695 research outputs found
Seafood from Norway : food safety
Since Norway is a major supplier of seafood
worldwide, monitoring the food safety of Norwegian fish
products is a priority. This commentary gives a brief
overview of the food safety of seafood from Norwegian
waters. Several preventative measures during harvest/catch,
processing and distribution have been established and
are implemented regularly. Furthermore, comprehensive
monitoring programmes to detect and quantify undesirable
substances, such as heavy metals and polychlorinated
biphenyls (PCBs), in Norwegian seafood are carried out.
Substances with health benefits, such as omega-3 fatty
acids, are also analysed. In general, evidence shows the
level of undesirable substances in seafood from Norway to
be low. In fact, in the majority of samples analysed, levels
of undesirable substances were reported to be below the
maximum limit set by the European Union (EU). This leads
to the conclusion that consumption of seafood originating
from Norway involves a low risk of negative health effects
and that consumers can have confidence in the products
they purchase.peer-reviewe
Measuring subdiffusion parameters
We propose a method to extract from experimental data the subdiffusion
parameter and subdiffusion coefficient which are defined by
means of the relation where
denotes a mean square displacement of a random walker starting from
at the initial time . The method exploits a membrane system where a
substance of interest is transported in a solvent from one vessel to another
across a thin membrane which plays here only an auxiliary role. Using such a
system, we experimentally study a diffusion of glucose and sucrose in a gel
solvent. We find a fully analytic solution of the fractional subdiffusion
equation with the initial and boundary conditions representing the system under
study. Confronting the experimental data with the derived formulas, we show a
subdiffusive character of the sugar transport in gel solvent. We precisely
determine the parameter , which is smaller than 1, and the subdiffusion
coefficient .Comment: 17 pages, 9 figures, revised, to appear in Phys. Rev.
Epidemics with mutating infectivity on small-world networks
Epidemics and evolution of many pathogens occur on similar timescales so that their dynamics are often entangled. Here, in a first step to study this problem theoretically, we analyze mutating pathogens spreading on simple SIR networks with grid-like connectivity. We have in mind the spatial aspect of epidemics, which often advance on transport links between hosts or groups of hosts such as cities or countries. We focus on the case of mutations that enhance an agent's infection rate. We uncover that the small-world property, i.e., the presence of long-range connections, makes the network very vulnerable, supporting frequent supercritical mutations and bringing the network from disease extinction to full blown epidemic. For very large numbers of long-range links, however, the effect reverses and we find a reduced chance for large outbreaks. We study two cases, one with discrete number of mutational steps and one with a continuous genetic variable, and we analyze various scaling regimes. For the continuous case we derive a Fokker-Planck-like equation for the probability density and solve it for small numbers of shortcuts using the WKB approximation. Our analysis supports the claims that a potentiating mutation in the transmissibility might occur during an epidemic wave and not necessarily before its initiation
Magnetotransport properties of a polarization-doped three-dimensional electron slab
We present evidence of strong Shubnikov-de-Haas magnetoresistance
oscillations in a polarization-doped degenerate three-dimensional electron slab
in an AlGaN semiconductor system. The degenerate free carriers
are generated by a novel technique by grading a polar alloy semiconductor with
spatially changing polarization. Analysis of the magnetotransport data enables
us to extract an effective mass of and a quantum
scattering time of . Analysis of scattering processes helps
us extract an alloy scattering parameter for the AlGaN material
system to be
Organotrifluoroborates as attractive self-assembling systems: the case of bifunctional dipotassium phenylene-1,4-bis(trifluoroborate)
A multitude of non-covalent interactions, investigated by X-ray crystallography and computational chemistry techniques, proved to be responsible of the spontaneous self-assembly of a bis(trifluoroborate) dipotassium salt
Status of the QCDSP project
We describe the completed 8,192-node, 0.4Tflops machine at Columbia as well
as the 12,288-node, 0.6Tflops machine assembled at the RIKEN Brookhaven
Research Center. Present performance as well as our experience in commissioning
these large machines is presented. We outline our on-going physics program and
