generally assume that the population has a stable age distribution.
2. To assess the effect of variable age distributions, we tested six egg ratio methods for estimating birth and death rates with data from thirty-seven laboratory populations of Daphnia pulicaria. The populations were grown under constant conditions, but the initial age distributions and egg ratios of the populations varied. Actual death rates were virtually zero, so the difference between the estimated and actual death rates measured the error in both birth and death rate estimates.
3. The results demonstrate that unstable population structures may produce large errors in the birth and death rates estimated by any of these methods. Among the methods tested, Taylor and Slatkin's formula and Paloheimo's formula were most reliable for the experimental data.
4. Further analyses of three of the methods were made using computer simulations of growth of age-structured populations with initially unstable age distributions. These analyses show that the time interval between sampling strongly influences the reliability of birth and death rate estimates. At a sampling interval of 2.5 days (equal to the duration of the egg stage), Paloheimo's formula was most accurate. At longer intervals (7.5–10 days), Taylor and Slatkin's formula which includes information on population structure was most accurate
Studying Flow Close to an Interface by Total Internal Reflection Fluorescence Cross Correlation Spectroscopy: Quantitative Data Analysis
Total Internal Reflection Fluorescence Cross Correlation Spectroscopy
(TIR-FCCS) has recently (S. Yordanov et al., Optics Express 17, 21149 (2009))
been established as an experimental method to probe hydrodynamic flows near
surfaces, on length scales of tens of nanometers. Its main advantage is that
fluorescence only occurs for tracer particles close to the surface, thus
resulting in high sensitivity. However, the measured correlation functions only
provide rather indirect information about the flow parameters of interest, such
as the shear rate and the slip length. In the present paper, we show how to
combine detailed and fairly realistic theoretical modeling of the phenomena by
Brownian Dynamics simulations with accurate measurements of the correlation
functions, in order to establish a quantitative method to retrieve the flow
properties from the experiments. Firstly, Brownian Dynamics is used to sample
highly accurate correlation functions for a fixed set of model parameters.
Secondly, these parameters are varied systematically by means of an
importance-sampling Monte Carlo procedure in order to fit the experiments. This
provides the optimum parameter values together with their statistical error
bars. The approach is well suited for massively parallel computers, which
allows us to do the data analysis within moderate computing times. The method
is applied to flow near a hydrophilic surface, where the slip length is
observed to be smaller than 10nm, and, within the limitations of the
experiments and the model, indistinguishable from zero.Comment: 18 pages, 12 figure
HST and UKIRT imaging observations of z~1 6C radio galaxies - II. Galaxy morphologies and the alignment effect
(abridged) Powerful radio galaxies often display enhanced optical/UV emission
regions, elongated and aligned with the radio jet axis. The aim of this series
of papers is to separately investigate the effects of radio power and redshift
on the alignment effect, together with other radio galaxy properties. In this
second paper, we present a deeper analysis of the morphological properties of
these systems, including both the host galaxies and their surrounding aligned
emission. The host galaxies of our 6C subsample are well described as de
Vaucouleurs ellipticals, with typical scale sizes of ~10kpc. This is comparable
to the host galaxies of low-z radio sources of similar powers, and also the
more powerful 3CR sources at the same redshift. The contribution of nuclear
point source emission is also comparable, regardless of radio power. The 6C
alignment effect is remarkably similar to that seen around more powerful 3CR
sources at the same redshift in terms of extent and degree of alignment with
the radio source axis, although it is generally less luminous. The bright,
knotty features observed in the case of the z~1 3CR sources are far less
frequent in our 6C subsample; neither do we observe such strong evidence for
evolution in the strength of the alignment effect with radio source size/age.
