Femoral injection of echo contrast medium may increase the sensitivity of testing for a patent foramen ovale

OBJECTIVE: The diagnosis of a patent foramen ovale (PFO) as a cause of stroke is of increasing interest especially in young (<45 years) patients. METHODS: We studied potential right-to-left shunting using transesophageal echocardiography (TEE) and bilateral transcranial Doppler sonography (TCD) of the middle cerebral artery (MCA) simultaneously in 44 patients. All patients were younger than age 45 years and suffered from an acute ischemic stroke or transient ischemic attack. Other possible etiologies were excluded. Echo contrast medium was injected in an alternating mode via antecubital or femoral veins. Tests were performed with and without the Valsalva maneuver. The criteria for a PFO were that the contrast pass from the right to the left atrium (TEE) and early detection (<10 seconds) of more than 10 micro air bubbles in at least one MCA by TCD. RESULTS: A PFO was diagnosed in 22 patients (50%). The detection rate with TEE/TCD was 11.4%/4.5% via antecubital injection, 18%/13.6% via antecubital injection plus the Valsalva maneuver, 38.6%/36% via femoral injection alone, and 50%/50% via femoral injection plus the Valsalva maneuver. The difference between femoral and antecubital injections was significant with and without the Valsalva maneuver (p < 0.01, chi2 test). There were no differences between TEE and TCD after femoral injection with the Valsalva maneuver. The brain transit time was 4.6 +/- 2.1 seconds for femoral injection and 6.3 +/- 4.1 seconds for antecubital injection. CONCLUSIONS: The sensitivity in detecting a PFO was markedly increased by femoral injection. This may be caused by different inflow patterns to the right atrium: inferior vena caval flow is directed to the right atrial septum, whereas superior vena caval flow is directed to the tricuspid valve. Thus, femoral injection may help to improve the detection of PFO and may explain the differences between TEE and TCD findings in previous studies.     

Implementation of finite element nonlinear Galerkin methods using hierarchical bases

The nonlinear Galerkin methods are investigated in the framework of finite element discretization We first describe the theoretical background in relation with multilevel and finite element approximations of attractors. Then on the computational side, we recall the definition of the hierarchical bases and analyze the structure associated to these bases. Finally we present the schemes and report on numerical experiments performed on two-dimensional equations of the Burgers and Navier-Stokes type. Their consistency with the approximation that we make and with the structure of the algorithm is discussed.     

Shear modulus,internal bond and density profile of medium density fibre board (MDF)

G _xz, G _yz), shear strength and internal bond (IB) as well as between mean density and internal bond, shear modulus and shear strength. A correlation between the failure position and parameters derived from the density profile could not be established. 69% of the failures were found in the outer layers of the specimens (15–35% and 65–85% of thickness, respectively), even if the lowest density was found in the core layer. Failures in the centre of the specimens were found only when the lowest density was less than 30% of the mean density.

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G _xz, G _yz), Schubfestigkeit und Querzugfestigkeit. Ein hoher Zusammenhang liegt auch zwischen der mittleren Dichte, der Querzugfestigkeit und den Schubeigenschaften vor. Keiner der herangezogenen charakteristischen Werte des Dichteprofils besitzt einen Zusammenhang zur Bruchposition der geprüften Proben. Beim Querzugtest waren 69% aller Brüche in einem Bereich von 15–35% bzw. 65–85% der Plattendicke zu finden. In diesen Bereichen war der Bruch auch zu finden, wenn die minimale Dichte deutlich in Plattenmitte lag. Brüche in der Mittellage der Proben konnten nur festgestellt werden, wenn die minimale Dichte mehr als 30% von der mittleren Dichte abwich.

