Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Structure and evolution of a tidally heated star

Context. The shearing motion of tidal flows that are excited in non-equilibrium binary stars transform kinetic energy into heat via a process referred to as tidal heating. Aims. We aim to explore the way tidal heating affects the stellar structure. Methods. We used the TIDES code, which solves the equations of motion of the three-dimensional (3D) grid of volume elements that conform multiple layers of a rotating binary star to obtain an instantaneous value for the angular velocity, ω″, as a function of position in the presence of gravitational, centrifugal, Coriolis, gas pressure, and viscous forces. The released energy, Ė, was computed using a prescription for turbulent viscosity that depends on the instantaneous velocity gradients. The Ė values for each radius were injected into a MESA stellar structure calculation. The method is illustrated for a 1.0 + 0.8 M⊙ binary system, with an orbital period of P = 1.44 d and departures from synchronous rotation of 5% and 10%. Results. Heated models have a larger radius and surface luminosity, a smaller surface convection zone, and lower nuclear reaction rates than the equivalent standard stellar models, and their evolutionary tracks extend to higher temperatures. The magnitude of these effects depends on the amount of injected energy, which, for a fixed set of stellar, rotation and orbital parameters, depends on the perturbed star’s density structure and turbulent viscosity. Conclusions. Tidal heating offers a possible alternative for describing phenomena such as bloated or overluminous binary components, age discrepancies, and aspherical mass ejection, as well as the extended main sequence turnoff in clusters. However, establishing its actual role requires 3D stellar structure models commensurate with the nonspherically symmetric properties of tidal perturbations

Predictors of Acute Renal Injury Study (PARIS) among HIV-positive individuals: design and methods

Abstract Background Acute kidney injury (AKI), which is common among HIV-positive individuals, may contribute to the excess burden of chronic kidney disease (CKD) in this patient population; however, conventional clinical methods to detect AKI do not capture kidney injury sufficiently early to prevent irreversible damage. Further, large observational and interventional studies of AKI generally exclude HIV-positive persons in spite of their disproportionate risk. Methods The Predictors of Acute Renal Injury Study (PARIS) is a prospective observational cohort study among HIV-positive individuals established to determine the ability of candidate kidney injury biomarkers to predict future hospitalized clinical AKI, to characterize hospitalized subclinical AKI, and to discern the risk of progressive kidney disease following subclinical and clinical AKI. Among the candidate kidney injury markers, we will select the most promising to translate into a clinically viable, multiplex panel of urinary biomarkers which we will integrate with clinical factors to develop a model prognostic of risks for AKI and subsequent kidney function decline. This study has a targeted enrollment of 2000 participants. The overall follow-up of participants consists of two phases: 1) a 5-year active follow-up phase which involves serial evaluations at enrollment, annual clinic visits, and among participants who are hospitalized during this period, an evaluation at index hospitalization and 3 and 12 months post-hospitalization; and 2) a subsequent passive follow-up phase for the duration that the participant receives medical care at The Johns Hopkins Hospital. Discussions This study will serve as an important resource for future studies of AKI by establishing a repository with both ambulatory and inpatient biospecimens, a resource that is currently lacking in existing HIV clinical cohorts and studies of AKI. Upon completion of this study, the resulting prognostic model which will incorporate results from the multiplex HIV-AKI Risk Pane could serve as a pharmacodynamic endpoint for early phase therapeutic candidates for AKI

Functional outcomes of sleep predict cardiovascular intermediary outcomes and all-cause mortality in patients on incident hemodialysis.

Study objectivesPatients with end-stage kidney disease commonly experience sleep disturbances. Sleep disturbance has been inconsistently associated with mortality risk in patients on hemodialysis, but the burden of symptoms from sleep disturbances has emerged as a marker that may shed light on these discrepancies and guide treatment decisions. This study examines whether functional outcomes of sleep are associated with increased risk of intermediary cardiovascular outcomes or mortality among adults initiating hemodialysis.MethodsIn 228 participants enrolled in the Predictors of Arrhythmic and Cardiovascular Risk in End-Stage Renal Disease study, the Functional Outcomes of Sleep Questionnaire-10 (FOSQ-10), which assesses functional outcomes of daytime sleepiness, was administered within 6 months of enrollment. Intermediary cardiovascular outcomes included QT correction (ms), heart rate variance (ms2), left ventricular mass index (g/m2), and left ventricular hypertrophy. The association of FOSQ-10 score with all-cause mortality was examined using proportional hazards regression.ResultsMean age was 55 years, and median body mass index was 28 kg/m2 (interquartile range, 24, 33), with 70% of patients being African Americans. Median FOSQ-10 score was 19.7 (interquartile range, 17.1, 20.0). A 10% lower FOSQ-10 score was associated with increased mortality risk (hazard ratio, 1.09; 95% confidence interval, 1.01-1.18). Lower FOSQ-10 scores were associated with longer QT correction duration and lower heart rate variance but not left ventricular mass index or left ventricular mass index.ConclusionsIn adults initiating dialysis, sleep-related functional impairment is common and is associated with intermediary cardiovascular disease measures and increased mortality risk. Future studies should assess the impact of screening for sleep disturbances in patients with end-stage kidney disease to identify individuals at increased risk for cardiovascular complications and death.CitationFitzpatrick J, Kerns ES, Kim ED, et al. Functional outcomes of sleep predict cardiovascular intermediary outcomes and all-cause mortality in patients on incident hemodialysis. J Clin Sleep Med. 2021;17(8):1707-1715

The incidence of and risk factors for hospitalized acute kidney injury among people living with HIV on antiretroviral treatment.

ObjectivesThe epidemiology of hospitalized acute kidney injury (AKI) among people living with HIV (PLWH) in the era of modern antiretroviral therapy (ART) for all PLWH is not well characterized. We evaluated the incidence of and risk factors for hospitalized AKI from 2005 to 2015 among PLWH on ART.MethodsWe conducted a retrospective analysis of PLWH from the Johns Hopkins HIV Clinical Cohort. We defined hospitalized AKI as a rise of ≥ 0.3 mg/dL in serum creatinine (SCr) within any 48-h period or a 50% increase in SCr from baseline and assessed associations of risk factors with incident AKI using multivariate Cox regression models.ResultsMost participants (75%) were black, 34% were female, and the mean age was 43 years. The incidence of AKI fluctuated annually, peaking at 40 per 1000 person-years (PY) [95% confidence interval (CI) 22-69 per 1000 PY] in 2007, and reached a nadir of 20 per 1000 PY (95% CI 11-34 per 1000 PY) in 2010. There was no significant temporal trend (-3.3% change per year; 95% CI -8.6 to 2.3%; P = 0.24). After multivariable adjustment, characteristics independently associated with AKI included black race [hazard ratio (HR) 2.44; 95% CI 1.42-4.20], hypertension (HR 1.62; 95% CI 1.09-2.38), dipstick proteinuria > 1 (HR 1.86; 95% CI 1.07-3.23), a history of AIDS (HR 1.82; 95% CI 1.29-2.56), CD4 count < 200 cells/µL (HR 1.46; 95% CI 1.02-2.07), and lower serum albumin (HR 1.73 per 1 g/dL decrease; 95% CI 1.02-2.07).ConclusionsIn this contemporary cohort of PLWH, the annual incidence of first AKI fluctuated during the study period. Attention to modifiable AKI risk factors and social determinants of health may further reduce AKI incidence among PLWH