58 research outputs found
Adverse Cardiovascular Events Arising From Atherosclerotic Lesions With and Without Angiographic Disease Progression
ObjectivesThe aim of this study was to use angiography and grayscale and intravascular ultrasoundâvirtual histology to assess coronary lesions that caused events during a median follow-up period of 3.4 years.BackgroundVulnerable plaque-related events are assumed to be the result of substantial progression of insignificant lesions.MethodsIn the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study, 697 patients with acute coronary syndromes underwent treatment of all culprit lesions followed by 3-vessel imaging to assess the natural history of culprit and untreated nonculprit (NC) lesions. Future adverse cardiovascular events adjudicated to NC lesions were divided into those with versus without substantial lesion progression (SLP) (â„20% angiographic diameter stenosis increase).ResultsNC lesion events occurred in 72 patients, 44 (61%) with and 28 (39%) without SLP. Myocardial infarctions (n = 6) occurred only in patients with SLP. Conversely, patients without SLP presented only with unstable or increasing angina requiring rehospitalization. Lesions with versus without SLP occurred later (median time to event 401 vs. 223 days, p = 0.07); were less severe at baseline (median diameter stenosis 26.4% vs. 53.8%, p < 0.0001) but more severe at the time of the event (mean diameter stenosis 73.8% vs. 56%, p < 0.0001); and had comparable baseline median plaque burden (68.7% vs. 70.1%, p = 0.17), minimum luminal area (3.7 vs. 4.0 mm2, p = 0.60), and intravascular ultrasoundâvirtual histology phenotype (83.3% vs. 90.9%, p = 0.68; classified as fibroatheromas at baseline).ConclusionsNC lesions responsible for future cardiovascular events showed angiographic increase during 3.4 years of follow-up, whereas SLP underlay many but not all of them. NC events due to lesions with SLP were angiographically less severe and presented with a delayed time course but were otherwise indistinguishable from NC events that were not associated with SLP
Characterization of a continuous muon source for the Muon-Induced X-ray Emission (MIXE) Technique
The toolbox for material characterization has never been richer than today.
Great progress with all kinds of particles and interaction methods provide
access to nearly all properties of an object under study. However, a
tomographic analysis of the subsurface region remains still a challenge today.
In this regard, the Muon-Induced X-ray Emission (MIXE) technique has seen
rebirth fueled by the availability of high intensity muon beams. We report here
a study conducted at the Paul Scherrer Institute (PSI). It demonstrates that
the absence of any beam time-structure leads to low pile-up events and a high
signal-to-noise ratio (SNR) with less than one hour acquisition time per sample
or data point. This performance creates the perspective to open this technique
to a wider audience for the routine investigation of non-destructive and
depth-sensitive elemental compositions, for example in rare and precious
samples. Using a hetero-structured sample of known elements and thicknesses, we
successfully detected the characteristic muonic X-rays, emitted during the
capture of a negative muon by an atom, and the gamma-rays resulting from the
nuclear capture of the muon, characterizing the capabilities of MIXE at PSI.
This sample emphasizes the quality of a continuous beam, and the exceptional
SNR at high rates. Such sensitivity will enable totally new statistically
intense aspects in the field of MIXE, e.g. elemental 3D-tomography and chemical
analysis. Therefore, we are currently advancing our proof-of-concept
experiments with the goal of creating a full fledged permanently operated user
station to make MIXE available to the wider scientific community as well as
industry
Strong near-infrared carbon in the Type Ia supernova iPTF13ebh
We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR C i lines, and the C iλ1.0693 ÎŒm line is the strongest ever observed in a SN Ia. Interestingly, no strong optical C ii counterparts were found, even though the optical spectroscopic time series began early and is densely cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR C i compared to the weaker optical C ii appears to be general in SNe Ia. iPTF13ebh is a fast decliner with Îm15(B) = 1.79 ± 0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a "transitional" event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest that composition and density of the inner core are similar to that of 91bg-like events, and that it has a deep-reaching carbon burning layer that is not observed in more slowly declining SNe Ia. There is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the Si iiλ0.6355 ÎŒm line, implying a long dark phase of âŒ4 days. © 2015 ESO
Astronomical Distance Determination in the Space Age: Secondary Distance Indicators
The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)
Diversity in warning coloration: selective paradox or the norm?
Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: genetic mechanisms, differences among predators and predator behaviour, and alternative selection pressures upon the signal. The mechanisms producing warning coloration are also important. Detailed studies of the genetic basis of warning signals in some species, most notably Heliconius butterflies, are beginning to shed light on the genetic architecture facilitating or limiting key processes such as the evolution and maintenance of polymorphisms, hybridisation, and speciation. Work on predator behaviour is changing our perception of the predator community as a single homogenous selective agent, emphasising the dynamic nature of predator-prey interactions. Predator variability in a range of factors (e.g. perceptual abilities, tolerance to chemical defences, and individual motivation), suggests that the role of predators is more complicated than previously appreciated. With complex selection regimes at work, polytypisms and polymorphisms may even occur in Mullerian mimicry systems. Meanwhile, phenotypes are often multifunctional, and thus subject to additional biotic and abiotic selection pressures. Some of these selective pressures, primarily sexual selection and thermoregulation, have received considerable attention, while others, such as disease risk and parental effects, offer promising avenues to explore. As well as reviewing the existing evidence from both empirical studies and theoretical modelling, we highlight hypotheses that could benefit from further investigation in aposematic species. Finally by collating known instances of variation in warning signals, we provide a valuable resource for understanding the taxonomic spread of diversity in aposematic signalling and with which to direct future research. A greater appreciation of the extent of variation in aposematic species, and of the selective pressures and constraints which contribute to this once-paradoxical phenomenon, yields a new perspective for the field of aposematic signalling.Peer reviewe
The real impact of financial crises
Output falls precipitously in most emerging nations that experience financial crises. The authors conjecture that a significant part of the real impact of financial crises is due to the fact that during turbulent times firms choose to leave a large fraction of productive resources idle until business conditions improve. In the case of Mexicoâs 1994â95 crisis, they calculate that capital utilization could account for as much as half the drop in standard measures of total factor productivity. Capital utilization matters much more during financial crises than during other periods, they argue, because crises create ideal conditions for large swings in utilization rates.Financial crises
Synthesis and Spectroscopic Characterization of Furan-2-Carbaldehyde-<i>d</i>
Here, we present a protocol for the one-step synthesis of the title compound in quantitative yield using adapted Vilsmeier conditions. The product was characterized by 1H-,2H-,13C-NMR-, as well as IR and Raman spectroscopy. Spectral data are given in detail
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