An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2’s Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu’s surface age

Precision Analysis of the 136Xe Two-Neutrino ββ Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements

We present a precision analysis of the 136Xe two-neutrino ββ electron spectrum above 0.8MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ββ rate allows us to measure the ratio of the leading and subleading 2νββ nuclear matrix elements (NMEs), ξ2ν31 = −0.26 +0.31−0.25. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ξ2ν31 range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ξ2ν31 values are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ββ decay, ξ2ν31 provides new insights toward reliable neutrinoless ββ NMEs

Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution

International audienc

Crk and CrkL adaptor proteins: networks for physiological and pathological signaling

The Crk adaptor proteins (Crk and CrkL) constitute an integral part of a network of essential signal transduction pathways in humans and other organisms that act as major convergence points in tyrosine kinase signaling. Crk proteins integrate signals from a wide variety of sources, including growth factors, extracellular matrix molecules, bacterial pathogens, and apoptotic cells. Mounting evidence indicates that dysregulation of Crk proteins is associated with human diseases, including cancer and susceptibility to pathogen infections. Recent structural work has identified new and unusual insights into the regulation of Crk proteins, providing a rationale for how Crk can sense diverse signals and produce a myriad of biological responses

Thermally altered subsurface material of asteroid (162173) Ryugu

International audienc

Collisional history of Ryugu's parent body from bright surface boulders

International audienc

Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body

Planetesimals – the initial stage of the planetary formation process – are considered to be initially very porous aggregates of dusts, and subsequent thermal and compaction processes reduce their porosity. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30-50%, higher than meteorites but lower than cometary nuclei, which are considered to be remnants of the original planetesimals. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters (70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations

Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth

International audienceThe Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu’s boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid

Experiences of perinatal women and public healthcare providers in a community affected by the great east Japan earthquake and tsunami: Concerns that must be considered for the mental healthcare of perinatal women in postdisaster settings

Particular support needs of perinatal women in a disaster have been difficult to grasp through preexisting quantitative epidemiological studies. This study aimed to extract concerns that must be considered for perinatal women's mental healthcare in postdisaster settings based on lessons from the Great East Japan Earthquake. Narrative messages regarding protective and risk factors for mothers' mental health from a representative population of mothers who had given birth and all official maternal caregivers, in a coastal town devastated by the catastrophe were subjected to qualitative analyses. Eight concerns were extracted as specific support needs: (1) improve information pathways, (2) maintain access to medical services, (3) sufficiently equip necessary items for perinatal women and children, (4) implement hygienic facilities, (5) prevent mothers from feeling diffidence, (6) encourage mothers to focus on positive aspects of being pregnant or taking care of their babies, (7) provide dedicated paths for relief supply distribution and dedicated rooms for mothers and children in shelters, and (8) resume usual healthcare activities as soon as possible. The comprehensive survey of the affected community presented concerns that needed to be considered for perinatal women's mental health in postdisaster settings