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Geocoronal Solar Wind Charge Exchange (SWCX) is the process by which heavy ions from the solar wind undergo charge exchange with neutral hydrogen atoms from the Earth's exosphere, releasing photons at discrete energies characteristic of the solar wind ions. This paper investigates the solar wind types driving geocoronal SWCX. We find that during periods of time‐variable SWCX, higher fractions of every ion species are recorded by ACE compared to the averages. Notably, a subset of the slow solar wind characterized by a systematic lower temperature and higher proton flux is surprisingly effective for producing SWCX. Given the degradation of the solar wind composition spectrometer on ACE in 2011, we explore the capabilities of XMM‐Newton as an alternative sensor to monitor heavy ion composition in the solar wind. Unlike the distributions of other ion line fluxes analyzed, only OVIII, extracted via spectral analysis of XMM‐Newton observations, display patterns similar to the corresponding parent ion abundances from ACE O8+/p $\left({\mathrm{O}}^{\mathrm{8}+}/\mathrm{p}\right)$. Finally, we employ a Random Forest Classifier model to predict solar wind types based on literature results. When combining proton data with XMM‐Newton features, the model performance improves significantly, achieving a macro‐averaged F1 score of 0.80 (with a standard deviation of 0.06). Key Points: Variable solar wind charge exchange is associated with periods of outlier wind having increased solar wind proton fluxXMM‐Newton observes differences in solar wind charge exchange emission count rate during different solar wind typesThe distribution of the OVIII line flux from XMM‐Newton is similar to that of the ACE O8+/p ratio across different solar wind types [ABSTRACT FROM AUTHOR]

The Earth's magnetosheath and cusps emit soft X‐rays due to the charge exchange between highly charged solar wind ions and exospheric hydrogen atoms. The Lunar Environment Heliospheric X‐ray Imager and Solar wind Magnetosphere Ionosphere Link Explorer missions are scheduled to image the Earth's dayside magnetosphere system in soft X‐rays to investigate global‐scale magnetopause reconnection modes under varying solar wind conditions. The exospheric neutral hydrogen density distribution, especially the value of this density at the subsolar magnetopause is of particular interest for understanding X‐ray emissions near this boundary. This paper estimates the exospheric density during solar minimum using the X‐ray Multimirror Mission (XMM) astrophysics observatory. We selected an event on 12 November 2008 from the XMM data archive, which detects soft X‐rays of magnetosheath origin while solar wind and interplanetary magnetic field conditions are relatively constant. During the event the location of the magnetopause was measured in situ by the THEMIS mission, thus the location of the solar wind ions responsible for the magnetosheath emission is well constrained by observation. We estimated the exospheric density using the Open Geospace Global Circulation Model (OpenGGCM) and a spherically symmetric exosphere model. The ratio of the magnetosheath plasma flux between the OpenGGCM model and the THEMIS, was nearly 1, which means the magnetohydrodynamic model reasonably reproduces the magnetosheath plasma conditions. The OpenGGCM magnetosheath parameters were used to deconvolve soft X‐rays of exospheric origin from the XMM signal. The lower‐limit of the exospheric density of this solar minimum event is 36.8 ± 11.7 cm−3 at 10 RE subsolar location. Key Points: From 11 years of X‐ray Multimirror Mission‐Newton X‐ray observations, we identified 193 intervals that can be used to estimate the exospheric neutral densityWe derived a solar minimum exospheric neutral density from the 12 November 2008 event using a global MagnetoHydroDynamics model and a simplified exosphere modelThe density estimate is 36.8 cm−3 near the subsolar magnetopause and is likely a lower‐limit value [ABSTRACT FROM AUTHOR]

The Cusp Plasma Imaging detector (CuPID) Cube Satellite Observatory is a six‐unit Cube Satellite developed to study macroscale properties of dayside magnetopause reconnection. Reconnection will be studied through imaging spatial and temporal ion dispersion signatures in the magnetospheric cusps. As reconnection enables shocked solar wind plasma to enter the cusp, high charge state solar wind ions will charge‐exchange with Earth's neutral exosphere. This process generates soft X‐rays imaged by the spacecraft. CuPID is in a circular, highly inclined (97.6°), sun‐synchronous, low Earth orbit (550 km), where it views upward through the cusp from its low altitude footprint. The mission carries three science instruments, an energetic (>50 keV) radiation detector, a soft X‐ray (0.1–2 keV) imager, and a body‐mounted magnetometer. The soft X‐ray imager employs a novel, wide field‐of‐view (4.6°) slumped micropore optical element to focus X‐rays. The radiation detector uses collimated micro‐dosimeters with blocking foils to discriminate particle species. The three‐axis magnetometer is part of the attitude determination and control system and has been calibrated to provide scientifically useful data.Plain Language Summary: The Cusp Imaging Plasma Instrument Detector (CuPID) CubeSat Observatory is a small spacecraft designed to study soft X‐rays from space. These X‐rays will not penetrate the Earth's atmosphere, so an observer must make measurements from space, and CuPID will fly in a low altitude (550 km) polar orbit. The spacecraft will carry the first ever wide field‐of‐view soft X‐ray imager into orbit to make measurements of the Earth's space environment in soft X‐rays. Scientifically, soft X‐rays are useful as their intensity and dynamics in the Earth's polar cusps provide a proxy for the driving from the sun's solar wind. The spacecraft packs a modular set of avionics as well as soft X‐ray telescope and radiation sensor into a small 10 cm × 20 cm × 30 cm box. The self‐sustained mission will provide the first regular images of the Earth's magnetic field and space environment in soft X‐rays.Key Points: The Cusp Plasma Imaging detector (CuPID) Cube Satellite Observatory is a small satellite built to study soft X‐rays in spaceCuPID is a pioneering wide field‐of‐view soft X‐ray imager in orbitCuPID studies solar wind‐magnetosphere coupling and magnetopause reconnection [ABSTRACT FROM AUTHOR]

