Impacts of artificial ocean alkalinization on the carbon cycle and climate in Earth system simulations

Using the state-of-the-art emissions-driven Max-Planck-Institute Earth system model, we explore the impacts of artificial ocean alkalinization (AOA) with a scenario based on the Representative Concentration Pathway (RCP) framework. Addition of 114 Pmol of alkalinity to the surface ocean stabilizes atmospheric CO2 concentration to RCP4.5 levels under RCP8.5 emissions. This scenario removes 940 GtC from the atmosphere and mitigates 1.5 K of global warming within this century. The climate adjusts to the lower CO2 concentration preventing the loss of sea-ice and high sea level rise. Seawater pH and the carbonate saturation state (Ω) rise substantially above levels of the current decade. Pronounced differences in regional sensitivities to AOA are projected, with the Arctic Ocean and tropical oceans emerging as hot spots for biogeochemical changes induced by AOA. Thus, the CO2 mitigation potential of AOA comes at a price of an unprecedented ocean biogeochemistry perturbation with unknown ecological consequences

Direct and adjoint global stability analysis of turbulent transonic flows over a NACA0012 profile

In this work, various turbulent solutions of the two-dimensional (2D) and three-dimensional compressible Reynolds averaged Navier?Stokes equations are analyzed using global stability theory. This analysis is motivated by the onset of flow unsteadiness (Hopf bifurcation) for transonic buffet conditions where moderately high Reynolds numbers and compressible effects must be considered. The buffet phenomenon involves a complex interaction between the separated flow and a shock wave. The efficient numerical methodology presented in this paper predicts the critical parameters, namely, the angle of attack and Mach and Reynolds numbers beyond which the onset of flow unsteadiness appears. The geometry, a NACA0012 profile, and flow parameters selected reproduce situations of practical interest for aeronautical applications. The numerical computation is performed in three steps. First, a steady baseflow solution is obtained; second, the Jacobian matrix for the RANS equations based on a finite volume discretization is computed; and finally, the generalized eigenvalue problem is derived when the baseflow is linearly perturbed. The methodology is validated predicting the 2D Hopf bifurcation for a circular cylinder under laminar flow condition. This benchmark shows good agreement with the previous published computations and experimental data. In the transonic buffet case, the baseflow is computed using the Spalart?Allmaras turbulence model and represents a mean flow where the high frequency content and length scales of the order of the shear-layer thickness have been averaged. The lower frequency content is assumed to be decoupled from the high frequencies, thus allowing a stability analysis to be performed on the low frequency range. In addition, results of the corresponding adjoint problem and the sensitivity map are provided for the first time for the buffet problem. Finally, an extruded three-dimensional geometry of the NACA0012 airfoil, where all velocity components are considered, was also analyzed as a Triglobal stability case, and the outcoming results were compared to the previous 2D limited model, confirming that the buffet onset is well detected

Enhanced rates of regional warming and ocean acidification after termination of large-scale ocean alkalinization

Termination effects of large‐scale Artificial Ocean Alkalinization (AOA) have received little attention because AOA was assumed to pose low environmental risk. With the Max‐Planck‐Institute Earth System Model, we use emission‐driven AOA simulations following the Representative Concentration Pathway 8.5 (RCP8.5). We find that after termination of AOA warming trends in regions of the Northern hemisphere become ∼50% higher than those in RCP8.5 with rates similar to those caused by termination of solar geoengineering over the following three decades after cessation (up to 0.15 K/year). Rates of ocean acidification after termination of AOA outpace those in RCP8.5. In warm shallow regions where vulnerable coral reefs are located, decreasing trends in surface pH double (0.01 units/year) and the drop in the carbonate saturation state (Ω) becomes up to one order of magnitude larger (0.2 units/year). Thus, termination of AOA poses higher risks to biological systems sensitive to fast‐paced environmental changes than previously thought. <br

Conserved Quantities and Electroweak Phase Transitions

Some cosmological consequences of including the adequate conserved quantities in the density matrix of the electroweak theory are investigated. Several arguments against including the charges associated to the spontaneously broken symmetry are presented. Special attention is focused on the phenomenon of $W$-boson condensation and its interplay with the phase transition for the symmetry restoration is considered. The emerging cosmological implications, such as on the baryon and lepton number densities, are of interest.Comment: 9 pages, Latex, HU-SEFT R 1994-0

Magnetism in Dense Quark Matter

We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.Comment: To appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

Aging-associated symptoms in the physician-patient dialogue in a group of long-term diagnosed HIV-infected individuals

Background: The significant decrease in mortality has resulted in a large number of individuals aged over 50 living with HIV infection. Additionally, the coexistence of certain pathologies suggests premature aging. In this scenario, the presence of aging-associated symptoms in the physician-patient dialogue is yet to be explored. Methods: Cross-sectional observational study to evaluate the presence of aging-associated symptoms in the physician-patient dialogue and to explore the possible differences between genders in a sample of 100 HIV-1 infected subjects diagnosed at least 15 years ago. The survey assessed questions/comments made by the patient, questions/comments made by the physician and patients&#x2019; interest in obtaining more information than was provided. Number of patients and percentages were given and compared using the w2 or Fisher exact test (as appropriate). Results: Participants were 60 men and 40 women, diagnosed with HIV infection a median (IQ) of 18 (15.7&#x2013;21) years ago, who had a nadir CD4 and CD4 cell count at the study entry of 172 (95&#x2013;272) and 543 (403&#x2013;677), respectively. Eighty percent of the subjects had VL &#x3C;25 copies and 42% were HCV/HIV co-infected (31 subjects with low fibrosis stage). The infection route had been mainly intravenous drug use (37%) and MSM (32%). Men and women had similar demographic and clinical characteristics. Sixty-two percent of the participants acknowledged asking their physicians about aging-associated symptoms (58% men vs 66% women; p=0.50), 48% reported that their physicians had provided information without having been asked (48% men vs 55% women; p=0.51) and 75% confirmed that they would like to have more information about aging-associated symptoms (22% men vs 80% women; p&#x3C;0.001). Conclusions: Around half of the men and women interviewed had discussed aging-associated symptoms with their physician. However, this seemed insufficient for four-fifths of the women, who would have liked to have obtained more information about aging