42 research outputs found
Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid He
We have measured the temperature dependence of the time of flight of helium
excimer molecules He2* in superfluid 4He and find that the molecules behave
ballistically below 100mK and exhibit Brownian motion above 200 mK. In the
intermediate temperature range the transport cannot be described by either of
the models.Comment: 8 pages, 6 figures, submitted to the Proceedings of the International
Conference on Quantum Fluids and Solids 201
Universal Behaviour of the Superfluid Fraction and Tc of He-3 in 99.5% Open Aerogel
We have investigated the superfluid transition of He-3 in a 99.5% porosity
silica aerogel. This very dilute sample shows behaviour intermediary between
bulk He-3 and He-3 confined to the denser aerogels previously studied. We
present data on both the superfluid transition temperature and the superfluid
density and compare our results with previous measurements. Finally, we show
that the suppression of the superfluid transition temperature and suppression
of the superfluid density of He-3 in aerogel follow a universal relation for a
range of aerogel samples.Comment: 4 pages, 5 figures; 1 new figure, minor change
Second wind of the Dulong-Petit Law at a quantum critical point
Renewed interest in 3He physics has been stimulated by experimental
observation of non-Fermi-liquid behavior of dense 3He films at low
temperatures. Abnormal behavior of the specific heat C(T) of two-dimensional
liquid 3He is demonstrated in the occurrence of a T-independent term in C(T).
To uncover the origin of this phenomenon, we have considered the group velocity
of transverse zero sound propagating in a strongly correlated Fermi liquid. For
the first time, it is shown that if two-dimensional liquid 3He is located in
the vicinity of the quantum critical point associated with a divergent
quasiparticle effective mass, the group velocity depends strongly on
temperature and vanishes as T is lowered toward zero. The predicted vigorous
dependence of the group velocity can be detected in experimental measurements
on liquid 3He films. We have demonstrated that the contribution to the specific
heat coming from the boson part of the free energy due to the transverse
zero-sound mode follows the Dulong-Petit Law. In the case of two-dimensional
liquid 3He, the specific heat becomes independent of temperature at some
characteristic temperature of a few mK.Comment: 5 pages, 1 figur
Excimers He2* as tracers of quantum turbulence in He4 in the T=0 Limit
We have studied the interaction of metastable He2*4 excimer molecules with quantized vortices in superfluid He4 in the zero temperature limit. The vortices were generated by either rotation or ion injection. The trapping diameter of the molecules on quantized vortices was found to be 96±6 nm at a pressure of 0.1 bar and 27±5 nm at 5.0 bar. We have also demonstrated that a moving tangle of vortices can carry the molecules through the superfluid helium. © 2013 American Physical Society
Adaptation of the Landau-Migdal Quasiparticle Pattern to Strongly Correlated Fermi Systems
A quasiparticle pattern advanced in Landau's first article on Fermi liquid
theory is adapted to elucidate the properties of a class of strongly correlated
Fermi systems characterized by a Lifshitz phase diagram featuring a quantum
critical point (QCP) where the density of states diverges. The necessary
condition for stability of the Landau Fermi Liquid state is shown to break down
in such systems, triggering a cascade of topological phase transitions that
lead, without symmetry violation, to states with multi-connected Fermi
surfaces. The end point of this evolution is found to be an exceptional state
whose spectrum of single-particle excitations exhibits a completely flat
portion at zero temperature. Analysis of the evolution of the temperature
dependence of the single-particle spectrum yields results that provide a
natural explanation of classical behavior of this class of Fermi systems in the
QCP region.Comment: 26 pages, 14 figures. Dedicated to 100th anniversary of A.B.Migdal
birthda
Local mean-field study of capillary condensation in silica aerogels
We apply local mean-field (i.e. density functional) theory to a lattice model
of a fluid in contact with a dilute, disordered gel network. The gel structure
is described by a diffusion-limited cluster aggregation model. We focus on the
influence of porosity on both the hysteretic and the equilibrium behavior of
the fluid as one varies the chemical potential at low temperature. We show that
the shape of the hysteresis loop changes from smooth to rectangular as the
porosity increases and that this change is associated to disorder-induced
out-of-equilibrium phase transitions that differ on adsorption and on
desorption. Our results provide insight in the behavior of He in silica
aerogels.Comment: 19 figure
ЖЕЛЕЗИСТАЯ ГИПЕРПЛАЗИЯ ЭНДОМЕТРИЯ. ДИАГНОСТИКА, КЛИНИКА, ЛЕЧЕНИЕ
The results of examination and treatment of 105 patients with glandular hyperplasia of the endometrium, have done. The age of women ranged from 24 to 55 years, the average was equal to 42.3 +3.1 years ; reproductive age was 61 patients, 44 menopausal period. The diagnosis of glandular endometrial hyperplasia (ZHE) is set on the basis of ultrasound TVUZI, hysteroscopy, morphological study scraping the uterine mucosa. All patients carried hormone therapy for 6 months: estrogenprogestin, antiestrogen , progestin, progestogens. Efficacy in patients of reproductive age was observed in 43 (70.5 %) patients, in patients with perimenopausal in 30 ( 68.2 %) coses.In 34,8% patients relapse glandular hyperplasia of the endometrium (for the period from 1 to 3 years). Transcervical electrosurgical resection ( ablation) of the endometrium were performed. The results showed the effectiveness of endometrial ablation surgery in 90.6% of patients. Thus, in the absence of therapeutic effect of hormone therapy, recurrent uterine bleeding and endometrial hyperplasia, glandular, has hysteroscopic resection surgery (ablation) of the endometrium the high efficacy.Представлены результаты обследования и лечения 105 пациенток с железистой гиперплазией эндометрия. Возраст женщин колебался от 24 до 55 лет, в среднем был равен 42,3+3,1 года; в репродуктивном возрасте находилась 61 больная, в периоде перименопаузы-44. Диагноз железистой гиперплазии эндометрия (ЖГЭ) установлен на основании данных УЗИ, ТВУЗИ, гистероскопии, морфологического исследования соскоба слизистой оболочки матки. Всем пациенткам проводилась гормонотерапия в течение 6 месяцев: эстроген-гестагенами, антиэстрогенами, гестагенами, прогестагенами. Эффективность у больных репродуктивного возраста отмечена у 43(70,5%) пациенток, у больных в перименопаузе – у 30(68,2%).У 34,8% пациенток выявлен рецидив ЖГЭ (за период от 1 до 3 лет). Им была выполнена трансцервикальная электрохирургическая резекция (аблация) эндометрия. Результаты аблации эндометрия показали эффективность операции у 90,6% больных. Таким образом, при отсутствии лечебного эффекта гормонотерапии, рецидивах маточных кровотечений и железистой гиперплазии эндометрия высокой эффективностью обладает гистероскопическая операция-резекция (аблация) эндометрия.