3,118 research outputs found
Production of A+1 and Z+1 Isotopes in Proton-Induced Reactions on AZ Nuclei. Application to Po Production in p-209Bi and Bi Production in p-208Pb Reactions
peer reviewe
Echocardiography during submaximal isometric exercise in children with repaired coarctation of the aorta compared with controls
Objective Patients with repaired coarctation (RCoA) remain at higher risk of cardiac dysfunction, initially often only detected during exercise. In this study, haemodynamics of isometric handgrip (HG) and bicycle ergometry (BE) were compared in patients with RCoA and matched controls (MCs).
Methods Case-control study of 19 children with RCoA (mean age 12.9 +/- 2.3 years; mean age of repair 7 months) compared with 20 MC. HG with echocardiography followed by BE was performed in both groups.
Results During HG (blood pressure) BP increased from 114 +/- 11/64 +/- 4 mm Hg to 132 +/- 14/79 +/- 7 mm Hg, without significant differences. During HG as well as BE, HR increased less in patients with RCoA. There were no significant differences in (left ventricle) LV dimensions or LV mass.
The RCoA group had diastolic dysfunction: both at rest and during HG they had significantly higher transmitral E and A velocities and lower tissue Doppler E' and A' velocities. E/E' was higher, reaching statistical significance during HG (p<0001).
Conventional parameters of systolic function (FS and EF) were similar at rest and HG. More sensitive tissue Doppler S' was significantly lower at rest in CoA subjects (5.1 +/- 1.5 cm/s vs 6.5 +/- 1 +/- 1 cm/s; p<0.01), decreasing further during HG by 5% in the CoA group (NS) while unchanged in controls.
Conclusions We provide first evidence that HG with echocardiography is feasible, easy and patient-friendly. A decreased systolic (tissue Doppler) and impaired diastolic LV function was measured in the RCoA group, a difference that tended to increase during HG
Polarimetric distance-dependent models for large hall scenarios
A comprehensive polarimetric distance-dependent model of the power delay profile (PDP) and path gain is proposed. The model includes both specular multipath components (SMCs) and dense multipath components (DMC), the latter being modeled with an exponential and power law. The parameters of the model were estimated from polarimetric measurements of a large hall radio channel under line-of-sight (LOS) conditions at 1.3 GHz with a dedicated procedure. The validity and robustness of the proposed approach are provided by the good agreement between the polarimetric data and models for the investigated transmitter-receiver distance range. Furthermore, the description of the radio channel with path loss models is discussed for cases where the DMC is included, and a two-step method to compute the path loss characteristics directly from the measured data is developed. The results of this contribution highlight the fact that a complete polarimetric description of all propagation mechanisms and related path loss models is desired to design faithful polarimetric radio channel models
Bound of dissipation on a plane Couette dynamo
Variational turbulence is among the few approaches providing rigorous results
in turbulence. In addition, it addresses a question of direct practical
interest, namely the rate of energy dissipation. Unfortunately, only an upper
bound is obtained as a larger functional space than the space of solutions to
the Navier-Stokes equations is searched. Yet, in general, this upper bound is
in good agreement with experimental results in terms of order of magnitude and
power law of the imposed Reynolds number. In this paper, the variational
approach to turbulence is extended to the case of dynamo action and an upper
bound is obtained for the global dissipation rate (viscous and Ohmic). A simple
plane Couette flow is investigated. For low magnetic Prandtl number
fluids, the upper bound of energy dissipation is that of classical turbulence
(i.e. proportional to the cubic power of the shear velocity) for magnetic
Reynolds numbers below and follows a steeper evolution for magnetic
Reynolds numbers above (i.e. proportional to the shear velocity to
the power four) in the case of electrically insulating walls. However, the
effect of wall conductance is crucial : for a given value of wall conductance,
there is a value for the magnetic Reynolds number above which energy
dissipation cannot be bounded. This limiting magnetic Reynolds number is
inversely proportional to the square root of the conductance of the wall.
Implications in terms of energy dissipation in experimental and natural dynamos
are discussed.Comment: In this new version, amistake (in equation 23 of the first version)
is correcte
Identification of a cis‐acting element required for shunt‐mediated translational initiation of the Sendai virus Y proteins
Shunting is a mechanism that permits translational initiation at internal codons positioned in proximity to a ribosome acceptor sequence. Sendai virus exploits shunting to express a series of proteins that initiate at the fourth and fifth start sites on the P/C mRNA (namely, the Y1 and Y2 proteins, respectively). Shunt‐mediated initiation at these sites is codon independent. In an attempt to characterise the acceptor site, an extensive deletion analysis was performed spanning the entire C ORF. Only mutants flanking the Y1/Y2 start sites exhibited altered shunt phenotypes. Some of these significantly enhanced shunting efficiency to the point where the Y1/Y2 proteins were the major translational products of the mRNA. Additionally, removal of a short region just downstream of the Y2 start codon (referred to as Δ10) ablated all Y protein initiation via shunting but had no effect on Y expression when the AUG codons were viewed by a scanning ribosome. Point mutations introduced into this Δ10 sequence severely perturbed shunt‐mediated initiation. We also provide evidence that changes in this region of the P/C mRNA may be used to modulate Y protein expression levels in different viral strain
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