The use of pediatric flexible bronchoscopy in the COVID-19 pandemic era

On March 11, 2020, the World Health Organization (WHO) declared the pandemic because of a novel coronavirus, called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In January 2020, the first transmission to healthcare workers (HCWs) was described. SARS-CoV-2 is transmitted between people because of contact, droplets, and airborne. Airborne transmission is caused by aerosols that remain infectious when suspended in air over long distances and time. In the clinical setting, airborne transmission may occur during aerosol generating procedures like flexible bronchoscopy. To date, although the role of children in the transmission of SARS-CoV-2 is not clear the execution of bronchoscopy is associated with a considerably increased risk of SARS-CoV-2 transmission to HCWs. The aim of this overview is to summarize available recommendations and to apply them to pediatric bronchoscopy. We performed systematic literature searches using the MEDLINE (accessed via PubMed) and Scopus databases. We reviewed major recommendations and position statements published at the moment by the American Association for Bronchology and Interventional Pulmonology, WHO, European Center for Disease Prevention and Control and expert groups on the management of patients with COVID-19 to limit transmission among HCWs. To date there is a lack of recommendations for safe bronchoscopy during the pandemic period. The main indications concern adults and little has been said about children. We have summarized available recommendations and we have applied them to pediatric bronchoscopy

Neutron star properties and the equation of state of neutron-rich matter

We calculate total masses and radii of neutron stars (NS) for pure neutron matter and nuclear matter in beta-equilibrium. We apply a relativistic nuclear matter equation of state (EOS) derived from Dirac-Brueckner-Hartree-Fock (DBHF) calculations. We use realistic nucleon-nucleon (NN) interactions defined in the framework of the meson exchange potential models. Our results are compared with other theoretical predictions and recent observational data. Suggestions for further study are discussed.Comment: 13 pages, 9 figures, 1 table; Revised version, accepted for publication in Physical Review

The maximum and minimum mass of protoneutron stars in the Brueckner theory

We study the structure of protoneutron stars within the finite-temperature Brueckner-Bethe-Goldstone theoretical approach, paying particular attention to how it is joined to a low-density nuclear equation of state (EOS). We find a slight sensitivity of the minimum value of the protoneutron star mass on the low-density equation of state, whereas the maximum mass is hardly affected.Comment: 8 pages, 8 figure

Important HIV-associated conditions in HIV-infected infants and children

This article is the last in a series of 6 articles that discussed the management of HIV-infected children in a clinically orientated, practical and concise fashion. The topics covered previously include; 1) Preventing and diagnosing HIV-infection in infants and children, 2) Initiating anti-retroviral therapy in HIV-infected infants and children, 3) Maintaining HIV-infected infants and children on anti-retroviral therapy, 4) Common opportunistic infection in HIV-infected children: Part 1-respiratory infections and 5) Part 2 non-respiratory infections. South African Family Practice Vol. 49 (4) 2007: pp.19-2

The Magnetorotational Instability in Core Collapse Supernova Explosions

We investigate the action of the magnetorotational instability (MRI) in the context of iron-core collapse. Exponential growth of the field on the rotation time scale by the MRI will dominate the linear growth process of field line "wrapping" with the same characteristic time. We examine a variety of initial rotation states, with solid body rotation or a gradient in rotational velocity, that correspond to models in the literature. A relatively modest value of the initial rotation, a period of ~ 10 s, will give a very rapidly rotating PNS and hence strong differential rotation with respect to the infalling matter. We assume conservation of angular momentum on spherical shells. Results are discussed for two examples of saturation fields, a fiducial field that corresponds to Alfven velocity = rotational velocity and a field that corresponds to the maximum growing mode of the MRI. Modest initial rotation velocities of the iron core result in sub-Keplerian rotation and a sub-equipartition magnetic field that nevertheless produce substantial MHD luminosity and hoop stresses: saturation fields of order 10^{15} - 10^{16} G develop within 300 msec after bounce with an associated MHD luminosity of about 10^{52} erg/s. Bi-polar flows driven by this MHD power can affect or even cause the explosions associated with core-collapse supernovae.Comment: 42 pages, including 15 figures. Accepted for publication in ApJ. We have revised to include an improved treatment of the convection, and some figures have been update

