X-ray flares raising upon magnetar plateau as an implication of a surrounding disk of newborn magnetized neutron star

The X-ray flares have usually been ascribed to long-lasting activities of the central engine of gamma-ray bursts (GRBs), e.g., fallback accretion. The GRB X-ray plateaus, however, favor a millisecond magnetar central engine. The fallback accretion can be significantly suppressed due to the propeller effect of a magnetar. Therefore, if the propeller regime cannot resist the mass flow onto the surface of the magnetar efficiently, the X-ray flares raising upon the magnetar plateau would be expected. In this work, such peculiar cases are connected to the accretion process of the magnetars, and an implication for magnetar-disc structure is given. We investigate the repeated accretion process with multi-flare GRB 050730, and give a discussion for the accretion-induced variation of the magnetic field in GRB 111209A. Two or more flares exhibit in the GRB 050730, 060607A and 140304A; by adopting magnetar mass M = 1.4 M ⊙ and radius R = 12 km, the average mass flow rates of the corresponding surrounding disk are 3.53 × 10−4 M ⊙ s−1, 4.23 × 10−4 M ⊙ s−1, and 4.33 × 10−4 M ⊙ s−1, and the corresponding average sizes of the magnetosphere are 5.01 × 106 cm, 6.45 × 106 cm, and 1.09 × 107 cm, respectively. A statistic analysis that contains eight GRBs within 12 flares shows that the total mass loading in single flare is ∼ 2 × 10−5 M ⊙. In the lost mass of a disk, there are about 0.1% used to feed a collimated jet.

Imaging the Water Snowline around Protostars with Water and HCO+ Isotopologues

The water snowline location in protostellar envelopes provides crucial information about the thermal structure and the mass accretion process as it can inform about the occurrence of recent (≲1000 yr) accretion bursts. In addition, the ability to image water emission makes these sources excellent laboratories to test indirect snowline tracers such as H13CO+. We study the water snowline in five protostellar envelopes in Perseus using a suite of molecular-line observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA) at ∼0.″2−0.″7 (60–210 au) resolution. B1-c provides a textbook example of compact H 2 18 O (31,3−22,0) and HDO (31,2−22,1) emission surrounded by a ring of H13CO+ (J = 2−1) and HC18O+ (J = 3−2). Compact HDO surrounded by H13CO+ is also detected toward B1-bS. The optically thick main isotopologue HCO+ is not suited to trace the snowline, and HC18O+ is a better tracer than H13CO+ due to a lower contribution from the outer envelope. However, because a detailed analysis is needed to derive a snowline location from H13CO+ or HC18O+ emission, their true value as a snowline tracer will lie in the application in sources where water cannot be readily detected. For protostellar envelopes, the most straightforward way to locate the water snowline is through observations of H 2 18 O or HDO. Including all subarcsecond-resolution water observations from the literature, we derive an average burst interval of ∼10,000 yr, but high-resolution water observations of a larger number of protostars are required to better constrain the burst frequency.

Monitoring of Recovery Process at Yeongildae Beach, South Korea, Using a Video System

Once a beach is eroded by storm waves, it is generally recovered under milder wave conditions. To prevent or reduce damage, it is therefore important to understand the characteristics of the site-specific recovery process. Here, we present the results, based on a data set from a video monitoring system and wave measurements, of the recovery process in a pocketed beach located inside a bay where the shoreline retreated harshly (~12 m, on average, of beach width) during Typhoon TAPAH (T1917) in September 2019. It took about 1.5 years for the beach to be recovered to the level before the typhoon. During this period, the erosion and accretion were repeated, with the pattern highly related to the wave power (Pw); most of the erosion occurred when Pw became greater than 30 kWatt/m, whereas the accretion prevailed when Pw was no greater than 10 kWatt/m. The recovery pattern showed discrepancies between different parts of the beach. The erosion during storm events was most severe in the southern part, whereas the northern shoreline did not significantly change even during TAPAH (T1917). In contrast, the recovery process occurred almost equally at all locations. This discrepancy in the erosion/accretion process was likely due to human intervention, as a shadow zone was formed in the northern end due to the breakwaters, causing disequilibrium in the sediment transport gradient along the shore. The results in this study could be applied in designing the protection plans from severe wave attacks by effectively estimating the size of coastal structures and by correctly arranging the horizontal placement of such interventions or beach nourishment. Although the application of these results should be confined to this specific site, the method using wave energy parameters as criteria can be considered in other areas with similar environments, for future planning of beach protection.

