Shortening of the Short Refractory Periods in Short QT Syndrome.

BACKGROUND: Diagnosis of short QT syndrome (SQTS) remains difficult in case of borderline QT values as often found in normal populations. Whether some shortening of refractory periods (RP) may help in differentiating SQTS from normal subjects is unknown. METHODS AND RESULTS: Atrial and right ventricular RP at the apex and right ventricular outflow tract as determined during standard electrophysiological study were compared between 16 SQTS patients (QTc 324±24 ms) and 15 controls with similar clinical characteristics (QTc 417±32 ms). Atrial RP were significantly shorter in SQTS compared with controls at 600- and 500-ms basic cycle lengths. Baseline ventricular RP were significantly shorter in SQTS patients than in controls, both at the apex and right ventricular outflow tract and for any cycle length. Differences remained significant for RP of any subsequent extrastimulus at any cycle length and any pacing site. A cut-off value of baseline RP <200 ms at the right ventricular outflow tract either at 600- or 500-ms cycle length had a sensitivity of 86% and a specificity of 100% for the diagnosis of SQTS. CONCLUSIONS: Patients with SQTS have shorter ventricular RP than controls, both at baseline during various cycle lengths and after premature extrastimuli. A cut-off value of 200 ms at the right ventricular outflow tract during 600- and 500-ms basic cycle length may help in detecting true SQTS from normal subjects with borderline QT values

Following red blood cells in a pulmonary capillary

The red blood cells or erythrocytes are biconcave shaped cells and consist mostly in a membrane delimiting a cytosol with a high concentration in hemoglobin. This membrane is highly deformable and allows the cells to go through narrow passages like the capillaries which diameters can be much smaller than red blood cells one. They carry oxygen thanks to hemoglobin, a complex molecule that have very high affinity for oxygen. The capacity of erythrocytes to load and unload oxygen is thus a determinant factor in their efficacy. In this paper, we will focus on the pulmonary capillary where red blood cells capture oxygen. We propose a camera method in order to numerically study the behavior of the red blood cell along a whole capillary. Our goal is to understand how erythrocytes geometrical changes along the capillary can affect its capacity to capture oxygen. The first part of this document presents the model chosen for the red blood cells along with the numerical method used to determine and follow their shapes along the capillary. The membrane of the red blood cell is complex and has been modelled by an hyper-elastic approach coming from Mills et al (2004). This camera method is then validated and confronted with a standard ALE method. Some geometrical properties of the red blood cells observed in our simulations are then studied and discussed. The second part of this paper deals with the modeling of oxygen and hemoglobin chemistry in the geometries obtained in the first part. We have implemented a full complex hemoglobin behavior with allosteric states inspired from Czerlinski et al (1999).Comment: 17 page

Books Reviewed

Books Reviewed: Public Utility Regulatory Law. By Everett C. McKeage Report of Committee of New York City Bar Association on the Federal Loyalty Security Program Say It Safely: Legal Limits in Journalism and Broadcasting. By Paul P. Ashley

Cr-based MOCVD layers as conducting diffusion barriers for copper metallization

Two types of amorphous Cr-based thin films, CrCxNy and CrSixCy, were grown by low pressure MOCVD on Si substrates using respectively Cr(NEt2)4 and Cr[CH2SiMe3]4 as single-source precursor in the low temperature range 400-420 °C and 475-500 °C. Their properties as conducting diffusion barrier against Cu were investigated and the results are discussed. CrSixCy exhibits a better thermal stability and a good Cu wettability but a high resistivity, which is detrimental for this application. CrCxNy has a low resistivity, a satisfactory stability up to 650 °C without undesirable interfacial reactions and an excellent conformality.Two types of amorphous Cr-based thin films, CrCxNy and CrSixCy, were grown by low pressure MOCVD on Si substrates using respectively Cr(NEt2)4 and Cr[CH2SiMe3]4 as single-source precursor in the low temperature range 400-420 °C and 475-500 °C. Their properties as conducting diffusion barrier against Cu were investigated and the results are discussed. CrSixCy exhibits a better thermal stability and a good Cu wettability but a high resistivity, which is detrimental for this application. CrCxNy has a low resistivity, a satisfactory stability up to 650 °C without undesirable interfacial reactions and an excellent conformality

Books Reviewed

Books Reviewed: Public Utility Regulatory Law. By Everett C. McKeage Report of Committee of New York City Bar Association on the Federal Loyalty Security Program Say It Safely: Legal Limits in Journalism and Broadcasting. By Paul P. Ashley

First results from the CALYPSO IRAM-PdBI survey. I. Kinematics of the inner envelope of NGC1333-IRAS2A

