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1.
Article in English | MEDLINE | ID: mdl-26565370

ABSTRACT

The long-standing discrepancy in the equation of state of charge neutral plasmas, the occurrence of an e(2) direct term in the second virial coefficient, is dealt with. We state that such a contribution should not appear for a pure Coulomb interaction.

2.
Article in English | MEDLINE | ID: mdl-25679724

ABSTRACT

We discuss a long-standing discrepancy in the equation of state of charge-neutral plasmas, the occurrence of an e(2) direct term. This e(2) term may appear in dependence of the way to determine the mean value of the potential energy. We show that such a contribution should not appear for pure Coulomb interaction.

3.
Phys Rev E Stat Nonlin Soft Matter Phys ; 70(5 Pt 2): 057401, 2004 Nov.
Article in English | MEDLINE | ID: mdl-15600800

ABSTRACT

We propose a theoretical Hugoniot relation obtained by combining results for the equation of state from the direct path integral Monte Carlo technique (DPIMC) and those from reaction ensemble Monte Carlo (REMC) simulations. The main idea of this proposal is based on the fact that the DPMIC technique provides first-principle results for a wide range of densities and temperatures including the region of partially ionized plasmas. On the other hand, for lower temperatures where the formation of molecules becomes dominant, DPIMC simulations become cumbersome and inefficient. For this region it is possible to use accurate REMC simulations where bound states (molecules) are treated on the Born-Oppenheimer level. The remaining interaction is then reduced to the scattering between neutral particles which is reliably treated classically by applying effective potentials. The resulting Hugoniot is located between the experimental values of Knudson et al. [Phys. Rev. Lett. 87, 225501 (2001)] and Collins et al. [Science 281, 1178 (1998)].

4.
Phys Rev E Stat Nonlin Soft Matter Phys ; 69(6 Pt 1): 061204, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15244551

ABSTRACT

In spite of the simple structure of hydrogen, up to now there is no unified theoretical and experimental description of hydrogen at high pressures. Recent results of Z-pinch experiments show a large deviation from those obtained by laser driven ones. Theoretical investigations including ab initio computer simulations show considerable differences at such extreme conditions from each other and from experimental values. We apply the reaction ensemble Monte Carlo technique on one hand and a combination of the hypernetted chain approximation with the mass action law on the other to study the behavior of dense hydrogen at such conditions. The agreement between both methods for the equation of state and for the Hugoniot curve is excellent. Comparison to other methods and experimental results is also performed.

5.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(2 Pt 2): 026405, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11497709

ABSTRACT

Anomalously high generation efficiency of coherent higher field harmonics in collisions between oppositely charged particles in the field of femtosecond lasers is predicted. This is based on rigorous numerical solutions of a quantum kinetic equation for dense laser plasmas that overcomes limitations of previous investigations.

6.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(2 Pt 2): 026414, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11497718

ABSTRACT

Collisional absorption of dense, fully ionized plasmas in strong laser fields is investigated starting from a quantum kinetic equation with non-Markovian and field-dependent collision integrals in dynamically screened Born approximation. This allows to find rather general balance equations for the energy and the current. For high-frequency laser fields, quantum statistical expressions for the electrical current density and the cycle-averaged electron-ion collision frequency in terms of the Lindhard dielectric function are derived. The expressions are valid for arbitrary field strength assuming the nonrelativistic case. Numerical results are presented to discuss these quantities as a function of the applied laser field and for different plasma parameters. In particular, nonlinear phenomena such as higher harmonics generation and multiphoton emission and absorption in electron-ion collisions are considered. The significance to include quantum effects is demonstrated comparing our results for the collision frequency with previous results obtained from classical theories.

7.
Phys Rev E Stat Nonlin Soft Matter Phys ; 64(1 Pt 2): 016409, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11461412

ABSTRACT

Classical Molecular Dynamics simulations for a one-component plasma are presented. Quantum effects are included in the form of the Kelbg potential. Results for the dynamical structure factor are compared with the Vlasov and random phase approximation theories. The influence of the coupling parameter Gamma, degeneracy parameter rho Lambda(3), and the form of the pair interaction on the optical plasmon dispersion is investigated. An improved analytical approximation for the dispersion of Langmuir waves is presented.

