Context. Near-Earth asteroid 162173 (1999 JU3) is a potential flyby and rendezvous target for interplanetary missions because of its easy-to-reach orbit. The physical and thermal properties of the ...asteroid are relevant for establishing the scientific mission goals and also important in the context of near-Earth object studies in general. Aims. Our goal was to derive key physical parameters such as shape, spin-vector, size, geometric albedo, and surface properties of 162173 (1999 JU3). Methods. With three sets of published thermal observations (ground-based N-band, Akari IRC, Spitzer IRS), we applied a thermophysical model to derive the radiometric properties of the asteroid. The calculations were performed for the full range of possible shape and spin-vector solutions derived from the available sample of visual lightcurve observations. Results. The near-Earth asteroid 162173 (1999 JU3) has an effective diameter of 0.87 ± 0.03 km and a geometric albedo of 0.070 ± 0.006. The χ2-test reveals a strong preference for a retrograde sense of rotation with a spin-axis orientation of λecl = 73°, βecl = −62° and Psid = 7.63 ± 0.01 h. The most likely thermal inertia ranges between 200 and 600 J m-2 s-0.5 K-1, about a factor of 2 lower than the value for 25143 Itokawa. This indicates that the surface lies somewhere between a thick-dust regolith and a rock/boulder/cm-sized, gravel-dominated surface like that of 25143 Itokawa. Our analysis represents the first time that shape and spin-vector information has been derived from a combined data set of visual lightcurves (reflected light) and mid-infrared photometry and spectroscopy (thermal emission).
Context.The recently discovered Apollo asteroid 2005 UD is the most likely candidate for being a large member of the Phaethon-Geminid stream Complex (PGC). Aims.Detecting more complex members like ...this should clarify the formation and evolution of the PGC. Methods.Our backward and forward (±$10\,000$-yr) integration of the Kustaanheimo-Stiefel regularized equation of motion revealed that the orbital evolutions of Apollo asteroids (3200) Phaethon and 2005 UD show a similar profile, time-shifting by ~4600 yr. Results. Within the PGC, this time shift is rather large against the time-lag of 220 yr for Phaethon-Geminids and ~3900 yr between Phaethon-Sextantids, although much smaller than that of ~$19\,000$ yr between Phaethon-Canis Minorids. Conclusions.This is a km-order object, hence may be a split nucleus of Phaethon. Besides, the orbital parameters of 2005 UD and the Sextantids are in good agreement along with the time-lag of 100 yr. Therefore, the Sextantid meteor shower seems to be associated more closely with 2005 UD than Phaethon.
Subaru Telescope Observations of Deep Impact Sugita, S; Ootsubo, T; Kadono, T ...
Science (American Association for the Advancement of Science),
10/2005, Letnik:
310, Številka:
5746
Journal Article
Recenzirano
Odprti dostop
The impact cratering process on a comet is controversial but holds the key for interpreting observations of the Deep Impact collision with comet 9P/Tempel 1. Mid-infrared data from the Cooled ...Mid-Infrared Camera and Spectrometer (COMICS) of the Subaru Telescope indicate that the large-scale dust plume ejected by the impact contained a large mass (approximately10⁶ kilograms) of dust and formed two wings approximately ±45° from the symmetric center, both consistent with gravity as the primary control on the impact and its immediate aftermath. The dust distribution in the inner part of the plume, however, is inconsistent with a pure gravity control and implies that evaporation and expansion of volatiles accelerated dust.
Depression research needs new animal models in order to increase knowledge of the disease and search for new therapies. This work aims at providing a neurobiologically validated model to investigate ...the relationship between sickness behavior, antidepressants treatment and social dominance behavior in mice. Dominant individuals from dyads of male swiss mice were treated with the bacterial endotoxin LPS (400 μ g/ kg i.p. for three consecutive days) to induce social hierarchy destabilization. There were five groups. One was treated only with LPS. Two other groups were treated with the antidepressants imipramine or fluoxetine (20 mg/kg 1 h prior to LPS administration). Another two groups were treated only with imipramine or fluoxetine. Antidepressant treatment prevented the occurrence of social destabilization. Behavioral analysis of the social behavior as well the Tail Suspension Test showed that antidepressants were responsible for increased reactivity in mice treated with LPS in an adaptively relevant way. Fluoxetine but not imipramine exarcebated LPS induced increase in corticosterone secretion. Specific brain nuclei activation assessed by immunohistochemical analysis of fos and egr expression indicated that imipramine but not fluoxetine treatment prevented increased activation of the paraventricular nucleus of the hypothalamus in LPS treated animals. These results indicate that this model could be useful to provide new insights on the interaction among brain systems involved in depression and sickness behavior.
