In the case of Li-promoted MgO two different mechanisms for regeneration of the active site are found when varying the temperature between 550 and 700
°C. Propane titration showed that the active ...site is deactivated through formation of hydroxyl groups that are stable at 550
°C and below in absence of oxygen. On the contrary at 700
°C, propane pulses resulted in hydrocarbon activation, accompanied by evolution of water molecules. In addition, simultaneous evolution of hydrogen molecules pulsing propane indicate that ODH of propane follows a mixed heterogeneous–homogeneous radical chemistry. No CO
x
was observed while pulsing propane at both temperatures. Moreover CO
x
molecules were not detected even during catalyst regeneration by pulsing oxygen showing that Li/MgO materials are not affected by coke formation. Formation of CO
x
molecules seems to be feasible exclusively by co-feeding propane and oxygen.
Late occurrence of atrioventricular nodal block is an extremely rare occurrence after radiofrequency catheter modification of the slow pathway and has yet to be reported after cryoablation. We report ...a case of late transient advanced second degree atrioventriuclar block after cryomodification of the slow pathway.
To obtain information regarding patterns of alcohol and substance use, portions of the Diagnostic Interview Schedule (DIS) were administered to 53 schizophrenic patients who presented to the crisis ...service of an emergency room in a major general hospital. The number of individuals in the sample qualifying for a lifetime diagnosis of an alcohol abuse-related disorder was quite high (47%), and there was a strong correlation between disorders of alcohol abuse and the use of other drugs. Other than alcohol, marijuana was the most frequently abused drug. Individuals who qualified for a diagnosis of an alcohol-related disorder were compared with those who did not on a variety of diagnostic and demographic variables. The authors conclude by suggesting that the high-risk rates of drug use-related disorders reported in this sample may be due to the preferential use of emergency services by schizophrenic patients with alcohol and drug abuse-related disorders.
Indirect measurement of lower extremity blood pressure is often used in the clinical setting, although normative data after the newborn period are not readily available.
Indirect blood pressure (BP) ...measurement was obtained in the right arms and right calves of 148 healthy infants and young children 2 weeks to 3 years of age. All measurements were made using an oscillometric device. The infants and children are quiet or asleep and in the supine position. A BP cuff of proper size was chosen. Three measurements were made in both extremities; the average of the second and third measurements was used for all analyses.
Age correlated better with calf systolic blood pressure (SBPc) than with arm SBP (SBPa) (r = .52 vs .17). Calf diastolic blood pressure (DBPc) and calf mean blood pressure (MBPc) correlated moderately poorly with age (r = .37 and .39, respectively). There was no order effect. SBPc correlated best with height (r = .53), then age (r = .52), and, finally, weight (r = .51). The correlation between BPc and BPa was moderately low. The correlation of SBPc with SBPa was r = .46; that of DBPc with DBPa was r = .37; and that of MBPc with MBPa was r = .41. From birth to 6 months, SBPc was slightly lower than SBPa (1 to 3 mm Hg). SBPc increased linearly relative to SBPa and began to exceed SBPa at 6 months of age. The pattern of DBP and MBP was similar. Wide variability of blood pressure parameters was noted between the infants and children at all ages.
Reference data are presented for BPc and the difference between BPc and BPa in healthy infants and children from 2 weeks to 3 years of age. BPc is not equivalent to BPa and should not be arbitrarily substituted. Because of the wide variability among healthy infants and children, SBPc measurements should be interpreted with caution when evaluating for coarctation of the aorta.
BL Lacertae has been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present UBVRI light curves obtained by the WEBT from 1994 to ...2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the similar to 15 600 observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a few-day time scale appear as mildly-chromatic events, while a strong bluer-when-brighter chromatism characterizes very fast (intraday) flares. By decoupling the two components, we quantify the degree of chromatism inferring that longer-term flux changes imply moving along a similar to 0.1 bluer-when-brighter slope in the B - R versus R plane; a steeper slope of similar to 0.4 would distinguish the shorter-term variations. This means that, when considering the long-term trend, the B-band flux level is related to the R-band one according to a power law of index similar to 1.1. Doppler factor variations on a "convex" spectrum could be the mechanism accounting for both the long-term variations and their slight chromatism.
A multiwavelength campaign to observe the BL Lac object AO 0235+16 (z = 0.94) was set up by the Whole Earth Blazar Telescope (WEBT) collaboration during the observing seasons 2003-2004 and 2004-2005, ...involving radio, near-IR and optical photometric monitoring, VLBA monitoring, optical spectral monitoring, and three pointings by the XMM-Newton satellite. Here we report on the results of the first season, which involved the participation of 24 optical and near-IR telescopes and 4 radio telescopes, as well as the first XMM-Newton pointing, which occurred on January 18-19, 2004. Unpublished data from previous epochs were also collected (from 5 optical-NIR and 3 radio telescopes), in order to fill the gap between the end of the period presented in Raiteri et al. (2001) and the start of the WEBT campaign. The contribution of the southern AGN, 2 arcsec distant from the source, is taken into account. It is found to especially affect the blue part of the optical spectrum when the source is faint. In the optical and near-IR the source has been very active in the last 3 years, although it has been rather faint most of the time, with noticeable variations of more than a magnitude over a few days. In contrast, in the radio bands it appears to have been "quiescent" since early 2000. The major radio (and optical) outburst predicted to peak around February-March 2004 (with a six month uncertainty) has not occurred yet. When comparing our results with the historical light.
