112 research outputs found
Suzaku Observation of the Anomalous X-ray Pulsar 1E 1841-045
We report the results of a Suzaku observation of the anomalous X-ray pulsar
(AXP) 1E 1841-045 at a center of the supernova remnant Kes 73. We confirmed
that the energy-dependent spectral models obtained by the previous separate
observations were also satisfied over a wide energy range from 0.4 to ~70 keV,
simultaneously. Here, the models below ~10 keV were a combination of blackbody
(BB) and power-law (PL) functions or of two BBs wit h different temperatures at
0.6 - 7.0 keV (Morii et al. 2003), and that above ~20 keV was a PL function
(Kuiper Hermsen Mendez 2004). The combination BB + PL + PL was found to best
represent the phase-averaged spectrum. Phase-resolved spectroscopy indicated
the existence of two emission regions, one with a thermal and the other with a
non-thermal nature. The combination BB + BB + PL was also found to represent
the phase-averaged spectrum well. However, we found that this model is
physically unacceptable due to an excessively large area of the emission region
of the blackbody. Nonetheless, we found that the temperatures and radii of the
two blackbody components showed moderate correlations in the phase-resolved
spectra. The fact that the same correlations have been observed between the
phase-averaged spectra of various magnetars (Nakagawa et al. 2009) suggests
that a self-similar function can approximate the intrinsic energy spectra of
magnetars below ~10 keV.Comment: Accepted for publication in the PAS
Intensified Multifactorial Intervention in Patients with Type 2 Diabetes Mellitus
In the management of diabetes mellitus, one of the most important goals is to prevent its micro- and macrovascular complications, and to that end, multifactorial intervention is widely recommended. Intensified multifactorial intervention with pharmacotherapy for associated risk factors, alongside lifestyle modification, was first shown to be efficacious in patients with microalbuminuria (Steno-2 study), then in those with less advanced microvascular complications (the Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care [ADDITION]-Europe and the Japan Diabetes Optimal Treatment study for 3 major risk factors of cardiovascular diseases [J-DOIT3]), and in those with advanced microvascular complications (the Nephropathy In Diabetes-Type 2 [NID-2] study and Diabetic Nephropathy Remission and Regression Team Trial in Japan [DNETT-Japan]). Thus far, multifactorial intervention led to a reduction in cardiovascular and renal events, albeit not necessarily significant. It should be noted that not only baseline characteristics but also the control status of the risk factors and event rates during intervention among the patients widely varied from one trial to the next. Further evidence is needed for the efficacy of multifactorial intervention in a longer duration and in younger or elderly patients. Moreover, now that new classes of antidiabetic drugs are available, it should be addressed whether strict and safe glycemic control, alongside control of other risk factors, could lead to further risk reductions in micro- and macrovascular complications, thereby decreasing all-cause mortality in patients with type 2 diabetes mellitus
A new crystal phase of N,N,N′,N′-tetraphenyl-1,1′-biphenyl-4,4′-diamine
The complete molecule of the title compound, C36H28N2, is generated by a crystallographic centre of inversion. The biphenyl unit is forced by symmetry to be essentially flat (r.m.s. deviation = 0.008 Å); the dihedral angles between it and the two terminal phenyl rings are 69.39 (5) and 59.53 (5)°
Effect of vasopressin V1- and V2-receptor stimulation on blood pressure in DOCA-salt hypertensive rats.
We recently reported that stimulation of the arginine vasopressin (AVP) V1-receptor enhanced the pressor response in spontaneously hypertensive rats (SHR). In the present study, we investigated acute changes in systolic blood pressure (SBP) and heart rate (HR) after intravenous injections of AVP, OPC-21268 (a V1-receptor antagonist), and OPC-31260 (a V2-receptor antagonist), in anesthetized DOCA-salt hypertensive rats (DOCA) and age-matched sham-operated Wistar rats (control) to determine whether the pressor effect is specific to SHR or is present in other hypertensive animal models. SBP increased significantly in DOCA rats 9 min after injection of AVP 5 ng/kg without a concomitant increase in HR. Neither OPC-21268 3mg/kg nor OPC-31260 3mg/kg caused significant changes in SBP or HR. SBP tended to increase when AVP was administered after injection of OPC-31260. HR increased significantly 15 min after the combined treatment with OPC-31260 and AVP in DOCA rats compared with control rats. SBP did not change significantly when AVP was administered after injection of OPC-21268 in DOCA or control rats, but HR decreased significantly from 1 to 4 min after injection of AVP in DOCA rats. Our results suggest that V1-receptor stimulation does not enhance the pressor response in the DOCA rat, which is a model of volume-dependent hypertension, suggesting that the AVP system, especially V1-receptor, is not as important in the development or maintenance of hypertension in DOCA rats as in SHR.</p
Discovery of a possible X-ray counterpart to HESS J1804-216
Suzaku deep observations have discovered two highly significant nonthermal
X-ray sources, Suzaku J18042142 (Src 1) and Suzaku J18042140 (Src 2),
positionally coincident with the unidentified TeV -ray source, HESS
J1804216. The X-ray sources are not time variable and show no counterpart in
other wavebands, except for the TeV source. Src 1 is unresolved at Suzaku
spatial resolution, whereas Src 2 is extended or composed of multiple sources.
