The photometric observation of the quasi-simultaneous mutual eclipse and occultation between Europa and Ganymede on 22 August 2021

Mutual events (MEs) are eclipses and occultations among planetary natural satellites. Most of the time, eclipses and occultations occur separately. However, the same satellite pair will exhibit an eclipse and an occultation quasi-simultaneously under particular orbital configurations. This kind of rare event is termed as a quasi-simultaneous mutual event (QSME). During the 2021 campaign of mutual events of jovian satellites, we observed a QSME between Europa and Ganymede. The present study aims to describe and study the event in detail. We observed the QSME with a CCD camera attached to a 300-mm telescope at the Hong Kong Space Museum Sai Kung iObservatory. We obtained the combined flux of Europa and Ganymede from aperture photometry. A geometric model was developed to explain the light curve observed. Our results are compared with theoretical predictions (O-C). We found that our simple geometric model can explain the QSME fairly accurately, and the QSME light curve is a superposition of the light curves of an eclipse and an occultation. Notably, the observed flux drops are within 2.6% of the theoretical predictions. The size of the event central time O-Cs ranges from -14.4 to 43.2 s. Both O-Cs of flux drop and timing are comparable to other studies adopting more complicated models. Given the event rarity, model simplicity and accuracy, we encourage more observations and analysis on QSMEs to improve Solar System ephemerides.Comment: 23 pages, 5 appendixes, 16 figures, 7 table

The impact of compassion from others and self-compassion on psychological distress, flourishing, and meaning in life among university students

Objectives: Research shows that compassion from others and from the self may enable university students to face, overcome, and bounce back from adversity and generate a greater sense of thriving and meaning in life. However, the underlying processes are largely unknown. The present study aimed to examine the associations of compassion with psychological distress, flourishing, and meaning in life among university students and explore the mechanisms underlying these associations. Methods: A total of 536 Hong Kong university students completed questionnaires measuring their experiences of compassion from others, self-compassion, resilience, psychological distress, flourishing, and meaning in life. Results: Serial mediation analyses showed that compassion from others was associated positively with self-compassion, which was, in turn, linked to greater resilience and consequently lower levels of psychological distress and higher levels of flourishing and meaning in life. Conclusions: Our findings reveal the associations of compassion from others and self-compassion with the well-being and life meaning of university students. The findings highlight the importance of being open and receptive to love and kindness from others. The findings also point to the importance of developing a caring attitude toward oneself

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

In vivo study of asporin function in cartilage tissues

Asporin (ASPN) is a risk factor for osteoarthritis and intervertebral disc degeneration. Its expression increases with aging and degeneration. D14 (14 aspartate-repeat polymorphism) is the risk allele and D13 is the most common allele. In vitro studies suggest that Asporin functions as a negative regulator of Tgf-β signaling, an important stimulator of matrix formation in bone and cartilage. However, the in vivo role of Asporin in development or its involvement in the pathogenesis of degenerative cartilage diseases is unclear. Here, we use mouse as a model to study the impact of Asporin in the intervertebral discs of the spine. In wide type mice, we showed that Asporin is expressed and localized in the nucleus pulposus and annulus fibrosis of intervertebral discs, and the articular cartilage in knee joints. Furthermore, Asporin expressing cells in these tissues are active in Tgf-β signaling, suggesting a relationship between Asporin and Tgf-β signaling and a role in disc and articular joint maintenance. Using natural degeneration with aging, and models for induced degeneration in the mouse-tail discs, Asporin expression was shown to be up-regulated in nucleus pulposus and annulus fibrosis cells of degenerating intervertebral discs. These cells are also active in Tgf-β signaling supporting a potential relationship with the pathogenesis of disc degeneration. Transgenic mice overexpressing Asporin in cartilage tissues were generated to study this relationship and the impact on the differentiation and function of disc cells. Interestingly, overexpression of Asporin in the nucleus pulposus leads to enhanced production and deposition of extracellular matrix such as glycosaminoglycans, with concomitant changes in cell morphology, suggesting Asporin altered the extracellular matrix niche of resident nucleus pulposus cells. However, such changes are only observed in discs in the tail region but not in lumbar discs. We propose a relationship to mechanical loading as an environmental factor. Molecular analysis of transgene expressing cells showed Tgf-β signaling is active and its downstream target genes up-regulated. Furthermore, overexpression of Asporin enhances differentiation of notochordal-like cells (NCCs) in mouse nucleus pulposus toward the more mature nucleus pulposus cells (NPCs) and chondrocyte-like cells (CLCs) that are more abundant in the human nucleus pulposus and other larger animals that prompt to intervertebral disc degeneration. This study provided new insights into the function of Asporin in the pathogenesis of intervertebral disc degeneration. We proposed a model whereby Asporin, as a genetic risk factor, alters the extracellular environment of the nucleus pulposus, that in conjunction with environmental factors such as mechanical loading, enhances Tgf-β signaling, and consequentially, promotes the maturation of NCCs towards NPCs and CLCs, a hallmark of degenerative process proposed in human and other larger animal models. These transgenic mice provide the opportunity to better understand the relationship between genetic and environmental factors, and the molecular controls leading to the maturation process of NCCs in intervertebral disc degeneration.published_or_final_versionBiochemistryDoctoralDoctor of Philosoph