Context.The recently discovered Apollo-type near-Earth asteroid 2005 UD has been suggested to be a fragment of (3200) Phaethon. Aims.To test this hypothesis, we carried out photometric observations ...of 2005 UD using the 1-m telescope at Lulin Observatory. Methods.Multi-color photometry was used to compare the surface properties of (3200) Phaethon and 2005 UD. Surface-color variation due to the rotation was also examined. Results.The time-resolved differential photometry showed clear brightness variation, and the lightcurve was fitted with a rotation period of 5.23 h and an amplitude of 0.44 mag. Using this rotational lightcurve, we derived the surface colors of 2005 UD. The surface of 2005 UD exhibits colors similar to those of F- and B-type asteroids, which is consistent with (3200) Phaethon. Furthermore, the ($R-I$) color of 2005 UD shows variation during the rotation of the body. Conclusions.The similarity of surface colors between (3200) Phaethon and 2005 UD observationally supports the hypothesis that 2005 UD is likely to be a fragment of (3200) Phaethon. A simple explanation for the inhomogeneity of the surface is that we see the surface and subsurface of the precursor object. Another explanation is the topographical structure that such as a large crater causes on this heterogeneous surface.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Shorter duration of dual antiplatelet therapy after drug-eluting stent implantation is required in patients with high ...bleeding risk (HBR) irrespective of the presence of concomitant high thrombotic risk (HTR). The prevalence of post-stent suboptimal findings in patients with HBR remains unclear.
Purpose
To clarify the prevalence of post-stent suboptimal findings assessed by optical coherence tomography (OCT) in patients with HBR according to the presence of HTR.
Methods
A total of 607 consecutive patients with stable coronary disease, who underwent OCT imaging of the culprit lesion were included. HBR was defined based on the Academic Research Consortium for High Bleeding Risk (ARC-HBR). HTR was defined as lesions with diffuse long (≧60 mm), treated with more than three stents, chronic total occlusion or diffuse long lesion (≧32 mm) in patients with diabetes mellitus. Post-stent suboptimal OCT criteria was defined as minimum stent area (MSA) <4.5 mm2, edge dissection and stent malapposition.
Results
The prevalence of HBR was 55.8%. The prevalence of HTR was significantly higher in patients with HBR than in those without HBR (35.0 vs. 26.6%, p=0.028) (Figure A). Among patients with HBR, the prevalence of post-stent suboptimal OCT criteria was significantly higher in patients with HTR than in those without HTR (86.2 vs. 64.7%, p<0.001), mainly due to the higher prevalence of MSA <4.5 mm2 (Figure B) in patients with HTR.
Conclusions
HTR was associated with a higher prevalence of post-stent suboptimal findings among patients with HBR. The present results may suggest the importance of optimal stenting in patients with HBR, particularly in those with concomitant HTR.
Abstract
Background
The impact of the high triglyceride (TG) level on the characteristics of coronary plaque in nonculprit lesion remains to be elucidated.
Purpose
To clarify the association between ...the TG level and the characteristics of nonculprit coronary plaque in patients with stable coronary disease using optical coherence tomography (OCT).
Methods
A total of 531 consecutive patients who underwent OCT imaging of the nonculprit lesion were included. Patients were classified into either the higher TG group (non-fasting TG ≥150 mg/dL, n=197) or the lower TG group (non-fasting TG <150 mg/dL, n=334). The morphologies of nonculprit plaque assessed by OCT were compared between the two groups.
Results
The median (interquartile range) of TG in the two groups was 193.0 (168.0–244.0) mg/dL and 95.0 (75.0–120.0) mg/dL, respectively. The prevalence of layered plaque was significantly higher in the higher TG group than the lower TG group (40.1 vs. 27.5%, p=0.004), whereas the prevalence of other plaque components was comparable between the two groups (Figure 1). The prevalence of layered plaque was significantly higher in the higher TG group than in the lower TG group among patients with diabetes mellitus (DM) (44.2 vs. 28.7%, p=0.037) although it was comparable between the two groups among patients without DM (Figure 2).
Conclusion
A higher TG level was associated with a higher prevalence of layered plaque in nonculprit plaques in patients with stable coronary disease, particularly in patients with DM. The present results may partly explain the impact of TG on the progression of coronary plaque and the increased incidence of recurrent events in patients with coronary artery disease.
Funding Acknowledgement
Type of funding sources: None.
Abstract
Background
It has been reported that young patients with diabetes mellitus (DM) had a higher mortality rate after myocardial infarction. However, plaque characteristics among different age ...groups in patients with acute coronary syndromes (ACS) with or without DM are unknown.
Purpose
The aim of this study was to investigate the plaque characteristics among different age groups in ACS patients with or without DM in a large population.
Methods
Patients who presented with ACS and underwent preintervention OCT imaging were included. The culprit plaque was categorized as plaque rupture (PR), plaque erosion (PE) or calcified plaque (CP), and stratified by 5 age groups. Features of plaque vulnerability were also analyzed.
Results
Among 1394 patients, 482 (34.6%) had DM. DM patients had a higher prevalence of lipid-rich plaque (71.2% vs. 64.8%, p=0.016), macrophage (72.0% vs. 62.6%, p<0.001), and cholesterol crystal (27.6% vs. 19.7%, p<0.001) than non-DM patients. Non-DM patients showed a significant ascending trend with age in PR (p=0.004), lipid-rich plaque (p=0.018), whereas DM patients had a high prevalence of these vulnerable features at early age, which plateaued across the different age groups. Both DM and non-DM groups showed a significant decreasing trend in PE with age (non-DM patients, p<0.001; DM patients, p=0.020).
Conclusions
DM patients had a high prevalence of lipid-rich plaque and a high incidence of plaque rupture at early age. This pattern persisted across the different age groups.
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