Quantum-electrodynamic magnetic reconnection as the origin of the FRB 200428-associated X-ray burst from SGR J1935+2154

Magnetars, often under the name soft gamma-ray repeaters (SGRs) or anomalous X-ray pulsars, are highly magnetized neutron stars that exhibit diverse X-ray activities. Recently, a unique non-thermal X-ray burst with cut-off energy up to 84 keV is detected and thought to be associated with the fast radio burst (FRB) 200428 in the same single explosive event from SGR J1935+2154, as their spectra show similar feature of narrow double peaks that are emitted almost simultaneously. However, the physical origin of this FRB 200428-associated X-ray burst is still unknown yet. Here, with the first cross-scale numerical simulation in which modeling of particle acceleration by magnetic reconnections is self-consistently coupled with that of photon emission by multiple Compton scatterings, we identify that magnetic reconnection at the quantum-electrodynamic field strength inside the magnetar magnetosphere is the much likely driving source of such FRB-associated non-thermal X-ray burst. Both its temporal and spectral features are well reproduced in our simulations by assuming the plasma magnetization parameter σ~102-103 in consistency with the astronomical observations. The results could greatly promote our understandings of various X-ray burst events from magnetars.

Statistical Analyses of the Energies of X-Ray Plateaus and Flares in Gamma-Ray Bursts

Distinct X-ray plateau and flare phases have been observed in the afterglows of gamma-ray bursts (GRBs), and most of them should be related to central engine activities. In this paper, we collect 174 GRBs with X-ray plateau phases and 106 GRBs with X-ray flares. There are 51 GRBs that overlap in the two selected samples. We analyze the distributions of the proportions of the plateau energy E plateau and the flare energy E flare relative to the isotropic prompt emission energy E γ,iso. The results indicate that they well meet the Gaussian distributions and the medians of the logarithmic ratios are ∼−0.96 and −1.39 in the two cases. Moreover, strong positive correlations between E plateau (or E flare ) and E γ,iso with slopes of ∼0.95 (or ∼0.80) are presented. For the overlapping sample, the slope is ∼0.80. We argue that most of X-ray plateaus and flares might have the same physical origin but appear with different features because of the different circumstances and radiation mechanisms. We also test the applicabilities of two models, i.e., black holes surrounded by fractured hyperaccretion disks and millisecond magnetars, on the origins of X-ray plateaus and flares.

Szorstki i chropowaty dotyk – o dramaturgii zmysłów

Today, the concept of dramaturgy refers primarily to the space of theater or, more broadly, to performative arts. But as the concept of drama has passed into the scientific discourse of sociology, anthropology or literary studies, so is it with dramaturgy. The understanding that appears here refers to its meaning as a special tension on the level of sensually experienced and perceived artistic events. The subject of interest here is the dramatic aesthetics of experience in the field of performing and visual arts. The aesthetic categories related to the senses are often of a physical origin and amorphous in nature. The roughness and harshness of the title in their origin are physical categories that can be experienced primarily through the sense of touch. In this intertwining of senses, we are talking about their dramaturgy, because they cannot usually be separated from each other and various works appeal to touch and other senses at the same time. The process of creating a work and its reception is an action, process, meeting, the playwright of which is both the creator / creator and the recipient. The considerations concern changes in the perception of the senses, from the glorification of the sense of sight to the ennoblement of the “lower” senses, the place and function of the classical and interactive museum and haptic art, as well as the polysensory and immersive reception designed in performance and theater.

Introduction of high tensile strain into Ge-on-Insulator structures by oxidation and annealing at high temperature

It is demonstrated in this work that a high temperature thermal process including oxidation and N2 annealing at 850 oC can provide tensile strain of ~0.58 % at maximum into Ge-on-Insulator (GOI) structures without any special patterning or external stressors. The different impacts of oxidation and annealing on tensile strain generation, surface roughness and crystal qualities in the GOI structures fabricated by Ge condensation and wafer bonding are systematically examined. Tensile strain of 0.47 % is achieved without severe thermal damages under the optimal thermal process condition, which indicates the high potential of the present method for improving the performance of GOI n-channel MOSFETs. The influence of thermal expansion mismatch between Ge and SiO2 are suggested as a possible physical origin of high amount of tensile strain into GOI structures.

Unambiguous state discrimination and joint measurement attacks on passive side channel of the light source in BB84 decoy-state protocol

Quantum key distribution (QKD) has a promise of unconditionally secure communication between the remote sides. The real-world QKD implementations, however, have numerous loopholes, both of engeneering and physical origin, and compromise the security promise. In this work, we investigate two attack strategies on the passive side channel of the light source along with the optimal cloning attack on the BB84 protocol with decoy-states. We calculate an upper bound of a secret key rate for these situations and show that the joint measurement attack on the signal and side channel degree of freedom is more effective to the adversary.

Rheotaxis and migration of an unsteady microswimmer

Rheotaxis and migration of cells in a flow field have been investigated intensively owing to their importance in biology, physiology and engineering. In this study, first, we report our experiments showing that the microalgae Chlamydomonas can orient against the channel flow and migrate to the channel centre. Second, by performing boundary element simulations, we demonstrate that the mechanism of the observed rheotaxis and migration has a physical origin. Last, using a simple analytical model, we reveal the novel physical mechanisms of rheotaxis and migration, specifically the interplay between cyclic body deformation and cyclic swimming velocity in the channel flow. The discovered mechanism can be as important as phototaxis and gravitaxis, and likely plays a role in the movement of other natural microswimmers and artificial microrobots with non-reciprocal body deformation.