Full light absorption in single arrays of spherical nanoparticles

In this paper we show that arrays of core-shell nanoparticles function as effective thin absorbers of light. In contrast to known metamaterial absorbers, the introduced absorbers are formed by single planar arrays of spherical inclusions and enable full absorption of light incident on either or both sides of the array. We demonstrate possibilities for realizing different kinds of symmetric absorbers, including resonant, ultra-broadband, angularly selective, and all-angle absorbers. The physical principle behind these designs is explained considering balanced electric and magnetic responses of unit cells. Photovoltaic devices and thermal emitters are the two most important potential applications of the proposed designs.Comment: (e.g.: 18 pages, 5 figures

Symmetry and reciprocity constraints on diffraction by gratings of quasi-planar particles

Symmetry and reciprocity constraints on polarization state of the field diffracted by gratings of quasi-planar particles are considered. It is shown that the optical activity effects observed recently in arrays of quasi-planar plasmonic particles on a dielectric substrate are due to the reflection of the field at the air-dielectric slab interface and are proportional to this reflection coefficient.Comment: 11 pages, 3 figures, 12 references; minor corrections for better appearanc

Infective endocarditis caused by gram-negative bacteria

Infective endocarditis (IE) caused by Gram-negative bacteria is a rare and insufficiently characterized form of endocarditis. The literature review presents data on the frequency, course, risk factors, diagnosis and treatment of both IE caused by the HACEK microorganisms (Haemophilus spр., Aggregatibacter spp., Cardiobacterium hominis, Eikenella corrodens, Kingella) and other Gram-negative bacteria. Gram-negative bacteria are the cause of 3.6–13.6 % IE cases (HACEK microorganisms in 0.8–3 % of IE cases in adults, non-HACEK in 1.8–3.9 %). Patients with IE caused by the HACEK microorganisms are younger, their disease is not associated with previous in-hospital treatment and is subacute with favorable prognosis (intrahospital mortality is 2–3 %). HACEK microorganisms mostly retain sensitivity to many antibiotics. Risk factors of IE caused by HACEK microorganisms are dental interventions, heart disorders, valve prostheses and other implanted cardiac devices. IE caused by non-HACEK Gram-negative bacteria is more common in elderly with concomitant disorders and usually is acute; intrahospital mortality is 13–36.5 %. Risk factors of IE caused by non-HACEK microorganisms are valve prostheses, electrical pacemakers, venous and central catheters, recent in-hospital treatment, Gram-negative bacteremia, decreased immunity, drug abuse, urinary infection, alcoholism, cirrhosis of the liver, removed spleen, consequences of dog and cat bites, working with the soil. Among Gram-negative non-HACEK bacteria causing IE, 28 % have multi-drug resistance (MDR / XDR) against antibiotics. Therefore, Gram-negative bacteria rarely cause IE but during selection of empiric therapy in patients with IE with corresponding risk factors, probability of Gram-negative causative microorganisms in IE etiology should be taken into account