948 research outputs found
Phonons in magnon superfluid and symmetry breaking field
Recent experiments [1],[2] which measured the spectrum of the Goldstone
collective mode of coherently precessing state in 3He-B are discussed using the
presentation of the coherent spin precession in terms of the Bose-Einstein
condensation of magnons. The mass in the spectrum of the Goldstone boson --
phonon in the superfluid magnon liquid -- is induced by the symmetry breaking
field, which is played by the RF magnetic fieldComment: 2 pages, JETP Letters style, no figures, version accepted in JETP
Letter
Solution of the problem of catastrophic relaxation of homogeneous spin precession in superfluid He-B
The quantitative analysis of the "catastrophic relaxation" of the coherent
spin precession in He-B is presented. This phenomenon has been observed
below the temperature about 0.5 T as an abrupt shortening of the induction
signal decay. It is explained in terms of the decay instability of homogeneous
transverse NMR mode into spin waves of the longitudinal NMR. Recently the cross
interaction amplitude between the two modes has been calculated by Sourovtsev
and Fomin \cite{SF} for the so-called Brinkman-Smith configuration, i.e. for
the orientation of the orbital momentum of Cooper pairs along the magnetic
field, . In their treatment, the interaction is
caused by the anisotropy of the speed of the spin waves. We found that in the
more general case of the non-parallel orientation of corresponding to
the typical conditions of experiment, the spin-orbital interaction provides the
additional interaction between the modes. By analyzing experimental data we are
able to distinguish which contribution is dominating in different regimes.Comment: 6 pages, 1 figure, submited to JETP letter
Stable Spin Precession at one Half of Equilibrium Magnetization in Superfluid 3He-B
New stable modes of spin precession have been observed in superfluid 3He-B.
These dynamical order parameter states include precession with a magnetization
S=pS_{eq} which is different from the equilibrium value S_{eq}. We have
identified modes with p=1, 1/2 and \approx 0. The p=1/2 mode is the second
member of phase correlated states of a spin superfluid. The new states can be
excited in the temperature range 1-T/T_c \lesssim 0.02 where the energy
barriers between the different local minima of the spin-orbit energy are small.
They are stable in CW NMR due to low dissipation close to T_c.Comment: submitted to Physical Review Letters, 4 pages, revtex, 4 Figures in
ftp://boojum.hut.fi/pub/publications/lowtemp/LTL-96005.p
Exciton spin decay modified by strong electron-hole exchange interaction
We study exciton spin decay in the regime of strong electron-hole exchange
interaction. In this regime the electron spin precession is restricted within a
sector formed by the external magnetic field and the effective exchange fields
triggered by random spin flips of the hole. Using Hanle effect measurements, we
demonstrate that this mechanism dominates our experiments in CdTe/(Cd,Mg)Te
quantum wells. The calculations provide a consistent description of the
experimental results, which is supported by independent measurements of the
parameters entering the model.Comment: 5 pages, 3 figure
Magnon BEC in superfluid 3He-A
The new mode of magnetization precession in superfluid 3He-A in a squeezed
aerogel has been recently reported. We consider this mode in terms of the
Bose-Einstein condensation (BEC) of magnons. The difference between magnon BEC
states in 3He-A and in 3He-B is discussed.Comment: 6 pages, 2 figures, JETP Letters style, published versio
Observation of Coherent Precession of Magnetization in Superfluid 3He A-phase
We report the first observation of coherent quantum precession of
magnetization (CQP) in superfluid 3He-A in aerogel. The coherent precession in
bulk 3He A-phase is unstable due to the positive feedback of spin supercurrent
to the gradient of phase of precession. It was predicted that the homogeneous
precession will be stable if the orbital momentum of 3He-A could be oriented
along the magnetic field. We have succeeded to prepare this configuration by
emerging 3He in uniaxially-deformed anisotropic aerogel. The dissipation rate
of coherent precession states in aerogel is much larger then one in bulk 3He-B.
We propose a mechanism of this dissipation.Comment: 4 pages, 4 figure
Treatment of vulvovaginal candidiasis in preparation programs for in vitro fertilization
Vulvovaginal candidiasis (VVC) is considered as the second most common cause of vaginitis after bacterial vaginosis. About three quarters of women of reproductive age have a history of at least one episode of VVC, and about a half of women have two or more episodes. Candida albicans is responsible for85% to 90% of vulvovaginal candidiasis. There are uncomplicated and complicated forms of VVC. Uncomplicated forms are not severe cases caused by C. albicans. Complicated forms are cases caused by other Candida species, severe cases, cases that develop during pregnancy or associated with other diseases such as diabetes mellitus or immunosuppressive conditions. Reccurent cases are also complicated ones. Therapeutic schemes should depend on the form of the VVC. Short-term topical therapy or a single oral dose are effective in 90% of uncomplicated cases. Complicated forms of VVC require longer treatment. Oral fluconazole can be administered three times with a break of 72 hours. Topical azoles can be administered daily for at least 1 week. So, sertaconazole in the form of suppositories is used once intravaginally. The data on the use of probiotics in the treatment of VVC today are contradictory and heterogeneous. Treatment of VVC during pregnancy, especially in the first trimester, may be associated with adverse perinatal outcomes. On the other hand, during pregnancy, VVC can be more severe than in non-pregnant women, especially in the second half of pregnancy. In addition, the risk of transmission to a newborn is about 50%. Thus, the identification and treatment of VVC is one of the important tasks in pregnancy planning, including assisted reproduction
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