Search for Invisible Axion Dark Matter in the 3.3-4.2 µeV Mass Range.

We report the results from a haloscope search for axion dark matter in the 3.3-4.2 µeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible" axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals.

Extended Search for the Invisible Axion with the Axion Dark Matter Experiment.

This Letter reports on a cavity haloscope search for dark matter axions in the Galactic halo in the mass range 2.81-3.31 µeV. This search utilizes the combination of a low-noise Josephson parametric amplifier and a large-cavity haloscope to achieve unprecedented sensitivity across this mass range. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics.

Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment.

This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 µeV. The search excludes the range of axion-photon couplings predicted by plausible models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at subkelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultralow-noise superconducting quantum interference device amplifier used for the signal power readout. Ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.

Piezoelectrically Tuned Multimode Cavity Search for Axion Dark Matter.

The µeV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches. This testbed experiment lives inside of and operates in tandem with the main ADMX experiment. The Sidecar experiment excludes masses in three widely spaced frequency ranges (4202-4249, 5086-5799, and 7173-7203 MHz). In addition, Sidecar demonstrates the successful use of a piezoelectric actuator for cavity tuning. Finally, this publication is the first to report data measured using both the TM_{010} and TM_{020} modes.

Multi-mode analysis of surface losses in a superconducting microwave resonator in high magnetic fields.

This paper reports on a surface impedance measurement of a bulk metal niobium-titanium superconducting radio frequency (SRF) cavity in a magnetic field (up to 10 T). A novel method is employed to decompose the surface resistance contributions of the cylindrical cavity end caps and walls using measurements from multiple TM cavity modes. The results confirm that quality factor degradation of a NbTi SRF cavity in a high magnetic field is primarily from surfaces perpendicular to the field (the cavity end caps), while parallel surface resistances (the walls) remain relatively constant. This result is encouraging for applications needing high Q cavities in strong magnetic fields, such as the Axion Dark Matter eXperiment because it opens the possibility of hybrid SRF cavity construction to replace conventional copper cavities.

Dark matter axion search using a Josephson Traveling wave parametric amplifier.

We describe the first implementation of a Josephson Traveling Wave Parametric Amplifier (JTWPA) in an axion dark matter search. The operation of the JTWPA for a period of about two weeks achieved sensitivity to axion-like particle dark matter with axion-photon couplings above 10-13 Ge V-1 over a narrow range of axion masses centered around 19.84 µeV by tuning the resonant frequency of the cavity over the frequency range of 4796.7-4799.5 MHz. The JTWPA was operated in the insert of the axion dark matter experiment as part of an independent receiver chain that was attached to a 0.56-l cavity. The ability of the JTWPA to deliver high gain over a wide (3 GHz) bandwidth has engendered interest from those aiming to perform broadband axion searches, a longstanding goal in this field.

Intimate partner violence and HIV treatment adherence in urban South Africa: Mediating role of perinatal common mental disorders.

Background: Antiretroviral therapy (ART) has potential to eliminate perinatal HIV infections, but adherence to ART in late pregnancy and postpartum is often suboptimal. Intimate partner violence (IPV) may influence non-adherence among perinatal women living with HIV (WWH), but few quantitative studies have examined this over time or explored mechanisms for this association. Methods: We used secondary data from a parent trial in Johannesburg comprising WWH from the control arm (n=63) and WWH ineligible for the trial (n=133). Trained nurse researchers administered questionnaires at first antenatal visit on past-year psychological, physical, and/or sexual IPV (WHO instrument), socio-demographics (age, food security, education), and perinatal common mental symptoms of depression (Hospital Anxiety and Depression Screener-d); anxiety (HADS-a); post-traumatic stress disorder (PTSD; Harvard Trauma Questionnaire). At endline visit 2-4 months postpartum, nurse researchers assessed self-reported ART adherence using a visual analog scale (with ≥95% considered "good"). We fitted structural equation models (SEM) in MPlus to explore direct and indirect effects of IPV on ART adherence. Results: Of 196 perinatal WWH, 53.1% reported IPV exposure at baseline. The majority of participants (85.7%) had good perinatal ART adherence. In adjusted models, IPV at baseline was associated with halved odds of good adherence (aOR=0.51, 95%CI=0.20-0.96). IPV was associated with higher adjusted odds of probable depression (aOR=4.64), anxiety (aOR=2.85), and PTSD (aOR=3.42). In SEM, IPV had a direct (standardized coef=-0.22) and indirect effect (coef=-0.05) on ART via common mental disorders. The total effect of IPV on perinatal adherence was of moderate size (coef= -0.27) and the model had good fit (CFI=0.972; TLI=0.969; RMSEA=0.045; SRMR=0.076). Conclusion: IPV was longitudinally associated with perinatal ART non-adherence in part due to its relationship with mental health symptomology. Addressing IPV within clinical care has potential to improve perinatal mental health, maternal HIV outcomes, and HIV-free infant survival.

Axion Dark Matter Experiment: Detailed design and operations.

Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66-3.1 µeV mass range with Dine-Fischler-Srednicki-Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.

Mechanisms linking intimate partner violence and prevention of mother-to-child transmission of HIV: A qualitative study in South Africa.

Prevention of mother-to-child transmission (PMTCT) can virtually eliminate HIV infection among infants, yet up to one-third of women miss PMTCT steps. Little is known about how partner dynamics such as intimate partner violence (IPV) influence pregnant and postpartum women's adherence to PMTCT. We conducted 32 qualitative interviews with HIV-positive pregnant and postpartum women in Johannesburg who experienced IPV. Trained researchers conducted in-depth interviews over the period of May 2014-Nov 2015 using narrative and social constructionist approaches. Interviews were transcribed verbatim and analyzed thematically and inductively using Dedoose qualitative software. Twenty-six women experienced recent IPV and one-third had poor adherence to PMTCT. Women's experience of partner violence influenced PMTCT behaviors through four pathways. First, fear of partner disclosure led some women to hide their HIV status to avoid a violent reaction. Despite strategic non-disclosure, several maintained good adherence by hiding medication or moving out from their partner's home. Second, IPV caused feelings of depression and anxiety that led to intentionally or accidentally missing medication. Five women stopped treatment altogether, in a type of passive suicidality, hoping to end the distress of IPV. Third, men's controlling behaviors reduced access to friends and family, limiting social support needed for good adherence. Fourth, in a protective pathway, women reported good adherence partly due to their mothering role. The identity around motherhood was used as a coping technique, reminding women that their infant's wellbeing depended on their own health. PMTCT is essential to prevent vertical HIV transmission, but women living with IPV face multiple pathways to non-adherence. Addressing IPV in antenatal care can support the health of women and infants and may enhance PMTCT coverage.