Treating Vertical Root Fracture using Plasma-Rich Fibrin: A Case Report

Regenerative Endodontic Procedures (REP) are used to treat apical periodontitis in immature necrotic teeth and promote root maturation. Recently, REP has been speculated to arrest inflammatory external root resorption. Herein, we report the complicated treatment of apical root fracture using Plasma-Rich Fibrin (PRF) in a 12-year-old boy with a history of trauma to the right maxillary central incisor. The tooth was diagnosed to have necrotic pulp accompanied by symptomatic apical periodontitis and was treated with REP using PRF as a scaffold and restored. The tooth was asymptomatic at the 9-month follow-up; however, a sinus tract was detected on the buccal side. Retreatment was performed, and the tooth was filled with an apical plug of mineral trioxide aggregate and gutta-percha. Following the root canal, an apicoectomy was performed. During the surgery, a Vertical Root Fracture (VRF) was detected on the lateral aspect of the root extending to the middle third. The surface of the fracture was cleaned meticulously with a high-speed fine round diamond bur. The VRF was covered with PRF mixed with autologous bone. A follow-up at 57 months revealed a symptomless functioning tooth. This case highlights the importance of making every acceptable effort to preserve a hopeless tooth with VRF in a youngster for a few years and thereby preserve the surrounding alveolar bone

Пережити негаразди війни. Короткі поради щодо виживання для цивільних осіб в умовах військового стресу.

As the Ukrainian war rages, countless civilians are exposed to shelling, bombardments, relocation, loss of live and other modalities of war-related adversities. Whilst much has been learned about the late psychological outcome of traumatic exposure, , for most civilians the task at hand now is to successfully survive whatever level of adversity and horror they have been exposed to; efficiently protect themselves and others around them, and ultimately emerge victorious and minimally scathed by war. This document offers an easy-to-follow survival advice. We start by defining war stress and its many facets, review successful and less successful ways to mitigate war stress, outline critical aspects of life that must be dealt with during war, and provide a simple self-assessment tool of one’s achievement and resilience.У той час, як вирує українська війна, незліченна кількість мирних жителів зазнає обстрілів, бомбардування, переселення, загибелі людей та інших негараздів, пов'язаних з війною. Хоча багато відомо про відтерміновані психологічні наслідки травматичного впливу, для більшості цивільних осіб зараз стоїть завдання успішно пережити скруту та жахи будь-якого рівня, яких вони зазнають; ефективно захистити себе та оточуючих і зрештою вийти переможцями та мінімізувати втрати від війни.   Цей документ пропонує прості поради щодо виживання. Ми почнемо з визначення військового стресу та його численних аспектів, розглянемо успішні та менш успішні способи пом'якшення стресу від війни, намітимо критичні аспекти життя, з якими необхідно справлятись під час війни, та запропонуємо простий інструмент самооцінки своїх досягнень та стійкості

Right ventricular outflow tract velocity time integral-to-pulmonary artery systolic pressure ratio: a non-invasive metric of pulmonary arterial compliance differs across the spectrum of pulmonary hypertension.

Pulmonary arterial compliance (PAC), invasively assessed by the ratio of stroke volume to pulmonary arterial (PA) pulse pressure, is a sensitive marker of right ventricular (RV)-PA coupling that differs across the spectrum of pulmonary hypertension (PH) and is predictive of outcomes. We assessed whether the echocardiographically derived ratio of RV outflow tract velocity time integral to PA systolic pressure (RVOT-VTI/PASP) (a) correlates with invasive PAC, (b) discriminates heart failure with preserved ejection-associated PH (HFpEF-PH) from pulmonary arterial hypertension (PAH), and (c) is associated with functional capacity. We performed a retrospective cohort study of patients with PAH (n = 70) and HFpEF-PH (n = 86), which was further dichotomized by diastolic pressure gradient (DPG) into isolated post-capillary PH (DPG \u3c 7 mmHg; Ipc-PH, n = 54), and combined post- and pre-capillary PH (DPG ≥ 7 mm Hg; Cpc-PH, n = 32). Of the 156 patients, 146 had measurable RVOT-VTI or PASP and were included in further analysis. RVOT-VTI/PASP correlated with invasive PAC overall (ρ = 0.61, P \u3c 0.001) and for the PAH (ρ = 0.38, P = 0.002) and HFpEF-PH (ρ = 0.63, P \u3c 0.001) groups individually. RVOT-VTI/PASP differed significantly across the PH spectrum (PAH: 0.13 [0.010-0.25] vs. Cpc-PH: 0.20 [0.12-0.25] vs. Ipc-PH: 0.35 [0.22-0.44]; P \u3c 0.001), distinguished HFpEF-PH from PAH (AUC = 0.72, 95% CI = 0.63-0.81) and Cpc-PH from Ipc-PH (AUC = 0.78, 95% CI = 0.68-0.88), and remained independently predictive of 6-min walk distance after multivariate analysis (standardized β-coefficient = 27.7, 95% CI = 9.2-46.3; P = 0.004). Echocardiographic RVOT-VTI/PASP is a novel non-invasive metric of PAC that differs across the spectrum of PH. It distinguishes the degree of pre-capillary disease within HFpEF-PH and is predictive of functional capacity

