159 research outputs found
THE FRICTIONAL COEFFICIENTS IN TI-NB ALLOY
Objectives: To determine the frictional force (FF) of the novel, elastic, bendable titanium-niobium (Ti-Nb) alloy orthodontic wire in stainless steel (SS) brackets and to compare it with those of titanium-nickel (Ti-Ni) and titanium-molybdenum (Ti-Mo) alloy wires.
Materials and Methods: Three sizes of Ti-Nb, Ti-Ni, and Ti-Mo alloy wires were ligated with elastic modules to 0.018-inch and 0.022-inch SS brackets. The dynamic FFs between the orthodontic wires and SS brackets were measured at three bracket-wire angles (0゜, 5゜, and 10゜) with an Instron 5567 loading apparatus (Canton, Mass).
Results: FFs increased gradually with the angle and wire size. In the 0.018-inch-slot bracket, the dynamic FFs of Ti-Nb and Ti-Ni alloy wires were almost the same, and those of the Ti-Mo alloy wire were significantly greater (P<0.05). FF values were 1.5–2 times greater in the 0.022-inch-slot bracket than in the 0.018-inch-slot bracket, regardless of alloy wire type, and the Ti-Mo alloy wire showed the greatest FF. Scanning electric microscopic images showed that the surface of the Ti-Mo alloy wire was much rougher than that of the Ti-Ni and Ti-Nb alloy wires.
Conclusion: These findings demonstrate that the Ti-Nb alloy wire has almost the same frictional resistance as the Ti-Ni alloy wire, although it has a higher elastic modulus
Morse theory of the moment map for representations of quivers
The results of this paper concern the Morse theory of the norm-square of the
moment map on the space of representations of a quiver. We show that the
gradient flow of this function converges, and that the Morse stratification
induced by the gradient flow co-incides with the Harder-Narasimhan
stratification from algebraic geometry. Moreover, the limit of the gradient
flow is isomorphic to the graded object of the
Harder-Narasimhan-Jordan-H\"older filtration associated to the initial
conditions for the flow. With a view towards applications to Nakajima quiver
varieties we construct explicit local co-ordinates around the Morse strata and
(under a technical hypothesis on the stability parameter) describe the negative
normal space to the critical sets. Finally, we observe that the usual Kirwan
surjectivity theorems in rational cohomology and integral K-theory carry over
to this non-compact setting, and that these theorems generalize to certain
equivariant contexts.Comment: 48 pages, small revisions from previous version based on referee's
comments. To appear in Geometriae Dedicat
Sex differences in the effects of aromatherapy on anxiety and salivary oxytocin levels
ObjectiveAromatherapy is a holistic healing method to promote health and well-being by using natural plant extracts. However, its precise mechanism of action and influence on the endocrine system remains unclear. Since recent studies reported that a neuropeptide, oxytocin, can attenuate anxiety, we hypothesized that if oxytocin secretion is promoted through aromatherapy, it may improve mood and anxiety. The present study is aimed to investigate the relationship between oxytocin and the effects of aromatherapy with lavender oil on anxiety level, by measuring salivary oxytocin levels in healthy men and women.MethodsWe conducted a randomized open crossover trial in 15 men and 10 women. Each participant received a placebo intervention (control group) and aromatherapy with lavender oil (aromatherapy group). For the aromatherapy group, each participant spent a 30-min session in a room with diffused lavender essential oil, followed by a 10-min hand massage using a carrier oil containing lavender oil. Anxiety was assessed using the State-Trait Anxiety Inventory (STAI) before the intervention, 30-min after the start of intervention, and after hand massage, in both groups. Saliva samples were collected at the same time points of the STAI.ResultsIn women, either aromatherapy or hand massage was associated with a reduction in anxiety levels, independently. Moreover, salivary oxytocin levels were increased after aromatherapy. On the other hand, in men, anxiety levels were decreased after aromatherapy, as well as after hand massage, regardless of the use of lavender oil. However, there were no significant differences in changes of salivary oxytocin levels between the control and aromatherapy groups during the intervention period. Interestingly, there was a positive correlation between anxiety levels and salivary oxytocin levels before the intervention, but a negative correlation was observed after hand massage with lavender oil.ConclusionThe results of the present study indicate that in women, aromatherapy with lavender oil attenuated anxiety with increase in oxytocin level in women, whereas in men, there was no clear relationship of aromatherapy with anxiety or oxytocin levels but, there was a change in correlation between anxiety and oxytocin. The results of the present study suggest that the effect of aromatherapy can vary depending on sex