The X-ray spectra are highly absorbed, hard, and featureless, and are well
fitted by absorbed power-law models with best-fit photon indices and absorption
columns of and cm
for Src 1, and and
cm for Src 2. The measured X-ray absorption to the latter source is
significantly larger than the total Galactic neutral hydrogen column in that
direction. The unabsorbed 2--10 keV band luminosities are ergs s (Src 1) and ergs s (Src 2), where is the source distance. Among the
handful of TeV sources with known X-ray counterparts, HESS J1804216 has the
largest ratio of TeV -ray to hard X-ray fluxes. We discuss the nature
of the emission and propose the Suzaku sources as plausible counterparts to the
TeV source, although further observations are necessary to confirm this.Comment: 12 pages, 5 figures, Publications of the Astronomical Society of
Japan, in pres
Enhanced pressor response in spontaneously hypertensive rats induced by stimulation of vasopressin-V1 receptors.
To elucidate the effect of the arginine vasopressin (AVP) system in vivo, especially V1 and V2 activity, on blood pressure, we measured the acute changes in blood pressure and heart rate after AVP, OPC-21,268 (a V1 receptor antagonist), and OPC-31,260 (a V2 receptor antagonist) were injected intravenously in anesthetized spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at the age of 15 weeks. Compared with the control period, single injection of AVP 5 ng/kg significantly increased systolic blood pressure in WKY rats without a concomitant increase in heart rate, but there was no significant increase in blood pressure in SHR. In contrast, single injection of either OPC-21,268 3 mg/kg or OPC-31,260 3 mg/kg did not affect blood pressure or heart rate in either SHR or WKY rats. Injection of AVP after the administration of OPC-31,260 induced a greater increase in blood pressure in SHR than in WKY rats, whereas injection of AVP after the administration of OPC-21,268 did not induce any clear increase in blood pressure in SHR or WKY rats. These results suggest that SHR have enhanced pressor activity mediated by V1 receptors and that this increase may be due to an increase in their number. In conclusion, enhancement of V1 activity may contribute to the development of high blood pressure in SHR.</p
Spectral evolution of GRB 060904A observed with Swift and Suzaku -- Possibility of Inefficient Electron Acceleration
We observed an X-ray afterglow of GRB 060904A with the Swift and Suzaku
satellites. We found rapid spectral softening during both the prompt tail phase
and the decline phase of an X-ray flare in the BAT and XRT data. The observed
spectra were fit by power-law photon indices which rapidly changed from to within a few hundred
seconds in the prompt tail. This is one of the steepest X-ray spectra ever
observed, making it quite difficult to explain by simple electron acceleration
and synchrotron radiation. Then, we applied an alternative spectral fitting
using a broken power-law with exponential cutoff (BPEC) model. It is valid to
consider the situation that the cutoff energy is equivalent to the synchrotron
frequency of the maximum energy electrons in their energy distribution. Since
the spectral cutoff appears in the soft X-ray band, we conclude the electron
acceleration has been inefficient in the internal shocks of GRB 060904A. These
cutoff spectra suddenly disappeared at the transition time from the prompt tail
phase to the shallow decay one. After that, typical afterglow spectra with the
photon indices of 2.0 are continuously and preciously monitored by both XRT and
Suzaku/XIS up to 1 day since the burst trigger time. We could successfully
trace the temporal history of two characteristic break energies (peak energy
and cutoff energy) and they show the time dependence of while the following afterglow spectra are quite stable. This fact
indicates that the emitting material of prompt tail is due to completely
different dynamics from the shallow decay component. Therefore we conclude the
emission sites of two distinct phenomena obviously differ from each other.Comment: 19 pages, 9 figures, accepted for publication in PASJ (Suzaku 2nd
Special Issue
- …