We report the wave observations, associated plasma measurements, and linear theory testing of electromagnetic ion cyclotron (EMIC) wave events observed by the Van Allen Probes on 28 April 2013. The ...wave events are detected in their generation regions as three individual events in two consecutive orbits of Van Allen Probe‐A, while the other spacecraft, B, does not detect any significant EMIC wave activity during this period. Three overlapping H+ populations are observed around the plasmapause when the waves are excited. The difference between the observational EMIC wave growth parameter (Σh) and the theoretical EMIC instability parameter (Sh) is significantly raised, on average, to 0.10 ± 0.01, 0.15 ± 0.02, and 0.07 ± 0.02 during the three wave events, respectively. On Van Allen Probe‐B, this difference never exceeds 0. Compared to linear theory (Σh > Sh), the waves are only excited for elevated thresholds.
Key Points
Three EMIC wave events are observed only on Van Allen Probe‐A
Three overlapping H+ populations are present when the waves are observed
Linear theory predicts the excitation of the waves with elevated thresholds
Abstract
The fast transitions between different types of quasi-periodic oscillations (QPOs) are generally observed in black hole transient sources (BHTs). We present a detailed study of the timing ...and spectral properties of the transitions of type-B QPOs in MAXI J1348–630, observed by Insight-HXMT. The fractional rms variability–energy relationship and energy spectra reveal that type-B QPOs probably originate from jet precession. Compared to a weak power-law dominated power spectrum, when type-B QPOs are present, the corresponding energy spectrum shows an increase in the Comptonization component and the need for the
xillverCp
component, and a slight increase in the height of the corona when using the
relxilllp
model. Therefore, we suggest that a coupled inner disk-jet region is responsible for the observed type-B QPO transitions. The timescale for the appearance/disappearance of type-B QPOs is either long or short (seconds), which may indicate instability of the disk-jet structure. For these phenomena, we hypothesize that the Bardeen–Petterson effect causes the disk-jet structure to align with the BH spin axis or that the disappearance of small-scale jets bound by the magnetic flux tubes leads to the disappearance of type-B QPOs. We observed three events regarding the B/C transitions, one of which occurred over a short time period from ∼9.2 Hz (C) to ∼4.8 Hz (B). The energy spectral analysis for the other two transitions shows that when type-C QPO is present, the Comptonization flux is higher, the spectrum is harder, and the inner radius of the disk changes insignificantly. We suggest that type-C QPOs probably originate from relatively stronger jets or the corona.
Despite significant clinical progress in cell and gene therapies, maximizing protein expression in order to enhance potency remains a major technical challenge. Here, we develop a high-throughput ...strategy to design, screen, and optimize 5' UTRs that enhance protein expression from a strong human cytomegalovirus (CMV) promoter. We first identify naturally occurring 5' UTRs with high translation efficiencies and use this information with in silico genetic algorithms to generate synthetic 5' UTRs. A total of ~12,000 5' UTRs are then screened using a recombinase-mediated integration strategy that greatly enhances the sensitivity of high-throughput screens by eliminating copy number and position effects that limit lentiviral approaches. Using this approach, we identify three synthetic 5' UTRs that outperform commonly used non-viral gene therapy plasmids in expressing protein payloads. In summary, we demonstrate that high-throughput screening of 5' UTR libraries with recombinase-mediated integration can identify genetic elements that enhance protein expression, which should have numerous applications for engineered cell and gene therapies.
We present photometric and spectroscopic observations of the type Ibn supernova (SN) 2019uo, the second ever SN Ibn with flash ionization (He ii, C iii, N iii) features in its early spectra. SN ...2019uo displays a rapid post-peak luminosity decline of 0.1 mag day−1 similar to most of the SNe Ibn, but is fainter ( mag) than a typical SN Ibn and shows a color evolution that places it between SNe Ib and the most extreme SNe Ibn. SN 2019uo shows P-cygni He i features in the early spectra which gradually evolve and become emission dominated post peak. It also shows faster evolution in line velocities as compared to most other members of the type Ibn subclass. The bolometric light curve is fairly well described by a 56Ni + circumstellar interaction model.
