3,543 research outputs found
A new species of Rhodomyrtus (Myrtaceae) with brochidodromous venation from north-eastern Queensland, Australia.
Rhodomyrtus verecunda A.J.Ford & Peter G. Wilson from north-east Queensland, Australia, is formally described and illustrated. Notes on habitat, distribution and conservation status are provided, as are details of how it can be distinguished from R. macrocarpa, the only other species of the genus in the region that lacks acrodromous venation. A revised key to the species of Rhodomyrtus in Australia is also presented
Single versus two-stent strategies for coronary bifurcation lesions: a systematic review and meta-analysis of randomized trials with long-term follow-up
Background:
The majority of coronary bifurcation lesions are treated with a provisional singleâstent strategy rather than an upâfront 2âstent strategy. This approach is supported by multiple randomized controlled clinical trials with shortâ to mediumâterm followâup; however, longâterm followâup data is evolving from many data sets.
Methods and Results:
Metaâanalysis of randomized controlled trials evaluating longâterm outcomes (â„1 year) according to treatment strategy for coronary bifurcation lesions. Nine randomized controlled trials with 3265 patients reported longâterm clinical outcomes at mean weighted followâup of 3.1±1.8 years. Provisional single stenting was associated with lower allâcause mortality (2.94% versus 4.23%; risk ratio: 0.69; 95% confidence interval, 0.48â1.00; P=0.049; I2=0). There was no difference in major adverse cardiac events (15.8% versus 15.4%; P=0.79), myocardial infarction (4.8% versus 5.5%; P=0.51), target lesion revascularization (9.3% versus 7.6%; P=0.19), or stent thrombosis (1.8% versus 1.6%; P=0.28) between the groups. Prespecified sensitivity analysis of longâterm mortality at a mean of 4.7 years of followâup showed that the provisional singleâstent strategy was associated with reduced allâcause mortality (3.9% versus 6.2%; risk ratio: 0.63; 95% confidence interval, 0.42â0.97; P=0.036; I2=0).
Conclusions:
Coronary bifurcation percutaneous coronary intervention using a provisional singleâstent strategy is associated with a reduction in allâcause mortality at longâterm followâup
Chandra Observation of an X-ray Flare at Saturn: Evidence for Direct Solar Control on Saturn's Disk X-ray Emissions
Saturn was observed by Chandra ACIS-S on 20 and 26-27 January 2004 for one
full Saturn rotation (10.7 hr) at each epoch. We report here the first
observation of an X-ray flare from Saturn's non-auroral (low-latitude) disk,
which is seen in direct response to an M6-class flare emanating from a sunspot
that was clearly visible from both Saturn and Earth. Saturn's disk X-ray
emissions are found to be variable on time scales of hours to weeks to months,
and correlated with solar F10.7 cm flux. Unlike Jupiter, X-rays from Saturn's
polar (auroral) region have characteristics similar to those from its disk.
This report, combined with earlier studies, establishes that disk X-ray
emissions of the giant planets Saturn and Jupiter are directly regulated by
processes happening on the Sun. We suggest that these emissions could be
monitored to study X-ray flaring from solar active regions when they are on the
far side and not visible to Near-Earth space weather satellites.Comment: Total 12 pages including 4 figure
Navigating the Backlash Against Global Law and Institutions
This article considers the recent âBacklashâ against global norms and institutions fuelled by
various contemporary political developments within and between states. Understanding the
shape, significance and drivers of this phenomenon better is a pre-requisite to developing and
analysing possible responses by Australia and other states. The current global legal order was
established after World War II and is underpinned by the United Nations Charter, international
law in general, and the growing collection of multilateral international legal instruments by
which states agree to conduct their international relations. The sweep of the global legal order
is broad, encompassing norms and institutions that seek to foster international cooperation
across a range of spheres, including development, the environment, finance, health, human
rights, science, security and trade. The United States has historically been considered the leader
and guarantor of the post-1945 legal order, playing host to its most important institutions. The
US has provided key economic, political, and diplomatic backing throughout its time as one of
two superpowers during the Cold War, and as the hegemonic power for most of the period
since. Australia has also been a strong supporter of the liberal rules-based order, commitment
to which explicitly underpins its current official foreign policy posture.1
It was a founding
member of the United Nations and has traditionally been involved in the drafting of, and been
swift to sign on to, new international covenants that clarify and crystalise the heretofore
expanding reach of international law
Microvascular resistance predicts myocardial salvage and infarct characteristics in ST-elevation myocardial infarction
<b>Background:</b> The pathophysiology of myocardial injury and repair in patients with STâelevation myocardial infarction is incompletely understood. We investigated the relationships among culprit artery microvascular resistance, myocardial salvage, and ventricular function.<p></p>