8.
Phys Rev E Stat Nonlin Soft Matter Phys ; 63(2 Pt 1): 020102, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11308449

ABSTRACT

The short-time dynamics of correlated systems is strongly influenced by initial correlations, giving rise to an additional collision integral in the non-Markovian kinetic equation. Exact cancellation of the two integrals is found if the initial state is thermal equilibrium, which is an important consistency criterion. Analytical results are given for the time evolution of the correlation energy, which are confirmed by comparisons with molecular dynamics simulations.

9.
Article in English | MEDLINE | ID: mdl-11970338

ABSTRACT

A kinetic theory for quantum many-particle systems in time-dependent electromagnetic fields is developed based on a gauge-invariant formulation. The resulting kinetic equation generalizes previous results to quantum systems and includes many-body effects. It is, in particular, applicable to the interaction of strong laser fields with dense correlated plasmas.

10.
Article in English | MEDLINE | ID: mdl-11970552

ABSTRACT

The two-particle problem within a nonequilibrium many-particle system is investigated in the framework of real-time Green's functions. Starting from the nonequilibrium Bethe-Salpeter equation on the Keldysh contour, a Dyson equation is given for two-time two-particle Green's functions. Thereby the well-known Kadanoff-Baym equations are generalized to the case of two-particle functions. The two-time structure of the equations is achieved in an exact way using the semigroup property of the free-particle propagators. The frequently used Shindo approximation is thus avoided. It turns out that results obtained earlier are valid only in limiting cases of a nondegenerate system or a static interaction, respectively. For the case of thermodynamic equilibrium, the differences to former results obtained for the effective two-particle Hamiltonian are discussed.

16.
Phys Rev A ; 42(4): 2340-2345, 1990 Aug 15.
Article in English | MEDLINE | ID: mdl-9904285
17.
Dev Sante ; (84): 4-6, 1989 Dec.
Article in French | MEDLINE | ID: mdl-12282920

ABSTRACT

PIP: Dietary deficiency in iron and to a lesser extent folic acid is the principle cause of anemia in the world. Reproductive aged women and growing children are the principle groups at risk of anemia. About half of nonpregnant reproductive aged women in tropical countries have hemoglobin levels lower than 12 g/100 ml, the level used by the World Health Organization to define anemia. Nutritional anemia is even more widespread among pregnant and lactating women because of the increased needs for iron during those periods. Pregnant women need almost 500 mg of iron for their increased red blood cell mass, 220 mg for routine iron loss through the urine, bile, sweat, and other routes; 290 mg for the fetus, and almost 25 mg for the placenta. In all, the pregnant women theoretically requires over 1000 mg of iron through diet or bodily reserves. Healthy, well-nourished women have total iron reserves of 2500 mg, but according to published data almost 2/3 of pregnant women even in favorable circumstances end their pregnancies with no remaining iron reserves. In tropical regions the lack of iron reserves is aggravated by parasites and infections, closely spaced pregnancies that do not allow restoration of reserves, and poor dietary availability of iron. Anemia during pregnancy is associated with elevated risks of maternal morbidity and mortality. Fatigue, dyspnea, palpitations and tachycardia, vertigo, loss of appetite and cravings for soil or other inappropriate substances are frequently observed in anemic women. The risks of prematurity and low weight are increased for infants of anemic women. Fetal malformation may be associated with folic acid deficiency. Nutrition education is needed for pregnant women. Local foods may be enriched with iron, and pregnant women may be given iron and vitamin B12 supplements directly. Iron supplements may rapidly increase iron reserves, but they are poorly tolerated by many women. The supplements should be avoided if possible early in the pregnancy because digestive intolerance is more likely in the 1st months of pregnancy. Parasitic and bacterial infections should be diagnosed and treated as a step in controlling anemia.^ieng


Subject(s)
Deficiency Diseases , Evaluation Studies as Topic , Folic Acid , Health Planning , Iron , Nutrition Disorders , Population Characteristics , Prenatal Care , Risk Factors , Therapeutics , Biology , Blood , Chemical Phenomena , Chemistry , Delivery of Health Care , Disease , Health , Health Services , Inorganic Chemicals , Maternal Health Services , Maternal-Child Health Centers , Metals , Physiology , Primary Health Care , Research
18.
Phys Rev A Gen Phys ; 38(4): 2174-2177, 1988 Aug 15.
Article in English | MEDLINE | ID: mdl-9900620
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