Radial and vertical angular momentum transport in protostellar discs

Angular momentum in protostellar discs can be transported either radially, through turbulence induced by the magnetorotational instability (MRI), or vertically, through the torque exerted by a large-scale magnetic field. We present a model of steady-state discs where these two mechanisms operate at the same radius and derive approximate criteria for their occurrence in an ambipolar diffusion dominated disc. We obtain "weak field'' solutions - which we associate with the MRI channel modes in a stratified disc - and transform them into accretion solutions with predominantly radial angular-momentum transport by implementing a turbulent-stress prescription based on published results of numerical simulations. We also analyze "intermediate field strength'' solutions in which both radial and vertical transport operate at the same radial location. Our results suggest, however, that this overlap is unlikely to occur in real discs.Comment: 5 pages, 2 figures, 1 table, aastex.cls. Accepted for publication in Astrophysics & Space Scienc

Force-Free Models of Magnetically Linked Star-Disk Systems

Disk accretion onto a magnetized star occurs in a variety of astrophysical contexts, from young stars to X-ray pulsars. The magnetohydrodynamic interaction between the stellar field and the accreting matter can have a strong effect on the disk structure, the transfer of mass and angular momentum between the disk and the star, and the production of bipolar outflows, e.g., plasma jets. We study a key element of this interaction - the time evolution of the magnetic field configuration brought about by the relative rotation between the disk and the star - using simplified, largely semianalytic, models. We first discuss the rapid inflation and opening up of the magnetic field lines in the corona above the accretion disk, which is caused by the differential rotation twisting. Then we consider additional physical effects that tend to limit this expansion, such as the effect of plasma inertia and the possibility of reconnection in the disk's corona, the latter possibly leading to repeated cycles in the evolution. We also derive the condition for the existence of a steady state for a resistive disk and conclude that a steady state configuration is not realistically possible. Finally, we generalize our analysis of the opening of magnetic field lines by using a non-self-similar numerical model that applies to an arbitrarily rotating (e.g. keplerian) disk.Comment: 75 pages, 22 figures, 2 tables. Submitted to Astrophysical Journa

Megamaser Disks in Active Galactic Nuclei

Recent spectroscopic and VLBI-imaging observations of bright extragalactic water maser sources have revealed that the megamaser emission often originates in thin circumnuclear disks near the centers of active galactic nuclei (AGNs). Using general radiative and kinematic considerations and taking account of the observed flux variability, we argue that the maser emission regions are clumpy, a conclusion that is independent of the detailed mechanism (X-ray heating, shocks, etc.) driving the collisionally pumped masers. We examine scenarios in which the clumps represent discrete gas condensations (i.e., clouds) and do not merely correspond to velocity irregularities in the disk. We show that even two clouds that overlap within the velocity coherence length along the line of sight could account (through self-amplification) for the entire maser flux of a high-velocity ``satellite'' feature in sources like NGC 4258 and NGC 1068, and we suggest that cloud self-amplification likely contributes also to the flux of the background-amplifying ``systemic'' features in these objects. Analogous interpretations have previously been proposed for water maser sources in Galactic star-forming regions. We argue that this picture provides a natural explanation of the time-variability characteristics of extragalactic megamaser sources and of their apparent association with Seyfert 2-like galaxies. We also show that the requisite cloud space densities and internal densities are consistent with the typical values of nuclear (broad emission-line region-type) clouds.Comment: 55 pages, 7 figures, AASTeX4.0, to appear in The Astrophysical Journal (1999 March 1 issue

Trends in Veno-Arterial Extracorporeal Life Support With and Without an Impella or Intra-Aortic Balloon Pump for Cardiogenic Shock

Background: Mechanical circulatory support devices, such as the intra-aortic balloon pump (IABP) and Impella, are often used in patients on veno-arterial extracorporeal life support (VA-ECLS) with cardiogenic shock despite limited supporting clinical trial data. Methods and Results: Hospitalizations for cardiogenic shock from 2016 to 2018 were identified from the National Inpatient Sample. Trends in the use of VA-ECLS with and without an IABP or Impella were assessed semiannually. Multivariable logistic regression and general linear regression evaluated the association of Impella and IABP use with in-hospital outcomes. Overall, 12 035 hospitalizations with cardiogenic shock and VA-ECLS were identified, of which 3115 (26%) also received an IABP and 1880 (16%) an Impella. Use of an Impella with VA-ECLS substantially increased from 10% to 18% over this period (P\u3c0.001), whereas an IABP modestly increased from 25% to 26% (P\u3c0.001). In-hospital mortality decreased 54% to 48% for VA-ECLS only, 61% to 58% for VA-ECLS with an Impella, and 54% to 49% for VA-ECLS with an IABP (P\u3c0.001 each). Most (57%) IABPs or Impellas were placed on the same day as VA-ECLS. After adjustment, there were no differences in in-hospital mortality or length of stay with the addition of an IABP or Impella compared with VA-ECLS alone. Conclusions: From 2016 to 2018 in the United States, use of an Impella and IABP with VA-ECLS significantly increased. More than half of Impellas and IABPs were placed on the same day as VA-ECLS, and the use of a second mechanical circulatory support device did not impact in-hospital mortality. Further studies are needed to decipher the optimal timing and patient selection for this growing practice