The Multi-scale Continuum and Line Exploration of W49 is a comprehensive gas and dust survey of the giant molecular cloud (GMC) of W49A, the most luminous star-formation region in the Milky Way. In ...this paper, we present (1) an all-configuration Submillimeter Array mosaic in the 230 GHz (1.3 mm) band covering the central ~3' x 3' (~10 pc, known as W49N), where most of the embedded massive stars reside and (2) Purple Mountain Observatory 14 m telescope observations in the 90 GHz band, covering the entire GMC with maps of up to ~35' x 35' in size, or ~113 pc. We also make use of archival data from the Very Large Array, JCMT-SCUBA, the IRAM 30 m telescope, and the Caltech Submillimeter Observatory BOLOCAM Galactic Plane Survey. The resulting stellar content will probably remain as a gravitationally bound massive star cluster or a small system of bound clusters.
Early Palaeozoic evolution of the Kazakhstan orocline in the Central Asian Orogenic Belt (CAOB) is key to reconstructing the Palaeozoic tectonic framework in Central Asia. This study presents field ...mapping, geochemistry, and geochronological data from the Wulasitai area of northern West Junggar to constrain the subduction polarity and major tectonic events in the Chingiz arc of the Kazakhstan orocline during the Early Palaeozoic. The mapping area outcrops imbricated coherent turbidite slices and mélanges that consist of chert, limestone, silt, sandstone, and conglomerate blocks in mudstone matrix, representing an OPS (Ocean Plate Stratigraphy) mélange in an accretionary complex. Existing fossil ages from these blocks range from the Ordovician to Silurian, while our new detrital zircon U-Pb samples from the turbiditic matrix yield maximum depositional ages (MDTs) from 428 ± 2 Ma to 450 ± 1 Ma. Detrital zircon ages of ~510 to 430 Ma in the mélange suggest the Chingiz arc to the south of the study area as a major sediment source, providing an indirect constraint on the polarity of subduction. We suggest that the northern part of the Chingiz arc may be underlain by southward subduction, with the accretionary complex located on the Wulasitai area of the northern West Junggar. The Wulasitai mélange is overlain depostionally by volcanic rocks carrying depleted HFSE and enriched LILE, LREE. The andesite and tuff are dated to 415 ± 5 Ma, 414 ± 3 Ma, and 402 ± 6 Ma, which we interpret as reflecting the development of the volcanic arc onto the previous subduction complex. This model implies the generation of the arc (accretion arc) as the slab rolling back and trench retreating, which may play an important role in the evolutionary history of CAOB.
Abstract
Recent observations of Her X-1 with NuSTAR (as well as with INTEGRAL, Swift, and Astrosat) have provided evidence that the nearly 20 yr-long decay of the cyclotron line energy since ∼1994 ...has ended and that a stable value has replaced the decay. Using the observations of the Hard X-ray Modulation Telescope (Insight-HXMT) performed between 2017 July and 2020 February, we analyze the spectra of Her X-1 in its main-on state, focusing on tracing the evolution of cyclotron line energy. While our analysis of eight main-on observations with Insight-HXMT (two in coordination with NuSTAR) shows significant differences with the results of NuSTAR, two earlier findings are confirmed: the positive correlation between the cyclotron line energy and the X-ray flux (source luminosity) and the constancy of the flux-normalized cyclotron line energy during 2017–2020—albeit with significant uncertainty about the absolute value.
Recently, a triple-network model suggested the abnormal interactions between the executive-control network (ECN), default-mode network (DMN) and salience network (SN) are important characteristics of ...addiction, in which the SN plays a critical role in allocating attentional resources toward the ECN and DMN. Although increasing studies have reported dysfunctions in these brain networks in Internet gaming disorder (IGD), interactions between these networks, particularly in the context of the triple-network model, have not been investigated in IGD. Thus, we aimed to assess alterations in the inter-network interactions of these large-scale networks in IGD, and to associate the alterations with IGD-related behaviors.
DMN, ECN and SN were identified using group-level independent component analysis (gICA) in 39 individuals with IGD and 34 age and gender matched healthy controls (HCs). Then alterations in the SN-ECN and SN-DMN connectivity, as well as in the modulation of ECN versus DMN by SN, using a resource allocation index (RAI) developed and validated previously in nicotine addiction, were assessed. Further, associations between these altered network coupling and clinical assessments were also examined.
Compared with HCs, IGD had significantly increased SN-DMN connectivity and decreased RAI in right hemisphere (rRAI), and the rRAI in IGD was negatively associated with their scores of craving.
These findings suggest that the deficient modulation of ECN versus DMN by SN might provide a mechanistic framework to better understand the neural basis of IGD and might provide novel evidence for the triple-network model in IGD.
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