However, we do find a very strong link between the most extreme alignment
effects and emission line region properties indicative of shocks, regardless of
source size/age or power. In general, the 6C alignment effect is still
considerably stronger than that seen around lower redshift galaxies of similar
radio powers. (abridged)Comment: 23 pages, 15 figures, accepted for publication in MNRAS. See
http://www.mrao.cam.ac.uk/~kji/MorphPaper/ for version of paper with full
resolution images of Figs 1-1
Gallstone Obstructive Ileus 3 Years Post-cholecystectomy to a Patient with an Old Ileoileal Anastomosis
The present case is one of gallstone obstructive ileus due to gallstones 3 yr after laparoscopic cholecystectomy. It is interesting because of the sex of the patient, the fact that ileus occurred 3 yr after cholecystectomy and that the localization of the obstruction was an old side-to-side ileoileal anastomosis due to a diverticulectomy following intussusception of Meckels' diverticulum at the age of 3
HST, radio and infrared observations of 28 3CR radio galaxies at redshift z ~ 1: I. Old stellar populations in central cluster galaxies
Hubble Space Telescope images of 3CR radio galaxies at redshifts 0.6 < z <
1.8 have shown a remarkable variety of structures, generally aligned along the
radio axis, indicating that the radio source strongly influences the optical
appearance of these galaxies. In this paper we investigate the host galaxies
underlying this aligned emission, combining the HST data with ground-based
infrared images. An investigation of the spectral energy distributions of the
galaxies shows that the contribution of the aligned blue component to the
K--band light is generally small (about 10%). The radial intensity profiles of
the galaxies are well matched at radii <~ 35 kpc by de Vaucouleurs' law,
demonstrating that the K--band light is dominated by that of an elliptical
galaxy. There is no evidence for a nuclear point source, in addition to the de
Vaucouleurs profile, with a contribution >~15% of the total K--band flux
density, except in two cases, 3C22 and 3C41. Large characteristic radii are
derived, indicating that the 3CR galaxies must be highly evolved dynamically,
even at a redshift of one. At radii > 35 kpc, a combined galaxy profile clearly
shows an excess of emission reminiscent of cD--type halos. This supports other
independent evidence for the hypothesis that the distant 3CR galaxies lie in
moderately rich (proto--)clusters. Since the nearby FR II galaxies in the 3CR
catalogue lie in more diffuse environments and do not possess cD halos, the
galactic environments of the 3CR galaxies must change with redshift. The K-z
relation of the 3CR galaxies cannot, therefore, be interpreted using a standard
`closed-box, passive stellar evolution' model. We offer a new interpretation,
and compare the model with the K-z relations of lower power radio galaxies and
brightest cluster galaxies. (abridged)Comment: 21 pages including 13 figures, LaTeX. To appear in MNRA
Single-Molecule characterization of oligomerization kinetics and equilibria of the tumor suppressor p53
The state of oligomerization of the tumor suppressor p53 is an important factor in its various biological functions. It has a well-defined tetramerization domain, and the protein exists as monomers, dimers and tetramers in equilibrium. The dissociation constants between oligomeric forms are so low that they are at the limits of measurement by conventional methods in vitro. Here, we have used the high sensitivity of single-molecule methods to measure the equilibria and kinetics of oligomerization of full-length p53 and its isolated tetramerization domain, p53tet, at physiological temperature, pH and ionic strength using fluorescence correlation spectroscopy (FCS) in vitro. The dissociation constant at 37°C for tetramers dissociating into dimers for full-length p53 was 50 ± 7 nM, and the corresponding value for dimers into monomers was 0.55 ± 0.08 nM. The half-lives for the two processes were 20 and 50 min, respectively. The equivalent quantities for p53tet were 150 ± 10 nM, 1.0 ± 0.14 nM, 2.5 ± 0.4 min and 13 ± 2 min. The data suggest that unligated p53 in unstressed cells should be predominantly dimeric. Single-molecule FCS is a useful procedure for measuring dissociation equilibria, kinetics and aggregation at extreme sensitivity
Black hole masses, accretion rates and hot- and cold-mode accretion in radio galaxies at z ~ 1
Date of Acceptance: 25/11/2014Understanding the evolution of accretion activity is fundamental to our understanding of how galaxies form and evolve over the history of the Universe. We analyse a complete sample of 27 radio galaxies which includes both high-excitation galaxies (HEGs) and low-excitation galaxies (LEGs), spanning a narrow redshift range of 0.9 < z < 1.1 and covering a factor of ~1000 in radio luminosity. Using data from the Spitzer Space Telescope combined with ground-based optical and near-infrared imaging, we show that the host galaxies have masses in the range of 10.7<log10(M/M⊙)<12.0with HEGs and LEGs exhibiting no difference in their mass distributions. We also find that HEGs accrete at significantly higher rates than LEGs, with the HEG/LEG division lying at an Eddington ratio of λ~0.04, which is in excellent agreement with theoretical predictions of where the accretion rate becomes radiatively inefficient, thus supporting the idea of HEGs and LEGs being powered by different modes of accretion. Our study also shows that at least up to L151MHz ~ 3 × 1027WHz-1 sr-1, HEGs and LEGs are indistinguishable in terms of their radio properties. From this result we infer that, at least for the lower radio luminosity range, another factor besides accretion rate must play an important role in the process of triggering jet activity.Peer reviewe
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