The interstellar C18O/C17O ratio in the solar neighbourhood: The rho Oph cloud

Observations of up to ten carbon monoxide (CO and isotopomers) transitions are presented to study the interstellar C18O/C17O ratio towards 21 positions in the nearby (d~140pc) low-mass star forming cloud rho Oph. A map of the C18O J=1-0 distribution of parts of the cloud is also shown. An average 12C18O/12C17O isotopomeric ratio of 4.11 +/- 0.14, reflecting the 18O/17O isotope ratio, is derived from Large Velocity Gradient (LVG) calculations. From LTE column densities we derive a ratio of 4.17 +/-0.26. These calculations also show that the kinetic temperature decreases from about 30 K in the cloud envelope to about 10 K in the cloud cores. This decrease is accompanied by an increase of the average molecular hydrogen density from 10^4 cm-3 to >10^5 cm-3. Towards some lines of sight C18O optical depths reach values of order unity.Comment: 13 pages, 9 figures; accepted for publication in A&

Transitional hemodynamics in infants of diabetic mothers by targeted neonatal echocardiography, electrocardiography and peripheral flow study

Objective: Metabolic alterations of intrauterine environment in diabetes mellitus (DM) lead to fetal cardiac dysfunctions that can persist after birth. The aim of the study was to assess the cardiovascular adaptation in infants born to diabetic mothers (IDM) with different degrees of glycometabolic control, in relation to revised guidelines for diagnosis of DM and quality improvements in neonatal care. Materials and methods: An observational case-control study was conducted on IDM with gestational, type 1 and type 2\ue2\u80\u89DM. Relevant maternal and neonatal anamnestic, clinical and laboratory data were analyzed. Electrocardiographic and echocardiographic analyses, including structural and systo-diastolic evaluation, were performed. Results: In 68 IDM enrolled, we observed a lower incidence of negative perinatal outcome than expected. Comparing to non-IDM, they presented larger fetal shunts, higher pulmonary pressures, early and atrial wave velocities. At 72\ue2\u80\u89hours, kinesis and heart rate variability remained low. Cerebral blood flow velocities were higher. The most serious impairment of transition was in pregestational IDM. Conclusion: Maternal DM impaired neonatal transitional hemodynamics also in asymptomatic IDM with good glycometabolic control. These results confirm the need for an early cardiologic and cerebrovascular evaluation, to identify IDM with delayed maturation at risk of worse long-term metabolic, cardiovascular, and neurodevelopmental outcome

A Fractal Origin for the Mass Spectrum of Interstellar Clouds: II. Cloud Models and Power Law Slopes

Three-dimensional fractal models on grids of 200**3 pixels are generated from the inverse Fourier transform of noise with a power law cutoff, exponentiated to give a log normal distribution of density. The fractals are clipped at various intensity levels and the mass and size distribution functions of the clipped peaks and their subpeaks are determined. These distribution functions are analogous to the cloud mass functions determined from maps of the fractal interstellar medium using various thresholds for the definition of a cloud. The model mass functions are found to be power laws with powers ranging from -1.6 to -2.4 in linear mass intervals as the clipping level increases from 0.03 to 0.3 of the peak intensity. The low clipping value gives a cloud filling factor of 0.1 and should be a good model for molecular cloud surveys. The agreement between the mass spectrum of this model and the observed cloud and clump mass spectra suggests that a pervasively fractal interstellar medium can be interpreted as a cloud/intercloud medium if the peaks of the fractal intensity distribution are taken to be clouds. Their mass function is a power law even though the density distribution function in the gas is a log-normal. This is because the size distribution function of the clipped clouds is a power law, and with clipping, each cloud has about the same average density. A similar result would apply to projected clouds that are clipped fractals, giving nearly constant column densities for power law mass functions. The steepening of the mass function for higher clip values suggests a partial explanation for the steeper slope of the mass functions for star clusters and OB associations, which sample denser regions of interstellar gas.Comment: accepted for ApJ 564, January 10, 2002, 8 figure

Star Formation from Galaxies to Globules

The empirical laws of star formation suggest that galactic-scale gravity is involved, but they do not identify the actual triggering mechanisms for clusters in the final stages. Many other triggering processes satisfy the empirical laws too, including turbulence compression and expanding shell collapse. The self-similar nature of the gas and associated young stars suggests that turbulence is more directly involved, but the small scale morphology of gas around most embedded clusters does not look like a random turbulent flow. Most clusters look triggered by other nearby stars. Such a prominent local influence makes it difficult to understand the universality of the Kennicutt and Schmidt laws on galactic scales. A unified view of multi-scale star formation avoids most of these problems. Ambient self-gravity produces spiral arms and drives much of the turbulence that leads to self-similar structures, while localized energy input from existing clusters and field supernovae triggers new clusters in pre-existing clouds. The hierarchical structure in the gas made by turbulence ensures that the triggering time scales with size, giving the Schmidt law over a wide range of scales and the size-duration correlation for young star fields. The efficiency of star formation is determined by the fraction of the gas above a critical density of around 10^5 m(H2)/cc. Star formation is saturated to its largest possible value given the fractal nature of the interstellar medium.Comment: accepted for ApJ, 42 pages, Dannie Heineman prize lecture, January 200

