Search results

Filter

Filetype

Your search for "*" yielded 529975 hits

Conformational disorder of conjugated polymers

Conformational disorder of conjugated polymers is an important issue to be understood and quantified. In this paper we present a new method to assess the chain conformation of conjugated polymers based on measurements of intrachain energy transfer. The chain conformation is modeled on the basis of monomer-monomer interactions, such as torsion, bending, and stretching of the connecting bond. The la

Calibration of magnetic and celestial compass cues in migratory birds - a review of cue-conflict experiments

Migratory birds use multiple sources of compass information for orientation, including the geomagnetic field, the sun, skylight polarization patterns and star patterns. In this paper we review the results of cue-conflict experiments designed to determine the relative importance of the different compass mechanisms, and how directional information from these compass mechanisms is integrated. We focu

The FERRUM project: experimentally determined metastable lifetimes and transition probabilities for forbidden [Ti II] lines observed in eta Carinae

In the spectrum of an emission-line region ejected from the massive star Eta Carinae, called the strontium filament (SrF), forbidden lines from many elements, in particular [Sr II] and [Ti II], are observed. These lines are strong in this specific region and valuable for plasma diagnostics. Forbidden lines are not easily produced in laboratory light sources and the atomic parameters for these line

Helicobacter pylori infection in children in Estonia: Decreasing seroprevalence during the 11-year period of profound socioeconomic changes

Background. The prevalence of Helicobacter pylori infection is inversely associated with socioeconomic conditions in childhood. In Estonia, a high prevalence of H. pylori infection has been observed among children born in 1987 and earlier. Since 1991, after the dissolution of the USSR, profound social and economic changes have taken place in the country. The aim of the study was to evaluate change

Are neuronal markers and neocortical graft-host interface influenced by housing conditions in rats with cortical infarct cavity?

The aim was to study if exposure to an enriched environment influenced graft-host interface and neuronal markers in neocortical grafts implanted in cortical infarct cavities 3 weeks after distal ligation of the middle cerebral artery in adult hypertensive rats. Half the rats were exposed to an enriched environment for 2 h daily 5 days a week starting 1 week after the arterial ligation. The brain w

The genera Metalorryia and Tydeus (Acari : Prostigmata : Tydeidae), new and unrecorded species from south Sweden

Six tydeid mite species assigned to two genera are described and illustrated: Metalorryia anchisi n. sp. and Tydeus onestiae n. sp. from mosses, lichens and decaying wood; Tydeus belfiori n. sp. and T. armindae n. sp. from lichens and bark of old apple trees; Tydeus ramiri n. sp. from lichens and mosses of Pinus and Sphagnum moss on the ground; and Tydeus serpettae n. sp. from mosses on stones nea

Spatial-pattern analysis in a territorial spider: evidence for multi-scale effects

Territorial animals maintain a certain distance to neighbouring conspecifics, presumably leading to a regular spatial pattern through social spacing. Nevertheless, most animal populations are assumed to show aggregation at certain distance ranges, reflecting the scale dependency of spatial patterns. Leucorchestris arenicola (Araneae: Sparassidae) is a burrow-living spider species that shows territ

Clinical correlation between adenosine deaminase activity and pre-eclampsia severity

This study evaluated the relationship between the activity of the inflammatory indicator adenosine deaminase (ADA) in placental tissue and maternal and fetal (umbilical cord) plasma and the severity of pre-eclampsia. Maternal and umbilical vein whole blood and placental tissue samples were collected from women with normal pregnancies (n = 33) and patients with mild (n = 12) or severe (n = 17) pre-

Shear-induced sponge-to-lamellar phase transition studied by rheo-birefringence

We report on the shear induced transition from the L-3- to the L-alpha-phase studied by means of flow birefringence using the system pentaethyleneglycol monododecylether (C12E5), decane, water. The dependence of the critical shear rate, at which the transition from the isotropic state to the anisotropic takes place, on membrane volume fraction was studied in temperature ramp experiments at differe

Contribution of hip strength indices to hip fracture risk in elderly men and women