Relativistic Magnetohydrodynamics with Application to Gamma-Ray Burst Outflows: I. Theory and Semianalytic Trans-Alfvenic Solutions

We present a general formulation of special-relativistic magnetohydrodynamics and derive exact radially self-similar solutions for axisymmetric outflows from strongly magnetized, rotating compact objects. We generalize previous work by including thermal effects and analyze in detail the various forces that guide, accelerate, and collimate the flow. We demonstrate that, under the assumptions of a quasi-steady poloidal magnetic field and of a highly relativistic poloidal velocity, the equations become effectively time-independent and the motion can be described as a frozen pulse. We concentrate on trans-Alfvenic solutions and consider outflows that are super-Alfvenic throughout in the companion paper. Our results are applicable to relativistic jets in gamma-ray burst (GRB) sources, active galactic nuclei, and microquasars, but our discussion focuses on GRBs. We envision the outflows in this case to initially consist of a hot and optically thick mixture of baryons, electron-positron pairs, and photons. We show that the flow is at first accelerated thermally but that the bulk of the acceleration is magnetic, with the asymptotic Lorentz factor corresponding to a rough equipartition between the Poynting and kinetic-energy fluxes (i.e., \~50% of the injected total energy is converted into baryonic kinetic energy). The electromagnetic forces also strongly collimate the flow, giving rise to an asymptotically cylindrical structure.Comment: 22 pages, 5 figures, submitted to the Astrophysical Journal. The companion paper is astro-ph/030348

Gamma-Ray Burst Afterglows in Pulsar-Wind Bubbles

We propose to identify pulsar-wind bubbles (PWBs) as the environment in which the afterglow emission in at least some gamma-ray bursts (GRBs) originates. Such bubbles could naturally account for the high fraction of the internal energy residing in relativistic electrons/positrons ($\epsilon_e$) and the high magnetic-to-internal energy ratio ($\epsilon_B$) that have been inferred in a number of sources. GRBs might occur within PWBs under a number of scenarios: in particular, in the supranova model of GRB formation a prolonged (months to years) period of intense pulsar-type wind from the GRB progenitor precedes the burst. Focusing on this scenario, we construct a simple model of the early-time structure of a plerionic supernova remnant. The model is based on the assumption of an ``equipartition'' upper bound on the electromagnetic- to-thermal pressure ratio in the bubble and takes into account synchrotron- radiation cooling. We derive an expression for the effective hydrogen number density $n_{H,equiv}$ of the shocked pulsar wind in terms of the comoving particle pressure and electromagnetic fields. We show that, for plausible parameter values, $n_{H,equiv}$ spans the range inferred from spectral fits to GRB afterglows and that its radial profile varies within the bubble and may resemble a uniform interstellar medium or a stellar wind. We consider how the standard expressions for the characteristic synchrotron spectrum are modified when the afterglow-emitting shock propagates inside a PWB and demonstrate that the predictions for the empirically inferred values of $\epsilon_e$ and $\epsilon_B$ are compatible with the observations. Finally, we outline a self-consistent interpretation of the X-ray emission features detected in sources like GRB 991216 in the context of the supranova/PWB picture.Comment: expanded version with new figures, 46 pages, 5 figures, to appear in ApJ (Vol. 574, July 20, 2002 issue

Self-Similar Collapse of Nonrotating Magnetic Molecular Cloud Cores

We obtain self-similar solutions that describe the gravitational collapse of nonrotating, isothermal, magnetic molecular cloud cores. We use simplifying assumptions but explicitly include the induction equation, and the semianalytic solutions we derive are the first to account for the effects of ambipolar diffusion following the formation of a central point mass. Our results demonstrate that, after the protostar first forms, ambipolar diffusion causes the magnetic flux to decouple in a growing region around the center. The decoupled field lines remain approximately stationary and drive a hydromagnetic C-shock that moves outward at a fraction of the speed of sound (typically a few tenths of a kilometer per second), reaching a distance of a few thousand AU at the end of the main accretion phase for a solar-mass star. We also show that, in the absence of field diffusivity, a contracting core will not give rise to a shock if, as is likely to be the case, the inflow speed near the origin is nonzero at the time of point-mass formation. Although the evolution of realistic molecular cloud cores will not be exactly self-similar, our results reproduce the main qualitative features found in detailed core-collapse simulations (Ciolek & Konigl 1998)Comment: 25 pages, 3 figures, AASTeXv4.0 Accepted for publication in The Astrophysical Journa