Structural stability of cooling flows

Three-dimensional hydrodynamical simulations are used to investigate the structural stability of cooling flows that are episodically heated by jets from a central AGN. The radial profile of energy deposition is controlled by (a) the power of the jets, and (b) the pre-outburst density profile. A delay in the ignition of the jets causes more powerful jets to impact on a more centrally concentrated medium. The net effect is a sufficient increase in the central concentration of energy deposition to cause the post-outburst density profile to be less centrally concentrated than that of an identical cluster in which the outburst happened earlier and was weaker. These results suggest that the density profiles of cooling flows oscillate around an attracting profile, thus explaining why cooling flows are observed to have similar density profiles. The possibility is raised that powerful FR II systems are ones in which this feedback mechanism has broken down and a runaway growth of the source parameters has occurred.Comment: 4 pages, 2 figure

Management of severe acute respiratory distress syndrome: A primer

This narrative review explores the physiology and evidence-based management of patients with severe acute respiratory distress syndrome (ARDS) and refractory hypoxemia, with a focus on mechanical ventilation, adjunctive therapies, and veno-venous extracorporeal membrane oxygenation (V-V ECMO). Severe ARDS cases increased dramatically worldwide during the Covid-19 pandemic and carry a high mortality. The mainstay of treatment to improve survival and ventilator-free days is proning, conservative fluid management, and lung protective ventilation. Ventilator settings should be individualized when possible to improve patient-ventilator synchrony and reduce ventilator-induced lung injury (VILI). Positive end-expiratory pressure can be individualized by titrating to best respiratory system compliance, or by using advanced methods, such as electrical impedance tomography or esophageal manometry. Adjustments to mitigate high driving pressure and mechanical power, two possible drivers of VILI, may be further beneficial. In patients with refractory hypoxemia, salvage modes of ventilation such as high frequency oscillatory ventilation and airway pressure release ventilation are additional options that may be appropriate in select patients. Adjunctive therapies also may be applied judiciously, such as recruitment maneuvers, inhaled pulmonary vasodilators, neuromuscular blockers, or glucocorticoids, and may improve oxygenation, but do not clearly reduce mortality. In select, refractory cases, the addition of V-V ECMO improves gas exchange and modestly improves survival by allowing for lung rest. In addition to VILI, patients with severe ARDS are at risk for complications including acute cor pulmonale, physical debility, and neurocognitive deficits. Even among the most severe cases, ARDS is a heterogeneous disease, and future studies are needed to identify ARDS subgroups to individualize therapies and advance care

Kentucky Oil and Gas Conservation Laws

In this session, Bryan R. Reynolds discussed his article published in the KJEANRL: Kentucky Oil and Gas Conservation Laws: Keeping Pace with Technological Advances in the Oil and Gas Industry

Synthetic studies towards trichodermamide B: expedient synthesis enabled by arene oxide equivalents

Trichodermamide B, isolated from the marine fungus Trichoderma virens in 2003, is a potent anti-cancer agent and with complex molecular architecture. It is hypothesized herein that this molecule may be derived in nature from phenylalanine via a benzene oxide intermediate. Utilizing a bioinspired strategy, synthetic studies towards trichodermamide B have been conducted utilizing arene oxide equivalents as key synthetic intermediates. Notable synthetic transformations include alkylation with a novel, α–bromo oximoester electrophile and allylic bromination of an advanced, spirocyclic intermediate. This strategy has enabled access to advanced intermediates and should afford the natural product in far fewer steps than previously reported syntheses of this compound. Once complete, this concise synthetic strategy should afford enough material to conduct mechanism of action studies to uncover the origin of trichodermamide B’s impressive biological activity

CONTROLLING INFLAMMATION WITH DEXAMETHASONE AFTER ANTERIOR CRUCIATE LIGAMENT INJURY

INTRODUCTION Anterior Cruciate Ligament (ACL) injuries are increasingly common, with about 250 000 ACL ruptures occurring per year in the US [1]. The current treatment for ACL rupture is ACL reconstructive surgery (ACL-R), which aims to successfully restore the biomechanical function of the knee. However, individuals who suffer from ACL injuries, including those who undergo ACL reconstruction, have a 50% chance of developing osteoarthritis (OA) within 10-20 years [2]. Inflammation of the knee joint has been hypothesized to be a factor [3]. Dexamethasone (DEX) is a type of corticosteroid used to control inflammation [4]. The purpose of this study was to determine if DEX treatment following anterior cruciate ligament reconstruction was an effective mechanism of long-term joint protection against the progression of osteoarthritis. METHODS Six female Suffolk cross sheep were allocated into one of three groups: sham surgery, idealized ACL-R surgery, and control. Surgeries were previously accomplished by arthrotomy to the right stifle joint. Animals that underwent idealized ACL reconstructive surgery received a single injection of DEX at the time of the surgery. At 2 weeks post surgery animals were sacrificed and cartilage samples were harvested from both standard as well as visibly damaged locations on the patella (PAT), femoral groove (FG), lateral femoral condyle (LFC), medial femoral condyle (MFC), lateral tibial condyle (LTC), and medial tibial condyle (MTC). These samples were then blinded and graded by three experienced observers on the modified Mankin scale. This scale gives a grade out of 24 based on four categories: safranin-O staining, structure, cell density, and cluster formation. ANOVA with Bonferroni post-hoc analysis was used to determine differences in histological scores between groups, using SPSS 19.0.   RESULTS The average histological grades (and standard deviations) for the PAT, FG, LTP, MTP, LFC, and MFC are displayed in Figure 1. No significant differences were observed between the sham (n=2), ACL-R + DEX (n=2), and control groups in all locations. DISCUSSION AND CONCLUSIONS The similarity between the ACL-R+DEX and control groups indicates that DEX treatment has the potential to have a protective effect against the progression of OA, however further studies must be conducted to ensure long-term efficacy. Increasing the sample size as well as looking at longer time points is recommended to better understand the effect of dexamethasone on the progression of osteoarthriti

Pulp, Vol. 4 No. 1

This is the fourth issue of Pulp.https://scholarworks.sfasu.edu/pulp/1003/thumbnail.jp