Comprehensive deletion landscape of CRISPR-Cas9 identifies minimal RNA-guided DNA-binding modules

Proteins evolve through the modular rearrangement of elements known as domains. Extant, multidomain proteins are hypothesized to be the result of domain accretion, but there has been limited experimental validation of this idea. Here, we introduce a technique for genetic minimization by iterative size-exclusion and recombination (MISER) for comprehensively making all possible deletions of a protein. Using MISER, we generate a deletion landscape for the CRISPR protein Cas9. We find that the catalytically-dead Streptococcus pyogenes Cas9 can tolerate large single deletions in the REC2, REC3, HNH, and RuvC domains, while still functioning in vitro and in vivo, and that these deletions can be stacked together to engineer minimal, DNA-binding effector proteins. In total, our results demonstrate that extant proteins retain significant modularity from the accretion process and, as genetic size is a major limitation for viral delivery systems, establish a general technique to improve genome editing and gene therapy-based therapeutics.

How well is angular momentum accretion modelled in semi-analytic galaxy formation models?

Gas cooling and accretion in haloes delivers mass and angular momentum on to galaxies. In this work, we investigate the accuracy of the modelling of this important process in several different semi-analytic (SA) galaxy formation models (galform , l-galaxies and morgana ) through comparisons with a hydrodynamical simulation performed with the moving-mesh code arepo . Both SA models and the simulation were run without any feedback or metal enrichment, in order to focus on the cooling and accretion process. All of the SA models considered here assume that gas cools from a spherical halo. We found that the assumption that the gas conserves its angular momentum when moving from the virial radius, rvir, to the central region of the halo, r ∼ 0.1rvir, is approximately consistent with the results from our simulation. We also found that, compared to the simulation, the morgana model tends to overestimate the mean specific angular momentum of cooled-down gas, the l-galaxies model also tends to overestimate this in low-redshift massive haloes, while the two older galform models tend to underestimate the angular momentum. In general, the predictions of the new galform cooling model developed by Hou et al. agree agree the best with the simulation.

On the Relation among Satellite Observed Liquid Water Path, Cloud Droplet Number Concentration and Cloud Base Rain Rate and Its Implication to the Auto-Conversion Parameterization in Stratocumulus Clouds

Precipitation processes play a critical role in the longevity and spatial distribution of stratocumulus clouds through their interaction with the vertical profiles of humidity and temperature within the atmospheric boundary layer. One of the difficulties in understanding these processes is the limited amount of observational data. In this study, robust relations among liquid water path (LWP), cloud droplet number concentration (Nd) and cloud base rain rate (Rcb) from three subtropical stratocumulus decks are obtained from A-Train satellite observations in order to obtain a broad perspective on warm rain processes. Rcb has a positive correlation with LWP/Nd and the increase of Rcb becomes larger as LWP/Nd increases. However, the increase of Rcb with respect to LWP/Nd becomes more gradual in regions with larger Nd, which indicates the relation is moderated by Nd. These results are consistent with our theoretical understanding of warm rain processes and suggest that satellite observations are capable of elucidating the average manner of how precipitation processes are modulated by LWP and Nd. The sensitivity of the auto-conversion rate to Nd is investigated by examining pixels with small LWP in which the accretion process is assumed to have little influence on Rcb. The upper limit of the dependency of auto-conversion rate on Nd is assessed from the relation between Rcb and Nd, since the sensitivity is exaggerated by the accretion process, and was found to be a cloud droplet number concentration to the power of −1.44 ± 0.12.

A new K-Ar illite dating application to constrain the timing of subduction in West Sarawak, Borneo

The timing of subduction is a fundamental tectonic problem for tectonic models, yet there are few direct geological proxies for constraining it. However, the matrix of a tectonic mélange formed in a subduction-accretion setting archives the physical/chemical attributes at the time of deformation during the subduction-accretion process. Thus, the deformation age of the matrix offers the possibility to directly constrain the period of the subduction-accretion process. Here we date the Lubok Antu tectonic mélange and the overlying Lupar Formation in West Sarawak, Borneo by K-Ar analysis of illite. The ages of authigenic illite cluster around 60 Ma and 36 Ma. The maximum temperatures calculated by vitrinite reflectance values suggest that our dating results were not affected by external heating. Thus, the ages of authigenic illite represent the deformation age of the mélange matrix and the timing of the Rajang Unconformity, indicating that the subduction in Sarawak could have continued until ca. 60 Ma and the thermal and/or fluid flow events triggered by a major uplift of the Rajang Group occurred at ca. 36 Ma. Furthermore, this study highlights the potential of using the tectonic mélange to extract the timeframe of subduction zone episodic evolution directly.