The BL Lac object 3C 66A was the target of an extensive multiwavelength monitoring campaign from 2003 July through 2004 April (with a core campaign from 2003 September to 2003 December) involving ...observations throughout the electromagnetic spectrum. Radio, infrared, and optical observations were carried out by the WEBT-ENIGMA collaboration. At higher energies, 3C 66A was observed in X-rays (RXTE), and at very high energy (VHE) in g-rays (STACEE, VERITAS). In addition, the source has been observed with the VLBA at nine epochs throughout the period 2003 September to 2004 December, including three epochs contemporaneous with the core campaign. A gradual brightening of the source over the course of the campaign was observed at all optical frequencies, culminating in a very bright maximum around 2004 February 18. The WEBT campaign revealed microvariability with flux changes of 65% on timescales as short as 62 hr. The source was in a relatively bright state, with several bright flares on timescales of several days. The spectral energy distribution (SED) indicates a F sub( )peak in the optical regime. A weak trend of optical spectral hysteresis with a trend of spectral softening throughout both the rising and decaying phases has been found. On longer timescales, there appears to be a weak indication of a positive hardness-intensity correlation for low optical fluxes, which does not persist at higher flux levels. The 3-10 keV X-ray flux of 3C 66A during the core campaign was historically high and its spectrum very soft, indicating that the low-frequency component of the broadband SED extends beyond 610 keV. No significant X-ray flux and/or spectral variability was detected. STACEE and Whipple observations provided upper flux limits at >150 and >390 GeV, respectively. The 22 and 43 GHz data from the three VLBA epochs made between 2003 September and 2004 January indicate a rather smooth jet with only very moderate internal structure. Evidence for superluminal motion (8.5 c 5.6 h super(-1) c) was found in only one of six components, while the apparent velocities of all other components are consistent with 0. The radial radio brightness profile suggests a magnetic field decay 8r super(-1) and, thus, a predominantly perpendicular magnetic field orientation.
A multiwavelength campaign to observe the BL Lac object AO 0235+16 ($z=0.94$) was set up by the Whole Earth Blazar Telescope (WEBT) collaboration during the observing seasons 2003–2004 and 2004–2005, ...involving radio, near-IR and optical photometric monitoring, VLBA monitoring, optical spectral monitoring, and three pointings by the XMM-Newton satellite. Here we report on the results of the first season, which involved the participation of 24 optical and near-IR telescopes and 4 radio telescopes, as well as the first XMM-Newton pointing, which occurred on January 18–19, 2004. Unpublished data from previous epochs were also collected (from 5 optical-NIR and 3 radio telescopes), in order to fill the gap between the end of the period presented in Raiteri et al. (2001) and the start of the WEBT campaign. The contribution of the southern AGN, 2 arcsec distant from the source, is taken into account. It is found to especially affect the blue part of the optical spectrum when the source is faint. In the optical and near-IR the source has been very active in the last 3 years, although it has been rather faint most of the time, with noticeable variations of more than a magnitude over a few days. In contrast, in the radio bands it appears to have been “quiescent” since early 2000. The major radio (and optical) outburst predicted to peak around February–March 2004 (with a six month uncertainty) has not occurred yet. When comparing our results with the historical light curves, two different behaviours seem to characterize the optical outbursts: only the major events present a radio counterpart. The X-ray spectra obtained by the three EPIC detectors are well fitted by a power law with extra-absorption at $z=0.524$; the energy index in the 0.2–10 keV range is well constrained: $\alpha=0.645$ ± 0.028 and the 1 keV flux density is 0.311 ± $0.008~\rm \mu Jy$. The analysis of the X-ray light curves reveals that no significant variations occurred during the pointing. In contrast, simultaneous dense radio monitoring with the 100 m telescope at Effelsberg shows a ~2–3% flux decrease in 6–7 h, which, if intrinsic, would imply a brightness temperature well above the Compton limit and hence a lower limit to the Doppler factor $\delta \ga 46$. We construct the broad-band spectral energy distribution of January 18–19, 2004 with simultaneous radio data from Effelsberg, optical data from the Nordic Optical Telescope (NOT), optical–UV data from the Optical Monitor onboard XMM-Newton, and X-ray data by the EPIC instruments. Particular care is taken to correct data for extinction due to both the Milky Way and the $z=0.524$ absorber. The resulting SED suggests the existence of a bump in the UV spectral region.
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