226 research outputs found
The Adult Patient with Eisenmenger Syndrome: A Medical Update After Dana Point Part I: Epidemiology, Clinical Aspects and Diagnostic Options
Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death
The Adult Patient with Eisenmenger Syndrome: A Medical Update after Dana Point Part III: Specific Management and Surgical Aspects
Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death
The Adult Patient with Eisenmenger Syndrome: A Medical Update after Dana Point Part II: Medical Treatment - Study Results
Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death
A key factor initiating surface ablation of Arctic sea ice: earlier and increasing liquid precipitation
Snow plays an important role in the Arctic climate system,
modulating heat transfer in terrestrial and marine environments and
controlling feedbacks. Changes in snow depth over Arctic sea ice,
particularly in spring, have a strong impact on the surface energy budget,
influencing ocean heat loss, ice growth and surface ponding. Snow conditions
are sensitive to the phase (solid or liquid) of deposited precipitation.
However, variability and potential trends of rain-on-snow events over Arctic
sea ice and their role in sea-ice losses are poorly understood. Time series
of surface observations at Utqiaġvik, Alaska, reveal rapid reduction in
snow depth linked to late-spring rain-on-snow events. Liquid precipitation
is key in preconditioning and triggering snow ablation through reduction in
surface albedo as well as latent heat release determined by rainfall amount,
supported by field observations beginning in 2000 and model results.
Rainfall was found to accelerate warming and ripening of the snowpack, with
even small amounts (such as 0.3 mm recorded on 24 May 2017)
triggering the transition from the warming phase into the ripening phase.
Subsequently, direct heat input drives snowmelt, with water content of the
snowpack increasing until meltwater output occurs, with an associated rapid
decrease in snow depth. Rainfall during the ripening phase can further raise
water content in the snow layer, prompting onset of the meltwater output
phase in the snowpack. First spring rainfall in Utqiaġvik has been
observed to shift to earlier dates since the 1970s, in particular after the
mid-1990s. Early melt season rainfall and its fraction of total annual
precipitation also exhibit an increasing trend. These changes of
precipitation over sea ice may have profound impacts on ice melt through
feedbacks involving earlier onset of surface melt.</p
Platform Dependent Verification: On Engineering Verification Tools for 21st Century
The paper overviews recent developments in platform-dependent explicit-state
LTL model checking.Comment: In Proceedings PDMC 2011, arXiv:1111.006
Vertical and Horizontal Transmission of Cell Fusing Agent Virus in Aedes aegypti
Cell fusing agent virus (CFAV) is an insect-specific flavivirus (ISF) found in Aedes aegypti mosquitoes. ISFs have demonstrated the ability to modulate the infection or transmission of arboviruses such as dengue, West Nile, and Zika viruses. It is thought that vertical transmission is the main route for ISF maintenance in nature. This has been observed with CFAV, but there is evidence of horizontal and venereal transmission in other ISFs. Understanding the route of transmission can inform strategies to spread ISFs to vector populations as a method of controlling pathogenic arboviruses. We crossed individually reared male and female mosquitoes from both a naturally occurring CFAV-positive Ae. aegypti colony and its negative counterpart to provide information on maternal, paternal, and horizontal transmission. RT-PCR was used to detect CFAV in individual female pupal exuviae and was 89% sensitive, but only 42% in male pupal exuviae. This is a possible way to screen individuals for infection without destroying the adults. Female-to-male horizontal transmission was not observed during this study. However, there was a 31% transmission rate from mating pairs of CFAV-positive males to negative female mosquitoes. Maternal vertical transmission was observed with a filial infection rate of 93%. The rate of paternal transmission was 85% when the female remained negative, 61% when the female acquired CFAV horizontally, and 76% overall. Maternal and paternal transmission of CFAV could allow the introduction of this virus into wild Ae. aegypti populations through male or female mosquito releases, and thus provides a potential strategy for ISF-derived arbovirus control
Arctic Mission Benefit Analysis: impact of sea ice thickness, freeboard, and snow depth products on sea ice forecast performance
Assimilation of remote-sensing products of sea ice thickness (SIT) into sea
ice–ocean models has been shown to improve the quality of sea ice forecasts.
Key open questions are whether assimilation of lower-level data products such
as radar freeboard (RFB) can further improve model performance and what
performance gains can be achieved through joint assimilation of these data
products in combination with a snow depth product. The Arctic Mission Benefit
Analysis system was developed to address this type of question. Using the
quantitative network design (QND) approach, the system can evaluate, in a
mathematically rigorous fashion, the observational constraints imposed by
individual and groups of data products. We demonstrate the approach by
presenting assessments of the observation impact (added value) of different
Earth observation (EO) products in terms of the uncertainty reduction in a
4-week forecast of sea ice volume (SIV) and snow volume (SNV) for three
regions along the Northern Sea Route in May 2015 using a coupled model of the
sea ice–ocean system, specifically the Max Planck Institute Ocean
Model. We assess seven satellite products: three real products and four
hypothetical products. The real products are monthly SIT, sea ice freeboard
(SIFB), and RFB, all derived from CryoSat-2 by the Alfred Wegener Institute.
These are complemented by two hypothetical monthly laser freeboard (LFB)
products with low and high accuracy, as well as two hypothetical monthly snow
depth products with low and high accuracy.On the basis of the per-pixel uncertainty ranges provided with the CryoSat-2
SIT, SIFB, and RFB products, the SIT and RFB achieve a much better
performance for SIV than the SIFB product. For SNV, the performance of SIT is
only low, the performance of SIFB is higher and the performance of RFB is yet
higher. A hypothetical LFB product with low accuracy (20 cm
uncertainty) falls between SIFB and RFB in performance for both SIV and SNV.
A reduction in the uncertainty of the LFB product to 2 cm yields a
significant increase in performance.Combining either of the SIT or freeboard products with a hypothetical
snow depth product achieves a significant performance increase.
The uncertainty in the snow product matters: a higher-accuracy product
achieves an extra performance gain.
Providing spatial and temporal uncertainty correlations with the
EO products would be beneficial not only for QND assessments,
but also for assimilation of the products.</p
Antarctic pack ice algal distribution: Floe-scale spatial variability and predictability from physical parameters
©2017. Commonwealth of Australia. Antarctic pack ice serves as habitat for microalgae which contribute to Southern Ocean primary production and serve as important food source for pelagic herbivores. Ice algal biomass is highly patchy and remains severely undersampled by classical methods such as spatially restricted ice coring surveys. Here we provide an unprecedented view of ice algal biomass distribution, mapped (as chlorophyll a) in a 100 m by 100 m area of a Weddell Sea pack ice floe, using under-ice irradiance measurements taken with an instrumented remotely operated vehicle. We identified significant correlations (p < 0.001) between algal biomass and concomitant in situ surface measurements of snow depth, ice thickness, and estimated sea ice freeboard levels using a statistical model. The model's explanatory power (r2 = 0.30) indicates that these parameters alone may provide a first basis for spatial prediction of ice algal biomass, but parameterization of additional determinants is needed to inform more robust upscaling efforts
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