Outburst of LS V+44 17 Observed by MAXI and RXTE, and Discovery of a Dip Structure in the Pulse Profile
We report on the first observation of an X-ray outburst of a Be/X-ray binary
pulsar LS V +44 17/RX J0440.9+4431, and the discovery of an absorption dip
structure in the pulse profile. An outburst of this source was discovered by
MAXI GSC in 2010 April. It was the first detection of the transient activity of
LS V +44 17 since the source was identified as a Be/X-ray binary in 1997. From
the data of the follow-up RXTE observation near the peak of the outburst, we
found a narrow dip structure in its pulse profile which was clearer in the
lower energy bands. The pulse-phase-averaged energy spectra in the 3100 keV
band can be fitted with a continuum model containing a power-law function with
an exponential cutoff and a blackbody component, which are modified at low
energy by an absorption component. A weak iron K emission line is also
detected in the spectra. From the pulse-phase-resolved spectroscopy we found
that the absorption column density at the dip phase was much higher than those
in the other phases. The dip was not seen in the subsequent RXTE observations
at lower flux levels. These results suggest that the dip in the pulse profile
originates from the eclipse of the radiation from the neutron star by the
accretion column.Comment: 18 pages, 7 figures, accepted for publication in PAS
Long-term Monitoring of the Black Hole Binary GX 339-4 in the High/Soft State during the 2010 Outburst with MAXI/GSC
We present the results of monitoring the Galactic black hole candidate GX
339-4 with the Monitor of All-sky X-ray Image (MAXI) / Gas Slit Camera (GSC) in
the high/soft state during the outburst in 2010. All the spectra throughout the
8-month period are well reproduced with a model consisting of multi-color disk
(MCD) emission and its Comptonization component, whose fraction is <= 25% in
the total flux. In spite of the flux variability over a factor of 3, the
innermost disk radius is constant at R_in = 61 +/- 2 km for the inclination
angle of i = 46 deg and the distance of d=8 kpc. This R_in value is consistent
with those of the past measurements with Tenma in the high/soft state. Assuming
that the disk extends to the innermost stable circular orbit of a non-spinning
black hole, we estimate the black hole mass to be M = 6.8 +/- 0.2 M_sun for i =
46 deg and d = 8 kpc, which is consistent with that estimated from the Suzaku
observation of the previous low/hard state. Further combined with the mass
function, we obtain the mass constraint of 4.3 M_sun < M < 13.3 M_sun for the
allowed range of d = 6-15 kpc and i < 60 deg. We also discuss the spin
parameter of the black hole in GX 339-4 by applying relativistic accretion disk
models to the Swift/XRT data.Comment: 9 pages, 8 figures, accepted for publication in PASJ (Suzaku+MAXI
special issue
A Spectral Study of the Black Hole Candidate XTE J1752-223 in the High/Soft State with MAXI, Suzaku and Swift
We report on the X-ray spectral analysis of the black hole candidate XTE\
J1752--223 in the 2009--2010 outburst, utilizing data obtained with the
MAXI/Gas Slit Camera (GSC), the Swift/XRT, and Suzaku, which work
complementarily. As already reported by Nakahira et al. (2010) MAXI monitored
the source continuously throughout the entire outburst for about eight months.
All the MAXI/GSC energy spectra in the high/soft state lasting for 2 months are
well represented by a multi-color disk plus power-law model. The innermost disk
temperature changed from 0.7 keV to 0.4 keV and the disk flux
decreased by an order of magnitude. Nevertheless, the innermost radius is
constant at 41 km, where is the
source distance in units of 3.5 kpc and the inclination. The multi-color
disk parameters obtained with the MAXI/GSC are consistent with those with the
Swift/XRT and Suzaku. The Suzaku data also suggests a possibility that the disk
emission is slightly Comptonized, which could account for broad iron-K features
reported previously. Assuming that the obtained innermost radius represents the
innermost stable circular orbit for a non-rotating black hole, we estimate the
mass of the black hole to be 5.510.28 , where the correction for the stress-free inner boundary condition
and color hardening factor of 1.7 are taken into account. If the inclination is
less than 49 as suggested from the radio monitoring of transient jets
and the soft-to-hard transition in 2010 April occurred at 1--4% of Eddignton
luminosity, the fitting of the Suzaku spectra with a relativistic
accretion-disk model derives constraints on the mass and the distance to be
3.1--55 and 2.3--22 {\rm kpc}, respectively. This confirms that the
compact object in XTE J1752--223 is a black hole.Comment: 12 pages including 7 figures and 4 tables, accepted for publication
in PAS
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