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Quantum ratchets are Brownian motors in which the quantum dynamics of particles induces qualitatively new behavior. We review a series of experiments in which asymmetric semiconductor devices of sub-micron dimensions are used to study quantum ratchets for electrons. In rocked quantum-dot ratchets electron-wave interference is used to create a non-linear voltage response, leading to a ratchet effec
The former winter sports camp Frostavallen was connected by a track to the nearest railway halt, now part of the Skaneleden subtrail Ridge to Ridge. Rubus echinatus, R. senticosus and R. sciocharis occur at three sites in the area, probably a result of timber import half a century ago.
The sand-steppe is a unique vegetation type almost exclusively found in eastern Scania. It is dominated by rare species such as Koeleria glauca, Festuca polesica, Phleum arenarium, Dianthus arenarius, Astragalus arenarius, Anthericum ramosum and Syntrichia ruraliformis. In 1994, the area covered by this vegetation was estimated to be 57 ha but in the present study only 20-30 ha were refound. Prere
The primary aim of the study was to estimate the spatial scale of pollen dispersal and deposition for pollen assemblages from moss polsters in the cultivated landscape of southern Sweden, as a mean to improve future studies of the pollen/vegetation relationship in the region, and interpretation of fossil pollen data in terms of past cultural landscapes. This can be done by estimating the 'relevant
A 5-year retrospective study of the frequency of sensitization to the 25 allergens of the European standard series (ESS) was conducted in 10 centres in 8 European countries. Included were the results of 26 210 patients. The range in sensitivities differed moderately between the centres. Combining results of different centres and drawing conclusions on incidences can be done only with great care. T
J/psi production has been measured in proton-proton collisions at roots=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calcul
Adsorption of Co(II) at the aqueous interfaces of ZnO and ZnS (wurtzite) has been studied by classical wet-chemical methods, and the structure and composition of Co adsorption complexes at these interfaces have been determined by in-situ X-ray absorption fine structure (XAFS) spectroscopy. On both adsorbents, adsorption as a function of pH shows the normal behavior, i.e., a pronounced adsorption w
In this article the third-order response of an excitonically coupled dimer is studied. The three-pulse photon echo signals were calculated by extracting polarization components from the total polarization in the corresponding phase-matched directions. The total nonlinear response was obtained by numeric propagation of the density matrix, with the exciton-vibrational coupling modeled via Redfield r
A common explanation for the inability of the monetary model to beat the random walk in forecasting future exchange rates is that conventional time series tests may have low power, and that panel data should generate more powerful tests. This paper provides an extensive evaluation of this power argument to the use of panel data in the forecasting context. In particular, by using simulations it is
Ethanol production from lignocellulose has great potential and is an important step in changing fuel consumption to a more environmentally friendly alternative. Lignocellulose is a large source of biomass. However, with lignocellulose and softwood lingocellulose in particular, high conversion of cellulose into fermentable sugars requires large amounts of enzymes. Addition of surfactants is known t
Gel electrolytes based on amphiphilic copolymethacrylates containing ethylene oxide (EO)(n) side chains as ionophilic units and fluorocarbon (CF,), side chains as ionophobic units showed a substantial increase in ion conductivity, as compared to corresponding gels based on homopolymers of (EO),, methacrylate. The highest ion conductivity was found for a gel based on a copolymer composed of 24 wt%
Reduction of cellular polyamine pools results in inhibition of cell proliferation and sometimes in induction of cell death. Reduction of cellular polyamine pools can be achieved by several strategies involving all the mechanisms of polyamine homoeostasis, i.e. biosynthesis, catabolism and transport across the cell membrane. In the present paper, we concentrate on results achieved using the polyami
Boron Neutron Capture Therapy (BNCT) is an attractive concept for radiation treatment of malignant tumours. The patients receive a 10B-carrying compound with selective uptake in tumour cells, after which they are irradiated with epithermal neutrons. Theoretically, the tumour cells are killed by the high-LET particles produces in 10B(n, alpha)7Li reactions inside or close to the cell nucleus, while
The isoflurane-saving and CO2-retaining effects of a charcoal filter were compared with a Siemens standard heat and moisture (HME) exchanger and an emptied specimen (dummy). Isoflurane was delivered during the inspiratory phase and consumption investigated at 10, 15 and 25 cycles min-1. The investigation was performed by ventilation with humidified air with a constant end-tidal CO2 and temperature
It is known that ethnicity is a risk factor for diabetes. Thus, individuals of African, Latin American, and Asian descent are particularly susceptible (1). As an example, a health survey in six urban areas in Peru found a diabetes prevalence of 17% among women (2,3). It was also found that low socioeconomic status was associated with a high burden of noncommunicable diseases and appeared as an ind
High-risk human papillomavirus (HPV) types cause most cervical carcinomas and are sexually transmitted. Sexual behavior therefore affects HPV exposure and its cancer sequelae. The International Collaboration of Epidemiological Studies of Cervical Cancer has combined data on lifetime number of sexual partners and age at first sexual intercourse from 21 studies, or groups of studies, including 10,77
Simultaneous, spatially resolved monitoring of C2 and OH in a flame is reported. Data could be captured in 10 ns employing two pulsed lasers and a diode array detector. Laser-production of C2 was also observed and a kinetic study of such molecules was performed.
The aim of the study was to assess the short-term cardiorespiratory effects of a standard red cell transfusion in very low birth weight (<1500 g) infants undergoing intensive care. A total of 37 infants (birth weight 920+/-230 g, gestational age 27.8+/-2.1 weeks, age at study 6.1+/-3.9 days) with indwelling arterial lines were studied when 10 ml/kg of packed donor red cells were transfused based o