Equation of state of dense matter and the minimum mass of cold neutron stars

Equilibrium configurations of cold neutron stars near the minimum mass are studied, using the recent equation of state SLy, which describes in a unified, physically consistent manner, both the solid crust and the liquid core of neutron stars. Results are compared with those obtained using an older FPS equation of state of cold catalyzed matter. The value of M_min\simeq 0.09M_sun depends very weakly on the equation of state of cold catalyzed matter: it is 0.094 M_sun for the SLy model, and 0.088 M_sun for the FPS one. Central density at M_min is significantly lower than the normal nuclear density: for the SLy equation of state we get central density 1.7 10^{14} g/cm^3, to be compared with 2.3 10^{14} g/cm^3 obtained for the FPS one. Even at M_min, neutron stars have a small liquid core of radius of about 4 km, containing some 2-3% of the stellar mass. Neutron stars with 0.09 M_sun <M<0.17 M_sun are bound with respect to dispersed configuration of the hydrogen gas, but are unbound with respect to dispersed Fe^56. The effect of uniform rotation on the minimum-mass configuration of cold neutron stars is studied. Rotation increases the value of M_min; at rotation period of 10 ms the minimum mass of neutron stars increases to 0.13 M_sun, and corresponds to the mass-shedding (Keplerian) configuration. In the case of the shortest observed rotation period of radio pulsars 1.56 ms, minimum mass of uniformly rotating cold neutron stars corresponds to the mass-shedding limit, and is found at 0.61 M_sun for the SLy EOS and 0.54 M_sun for the FPS EOS.Comment: 7 pages, 5 figures, uses aa.cls, accepted in Astronomy and Astrophysic

Fully general relativistic simulation of coalescing binary neutron stars: Preparatory tests

We present our first successful numerical results of 3D general relativistic simulations in which the Einstein equation as well as the hydrodynamic equations are fully solved. This paper is especially devoted to simulations of test problems such as spherical dust collapse, stability test of perturbed spherical stars, and preservation of (approximate) equilibrium states of rapidly rotating neutron star and/or corotating binary neutron stars. These test simulations confirm that simulations of coalescing binary neutron stars are feasible in a numerical relativity code. It is illustrated that using our numerical code, simulations of these problems, in particular those of corotating binary neutron stars, can be performed stably and fairly accurately for a couple of dynamical timescales. These numerical results indicate that our formulation for solving the Einstein field equation and hydrodynamic equations are robust and make it possible to perform a realistic simulation of coalescing binary neutron stars for a long time from the innermost circular orbit up to formation of a black hole or neutron star.Comment: 36 pages, to be published in PRD 15, erase unnecessary figure

Use of a Priori Information for the Deconvolution of Ultrasonic Signals

The resolution of pulse-echo imaging technique is limited by the band-width of the transducer impulse response (IR). For flaws sizing or thickness measurement simple and accurate methods exist if the echoes do not overlap. These classical methods break if the echoes can not be separated in time domain

The diagnosis of asthma in children: An evidence-based approach to a common clinical dilemma

Background. Asthma is a heterogeneous condition characterised by chronic inflammation and variable expiratory airflow limitation, as well as airway reversibility. The diagnosis of asthma in young children is limited by the inability to perform objective lung function testing in this group of patients and the wide variety of conditions that can phenotypically present with asthma-like symptoms.Objectives. To provide an evidence-based approach for clinicians to accurately diagnose asthma in young children and to assess the level of control to guide therapeutic decisions.Methods. The South African Childhood Asthma Working Group (SACAWG) convened in January 2017 with task groups, each headed by a section leader, constituting the editorial committee on assessment of asthma epidemiology, diagnosis, control, treatments, novel treatments and self-management plans. The asthma diagnosis and control task groups reviewed the available scientific literature and assigned evidence according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) system, providing recommendations based on current evidence.Conclusions. Asthma in young children should only be diagnosed if all other causes of wheezing have been considered and excluded, and if there is a response to a therapeutic trial and worsening with withdrawal of asthma medication. Asthma control should be assessed at each visit to guide therapeutic decisions.

Why NS and BH mass distribition is bimodal?

The observed mass distribution for the compact remnants of massive stars (neutron stars and black holes) and its relationship to possible mechanisms for the ejection of the envelopes of type II and Ib/c supernovae is analyzed. The conclusion is drawn that this distribution can be obtained only by a magneto-rotational mechanism for the supernovae with sufficiently long time of the field amplification, and a soft equation of state for neutron stars with limiting masses \sim1.5-1.6M_\odot. Some consequences of this hypothesis are discussed.Comment: latex, 4 pages, 5 figures, Talk given at 5th Int. Tsessevich Conf. "Variable Stars", Odessa, Ukraine, August 200