Photocatalytic Carbon–Carbon σ‑Bond Anaerobic Oxidation of Ketones with Water by Rhodium(III) Porphyrins

Photocatalytic carbon–carbon σ-bond oxidation of unstrained ketones by water using rhodium­(III) porphyrin catalyst was accomplished. The catalysis yielded the corresponding one-carbon-less carbonyl compound and H₂ with up to 30 turnovers in both aliphatic and cyclic ketones with α substituents. No carbon loss was observed in aromatic ketone. Mechanistic studies suggest that (Ph₃P)­Rh^III(ttp)­OH (ttp = tetratolylporphyrinato dianion) is the key intermediate in the carbon–carbon σ-bond anaerobic oxidation

Mild and Selective C(CO)–C(α) Bond Activation of Ketones with Rhodium(III) Porphyrin β‑Hydroxyethyl

Rhodium­(III) porphyrin β-hydroxyethyl, Rh^III(ttp)­CH₂CH₂OH (ttp = 5,10,15,20-tetratolylporphyrinato dianion), was found to serve as a precursor of the highly reactive Rh^III(ttp)­OH for the C­(CO)–C­(α) bond activation (CCA) of ketones under mild and aerobic conditions of 25–50 °C

Crustal Velocity Structures Imaged from Four-Component OBS Data Across the Southern Gagua Ridge in the Western Philippine Sea

Crustal structures near a linear oceanic ridge, the Gagua Ridge, between the West Philippine Basin and the Huatung Basin in the western Philippine Sea were imaged based on head-wave, refracted and reflected P-wave arrivals recorded from 24 ocean-bottom seismometers (OBS). Velocity anomaly zones, one below the Gagua Ridge summit and the others beneath two toes of the Gagua Ridge, imaged by large lateral variations in P-wave velocity of 5.5 - 6.4 km s-1 and low velocity of 4 - 5 km s-1 in the upper crust may have been generated when the Gagua Ridge was formed. East of the ridge, velocity anomaly zones, constrained by large lateral variations in P-wave velocity (4.8 - 6.4 km s-1), relatively low velocity (4 - 5 km s-1) and laterally high anomaly of Poisson¡¦s ratio (0.02 - 0.04) in the upper crust and abrupt crustal thickening (6 - 8.5 km) northward were obtained. West of the ridge, the velocity anomaly zones indicated by large lateral variations in P-wave velocity (5.2 - 6.2 km s-1) and laterally high anomaly of Poisson¡¦s ratio (0.02 - 0.04) in the upper crust and thick crust (thickening southward from 9 - 12 km) were found below the Huatung Basin and the Western Trough of the Gagua Ridge. Abrupt crustal thickening northward east of the ridge may be related to northwestward convergence of the Philippine Sea Plate. These velocity anomaly zones in the upper crust at both sides of the ridge might result from deformed, fractured or faulted zones. These zones support E - W compression, N - S shearing (or transpression) and uplifting that may have also created the Gagua Ridge and crustal thickening west of the ridge