How to Search for Doubly Charmed Baryons and Tetraquarks

Possible experimental searches of doubly charmed baryons and tetraquarks at fixed target experiments with high energy hadron beams and a high intensity spectrometer are considered here. The baryons considered are: $\Xi_{cc}^{+}$ (ccd), $\Xi_{cc}^{++}$ (ccu), and $\Omega_{cc}^{+}$ (ccs); and the tetraquark is T ($cc\bar{u}\bar{d}$). Estimates are given of masses, lifetimes, internal structure, production cross sections, decay modes, branching ratios, and yields. Experimental requirements are given for optimizing the signal and minimizing the backgrounds. The discussion is in the spirit of an experimental and theoretical review, as part of the planning for a CHarm Experiment with Omni-Purpose Setup (CHEOPS) at CERN. The CHEOPS objective is to achieve a state-of-the-art very charming experiment, in the spirit of the aims of the recent CHARM2000 workshop.Comment: 18 pages text (latex), 16 March 1995, presented at "Physics with Hadron Beams with a High Intensity Spectrometer", revised 10 May for more complete bibliography and appropriate references to S. Paul et al., Letter of Intent, CHEOPS

Effect of maternal diabetes on fetal heart function on echocardiography: systematic review and meta‐analysis

Objective: Maternal diabetes in pregnancy is associated with structural anomalies of the fetal heart, as well as hypertrophy and functional impairment. This systematic review and meta-analysis aimed to estimate the effect of maternal diabetes on fetal cardiac function as measured by prenatal echocardiography. Methods: We performed a search of the EMBASE, PubMed and The Cochrane Library databases, from inception to 4 July 2019, for studies evaluating fetal cardiac function using echocardiography in pregnancies affected by diabetes compared with uncomplicated pregnancies. Outcome measures were cardiac hypertrophy and diastolic, systolic and overall cardiac function as assessed by various ultrasound parameters. The quality of the studies was assessed using the Newcastle–Ottawa Scale. Data on interventricular septal (IVS) thickness, myocardial performance index (MPI) and E/A ratio were pooled for the meta-analysis using random-effects models. For pregnancies with diabetes, results were reported overall and according to whether diabetes was pregestational (PDM) or gestational (GDM). Results were also stratified according to the trimester in which fetal cardiac assessment was performed. Results: Thirty-nine studies were included, comprising data for 2276 controls and 1925 women with pregnancy affected by diabetes mellitus (DM). Of these, 1120 had GDM, 671 had PDM and in 134 cases diabetes type was not specified. Fetal cardiac hypertrophy was more prevalent in diabetic pregnancies than in non-diabetic controls in 21/26 studies, and impaired diastolic function was observed in diabetic pregnancies in 22/28 studies. The association between DM and systolic function was inconsistent, with 10/25 studies reporting no difference between cases and controls, although more recent studies measuring cardiac deformation, i.e. strain, did show decreased systolic function in diabetic pregnancies. Of the studies measuring overall fetal cardiac function, the majority (14/21) found significant impairment in diabetic pregnancies. Results were similar when stratified according to GDM or PDM. These effects were already present in the first trimester, but were most profound in the third trimester. Meta-analysis of studies performed in the third trimester showed, compared with controls, increased IVS thickness in both PDM (mean difference, 0.75 mm (95% CI, 0.56–0.94 mm)) and GDM (mean difference, 0.65 mm (95% CI, 0.39–0.91 mm)) pregnancies, decreased E/A ratio in PDM pregnancies (mean difference, –0.09 (95% CI, –0.15 to –0.03)), no difference in E/A ratio in GDM pregnancies (mean difference, –0.01 (95% CI, –0.02 to 0.01)) and no difference in MPI in either PDM (mean difference, 0.04 (95% CI, –0.01 to 0.09)) or GDM (mean difference, 0.03 (95% CI, –0.01 to 0.06)) pregnancies. Conclusions: The findings of this review show that maternal diabetes is associated with fetal cardiac hypertrophy, diastolic dysfunction and overall impaired myocardial performance on prenatal ultrasound, irrespective of whether diabetes is pregestational or gestational. Further studies are needed to demonstrate the relationship with long-term outcomes