Propagation of different components of cosmic rays from Centaurus A in the Galactic magnetic fields

Propagation of different chemical composition ultrahigh energy cosmic rays in the galactic magnetic fields was simulated. The simulation for the ultra high energy events, registered by the AUGER observatory in the sky region near Centaurus A was performed. It is shown that some of these events could originate from Centaurus A

Nonthermal Electron Acceleration at Collisionless Quasi-perpendicular Shocks

Shock waves propagating in collisionless heliospheric and astrophysical plasmas have been studied extensively over the decades. One prime motivation is to understand the nonthermal particle acceleration at shocks. Although the theory of diffusive shock acceleration (DSA) has long been the standard for cosmic-ray acceleration at shocks, plasma physical understanding of particle acceleration remains elusive. In this review, we discuss nonthermal electron acceleration mechanisms at quasi-perpendicular shocks, for which substantial progress has been made in recent years. The discussion presented in this review is restricted to the following three specific topics. The first is stochastic shock drift acceleration (SSDA), which is a relatively new mechanism for electron injection into DSA. The basic mechanism, related in-situ observations and kinetic simulations results, and how it is connected with DSA will be discussed. Second, we discuss shock surfing acceleration (SSA) at very high Mach number shocks relevant to young supernova remnants (SNRs). While the original proposal under the one-dimensional assumption is unrealistic, SSA has now been proven efficient by a fully three-dimensional kinetic simulation. Finally, we discuss the current understanding of the magnetized Weibel-dominated shock. Spontaneous magnetic reconnection of self-generated current sheets within the shock structure is an interesting consequence of Weibel-generated strong magnetic turbulence. We argue that high Mach number shocks with both Alfven and sound Mach numbers exceeding 20-40 will likely behave as a Weibel-dominated shock. Despite a number of interesting recent findings, the relative roles of SSDA, SSA, and magnetic reconnection for electron acceleration at collisionless shocks and how the dominant particle acceleration mechanisms change depending on shock parameters remain to be answered.Comment: To appear in Reviews of Modern Plasma Physics as an invited revie

The influence of extragalactic magnetic fields on the propagation of cosmic rays from Centaurus A

The motion of different chemical composition of ultra high energy cosmic rays in the galactic magnetic fields with taking into account the extragalactic magnetic field was considered. The ultra high energy events registered by the AUGER observatory in the sky region near Centaurus A were investigated. It is shown that in the case when the extragalactic magnetic field is taken into account some of these events could originate from Centaurus A, but it leads to expanding of sky region of possible source localization

<em>TESS</em> Cycle 2 observations of roAp stars with 2-min cadence data

\ua9 The Author(s) 2023.We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations, while all new members are rotationally variable stars, leading to almost 70 per cent (22) of the roAp stars presented being α2 CVn-type variable stars. We show that targeted observations of known chemically peculiar stars are likely to overlook many new roAp stars, and demonstrate that multiepoch observations are necessary to see pulsational behaviour changes. We find a lack of roAp stars close to the blue edge of the theoretical roAp instability strip, and reaffirm that mode instability is observed more frequently with precise, space-based observations. In addition to the Cycle 2 observations, we analyse TESS data for all-known roAp stars. This amounts to 18 further roAp stars observed by TESS. Finally, we list six known roAp stars that TESS is yet to observe. We deduce that the incidence of roAp stars amongst the Ap star population is just 5.5 per cent, raising fundamental questions about the conditions required to excite pulsations in Ap stars. This work, coupled with our previous work on roAp stars in Cycle 1 observations, presents the most comprehensive, homogeneous study of the roAp stars in the TESS nominal mission, with a collection of 112 confirmed roAp stars in total

TESS Cycle 1 observations of roAp stars with 2-min cadence data

We present the results of a systematic search for new rapidly oscillating Ap (roAp) stars using the 2-min cadence data collected by the Transiting Exoplanet Survey Satellite (TESS) during its Cycle 1 observations. We identify 12 new roAp stars. Amongst these stars we discover the roAp star with the longest pulsation period, another with the shortest rotation period, and six with multiperiodic variability. In addition to these new roAp stars, we present an analysis of 44 known roAp stars observed by TESS during Cycle 1, providing the first high-precision and homogeneous sample of a significant fraction of the known roAp stars. The TESS observations have shown that almost 60 per cent (33) of our sample of stars are multiperiodic, providing excellent cases to test models of roAp pulsations, and from which the most rewarding asteroseismic results can be gleaned. We report four cases of the occurrence of rotationally split frequency multiplets that imply different mode geometries for the same degree modes in the same star. This provides a conundrum in applying the oblique pulsator model to the roAp stars. Finally, we report the discovery of non-linear mode interactions in $\alpha$ Cir (TIC 402546736, HD 128898) around the harmonic of the principal mode -- this is only the second case of such a phenomenon...

TESS Cycle 2 observations of roAp stars with 2-min cadence data

We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations, while all new members are rotationally variable stars, leading to almost 70 per cent (22) of the roAp stars presented being α2 CVn-type variable stars. We show that targeted observations of known chemically peculiar stars are likely to overlook many new roAp stars, and demonstrate that multi-epoch observations are necessary to see pulsational behaviour changes. We find a lack of roAp stars close to the blue edge of the theoretical roAp instability strip, and reaffirm that mode instability is observed more frequently with precise, space-based observations. In addition to the Cycle 2 observations, we analyse TESS data for all known roAp stars. This amounts to 18 further roAp stars observed by TESS. Finally, we list six known roAp stars that TESS is yet to observe. We deduce that the incidence of roAp stars amongst the Ap star population is just 5.5 per cent, raising fundamental questions about the conditions required to excite pulsations in Ap stars. This work, coupled with our previous work on roAp stars in Cycle 1 observations, presents the most comprehensive, homogeneous study of the roAp stars in the TESS nominal mission, with a collection of 112 confirmed roAp stars in total

Cyclooxygenases and the cardiovascular system.

Cyclooxygenase (COX)-1 and COX-2 are centrally important enzymes within the cardiovascular system with a range of diverse, sometimes opposing, functions. Through the production of thromboxane, COX in platelets is a pro-thrombotic enzyme. By contrast, through the production of prostacyclin, COX in endothelial cells is antithrombotic and in the kidney regulates renal function and blood pressure. Drug inhibition of COX within the cardiovascular system is important for both therapeutic intervention with low dose aspirin and for the manifestation of side effects caused by nonsteroidal anti-inflammatory drugs. This review focuses on the role that COX enzymes and drugs that act on COX pathways have within the cardiovascular system and provides an in-depth resource covering COX biology and pharmacology. The review goes on to consider the role of COX in both discrete cardiovascular locations and in associated organs that contribute to cardiovascular health. We discuss the importance of, and strategies to manipulate the thromboxane: prostacyclin balance. Finally within this review the authors discuss testable COX-2-hypotheses intended to stimulate debate and facilitate future research and therapeutic opportunities within the field