Reassigning CI chondrite parent bodies based on reflectance spectroscopy of samples from carbonaceous asteroid Ryugu and meteorites.

The carbonaceous asteroid Ryugu has been explored by the Hayabusa2 spacecraft to elucidate the actual nature of hydrous asteroids. Laboratory analyses revealed that the samples from Ryugu are comparable to unheated CI carbonaceous chondrites; however, reflectance spectra of Ryugu samples and CIs do not coincide. Here, we demonstrate that Ryugu sample spectra are reproduced by heating Orgueil CI chondrite at 300°C under reducing conditions, which caused dehydration of terrestrial weathering products and reduction of iron in phyllosilicates. Terrestrial weathering of CIs accounts for the spectral differences between Ryugu sample and CIs, which is more severe than space weathering that likely explains those between asteroid Ryugu and the collected samples. Previous assignments of CI chondrite parent bodies, i.e., chemically most primitive objects in the solar system, are based on the spectra of CI chondrites. This study indicates that actual spectra of CI parent bodies are much darker and flatter at ultraviolet to visible wavelengths than the spectra of CI chondrites.

Spectrally blue hydrated parent body of asteroid (162173) Ryugu.

Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent body. Hayabusa2 remote-sensing observations find that on the asteroid (162173) Ryugu both north and south pole regions preserve the material least processed by space weathering, which is spectrally blue carbonaceous chondritic material with a 0-3% deep 0.7-µm band absorption, indicative of Fe-bearing phyllosilicates. Here we report that spectrally blue Ryugu's parent body experienced intensive aqueous alteration and subsequent thermal metamorphism at 570-670 K (300-400 °C), suggesting that Ryugu's parent body was heated by radioactive decay of short-lived radionuclides possibly because of its early formation 2-2.5 Ma. The samples being brought to Earth by Hayabusa2 will give us our first insights into this epoch in solar system history.

Highly porous nature of a primitive asteroid revealed by thermal imaging.

Carbonaceous (C-type) asteroids1 are relics of the early Solar System that have preserved primitive materials since their formation approximately 4.6 billion years ago. They are probably analogues of carbonaceous chondrites2,3 and are essential for understanding planetary formation processes. However, their physical properties remain poorly known because carbonaceous chondrite meteoroids tend not to survive entry to Earth's atmosphere. Here we report on global one-rotation thermographic images of the C-type asteroid 162173 Ryugu, taken by the thermal infrared imager (TIR)4 onboard the spacecraft Hayabusa25, indicating that the asteroid's boulders and their surroundings have similar temperatures, with a derived thermal inertia of about 300 J m-2 s-0.5 K-1 (300 tiu). Contrary to predictions that the surface consists of regolith and dense boulders, this low thermal inertia suggests that the boulders are more porous than typical carbonaceous chondrites6 and that their surroundings are covered with porous fragments more than 10 centimetres in diameter. Close-up thermal images confirm the presence of such porous fragments and the flat diurnal temperature profiles suggest a strong surface roughness effect7,8. We also observed in the close-up thermal images boulders that are colder during the day, with thermal inertia exceeding 600 tiu, corresponding to dense boulders similar to typical carbonaceous chondrites6. These results constrain the formation history of Ryugu: the asteroid must be a rubble pile formed from impact fragments of a parent body with microporosity9 of approximately 30 to 50 per cent that experienced a low degree of consolidation. The dense boulders might have originated from the consolidated innermost region or they may have an exogenic origin. This high-porosity asteroid may link cosmic fluffy dust to dense celestial bodies10.

Improvement of functional independence of patients with acute schizophrenia through early occupational therapy: a pilot quasi-experimental controlled study.

