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An array of spheres descending slowly through a viscous fluid always clumps [J. M. Crowley, J. Fluid Mech. 45, 151 (1971)JFLSA70022-112010.1017/S0022112071003045]. We show that anisotropic particle shape qualitatively transforms this iconic instability of collective sedimentation. In experiment and theory on disks, aligned facing their neighbors in a horizontal one-dimensional lattice and settling at Reynolds number ∼10^{-4} in a quasi-two-dimensional slab geometry, we find that for large enough lattice spacing the coupling of disk orientation and translation rescues the array from the clumping instability. Despite the absence of inertia, the resulting dynamics displays the wavelike excitations of a mass-and-spring array, with a conserved “momentum” in the form of the collective tilt of the disks and an effective spring stiffness emerging from the viscous hydrodynamic interaction. However, the non-normal character of the dynamical matrix leads to algebraic growth of perturbations even in the linearly stable regime. Stability analysis demarcates a phase boundary in the plane of wave number and lattice spacing, separating the regimes of algebraically growing waves and clumping, in quantitative agreement with our experiments. Through the use of particle shape to suppress a classic sedimentation instability, our work uncovers an unexpected conservation law and hidden Hamiltonian dynamics which in turn open a window to the physics of transient growth of linearly stable modes.

Background. Postcapillary pulmonary hypertension (PH) can be seen in cirrhosis. Research and treatment goals exist for patients with portopulmonary hypertension but not for postcapillary PH. The aim of this study was to investigate outcomes after liver transplant (LT) for patients with postcapillary PH. Methods. This was a retrospective cohort study of 1173 patients who underwent LT at our center between 2010 and 2020. Using a propensity score matched analysis followed by multivariable Cox modeling on matched patients, we compared post-LT survival between patients with and without postcapillary PH. We also compared several post-LT outcomes between patient with different types of PH. Results. Sixty-eight patients had PH, and 50 had postcapillary PH. The median age was 59 y and the sample was 54% male. There was no significant difference in mortality between patients with postcapillary PH and patients without PH (hazard ratio, 1.72; 95% confidence interval, 0.90-3.31; P = 0.10). There was no significant difference in survival between patients with any type of PH and those without PH. There was no significance difference in post-LT survival, acute kidney injury, or pulmonary edema between patients with different types of PH. Patients with postcapillary PH who survived had a higher cardiac output than those who died (11 L/min in patients who lived, as compared with 8 L/min in patients who died; P = 0.03). Conclusions. Postcapillary PH does not appear to convey a negative impact on post-LT survival. A higher cardiac output may be protective against mortality in patients with postcapillary PH.

Introduction. The progression of chronic liver disease to cirrhosis involves both innate and adaptive immune system dysfunction resulting in increased risk of infectious complications. Vaccinations against pneumococcus, hepatitis A virus (HAV), and hepatitis B virus (HBV) are well tolerated and effective in disease prevention and reduction in morbidity and mortality. Prior studies assessing vaccination rates in patients with cirrhosis have specific limitations and to date no study has provided a comprehensive evaluation of vaccination rates in patients with cirrhosis in the United States. Aim. This study assessed vaccination rates for pneumococcus, HAV, and HBV in patients with cirrhosis. Results. Overall 59.7% of patients with cirrhosis received at least 1 vaccination during the study period. Vaccination rates within the same or following year of cirrhosis diagnosis were 19.9%, 7.7%, and 11.0% against pneumococcus, HAV, and HBV, respectively. Trend analysis revealed significant increases in vaccination rates for pneumococcus in all patients with cirrhosis and within subgroups based on age, gender, and presence of concomitant diabetes. Conclusion. The study demonstrated that vaccination rates in patients with cirrhosis remain suboptimal. Ultimately, the use of electronic medical record (EMR) reminders improved communication between healthcare professionals and public health programs to increase awareness are fundamental to reducing morbidity, mortality, and health-care related costs of vaccine preventable diseases in patients with cirrhosis.

Background and aims: The role of recently developed balloon-assisted enteroscopy (BAE) in small-bowel Crohn’s disease (CD) is not well established. The purpose of this study is to determine the clinical impact of BAE on patients with suspected and established small-bowel CD. Methods: This study included 22 patients (group A) with suspected small-bowel CD and 43 patients (group B) with established small-bowel CD with or without previous surgery, who underwent BAE, in a prospective BAE registry of a US academic medical institution. All underwent abdominal imaging studies including computed tomography (CT) or magnetic resonance (MR) enterography before BAE. The main outcome measurements were diagnostic yield and clinical outcomes. Results: In total, 78 BAE procedures were carried out in 65 patients. In group A (n = 22, 25 BAE procedures), enteroscopy led to a diagnosis of CD in six patients (27.3 %). Non-steroidal anti-inflammatory drug-related enteropathy was diagnosed in three patients (13.6 %), whereas no lesions were found in the remaining 13 patients. In group B (n = 43, 53 BAE procedures) enteroscopy revealed active intestinal inflammation with ulcers and/or luminal stenosis in 18 patients (41.9 %), which led to a change and escalation of medical therapy. Five patients without active ulcers underwent successful dilation of small-bowel strictures with resulting resolution of obstructive symptoms. Of the 78 BAE procedures, two patients (2.6 %) had bleeding complications which were successfully treated conservatively. One patient (1.3 %) underwent surgery due to procedure-related perforation. Conclusions: The use of BAE may help improve management in patients with suspected and established small-bowel CD.