2,932 research outputs found
Tetralogy of Fallot with absent pulmonary valve syndrome : an imaging challenge
Congenital absence of pulmonary valve syndrome (APV) represents a fascinating and unique
variant of congenital heart disease. It was Chever in 1847 who first described this unique structural
heart defect. The anatomic features consist of an incompletely formed, rudimentary pulmonary
valve that is both stenotic and regurgitant, massively dilated pulmonary arteries and a large
malaligned outlet ventricular septal defect. There is an association of this defect with Tetralogy of
Fallot (ToF) due to which this condition is often referred to as Tetralogy of Fallot/absent pulmonary
valve syndrome. Another characteristic feature is that there is virtually always absence of a patent
ductus arteriosus. That has been hypothesized as being responsible for the pathogenesis of
pulmonary artery dysplasia.peer-reviewe
Individual Attitudes towards Immigration in Aging Populations
This research empirically establishes the hypothesis that the process of
population aging in a society as a whole affects the attitudes of its members
towards immigration. Hence, an aging social environment exerts an effect
on the attitudes of individuals towards immigration after accounting for
their age and other individual characteristics. We test this hypothesis in
a multilevel analysis of individuals living in 25 European OECD countries
over the period 2002-2017. Our measure of “societal population aging” is the
old-age dependency ratio. “Attitudes” are taken from immigration related
questions in eight consecutive rounds of the European Social Survey. For
these attitudes we find non-linear, U-shaped relationships. Hence, the effect
of societal population aging on individual attitudes towards immigration is
negative in young societies and positive in old ones
Vegetation of the coastal dunes and wetland of Schinias National Park (NE Attica, Sterea Ellas, Greece)
The vegetation developing on the coastal sand dunes and wetland of Schinias National Park, a Natura 2000 Site, was studied following the Braun-Blanquet method. Vegetation units were delimited using cluster analysis and by applying the fidelity measure; the phi-coefficient was used for the definition of diagnostic species. The vegetation types distinguished (twenty associations, two sub-associations and thirteen communities not assigned formal rank), which belong to 18 alliances, 16 orders and 12 classes, are discussed and presented in phytosociological tables. Among them Mathiolo tricuspidatae-Anthemidetum tomentosae, Pistacio lentisci-Pinetum halepensis pinetosum pineae, Puccinellio festuciformis-Aeluropetum litoralis cressetosum creticae and Tamaricetum tetrandrae are described for the first time. The vegetation types recognized in the study area are linked to twelve EUNIS habitat types, nine of which are related to 13 Annex I habitat types (Directive 92/43/EEC), and one to a habitat type of national interest (72A0). One Annex I habitat type occurring in the study area has scattered presence in the Natura 2000 network in Greece (1420), two are infrequent (2190, 2260), two are rare (2230, 2270) and three are priority habitat types (1150, 2250, 2270)
Genetic interplay between the transcription factors Sp8 and Emx2 in the patterning of the forebrain
<p>Abstract</p> <p>Background</p> <p>The forebrain consists of multiple structures necessary to achieve elaborate functions. Proper patterning is, therefore, a prerequisite for the generation of optimal functional areas. Only a few factors have been shown to control the genetic networks that establish early forebrain patterning.</p> <p>Results and conclusion</p> <p>Using conditional inactivation, we show that the transcription factor Sp8 has an essential role in the molecular and functional patterning of the developing telencephalon along the anteroposterior axis by modulating the expression gradients of <it>Emx2 </it>and <it>Pax6</it>. Moreover, Sp8 is essential for the maintenance of ventral cell identity in the septum and medial ganglionic eminence (MGE). This is probably mediated through a positive regulatory interaction with Fgf8 in the medial wall, and Nkx2.1 in the rostral MGE anlage, and independent of SHH and WNT signaling. Furthermore, <it>Sp8 </it>is required during corticogenesis to sustain a normal progenitor pool, and to control preplate splitting, as well as the specification of cellular diversity within distinct cortical layers.</p
Mixed-Variable Bayesian Optimization
The optimization of expensive to evaluate, black-box, mixed-variable
functions, i.e. functions that have continuous and discrete inputs, is a
difficult and yet pervasive problem in science and engineering. In Bayesian
optimization (BO), special cases of this problem that consider fully continuous
or fully discrete domains have been widely studied. However, few methods exist
for mixed-variable domains and none of them can handle discrete constraints
that arise in many real-world applications. In this paper, we introduce MiVaBo,
a novel BO algorithm for the efficient optimization of mixed-variable functions
combining a linear surrogate model based on expressive feature representations
with Thompson sampling. We propose an effective method to optimize its
acquisition function, a challenging problem for mixed-variable domains, making
MiVaBo the first BO method that can handle complex constraints over the
discrete variables. Moreover, we provide the first convergence analysis of a
mixed-variable BO algorithm. Finally, we show that MiVaBo is significantly more
sample efficient than state-of-the-art mixed-variable BO algorithms on several
hyperparameter tuning tasks, including the tuning of deep generative models.Comment: IJCAI 2020 camera-ready; 17 pages, extended version with
supplementary materia
Storage of Heat, Cold and Electricity
A promising energy storage system is presented based on the combination of a heat pump, a heat engine, a hot and a cold storage. It can be operated as a pure bulk electricity storage (alternative to Pumped Heat Electrical Storage (PHES)/Compressed Air Energy Storage (CAES)) or as combined
storage of heat, cold and electricity. Both variations have been evaluated using a steady state, thermodynamic model and two promising concepts are proposed: A transcritical CO2 cycle for the pure electricity storage and a subcritical NH3 cycle for combined storage of
electricity, heat and cold. Parametric studies are used to evaluate the influence of different parameters on the roundtrip efficiency of the storage system
Population Aging and Inventive Activity
This research empirically establishes and interprets the hypothesis that the relationship
between population aging and inventive activity is hump-shaped. We estimate a reduced
form, hump-shaped relationship in a panel of 33 OECD countries over the period
1960–2012, as well as in a panel of 248 NUTS 2 regions in Europe over the period
2001–2012. The increasing part of the hump may be associated with various channels
including the acknowledgement that population aging requires inventive activity to
guarantee current and future standards of living, or the observation that older educated
workers are more innovative than their young peers. The decreasing part may reflect the
tendency of aging societies to lose dynamism and the willingness to take risks
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