A highly magnetized environment in a pulsar binary system.

Spider pulsars are millisecond pulsars in short-period (≲12-h) orbits with low-mass (~0.01-0.4 M⊙) companion stars. The pulsars ablate plasma from the companion star, causing time delays and eclipses of the radio emission from the pulsar. The magnetic field of the companion has been proposed to strongly influence both the evolution of the binary system1 and the eclipse properties of the pulsar emission2. Changes in the rotation measure (RM) have been seen in a spider system, implying that there is an increase in the magnetic field near the eclipse3. Here we report a diverse range of evidence for a highly magnetized environment in the spider system PSR B1744 - 24A4, located in the globular cluster Terzan 5. We observe semi-regular profile changes to the circular polarization, V, when the pulsar emission passes close to the companion. This suggests that there is Faraday conversion where the radio wave tracks a reversal in the parallel magnetic field and constrains the companion magnetic field, B (> 10 G). We also see irregular, fast changes in the RM at random orbital phases, implying that the magnetic strength of the stellar wind, B, is greater than 10 mG. There are similarities between the unusual polarization behaviour of PSR B1744 - 24A and some repeating fast radio bursts (FRBs)5-7. Together with the possible binary-produced long-term periodicity of two active repeating FRBs8,9, and the discovery of a nearby FRB in a globular cluster10, where pulsar binaries are common, these similarities suggest that a proportion of FRBs have binary companions.

Factors that influence the choice of long-acting reversible contraceptive use among adolescents post-abortion in Chongqing, China: a cross-sectional study.

BACKGROUND: Induced abortion can seriously harm the physical and mental health of adolescent women. Long-acting reversible contraception (LARC) can effectively reduce unplanned pregnancies and prevent repeated abortions among adolescents. This study aimed to analyse the factors affecting the choice of LARC among adolescents in Chongqing of China. METHODS: A total of 555 adolescents who underwent induced abortions for unplanned pregnancies between January 2019 and October 2021 were selected as study subjects. Logistic regression analysis was used to determine the factors affecting adolescent LARC choices following induced abortions. RESULTS: The factors that affected adolescent LARC choices included an average monthly income ≥ ¥3000 (OR = 3.432, 95% CI: 1.429∼8.244), history of previous abortions (OR = 3.141, 95% CI: 1.632∼6.045), worrying about unplanned pregnancy (OR = 0.365, 95% CI: 0.180∼0.740), parental support for using LARC (OR = 3.549, 95% CI: 1.607∼7.839), sexual partners' support for using LARC (OR = 2.349, 95% CI: 1.068∼5.167), concerns about using LARC (OR = 0.362, 95% CI: 0.176∼0.745), and willingness to use free IUDs (OR = 13.582, 95% CI: 7.173∼25.717). CONCLUSION: Cost is one of the factors affecting LARC choices. Parents and sexual partners may play important role in the choice of LARC.

The study analysed the choice of contraceptive methods and the factors affecting the choice of long-acting reversible contraception methods after induced abortion among adolescents in Chongqing, China. The results showed that the income level, history of previous abortions, extent of worrying about unplanned pregnancy, parents' and sexual partners' attitude towards to use long-acting reversible contraception methods, concerns about using long-acting reversible contraception methods, and willingness to use free intrauterine devices were the factors affecting the choice of long-acting reversible contraception methods after induced abortion among adolescents.

Development and validation of a clinical model to predict preconception risk of gestational diabetes mellitus in nulliparous women: A retrospective cohort study.

OBJECTIVE: To develop and validate a model to predict the preconception risk of gestational diabetes mellitus (GDM) in nulliparous women. METHODS: This was a retrospective cohort study. A total of 1565 women in early pregnancy who underwent preconception health examinations in the Women and Children's Hospital of Chongqing Medical University between January 2020 and June 2021 were invited to participate in a questionnaire survey. Logistic regression analysis was performed to determine the preconception risk factors for GDM. These factors were used to construct a model to predict GDM risk in nulliparous women. Then, the model was used to assess the preconception risk of GDM in 1060 nulliparous women. RESULTS: Independent preconception risk factors for GDM included the following: age 35 years or greater, diastolic blood pressure 80 mm Hg or greater, fasting plasma glucose 5.1 mmol/L or greater, body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) 24 or greater, weight gain 10 kg or greater in the year before pregnancy, age of menarche 15 years or greater, three or more previous pregnancies, daily staple food intake 300 g or greater, fondness for sweets, and family history of diabetes. BMI less than 18.5, daily physical activity duration 1 h or greater, and high-intensity physical activity were protective factors. These factors were used to construct a model to predict GDM risk in nulliparous women, and the incidence of GDM significantly increased as the risk score increased. The area under the curve of the prediction model was 0.82 (95% confidence interval 0.80-0.85). CONCLUSION: The preconception GDM risk prediction model demonstrated good predictive efficacy and can be used to identify populations at high risk of GDM before pregnancy, which provides the possibility for preconception intervention.

A radio pulsar phase from SGR J1935+2154 provides clues to the magnetar FRB mechanism.

The megajansky radio burst, FRB 20200428, and other bright radio bursts detected from the Galactic source SGR J1935+2154 suggest that magnetars can make fast radio bursts (FRBs), but the emission site and mechanism of FRB-like bursts are still unidentified. Here, we report the emergence of a radio pulsar phase of the magnetar 5 months after FRB 20200428. Pulses were detected in 16.5 hours over 13 days using the Five-hundred-meter Aperture Spherical radio Telescope, with luminosities of about eight decades fainter than FRB 20200428. The pulses were emitted in a narrow phase window anti-aligned with the x-ray pulsation profile observed using the x-ray telescopes. The bursts, conversely, appear in random phases. This dichotomy suggests that radio pulses originate from a fixed region within the magnetosphere, but bursts occur in random locations and are possibly associated with explosive events in a dynamically evolving magnetosphere. This picture reconciles the lack of periodicity in cosmological repeating FRBs within the magnetar engine model.

Magnetic field reversal in the turbulent environment around a repeating fast radio burst.

Fast radio bursts (FRBs) are brief, intense flashes of radio waves from unidentified extragalactic sources. Polarized FRBs originate in highly magnetized environments. We report observations of the repeating FRB 20190520B spanning 17 months, which show that the FRB's Faraday rotation is highly variable and twice changes sign. The FRB also depolarizes below radio frequencies of about 1 to 3 gigahertz. We interpret these properties as being due to changes in the parallel component of the magnetic field integrated along the line of sight, including reversing direction of the field. This could result from propagation through a turbulent magnetized screen of plasma, located 10-5 to [Formula: see text] parsecs from the FRB source. This is consistent with the bursts passing through the stellar wind of a binary companion of the FRB source.

Frequency-dependent polarization of repeating fast radio bursts-implications for their origin.

The polarization of fast radio bursts (FRBs), which are bright astronomical transient phenomena, contains information about their environments. Using wide-band observations with two telescopes, we report polarization measurements of five repeating FRBs and find a trend of lower polarization at lower frequencies. This behavior is modeled as multipath scattering, characterized by a single parameter, σRM, the rotation measure (RM) scatter. Sources with higher σRM have higher RM magnitude and scattering time scales. The two sources with the highest σRM, FRB 20121102A and FRB 20190520B, are associated with compact persistent radio sources. These properties indicate a complex environment near the repeating FRBs, such as a supernova remnant or a pulsar wind nebula, consistent with their having arisen from young stellar populations.