In this prospective, case-control study, femoral neck diameter, cross-sectional moment of inertia, or section modulus was an independent predictor of hip fracture risk after adjustment for BMD. However, the contribution of each of these indices to hip fracture prediction was modest in the presence of BMD. Introduction: The relative contribution of measures of hip strength to hip fracture predictio

Perinatal adaptive response of the adrenal and carotid blood flow in sheep fetuses subjected to total cord occlusion

Objective. To investigate the perinatal adaptive response of the adrenal blood flow/adrenal fractional moving blood volume (AFMBV) and carotid blood flow (CBF), in sheep fetuses subjected to severe acute intrauterine hypoxia/asphyxia induced by total cord occlusion.Methods. Adrenal blood flow velocity, AFMBV and CBF were measured in 13 exteriorized fetal sheep; eight of them underwent total umbili

Indirect estimates of wing-propulsion forces in horizontally diving Atlantic puffins (Fratercula arctica L.)

Instantaneous force production in wing-propelled diving Atlantic puffins (Fratercula arctica) was investigated using four birds for which instantaneous estimates of velocity and acceleration of the body were made. The quasi-steady resultant force acting on the body in the sagittal plane was calculated using acceleration reaction coefficients, buoyancy estimates, and drag coefficients taken from th

Morphometric variation in a hybrid zone between the weed, Silene vulgaris, and the endemic, Silene uniflora ssp petraea (Caryophyllaceae), on the Baltic island of Oland

On the island of Oland the weed, Silene vulgaris (Moench) Garcke, and the endemic, Silene uniflora Roth ssp. petraea, hybridize when brought into contact by anthropogenic disturbance. Variation was studied in transects across a hybrid zone where a linear population of S. vulgaris crossed the native habitat of S. uniflora ssp. petraea. Plants were scored for 20 morphological characters. Although in

Diurnal variations of the dominant cycle length of chronic atrial fibrillation

High-resolution digital Holter recording was carried out in 21 patients (15 men, 64 +/- 12 yr) with chronic atrial fibrillation. Dominating atrial cycle length (DACL) was derived by frequency domain analysis of QRST-reduced electrocardiograms. Daytime mean DACL was 150 +/- 17 ms, and nighttime mean was 157 +/- 22 ms (P = 0. 0002). Diurnal fluctuation in DACL differed among patients: it tended to b

Cryptanalysis of Achterbahn-Version 2

Achterbahn is one of the stream cipher proposals in the eSTREAM project. After the first version had been successfully cryptanalyzed, the second version, denoted Achterbahn-Version 2, was proposed. This paper demonstrates an attack on this second version. In the attack, a quadratic approximation of the output function is considered. The attack uses less keystream bits than the upper limit given by

A pancreatic islet-specific microRNA regulates insulin secretion

MicroRNAs (miRNAs) constitute a growing class of non-coding RNAs that are thought to regulate gene expression by translational repression(1). Several miRNAs in animals exhibit tissue-specific or developmental-stage-specific expression, indicating that they could play important roles in many biological processes(2-4). To study the role of miRNAs in pancreatic endocrine cells we cloned and identifie

Lymphoid aggregates in endobronchial biopsies from young elite cross-country skiers

Observation of bronchus-associated lymphoid tissue (BALT) in whole lung specimens from healthy nonsmoking adults has questioned the hypothesis that BALT is not constitutively present in healthy adult human lungs. In our study, we investigated endobronchial biopsies of the second- and third-generation carinae from 44 cross-country ski athletes and 12 healthy control subjects, all nonsmoking young a

Plant and microbial uptake and allocation of organic and inorganic nitrogen related to plant growth forms and soil conditions at two subarctic tundra types

In order to follow the uptake and allocation of N in different plant functional types and microbes in two tundra ecosystems differing in nutrient availability, we performed a 15N-labeling experiment with three N forms and followed the partitioning of 15N label among plants, microorganisms and soil organic matter. At both sites the deciduous dwarf shrub Betula nana and the evergreen Empetrum hermap