A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

Formation of the methyl cation by photochemistry in a protoplanetary disk

Forty years ago, it was proposed that gas-phase organic chemistry in the interstellar medium can be initiated by the methyl cation CH3+ (refs. 1-3), but so far it has not been observed outside the Solar System4,5. Alternative routes involving processes on grain surfaces have been invoked6,7. Here we report James Webb Space Telescope observations of CH3+ in a protoplanetary disk in the Orion star-forming region. We find that gas-phase organic chemistry is activated by ultraviolet irradiation.

Chlamydia trachomatis: opportunistic screening in primary care

Following the publication of the Chief Medical Officer's report on chlamydial screening, we identified the sexual health of young women as an area for concern. As part of our review we decided to opportunistically search for chlamydial genital infections using a non-invasive technique. Sexually active women under 25 years of age were invited to submit a first void urine sample for polymerase chain reaction analysis. Over the period of a year we found out that 10.9% of sexually active young women tested positive for chlamydia in our practice.

Forty years on--contact tracing in Wakefield

An audit of contact tracing activity for a range of common sexually transmitted diseases (STD) was performed prospectively on 100 consecutive referrals to the health advisers at the Genitourinary Medicine (GUM) clinic in Wakefield. Targets for contact attendance were set according to the initial index patient diagnosis. Health adviser contact tracing methods (telephone, letter, visit) were logged. A total of 119 contacts were identified; of these, 86 (73%) were seen and examined. Attendance within the target time of one working week was not achieved in gonorrhoea contacts, but 61% warts contacts attended within the target of 4 weeks. Tracing by patient-carried contact slips after interview with the health adviser was effective in the majority (68%) of notifications.