explain how the configuration of the machine is varied to support a wide range
of lattice QCD problems, requiring a variety of machine sizes. Finally a brief
discussion is given of future prospects for large-scale lattice QCD machines.Comment: LATTICE98(machines), 3 pages, 1 picture, 1 figur
Crystallographic and Magnetic Properties of the Spinel-type Ferrites ZnxCo1-xFe2O4 (0.0 <= x <= 0.75)
Ultrahigh frequencies (UHF) have applications in signal and power electronics to minimize product sizes, increase production quantity and lower manufacturing cost. In the UHF range of 300 MHz to 3 GHz, ferrimagnetic iron oxides (ferrites) are especially useful because they combine the properties of a magnetic material with that of an electrical insulator. Ferrites have much higher electrical resistivity than metallic ferromagnetic materials, resulting in minimization of the eddy current losses, and total penetration of the electromagnetic (EM) field. Hence ferrites are frequently applied as circuit elements, magnetic storage media like read/write heads, phase shifters and Faraday rotators. The electromagnetic properties of ferrites are affected by operating conditions such as field strength, temperature and frequency. The spinel system ZnxCo1-xFe2O4 (x= 0.0, 0.25, 0.50 and 0.75) has been prepared by the standard solid state sintering method. X-ray and neutron powder diffraction measurements were performed at room temperature. Neutron diffraction data analysis confirms the cubic symmetry corresponding to the space group Fd3m. The distribution of three cations Zn2+, Co2+ and Fe3+ over the spinel lattice and other crystallographic parameters like lattice constant, oxygen position parameter, overall temperature factor and occupancies of different ions in different lattice sites for the samples have been determined from the analysis of neutron diffraction data. The lattice constant increases with increasing Zn content in the system. The magnetic structure was found to be ferrimagnetic for the samples with x <= 0.50. Magnetization measurements show that with the increase of Zn content in the system the value of saturation magnetization first increases and then decreases. The variation of the magnetic moment with Zn substitution has been discussed in terms of the distribution of magnetic and non-magnetic ions over the A and B sub-lattices and their exchange coupling
Molecular markers for cervical cancer screening
This review gives an overview of current screening practices for cervical cancer. In the introduction, we will cover approaches of population screening focusing on high-risk Human Papilloma Virus (hrHPV) and the need for a better triage assay. We will further assess the impact of current vaccination programs on screening. Subsequently, the review will cover various technological aspects of nucleic acid- and protein-based biomarker assays. We will then detail different molecular markers in view of their use in triage assays, emphasizing epigenetic and protein markers. Finally, we will place this in the context of cost-effectiveness considerations in view of their implementation in high- as well as in low- to middle-income countries. Introduction: Cervical cancer remains a significant healthcare problem, notably in low- to middle-income countries. While a negative test for hrHPV has a predictive value of more than 99.5%, its positive predictive value is less than 10% for CIN2+ stages. This makes the use of a so-called triage test indispensable for population-based screening to avoid referring women, that are ultimately at low risk of developing cervical cancer, to a gynecologist. This review will give an overview of tests that are based on epigenetic marker panels and protein markers. Areas covered: There is a medical need for molecular markers with a better predictive value to discriminate hrHPV-positive women that are at risk of developing cervical cancer from those that are not. Areas covered are epigenetic and protein markers as well as health economic considerations in view of the fact that most cases of cervical cancer arise in low-to-middle-income countries. Expert opinion: While there are biomarker assays based on changes at the nucleic acid (DNA methylation patterns, miRNAs) and at the protein level, they are not widely used in population screening. Combining nucleic acid-based and protein-based tests could improve the overall specificity for discriminating CIN2+ lesions that carry a low risk of progressing to cervical cancer within the screening interval from those that carry an elevated risk. The challenge is to reduce unnecessary referrals without an undesired increase in false-negative diagnoses resulting in cases of cervical cancer that could have been prevented. A further challenge is to develop tests for low-and middle-income countries, which is critical to reduce the worldwide burden of cervical cancer
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