Dynamic properties and the roton mode attenuation in liquid 3He: ab initio study within the self-consistent method of moments.

The dynamic structure factor and the eigenmodes of density fluctuations in liquid 3He are studied using a novel non-perturbative approach. This new version of the self-consistent method of moments invokes up to nine sum rules and other exact relations, the two-parameter Shannon information entropy maximization procedure, and the ab initio path integral Monte Carlo simulations which provide necessary reliable input information on the system static properties. Detailed analysis is performed of the collective excitations dispersion relations, the modes' decrements and the static structure factor of 3He at the saturated vapour pressure. The results are compared to available experimental data by Albergamo et al. (Albergamo et al. 2007 Phys. Rev. Lett. 99, 205301. (doi:10.1103/PhysRevLett.99.205301)) and Fåk et al. (Fåk et al. 1994 J. Low Temp. Phys. 97, 445-487. (doi:10.1007/BF00754303)). The theory reveals a clear signature of the roton-like feature in the particle-hole segment of the excitation spectrum with a significant reduction of the roton decrement in the wavenumber range [Formula: see text]. The observed roton mode remains a well-defined collective mode even in the particle-hole band, where it is strongly damped. The existence of the roton-like mode in the bulk liquid 3He is confirmed like in other quantum fluids. The phonon branch of the spectrum is in a reasonable agreement with the same experimental data. This article is part of the theme issue 'Dynamic and transient processes in warm dense matter'.

Dynamic characteristics of three-dimensional strongly coupled plasmas.

The dynamic structure factor and other dynamic characteristics of strongly coupled one-component plasmas have been studied [Yu. V. Arkhipov et al., Phys. Rev. Lett. 119, 045001 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.045001] using the self-consistent version of the method of moments. Within any version of the latter, the system dielectric function satisfies all involved sum rules and other exact relations automatically, and the advantage of this version is that, in addition, the dynamic characteristics (the dynamic structure factor, the dispersion, and decay parameters of the collective modes) are all expressed in terms of the static ones (the static structure factor) without any adjustment to the simulation data. The approach outlined in the aforementioned Letter is justified in detail and applied mainly to the classical Coulomb systems achieving satisfactory agreement with new numerical simulation data. It is shown how the realm of applicability of the method can be extended to partly degenerate and multicomponent systems, even to simple liquids. Some additional theoretical results are presented in the Supplemental Material.

Direct Determination of Dynamic Properties of Coulomb and Yukawa Classical One-Component Plasmas.

Dynamic characteristics of strongly coupled classical one-component Coulomb and Yukawa plasmas are obtained within the nonperturbative model-free moment approach without any data input from simulations so that the dynamic structure factor (DSF) satisfies the first three nonvanishing sum rules automatically. The DSF, dispersion, decay, sound speed, and other characteristics of the collective modes are determined using exclusively the static structure factor calculated from various theoretical approaches including the hypernetted chain approximation. A good quantitative agreement with molecular dynamics simulation data is achieved.

Dielectric function of dense plasmas, their stopping power, and sum rules.

Mathematical, particularly, asymptotic properties of the random-phase approximation, Mermin approximation, and extended Mermin-type approximation of the coupled plasma dielectric function are analyzed within the method of moments. These models are generalized for two-component plasmas. Some drawbacks and advantages of the above models are pointed out. The two-component plasma stopping power is shown to be enhanced with respect to that of the electron fluid.

Dynamic ion structure factor of warm dense matter.

The dynamics of the ion structure in warm dense matter is determined by molecular dynamics simulations using an effective ion-ion potential. This potential is obtained from ab initio simulations and has a strong short-range repulsion added to a screened Coulomb potential. Models based on static or dynamic local field corrections are found to be insufficient to describe the data. An extended Mermin approach, a hydrodynamic model, and the method of moments with local constraints are capable of reproducing the numerical results but have rather limited predictive powers as they all need some numerical data as input. The method of moments is found to be the most promising.

[Surgical tactics and causes of death in ulcer gastroduodenal bleedings].

4212 patients with ulcer gastrointestinal bleedings were treated during 1990-2007 years. 364 patients had gastric ulcers, other patients had duodenal ulcers. 1819 patients (43.2%) were operated. 418 patients (23%) were operated due to ineffective endoscopic hemostasis and recurrent bleedings. 409 patients (22.5%) underwent urgent operations because of risk for recurrent bleeding. Elective operations were carried out to 1358 patients (74.7%). Postoperative lethality amounted 5.8% including 19.1% lethality after emergency operations, 4.2% lethality - after urgent operations and 0.8% lethality - after delayed operations. The general hospital lethality amounted 3.3%. Lethality can be decreased by extension of indications for urgent operations, preventing recurrent bleedings.

Dynamic properties of one-component strongly coupled plasmas: the sum-rule approach.

The dynamic characteristics of strongly coupled one-component plasmas are studied within the moment approach. Our results on the dynamic structure factor and the dynamic local-field correction satisfy the sum rules and other exact relations automatically. A quantitative agreement is obtained with numerous simulation data on the plasma dynamic properties, including the dispersion and decay of collective modes. Our approach allows us to correct and complement the results previously found with other treatments.

Fast-projectile stopping power of quantal multicomponent strongly coupled plasmas.

The Bethe-Larkin formula for the fast-projectile stopping power is extended to multicomponent plasmas. The results are to contribute to the correct interpretation of the experimental data, which could permit us to test existing and future models of thermodynamic, static, and dynamic characteristics of strongly coupled Coulomb systems.

Collective and static properties of model two-component plasmas.

Classical MD data on the charge-charge dynamic structure factor of two-component plasmas (TCP) modeled in Phys. Rev. A 23, 2041 (1981) are analyzed using the sum rules and other exact relations. The convergent power moments of the imaginary part of the model system dielectric function are expressed in terms of its partial static structure factors, which are computed by the method of hypernetted chains using the Deutsch effective potential. High-frequency asymptotic behavior of the dielectric function is specified to include the effects of inverse bremsstrahlung. The agreement with the MD data is improved, and important statistical characteristics of the model TCP, such as the probability to find both electron and ion at one point, are determined.

[Enteral tube feeding early after surgery on the stomach and the duodenum]. / Enteral'noe zondovoe pitanie v rannem periode posle operatsii na zheludke i dvenadtsatiperstnoi kishke.

Experience in enteral tube feeding (ETF) early after stomach resection, gastrectomy, reconstructive surgeries for chronic duodenal obstructions and postgastroresection disorders in 1716 patients is presented. Irrigators were installed in the jejunum during surgery, more rarely--through gastroscope below distal anastomosis. During the first day saline solutions were administered, further--nutritional cocktails. Period of ETF was 5.8 +/- 0.8 days in uncomplicated postoperative period and from 9 to 73 days in postoperative complications. ETF stimulates motor, resorption, synthetic, barrier functions of the small intestine. ETF permits to improve immediate results of stomach and duodenum surgery and to reduce cost of treatment.

Stopping power of strongly coupled electronic plasmas: sum rules and asymptotic forms.

The stopping power of coupled electronic plasmas is investigated. Within the dielectric formalism and employing the method of frequency moments for the dielectric function we obtain a general formula describing the linear stopping power of a coupled plasma. Analytical results for the low- and high-projectile-velocity asymptotic forms are obtained. A sum rule for the plasma heavy ions linear stopping power projectile velocity distribution is established to be related to the dielectric permeability "negative" frequency moment. This permits for a simple interpretation of stopping power data.