Nonlinear coupling of Alfvén and magnetoacoustic waves in partially ionized plasmas: the effect of thermal misbalance on propagating waves

Partially ionized plasmas constitute an essential ingredient of the solar atmosphere, and ground- and space-based observations have pointed out the presence of oscillations in partially ionized solar plasmas such as chromosphere, photosphere, prominences or spicules, which have been interpreted in terms of magnetohydrodynamic waves. Our aim is to study the spatial behaviour of propagating weakly and fully nonlinear Alfvén waves, and the subsequent excitation of field-aligned motions and perturbations, when dissipative mechanisms, such as ambipolar diffusion and radiative losses, together with parametrized heating mechanisms, are taken into account. When only ambipolar diffusion is taken into account, first-order Alfvén waves as well as ponderomotive-driven perturbations are spatially damped, while field-aligned motions and perturbations representing propagating slow waves are undamped. These perturbations are damped when thermal effects are also considered and their damping lengths can be longer or shorter than those of ponderomotive-driven perturbations. Therefore, after the initial excitation, Alfvén waves and ponderomotive-driven perturbations could be quickly damped while slow waves still remain in the plasma, and vice versa. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

Timing of umbilical cord occlusion, delayed vs early, in preterm babies: A randomized controlled trial (CODE-P Trial)

INTRODUCTION

Our hypothesis was that delayed cord clamping (DCC) (not earlier than 30 s; at 30-60 s) in premature neonates (born between 26.0 and 32.6 weeks of gestation), as compared with the usual early cord clamping (ECC), significantly reduces the need for blood transfusions and incidence of intraventricular haemorrhage (IVH) without an increased rate of maternal postpartum haemorrhage.

MATERIAL AND METHODS

A prospective, open-label, randomized, controlled trial was conducted at Vall d'Hebron Hospital from July 2014 to December 2018. All pregnant women at risk of impending preterm birth (≥26.0-<33.0 weeks of gestation) who were admitted to the obstetrics emergency department were evaluated for eligibility. If they met the eligibility criteria, they were invited to participate in the study and, if they agreed, they signed an informed consent. Patients were randomly assigned to one of two groups: ECC group and DCC group.

RESULTS

Our study included a total of 57 patients: 30 in the ECC group and 27 in the DCC group. Due to a lack of funding and low recruitment rates, the study was discontinued in 2018. Maternal characteristics and obstetric outcomes were similar between both groups. The intention-to-treat analysis did not reveal any differences between groups for neonatal red blood cell transfusions, neonatal IVH or maternal postpartum haemorrhage. There were no differences for secondary outcomes. Similarly, no differences were observed in the as-treated analysis.

CONCLUSION

The primary and secondary outcomes of our study were not achieved. Therefore, more meta-analysis and trials are needed to evaluate the appropriate timing of cord clamping in preterm birth.

Characteristics of Medically Transported Critically Ill Children with Respiratory Failure in Latin America: Implications for Outcomes

Several challenges exist for referral and transport of critically ill children in resource-limited regions such as Latin America; however, little is known about factors associated with clinical outcomes. Thus, we aimed to describe the characteristics of critically ill children in Latin America transferred to pediatric intensive care units for acute respiratory failure to identify risk factors for mortality. We analyzed data from 2,692 patients admitted to 28 centers in the Pediatric Collaborative Network of Latin America Acute Respiratory Failure Registry. Among patients referred from another facility (773, 28%), nonurban transports were independently associated with mortality (adjusted odds ratio = 9.4; 95% confidence interval: 2.4–36.3).

Rapid initiation of antiretroviral therapy in those with newly diagnosed HIV infection in London, UK

OBJECTIVES

In July 2016, as a result of patient demand, we introduced a rapid initiation option (RIO) to offer a first medical appointment and antiretroviral therapy (ART) initiation within 2 days of HIV diagnosis at 56 Dean Street (56DS) , a combined sexual health and HIV treatment service in London, UK.

METHODS

We performed a retrospective case-note review of patients newly diagnosed with HIV infection at 56DS following the introduction of the new RIO from July to October 2016. In order to assess the effect of the new service on ART uptake, we chose a comparison group of newly diagnosed patients at 56DS from 1 year earlier: July to October 2015.

RESULTS

In the 4 months following RIO introduction, there was a reduction in the median time from HIV diagnosis to the first medical appointment (7 versus 15 days; P < 0.00001) and to ART initiation (8 versus 21 days; P < 0.00001) compared with the same 4-month period 1 year previously. Uptake of ART at first appointment also significantly increased from 60% to 76% (P = 0.0074).

CONCLUSIONS

By increasing our clinic capacity and awareness of staff and patients of the RIO service, we were able to fulfil the aim of the service to offer ART more quickly following HIV diagnosis.

Sexual transmission of hepatitis C virus and its relation with hepatitis B virus and HIV

OBJECTIVE

To determine the extent of transmission of hepatitis C virus in sexual partners of intravenous drug misusers and to examine the relation between the prevalences of HIV, hepatitis B virus, and hepatitis C virus infections in homosexual men and intravenous drug misusers and their sexual partners.

DESIGN

Serum samples collected between 1984 and 1988 were tested for hepatitis B virus markers and antibodies against hepatitis C virus by enzyme linked immunosorbent assay (ELISA) and for HIV antibody by enzyme immune analysis and western blotting.

SETTING

Large referral university hospital with an external AIDS clinic in the metropolitan area of Barcelona, Spain.

SUBJECTS

243 Intravenous drug misusers, 143 of their regular heterosexual partners, and 105 homosexual men.

MAIN OUTCOME MEASURES

Prevalences of hepatitis C virus, hepatitis B virus, and HIV infections.

RESULTS

In all, 178 of the 243 (73%) intravenous drug misusers, 16 out of 143 (11%) of their partners, and 17 of the 105 (16%) homosexual men had antibodies against hepatitis C virus. The presence of hepatitis C virus infection was unrelated to sex, age, the presence of HIV or hepatitis B virus infections, or the Centers for Disease Control stage of HIV. In sexual partners of intravenous drug misusers there were strong correlations between the presence of hepatitis C virus infection and that of HIV (p = 0.001) and hepatitis B virus (p = 0.013) infections.

CONCLUSIONS

Intravenous drug misusers have a high risk of acquiring hepatitis C virus, hepatitis B virus, and HIV infections, but the presence of hepatitis C virus infection seems to be unrelated to the presence of the other two viruses. Homosexual men have a high prevalence of HIV and hepatitis B virus infections with a low prevalence of hepatitis C virus infection, the presence of which is not related to that of the other two infections. Conversely, heterosexual partners of intravenous drug misusers have low prevalences of the three virus infections, but the presence of hepatitis C virus infection correlates significantly with the presence of HIV and hepatitis B infections. The rate of sexual transmission of hepatitis C virus seems to be low, even in partners of people known to be seropositive for this virus.