OBJECTIVE: To clarify whether early occupational therapy for patients with acute schizophrenia improves their functional independence. DESIGN: Quasi-experimental controlled study. SETTING: A university hospital in Japan. SUBJECTS: Forty-six out of 85 eligible patients with schizophrenia. INTERVENTION: Participants were allocated into an intervention group or a control group according to the month of admission. Activities in one-on-one and mainly non-verbal occupational therapy were provided for the intervention group immediately after admission, and not for the control group. MAIN MEASURES: Functional independence was measured using the Functional Independence Measure (FIM), at admission, at one month and at three months after admission. Psychiatric symptoms were also measured by the Brief Psychiatric Rating Scale. RESULTS: Patients in both groups showed improved FIM total scores at one month and three months after admission. In the intervention group, the medians (interquartile ranges) were 89.0 (44.5) at admission, 113.0 (18.5) at one month, and 121.0 (6.5) at three months. In the control group, they were 88.0 (32.0), 107.0 (39.5), and 111.0 (17.0). At three months, the total FIM scores were significantly higher in the intervention group than in the control group (p = 0.016). In the FIM cognitive domain, the scores were significantly higher in the intervention group than in the control group at one month (p = 0.038) and, three months (p = 0.012). Both groups showed improvement in Brief Psychiatric Rating Scale total scores, while no significant differences were observed between the groups at any points. CONCLUSION: The results suggest that early occupational therapy may improve functional independence in patients with acute schizophrenia.

Subject-chosen activities in occupational therapy for the improvement of psychiatric symptoms of inpatients with chronic schizophrenia: a controlled trial.

OBJECTIVE: To compare the therapeutic effects of subject-chosen and therapist-chosen activities in occupational therapy for inpatients with chronic schizophrenia. DESIGN: Prospective comparative study. SETTING: A psychiatric hospital in Japan. SUBJECTS: Fifty-nine patients with chronic schizophrenia who had been hospitalized for many years. INTERVENTIONS: The subjects received six-months occupational therapy, participating in either activities of their choice (subject-chosen activity group, n = 30) or activities chosen by occupational therapists based on treatment recommendations and patient consent (therapist-chosen activity group, n = 29). MAIN MEASURES: The Positive and Negative Syndrome Scale and the Global Assessment of Functioning (GAF) Scale were used to evaluate psychiatric symptoms and psychosocial function, respectively. RESULTS: After six-months occupational therapy, suspiciousness and hostility scores of the positive scale and preoccupation scores of the general psychopathology scale significantly improved in the subject-chosen activity group compared with the therapist-chosen activity group, with 2(2) (median (interquartile range)) and 3(1.25), 2(1) and 2.5(1), and 2(1) and 3(1), respectively. There were no significant differences in psychosocial functions between the two groups. In within-group comparisons before and after occupational therapy, suspiciousness scores of the positive scale, preoccupation scores of the general psychopathology scale, and psychosocial function significantly improved only in the subject-chosen activity group, with 3(1) to 2(2), 3(1) to 2(1), and 40(9) to 40(16) respectively, but not in the therapist-chosen activity group. CONCLUSIONS: The results suggested that the subject-chosen activities in occupational therapy could improve the psychiatric symptoms, suspiciousness, and preoccupation of the inpatients with chronic schizophrenia.

Effects of occupational therapy on hospitalized chronic schizophrenia patients with severe negative symptoms.

The aim of this study was to determine whether occupational therapy (OT) can improve the interpersonal relationships and negative symptoms of hospitalized chronic schizophrenia patients with severe negative symptoms. Subjects were 38 patients with chronic schizophrenia. They were randomly divided into an OT group and a control group. Patients in the OT group participated in cooking activities once a week for 15 weeks, while patients in the control group did not. During this period, both groups had the usual treatment except for the cooking activities. In interviews, the patient was asked to place a chair toward the interviewer (a therapist). The angle and distance from the interviewer were taken as indicators of an ability to have interpersonal relationships. Negative symptoms were evaluated with the Scale for the Assessment of Negative Symptoms (SANS). Patients who received OT were able to sit at the smaller angle and shorter distance from the interviewer than before OT (p=0.015 and p=0.013, respectively). The total SANS score was lower after OT than before OT (p=0.033). In the control group, the distance from the interviewer also decreased during the experimental period (p=0.040) but the seating angle and the SANS scores did not change. The results suggest that OT can help to improve a relationship allowing the patient to face the therapist and that it might improve negative symptoms of schizophrenia.