<b>Methods and Results:</b> The index of microvascular resistance (IMR) was measured by means of a pressureâ and temperatureâsensitive coronary guidewire in 108 patients with STâelevation myocardial infarction (83% male) at the end of primary percutaneous coronary intervention. Paired cardiac MRI (cardiac magnetic resonance) scans were performed early (2 days; n=108) and late (3 months; n=96) after myocardial infarction. T2âweightedâ and late gadoliniumâenhanced cardiac magnetic resonance delineated the ischemic area at risk and infarct size, respectively. Myocardial salvage was calculated by subtracting infarct size from area at risk. Univariable and multivariable models were constructed to determine the impact of IMR on cardiac magnetic resonanceâderived surrogate outcomes. The median (interquartile range) IMR was 28 (17â42) mm Hg/s. The median (interquartile range) area at risk was 32% (24%â41%) of left ventricular mass, and the myocardial salvage index was 21% (11%â43%). IMR was a significant multivariable predictor of early myocardial salvage, with a multiplicative effect of 0.87 (95% confidence interval 0.82 to 0.92) per 20% increase in IMR; P<0.001. In patients with anterior myocardial infarction, IMR was a multivariable predictor of early and late myocardial salvage, with multiplicative effects of 0.82 (95% confidence interval 0.75 to 0.90; P<0.001) and 0.92 (95% confidence interval 0.88 to 0.96; P<0.001), respectively. IMR also predicted the presence and extent of microvascular obstruction and myocardial hemorrhage.<p></p>
<b>Conclusion:</b> Microvascular resistance measured during primary percutaneous coronary intervention significantly predicts myocardial salvage, infarct characteristics, and left ventricular ejection fraction in patients with STâelevation myocardial infarction.<p></p>
Discovery of a ~1 Hz quasi-periodic oscillation in the low-mass X-ray binary 4U 1746-37
We have discovered a ~1 Hz quasi-periodic oscillation (QPO) in the persistent
X-ray emission and during type I X-ray bursts of the globular cluster source,
dipper and low-mass X-ray binary (LMXB) 4U 1746-37. The QPO properties resemble
those of QPOs found recently in the LMXB dippers 4U 1323-62, and EXO 0748-676,
which makes 4U 1746-37 the third source known to exhibit this type of QPOs. We
present evidence for X-ray spectral changes in this source similar to those
observed in LMXBs referred to as atoll sources. We detect two states, a low
intensity and spectrally hard state, and a higher intensity and spectrally soft
state. This may explain the different spectral characteristics reported for 4U
1746-37 earlier. The high intensity state resembles the banana branch state of
atoll sources. The QPOs are only seen in the low intensity state, and are
absent when the source is in the banana branch. This strongly suggests that
either the accretion disk or an extended central source change shape between
the low intensity state and the banana branch. Twelve bursts were detected, of
which 5 took place while the source was on the banana branch and 7 when the
source was in the low intensity state. The bursts occurring on the banana
branch had an e-folding time ~3 times longer than those which occurred in the
low intensity state. Whereas previously detected dips showed only a decrease in
count rate of ~15%, we found in one observation a dip in which the count rate
dropped from ~200 counts per second to ~20 counts per second. This dip lasted
only ~250 seconds, during which clear spectral hardening occured. This is the
first time strong evidence for spectral changes during a dip are reported for
this source.Comment: 17 pages, accepted for publication in Ap
Of Some Theoretical Significance: Implications of Casimir Effects
In his autobiography Casimir barely mentioned the Casimir effect, but
remarked that it is "of some theortical significance." We will describe some
aspects of Casimir effects that appear to be of particular significance now,
more than half a century after Casimir's famous paper
Simultaneous Measurements of X-Ray Luminosity and Kilohertz Quasi-Periodic Oscillations in Low-Mass X-Ray Binaries
We measure simultaneously the properties of the energy spectra and the
frequencies of the kilohertz quasi-periodic oscillations (QPOs) in fifteen low
mass X-ray binaries covering a wide range of X-ray luminosities. In each source
the QPO frequencies cover the same range of approximately 300 Hz to 1300 Hz,
though the sources differ by two orders of magnitude in their X-ray
luminosities (as measured from the unabsorbed 2-50 keV flux). So the X-ray
luminosity does not uniquely determine the QPO frequency. This is difficult to
understand since the evidence from individual sources indicates that the
frequency and luminosity are very well correlated at least over short
timescales. Perhaps beaming effects or bolometric corrections change the
observed luminosities, or perhaps part of the energy in mass accretion is used
to power outflows reducing the energy emitted in X-rays. It is also possible
that the parameters of a QPO model are tuned in such a way that the same range
of frequencies appears in all sources. Different modes of accretion may be
involved for example (disk and radial) or multiple parameters may conspire to
yield the same frequencies.Comment: 14 pages, 2 figures (1 in color), accepted by ApJ, see the 'QPO
page': http://www.astro.uva.nl/~ecford/qpos.htm
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