     

Permeability and stability in buffer and in human serum of fluorinated phospholipid-based liposomes

Calsequestrin is the major Ca(2+)-binding protein localized in the terminal cisternae of the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle cells. Calsequestrin has been purified and cloned from both skeletal and cardiac muscle in mammalian, amphibian, and avian species. Two different calsequestrin gene products namely cardiac and fast have been identified. Fast and cardiac calsequestrin isoforms have a highly acidic amino acid composition. The amino acid composition of the cardiac form is very similar to the skeletal form except for the carboxyl terminal region of the protein which possess variable length of acidic residues and two phosphorylation sites. Circular dichroism and NMR studies have shown that calsequestrin increases its alpha-helical content and the intrinsic fluorescence upon binding of Ca2+. Calsequestrin binds Ca2+ with high-capacity and with moderate affinity and it functions as a Ca2+ storage protein in the lumen of the SR. Calsequestrin has been found to be associated with the Ca2+ release channel protein complex of the SR through protein-protein interactions. The human and rabbit fast calsequestrin genes have been cloned. The fast gene is skeletal muscle specific and transcribed at different rates in fast and slow skeletal muscle but not in cardiac muscle. We have recently cloned the rabbit cardiac calsequestrin gene. Heart expresses exclusively the cardiac calsequestrin gene. This gene is also expressed in slow skeletal muscle. No change in calsequestrin mRNA expression has been detected in animal models of cardiac hypertrophy and in failing human heart.     

Analysis of coaxial waveguide partially filled with chiral media

In this paper, the canonical problem of coaxial waveguide partially filled with chiral media is analyzed by a new equivalent transmission line network method. Both radial transmission lines in the cross section and multi-mode transmission lines in the longitudinal direction are introduced. The symmetrical properties of the structure are also discussed. Therefore, this method brings a clear physical picture into the wave propagation phenomena. Based on the analysis, the notable features and the role of the chirality parameter of the medium on the reflected and transmitted guided waves are discussed.     

Radio receivers for cellular networks: Possible architectures using a ΣΔ-converter

We first explain the constraints set on a receiver for digital cellular systems before showing how they are handled with the standard architectures (direct conversion and superheterodyne). We introduce then a new approach based on the direct sampling of the intermediate frequency in a superheterodyne receiver using a passband analog- to- digital ΣΔ -converter. We give design rules to minimize the complexity of the system and study within that scope the interest of under sampled ΣΔ -converters addressing more especially the stability problems. Undersampling allows to reduce the processing load in the digital part of the converter, compared to a standard ΣΔ conversion. The last chapter is dedicated to a presentation of cellular networks in order to justify the constraints set on receivers designed for this environment.     

Caractérisation de la remontée spectrale àla sortie d’un amplificateur de puissance

Power amplifier (m) is one of the most critical and costly components in a wireless communications system. Linearity and efficiency are two desirable but conflicting requirements of a pa. All amplifiers exhibit some degrees of nonlinearity which causes spectral regrowth and adjacent channel interference. Based on a complex polynomial behavior model of a pa, we have derived a simple closed form expression of the power spectral density of the output of the pa. Such analytical results are very useful in finding optimal operating conditions of the pa so that maximum efficiency can be achieved without violating the out-of-band emission requirement.     

Nitrate assimilation gene cluster from the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120

A region of the genome of the filamentous, nitrogen-fixing, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 that contains a cluster of genes involved in nitrate assimilation has been identified. The genes nir, encoding nitrite reductase, and nrtABC, encoding elements of a nitrate permease, have been cloned. Insertion of a gene cassette into the nir-nrtA region impaired expression of narB, the nitrate reductase structural gene which together with nrtD is found downstream from nrtC in the gene cluster. This indicates that the nir-nrtABCD-narB genes are cotranscribed, thus constituting an operon. Expression of the nir operon in strain PCC 7120 is subjected to ammonium-promoted repression and takes place from an NtcA-activated promoter located 460 bp upstream from the start of the nir gene. In the absence of ammonium, cellular levels of the products of the nir operon are higher in the presence of nitrate than in the absence of combined nitrogen.     

The cerebral hemispheres and neural network simulations: Design considerations.

The conclusions concerning hemispheric specializations based on neural network simulations, which were previously reported by Kosslyn, Chabris, Marsolek, and Koenig (see record 1992-37420-001), are shown not to be valid. Differences in network performance on tasks said to be "categorical" and "coordinate spatial" in nature were due to imbalances in the input stimuli and cannot, in principle, be related to differences in performance on such tasks in human subjects. The use of truth tables and correlation coefficients in the design of neural networks is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)