We report on an extremely narrow linewidth of a two-dimensional electron-gas photoluminescence in GaAs/AlGaAs quantum wells pumped by ultrasonic vibrations. Below the threshold pumping amplitude, the observed emission line is weak, broad, and undergoes a redshift consistent with the evolution of an electron-hole plasma recombination in the oscillating piezoelectric fields accompanying the sample v

The multi-layer dynamic model SAFE was applied to the forested catchment istebna (Southern Poland), to study recovery from acidification. Environmental pollution in the area has been historically high. The model uses data from an intensive monitoring plot established in 1999 in a spruce stand, which was planted in 1880. Observations showed that the soil was depleted of base cations. The measured b

In order to study the effect of heparin in inducing osteoporosis, 30 female rats were divided in two groups and treated with daily injections of 2 IU heparin/g body weight for 33 and 65 days and compared with the same number of rats acting as controls. The mineral bone mass in the femora of the animals was measured quantitatively. A significant (p less than 0.001) reduction in bone mineral mass wa

The phase behavior and phase structure of the SDS (sodium dodecyl sulfate)-Al(NO3)(3)-H2O system have been studied by combined NMR, SAXS, cryo-TEM and optical polarization microscopy methods at 298 K (25 degreesC) and 311 K (38 degreesC). At 298 K, the micellar solution phase of the binary system SDS-water is not capable of solubilising substantial amount of Al(NO3)(3) salt, and at a certain subst

An investigation of the polar glycosidic fraction from the leaves of myrtle afforded four galloylated nonprenylated phloroglucinol glucosides (3a-d) related to the endoperoxide hormone G3 (4) in terms of structure and biogenesis. Despite their close similarity, significant antibacterial activity was shown only by one of these compounds (3b, gallomyrtucommulone B), while the G3 hormone (4) was inac

Diffusion nuclear magnetic resonance methods traditionally used within colloid and porous media science have recently been applied to the study of microstructures in biological tissue using magnetic resonance imaging. Improved experimental design utilizing multiple diffusion periods or the length of the displacement encoding gradient pulses increases the information content of the diffusion experi

In the course of a screening for compounds inhibiting the growth of two human breast cancer cells lines, two highly cytotoxic compounds were isolated from fermentations of Myrothecium roridum. The elucidation of their structures revealed that they are macrocyclic trichothecenes of the verrucarin type, 16-hydroxyverrucarin A (1), reported here as a natural product for the first time, and verrucarin

Background: The Multiple Outcomes of Raloxifene Evaluation (MORE) study showed that treatment with raloxifene reduces the risk of vertebral fracture and breast cancer in postmenopausal women with osteoporosis. Objective: Based on the MORE study the aim of the present study was to assess the cost effectiveness of raloxifene (compared with no treatment) for the treatment of osteoporosis in postmenop

Migratory songbirds use the geomagnetic field, stars, the Sun, and polarized light patterns to determine their migratory direction. To prevent navigational errors, it is necessary to calibrate all of these compass systems to a common reference. We show that migratory Savannah sparrows use polarized light cues from the region of sky near the horizon to recalibrate the magnetic compass at both sunri

A pilot-plant study, made to clarify whether biological denitrification is a possible and suitable method for nitrate reduction of drinking water in Sweden is presented. The concentration of nitrate-nitrogen in un-treated water was 10–15 mg/l. The reactor was a 1.2 m aluminium tube with a inner diameter of 0.19 m. 0.75 m was filled with Filtralite®, expanded clay, through which the nitrate-contami

In this paper, the Ge overgrowth of oxidized and reduced Ge/Si islands is studied. The islands were grown in a hotwall ultrahigh vacuum chemical vapour deposition reactor. The oxidation was performed in air at room temperature and the reduction in a hydrogen atmosphere at 600degreesC. After reduction, Ge was deposited at the same temperature. The results of the overgrowth show that the reduced nat

High plasma levels of oestrogens are associated with increased breast cancer risk. If smoking, as has been suggested, have both a tumour initiating mutagenic effect and a protective anti-oestrogenic effect, one would assume that smokers who give up smoking have the highest incidence of breast cancer. This was evaluated in the follow-up of a cohort of 10,902 women of whom 4,359 were premenopausal.

Objectives: Sentinel surveys in Bissau, the capital of Guinea-Bissau, have shown low prevalence of HIV-1 but high HIV-2 prevalence before 1998. Guinea-Bissau experienced a civil war in 1998-1999. To examine specifically the trends of HIV prevalence from antenatal surveys in Bissau, Guinea-Bissau in 1987-2004, and whether the civil war in 1998-1999 could have an effect on HIV prevalence levels afte

New Zealand ground levels of UV-radiation have always been comparatively high, however, little attention has been paid to the effects of UV-radiation on biotic interactions in New Zealand freshwater systems. In two outdoor short term microcosm experiments we tested the effects of UV-radiation on the behaviour of grazing mayfly Deleatidium (Ephemeroptera) larvae. The relationship between pigmentati

BACKGROUND: Hepatitis G virus/GBV-C is a recently discovered virus, and its relevance in chronic hepatitis is still debated. METHODS: We have previously described 127 long-term-studied and well-characterized patients with chronic non-A, non-B hepatitis (NANBH). Ninety-one (71.7%) were positive for hepatitis C virus antibodies (anti-HCV) in a first-generation anti-HCV enzyme-linked immunosorbent as

We report single molecule photoluminescence spectra of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) in PMMA-matrix at 293 and 20 K with 90 s acquisition time. All spectra at 293 K are very similar, contrary to literature results with acquisition times < 5 s. We propose that fluctuations of conformations with distinct emission properties cause broadening of the spectra and

The leptoproduction of J/psi mesons is studied in inelastic reactions for four momentorri transfers 2 < Q(2) < 100GeV(2). The data were taken with the H1 detector at the electron proton collider HERA and correspond to an integrated luminosity of 77 pb(-1). Single differential and double differential cross sections are measured with increased precision compared with previous analyses. New leading o