A complete set of low-temperature second-order elastic constants
of corundum (
-Al
O
) was studied by resonant ultrasound spectroscopy. At ambient temperature, the obtained
show excellent agreement ...with those reported by Gladden et al. Our
exhibit monotonic elastic softening upon cooling, but stay positive over the entire temperature range considered. From a lattice-dynamics analysis, the softening can be attributed to an internal displacement that has two-dimensional
symmetry. The acoustic Debye temperature and Grüneisen parameter are calculated to be
K and
, respectively. The Einstein temperatures, estimated from
curves, are relatively small compared to
indicating that low-frequency modes are dominant in the zone-centred mode lattice vibrations. Also
is essentially temperature independent.
A complete set of elastic constants C
ij
and piezoelectric coefficients e
ij
of a La
3
Ga
5
SiO
14
(langasite) single crystal was determined from 5.5 to 275.5 K by resonant ultrasound spectroscopy. ...Unlike a conventional crystal, the elastic constants C
ij
of the langasite crystal showed three types of temperature dependence: (i) monotonic elastic stiffening upon cooling (C
44
and C
14
); (ii) monotonic elastic softening (C
66
); and (iii) a stiffening-to-softening transition below 150 K (C
11
, C
12
, C
13
and C
33
). In addition, a strong correlation between C
66
and the piezoelectric coefficient e
11
was confirmed. Group theoretical lattice dynamics analysis revealed that the novel phenomena of elastic softening and strong correlation are explained on the basis of two types of optical mode internal displacements which have the totally symmetric A
1
and doubly degenerated E symmetries in the point group D
3
.
The objective of this study was to examine the evolution of antidepressant switch and adjunctive therapy.
This chart review was conducted at 6 primary psychiatric clinics or hospitals, in Tokyo, ...Japan. A chart review of longitudinal prescriptions was conducted regarding 633 outpatients with major depressive disorder for up to 2 years after their first visit. Patients who had already received antidepressants prior to the visit were excluded.
22.6% (N=143) of the patients completed or continued the outpatient treatment over the 2 years while 27 (4.3%), 23 (3.6%), and 439 (69.4%) patients discontinued it due to hospitalization, referral to another clinic, and loss to follow-up, respectively. A total of 597 episodes of antidepressant treatment were identified. Among them, 482 episodes (80.7%) were associated with the suggested dose ranges while antidepressant drugs were under-dosed in 19.3% (N=115) of the episodes. 50 patients (7.9%) received adjunctive therapy; it was employed after a median of only one antidepressant had been tried.
Psychiatrists may be hasty in prescribing an adjunctive therapy in the treatment of depression.
The complete elastic constant tensor,
i.e. the real and imaginary parts
C
ijkl
and
Q
i
j
k
l
−
1
, of icosahedral AlPdMn quasicrystal were measured at megahertz frequencies, from 4
K to room ...temperature, using electromagnetic acoustic resonance. The temperature dependence of
C
ijkl
was analyzed using an Einstein oscillator model and a quasiharmonic approximation. The overall mode Grüneisen parameter
γ is 2.0, in agreement with a previous thermal expansion measurement. Internal friction
Q
i
j
k
l
−
1
behaved normally throughout the measured temperature range. These results suggest that the lattice anharmonicity of
i-AlPdMn is similar to usual crystalline materials despite its significant difference in structure.
Physically isolated and crystallographically oriented single-variant nanocrystals (NCs) have been successfully formed in an Ni-P amorphous alloy using focused ion-beam (FIB) irradiation. The ...amorphous alloy was irradiated by the FIB at an incident ion beam angle of 35° to the specimen surface. Transmission electron microscopy observation has shown the formation of a large amount of NCs, approximately 20 nm in size, throughout the irradiated area. Electron diffraction analysis has revealed that the NCs have an fcc structure, with the irradiated-plane normal parallel to 111
fcc
and the FIB direction parallel to 001
fcc
, indicating that the NCs are single variant.
The five independent elastic constants of hexagonal monocrystal titanium were determined up to the phase-transformation temperature, and the two isotropic elastic constants of polycrystalline ...titanium were determined beyond, up to 1300 K. Anomalous temperature dependences were observed just below the phase-transformation temperature:
C
11 and
C
66 increase with increasing temperature whereas
C
33 and
C
44 remarkably decrease, for example. To determine the
C
ij
, we used the free-vibration resonance frequencies obtained by electromagnetic acoustic resonance. After the phase transformation, the resonance frequencies changed little with the temperature increase, showing that the bcc-phase elastic constants change little with temperature. The polycrystalline elastic constants remained unchanged up to 1300 K after the phase transformation. The anomalous temperature dependence near the transformation is interpreted in terms of the small
c/
a ratio of the hcp phase and change of the atomic distances to meet the Burgers lattice relationship. Temperature-insensitive elastic constants in the bcc phase suggest the stabilizing of the bcc phase with increasing temperature.
A complete set of low-temperature second-order elastic constants Image omitted. of corundum (Image omitted.-AlImage omitted.OImage omitted.) was studied by resonant ultrasound spectroscopy. At ...ambient temperature, the obtained Image omitted. show excellent agreement with those reported by Gladden et al. Our Image omitted. exhibit monotonic elastic softening upon cooling, but stay positive over the entire temperature range considered. From a lattice-dynamics analysis, the softening can be attributed to an internal displacement that has two-dimensional Image omitted. symmetry. The acoustic Debye temperature and Grueneisen parameter are calculated to be Image omitted. K and Image omitted., respectively. The Einstein temperatures, estimated from Image omitted. curves, are relatively small compared to Image omitted. indicating that low-frequency modes are dominant in the zone-centred mode lattice vibrations. Also Image omitted. is essentially temperature independent.
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