The LEXI and SMILE missions will provide soft X-ray images of the Earth's magnetosheath and cusps after their anticipated launch in 2023 and 2024, respectively. The IBEX mission showed the potential of an Energetic Neutral Atom (ENA) instrument to image dayside magnetosheath and cusps, albeit over the long hours required to raster an image with a single pixel imager. Thus, it is timely to discuss the two imaging techniques and relevant science topics. We simulate soft X-ray and low-ENA images that might be observed by a virtual spacecraft during two interesting solar wind scenarios: a southward turning of the interplanetary magnetic field and a sudden enhancement of the solar wind dynamic pressure. We employ the OpenGGCM global magnetohydrodynamics model and a simple exospheric neutral density model for these calculations. Both the magnetosheath and the cusps generate strong soft X-rays and ENA signals that can be used to extract the locations and motions of the bow shock and magnetopause. Magnetopause erosion corresponds closely to the enhancement of dayside reconnection rate obtained from the OpenGGCM model, indicating that images can be used to understand global-scale magnetopause reconnection. When dayside imagers are installed with high-ENA innermagnetosphere and FUV/UV aurora imagers, we can trace the solar wind energy flow from the bow shock to the magnetosphere and then to the ionosphere in a self-standing manner without relying upon other observatories. Soft X-ray and/or ENA imagers can also unveil the dayside exosphere density structure and its response to space weather. [ABSTRACT FROM AUTHOR]

Objective: Recently, new treatment options for rheumatoid arthritis (RA) patients with an inadequate response to methotrexate (MTX) have become available. Given the wide variability in efficacy and costs among these different treatment options, we sought to determine their cost-effectiveness (CE) in order to guide policy in different cost-constrained settings., Methods: We performed a CE analysis comparing 6 treatment options for patients with MTX-resistant RA: 1) etanercept + MTX, 2) etanercept monotherapy, 3) cyclosporine + MTX, 4) triple therapy (hydroxychloroquine, sulfasalazine, and MTX), 5) continuation of MTX monotherapy, and 6) no second-line agent. A decision model was used with a time horizon of 6 months. We used 2 measures of effectiveness based on published clinical trial data: the American College of Rheumatology 20% response criteria (ACR 20); and a weighted average of proportions of patients achieving responses of ACR 70, ACR 50, and ACR 20 (ACR 70 weighted response [ACR 70WR]). Incremental CE ratios were calculated as the additional cost per patient achieving either outcome, compared with the next least expensive option. To help interpret CE relative to these RA-specific outcomes, we conducted a separate, "reference" CE analysis of MTX use in MTX-naive RA patients, using the same outcomes., Results: In our reference analysis, MTX therapy for MTX-naive RA cost $1,100 per ACR 20 outcome and $1,500 per ACR 70WR, compared with no second-line agent. In our base-case analysis with either outcome, MTX continuation, cyclosporine + MTX, and etanercept monotherapy cost more, but either were not more efficacious or had a higher incremental CE ratio than the next most expensive option (i.e., they were dominated). Therefore, these options were not cost-effective. The least expensive option, triple therapy, cost 1.3 times more per patient with ACR 20 outcome ($1,500/ACR 20) and 2.1 times more per ACR 70WR ($3,100/ACR 70WR) than MTX therapy for MTX-naive RA. The most efficacious option, the combination of etanercept and MTX, cost 38 times more per patient with ACR 20 outcome ($4,600/ACR 20) and 23 times more per ACR 70WR ($34,800/ACR 70WR) than MTX therapy for MTX-naive RA. Overall, the results of extensive sensitivity analyses did not substantially affect these results., Conclusion: Our analysis indicates that if 15 mg/week MTX is cost-effective for achieving ACR 20 or ACR 70WR in MTX-naive RA over a 6-month period, then most likely so is triple therapy in MTX-resistant RA. Whether etanercept + MTX is cost-effective depends on whether $34,800/ACR 70WR (or $42,600/ACR 20) over a 6-month period is considered acceptable.

Objective: To evaluate the cost-effectiveness of different strategies for preventing corticosteroid-induced osteoporosis., Methods: Simulated cohorts of postmenopausal women with rheumatoid arthritis (RA) starting corticosteroid treatment were examined. A Markov decision analysis model was developed to compare different management strategies, including watchful waiting, screen and treat, and empirical treatment. Treatment thresholds for the screen and treat strategy were varied from bone mineral density (BMD) T scores <-1.0 to BMD T scores <-4.0., Results: Compared with a watchful waiting approach, the incremental cost-effectiveness ratio for a strategy of screen and treat with alendronate at a BMD T score of <-1.0 was $92,600 per quality-adjusted life year (QALY) gained. This result was sensitive to the cost and efficacy of osteoporosis therapy and, importantly, to the treatment threshold. At a treatment threshold of a BMD T score <-2.5, the incremental cost-effectiveness ratio of screening and treating was $76,100 per QALY. None of these results differed substantially for women taking estrogen replacement therapy., Conclusion: The incremental cost-effectiveness ratio of a strategy of screening and treating postmenopausal female RA patients with BMD T scores of < -1.0, compared with watchful waiting, was greater than that of other well-accepted medical interventions. The cost-effectiveness ratios were more acceptable when a T score treatment threshold of <-2.5 was used. These conclusions are limited by the lack of data on fracture and treatment efficacy in corticosteroid-treated patients.