Photospheric Magnetic Field Changes Associated with Transition Region Explosive Events

From a comparison of SOHO SUMER spectral data and a time series of BBSO magnetograms, we present observational clues to the physical origin of transition region explosive events: First, explosive events rarely occur in the interior of strong magnetic flux concentrations, but rather are preferentially found in regions with weak and mixed polarity fluxes which display magnetic neutral lines. Second, the majority of explosive events happen during the "cancellation" of photospheric magnetic flux. Third, there is a strong tendency for explosive events to occur repeatedly, as bursts, while local photospheric magnetic flux continuously decreases due to cancellation. These results strongly support the idea that transition region explosive events are a manifestation of magnetic reconnection occurring in the quiet Sun. Further, one may infer from the third result that the explosive events represent repetitive fast magnetic reconnections in the transition region, which are initiated by slow magne..

Studies Of Microflares And C5.2 Flare Of September 27, 1998

. On September 27, 1998, Big Bear Solar Observatory (BBSO) and Transition Region and Coronal Explorer (TRACE) coordinated observations from 16:00 to 19:00 UT to study properties of microflares on AR NOAA #8340. Fortuitously, a C5.2 flare occurred at 16:30UT in this active region. Hff and magnetograph movies were obtained at BBSO; CIV 1550 A , FeIX 171 A and FeXII 195 A movies were obtained by TRACE; both with a cadence about 1 minute. In this paper, we concentrate on the study of magnetic properties of 70 CIV microflares, as well as their relationship to the C5.2 flare. We obtained the following results: (1) We found two kinds of microflares: microflares of transient brightenings with a time scale of 1 to 5 minutes (impulsive events) and microflares lasting half an hour or longer (persistent events). 90% of the microflares are impulsive events. Most of the events in this category are associated with well defined magnetic neutral lines, but some of them are found in non-neutral line are..

Evaluation of an Automated High-Throughput Liquid-Based RNA Extraction Platform on Pooled Nasopharyngeal or Saliva Specimens for SARS-CoV-2 RT-PCR

SARS-CoV-2 RT-PCR with pooled specimens has been implemented during the COVID-19 pandemic as a cost- and manpower-saving strategy for large-scale testing. However, there is a paucity of data on the efficiency of different nucleic acid extraction platforms on pooled specimens. This study compared a novel automated high-throughput liquid-based RNA extraction (LRE) platform (PHASIFY™) with a widely used magnetic bead-based total nucleic acid extraction (MBTE) platform (NucliSENS® easyMAG®). A total of 60 pools of nasopharyngeal swab and 60 pools of posterior oropharyngeal saliva specimens, each consisting of 1 SARS-CoV-2 positive and 9 SARS-CoV-2 negative specimens, were included for the comparison. Real-time RT-PCR targeting the SARS-CoV-2 RdRp/Hel gene was performed, and GAPDH RT-PCR was used to detect RT-PCR inhibitors. No significant differences were observed in the Ct values and overall RT-PCR positive rates between LRE and MBTE platforms (92.5% (111/120] vs. 90% (108/120]), but there was a slightly higher positive rate for LRE (88.3% (53/60]) than MBTE (81.7% (49/60]) among pooled saliva. The automated LRE method is comparable to a standard MBTE method for the detection of SAR-CoV-2 in pooled specimens, providing a suitable alternative automated extraction platform. Furthermore, LRE may be better suited for pooled saliva specimens due to more efficient removal of RT-PCR inhibitors