The structure and kinematics of Class 0 protostars on scales of a few hundred AU is poorly known. Recent observations have revealed the presence of Keplerian disks with a diameter of 150-180 AU in L1527-IRS and VLA1623A, but it is not clear if such disks are common in Class 0 protostars. Here we present high-angular-resolution observations of two methanol lines in NGC1333-IRAS2A. We argue that these lines probe the inner envelope, and we use them to study the kinematics of this region. Our observations suggest the presence of a marginal velocity gradient normal to the direction of the outflow. However, the position velocity diagrams along the gradient direction appear inconsistent with a Keplerian disk. Instead, we suggest that the emission originates from the infalling and perhaps slowly rotating envelope, around a central protostar of 0.1-0.2 M$_\odot$. If a disk is present, it is smaller than the disk of L1527-IRS, perhaps suggesting that NGC1333-IRAS2A is younger.Comment: Accepted for publication in A&A letter

Glycolaldehyde in Perseus young solar analogs

Aims: In this paper we focus on the occurrence of glycolaldehyde (HCOCH2OH) in young solar analogs by performing the first homogeneous and unbiased study of this molecule in the Class 0 protostars of the nearby Perseus star forming region. Methods: We obtained sub-arcsec angular resolution maps at 1.3mm and 1.4mm of glycolaldehyde emission lines using the IRAM Plateau de Bure (PdB) interferometer in the framework of the CALYPSO IRAM large program. Results: Glycolaldehyde has been detected towards 3 Class 0 and 1 Class I protostars out of the 13 continuum sources targeted in Perseus: NGC1333-IRAS2A1, NGC1333-IRAS4A2, NGC1333-IRAS4B1, and SVS13-A. The NGC1333 star forming region looks particularly glycolaldehyde rich, with a rate of occurrence up to 60%. The glycolaldehyde spatial distribution overlaps with the continuum one, tracing the inner 100 au around the protostar. A large number of lines (up to 18), with upper-level energies Eu from 37 K up to 375 K has been detected. We derived column densities > 10^15 cm^-2 and rotational temperatures Trot between 115 K and 236 K, imaging for the first time hot-corinos around NGC1333-IRAS4B1 and SVS13-A. Conclusions: In multiple systems glycolaldehyde emission is detected only in one component. The case of the SVS13-A+B and IRAS4-A1+A2 systems support that the detection of glycolaldehyde (at least in the present Perseus sample) indicates older protostars (i.e. SVS13-A and IRAS4-A2), evolved enough to develop the hot-corino region (i.e. 100 K in the inner 100 au). However, only two systems do not allow us to firmly conclude whether the primary factor leading to the detection of glycolaldehyde emission is the environments hosting the protostars, evolution (e.g. low value of Lsubmm/Lint), or accretion luminosity (high Lint).Comment: A&A, in pres

First results from the CALYPSO IRAM-PdBI survey - III. Monopolar jets driven by a proto-binary system in NGC1333-IRAS2A

Context: The earliest evolutionary stages of low-mass protostars are characterised by hot and fast jets which remove angular momentum from the circumstellar disk, thus allowing mass accretion onto the central object. However, the launch mechanism is still being debated. Aims: We would like to exploit high-angular (~ 0.8") resolution and high-sensitivity images to investigate the origin of protostellar jets using typical molecular tracers of shocked regions, such as SiO and SO. Methods: We mapped the inner 22" of the NGC1333-IRAS2A protostar in SiO(5-4), SO(65-54), and the continuum emission at 1.4 mm using the IRAM Plateau de Bure interferometer in the framework of the CALYPSO IRAM large program. Results: For the first time, we disentangle the NGC1333-IRAS2A Class 0 object into a proto-binary system revealing two protostars (MM1, MM2) separated by ~ 560 AU, each of them driving their own jet, while past work considered a single protostar with a quadrupolar outflow. We reveal (i) a clumpy, fast (up to |V-VLSR| > 50 km/s), and blueshifted jet emerging from the brightest MM1 source, and (ii) a slower redshifted jet, driven by MM2. Silicon monoxide emission is a powerful tracer of high-excitation (Tkin > 100 K; n(H2) > 10^5 cm-3) jets close to the launching region. At the highest velocities, SO appears to mimic SiO tracing the jets, whereas at velocities close to the systemic one, SO is dominated by extended emission, tracing the cavity opened by the jet. Conclusions: Both jets are intrinsically monopolar, and intermittent in time. The dynamical time of the SiO clumps is < 30-90 yr, indicating that one-sided ejections from protostars can take place on these timescales.Comment: Astronomy & Astrophysics Letter, in pres