We investigate the effect of exchange and correlation ͑XC͒ on the plasmon spectrum and the Coulomb drag between spatially separated low-density two-dimensional electron layers. We adopt a different approach, which employs dynamic XC kernels in the calculation of the bilayer plasmon spectra and of the plasmon-mediated drag, and static many-body local field factors in the calculation of the particle-hole contribution to the drag. The spectrum of bilayer plasmons and the drag resistivity are calculated in a broad range of temperatures taking into account both intra-and interlayer correlation effects. We observe that both plasmon modes are strongly affected by XC corrections. After the inclusion of the complex dynamic XC kernels, a decrease of the electron density induces shifts of the plasmon branches in opposite directions. This is in stark contrast with the tendency observed within random phase approximation that both optical and acoustical plasmons move away from the boundary of the particle-hole continuum with a decrease in the electron density. We find that the introduction of XC corrections results in a significant enhancement of the transresistivity and qualitative changes in its temperature dependence. In particular, the large high-temperature plasmon peak that is present in the random phase approximation is found to disappear when the XC corrections are included. Our numerical results at low temperatures are in good agreement with the results of recent experiments by Kellogg et al. ͓Solid State Commun. 123, 515 ͑2002͔͒.

Objective To investigate the incidence and clinical significance of cardiovascular disease in systemic lupus erythematosus patients. Methods We included systemic lupus erythematosus patients ( n = 18,575) without previous cardiovascular disease and age- and sex-matched individuals without systemic lupus erythematosus (controls; n = 92,875) from the Korean National Health Insurance Service database (2008–2014). Both cohorts were followed up for incident cardiovascular disease and death until 2015. Results During follow up, myocardial infarction occurred in 203 systemic lupus erythematosus patients and 325 controls (incidence rate: 1.76 and 0.56 per 1000 person-years, respectively), stroke occurred in 289 patients and 403 controls (incidence rate: 2.51 and 0.70 per 1000 person-years, respectively), heart failure occurred in 358 patients and 354 controls (incidence rate 3.11 and 0.61 per 1000 person-years, respectively), and death occurred in 744 patients and 948 controls (incidence rate 6.54 and 1.64 per 1000 person-years, respectively). Patients with systemic lupus erythematosus had higher risks for myocardial infarction (hazard ratio: 2.74, 95% confidence interval: 2.28–3.37), stroke (hazard ratio: 3.31, 95% confidence interval: 2.84–3.86), heart failure (hazard ratio: 4.60, 95% confidence interval: 3.96–5.35), and cardiac death (hazard ratio: 3.98, 95% confidence interval: 3.61–4.39). Conclusions Here, systemic lupus erythematosus was an independent risk factor for cardiovascular disease, thus cardiac assessment and management are critical in systemic lupus erythematosus patients.

We revisit the problem of the spontaneous magnetization of an sp impurity atom in a simple metal host. The main features of interest are: (i) Formation of the spherical spin density/charge density wave around the impurity; (ii) Considerable decrease in the size of the pseudoatom in the spinpolarized state as compared with the paramagnetic one, and (iii) Relevance of the electron affinity of the isolated atom to this spin polarization, which is clarified by tracing the transformation of the pseudoatom into an isolated negative ion in the low-density limit of the enveloping electron gas.PACS numbers: 75.30.Fv, 71.45.Lr, 71.55.Ak Interests in spintronics are on the rise from both scientific and technological points of view.1,2 Since devices in spintronics involve active control and manipulation of spin degrees of freedom in solid-state systems, it is absolutely necessary to have a deeper understanding of fundamental interactions between electron spins and its solidstate environments. In view of this situation, we are interested in a composite system of an atom immersed into the otherwise homogeneous electron gas (EG).In an isolated atom, the ground state obeys the Hund's multiplicity rule that requires the highest spin configuration compatible with the Pauli's exclusion principle. Physically this rule is interpreted as the consequence of an effectively larger nuclear charge in a higher spin configuration due essentially to the exchange effect.3 Similarly in a uniform EG, the same effect favors spin polarization, bringing about the spontaneous spin-symmetry breaking or the spin-density-wave state which was proven to be the ground state at arbitrary electron densities within the Hartree-Fock (exchange only) approximation.4,5 The correlation effect, however, acts in the opposite direction 5 and this effect is so strong in an EG as to lead eventually to the paramagnetic ground state for the majority of metals.This paper deals with the composite system of an atom immersed into EG. Investigation of atoms embedded in the EG in both their paramagnetic 6,7,8,9,10,11 and spinpolarized 12,13,14,15,16 states has a long history. However, to the best of our knowledge, some important features of the electronic structure of the spontaneously spinpolarized states of this system have not been addressed so far. More specifically, they include: (i) Formation of the spherical combined spin density/charge density wave, which slowly decays with the distance from the impurity; (ii) Significant shrinkage of spin-polarized pseudoatoms as compared with their spin-neutral counterparts, and (iii) Demonstration of the way how the spin-polarized states of the impurities turn into those of the negative ions of the corresponding isolated atoms as the density of the enveloping EG tends to zero. The purpose of this work is to elucidate the above points.We are concerned with an impurity of the atomic number Z (a pseudoatom) embedded into the otherwise homogeneous EG at zero temperature characterized by its electron-density parameter r s = (3/4πn...

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