580 results match your criteria: "University of Joensuu[Affiliation]"

Several elm-infesting bark beetles belonging to the genus Scolytus (Coleoptera: Scolytinae) are vectors of Ophiostoma spp., most notably the Dutch elm disease fungi. A related bark beetle species, Scolytus ratzeburgi, is known to infest birch in various parts of Europe, but it is unknown whether fungi are associated with this beetle.

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Article Synopsis
  • The study examines how human plasma fibrinogen (HPF) adsorbs on various treated titanium surfaces, including polished and titanium carbide coatings.
  • An innovative diffractive optical element (DOE) sensor is used to monitor changes in permittivity and optical roughness when exposed to both the background electrolyte and HPF.
  • Results indicate a correlation between the transmitted light and the thickness of the HPF layer, providing insights into the dynamics of fibrinogen adsorption at the nano-scale on different titanium surfaces.
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The shuttling motion of a macrocycle in rotaxane-based molecular switching devices has been studied by computational density functional methods. In the test case, energy profiles corresponding to the dethreading process of different types of guest molecules in a cyclobis(paraquat-p-phenylene) host verified the experimental preference of the tetrathiafulvalene recognition site over the dioxynaphthalene site in a Stoddart-Heath type molecular device. Furthermore, modification of the redox state of either the macrocycle or the guest molecule resulted in considerable changes in the computational energy profiles, which can be utilized in explaining the behavior of the host-guest system.

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A new member of the inward-rectifier K(+) channel subfamily Kir2 was isolated and characterised from the crucian carp (Carassius carassius) heart. When expressed in COS-1 cells this 422 amino acid protein produced an inward-rectifying channel with distinct single-channel conductance, mean open time and open probability. Phylogenetic sequence comparisons indicate that it is not homologous to any known vertebrate Kir channel, yet belongs to the Kir2 subfamily.

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The independent-elementary-source model recently developed for planar sources [Opt. Express 14, 1376 (2006)] is extended to volume source distributions. It is shown that the far-field radiation pattern is independent of the three-dimensional (3D) distribution of the coherent elementary sources, but the absolute value of the complex degree of spectral coherence is determined by the 3D Fourier transform of the weight function of the elementary fields.

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Abstract This study of vertical fatty acid profiles, based on analysis of 58 fatty acids sampled at 3-mm intervals throughout the blubber column of a model marine mammal, the ringed seal (Pusa hispida), revealed three chemically distinct layers. The average depths of the outer and inner layers were quite consistent (approximately 1.5 and approximately 1 cm, respectively).

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Hydrophobins are a group of low-molecular-mass, cysteine-rich proteins that have unusual biophysical properties. They are highly surface-active and can self-assemble at hydrophobic-hydrophilic interfaces, forming surface layers that are able to reverse the hydropathy of surfaces. Here we describe a novel hydrophobin from the edible mushroom Grifola frondosa, which was named HGFI and belongs to class I.

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Weighted compression of spectral color information.

J Opt Soc Am A Opt Image Sci Vis

June 2008

Department of Physics and Mathematics, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland.

Spectral color information is used nowadays in many different applications. Accurate spectral images are usually very large files, but a proper compression method can reduce needed storage space remarkably with a minimum loss of information. In this paper we introduce a principal component analysis (PCA) -based compression method of spectral color information.

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Cellobiohydrolase from Melanocarpus albomyces (Cel7B) is a thermostable, single-module, cellulose-degrading enzyme. It has relatively low catalytic activity under normal temperatures, which allows structural studies of the binding of unmodified substrates to the native enzyme. In this study, we have determined the crystal structure of native Ma Cel7B free and in complex with three different cello-oligomers: cellobiose (Glc(2)), cellotriose (Glc(3)), and cellotetraose (Glc(4)), at high resolution (1.

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In ectotherms, compensatory changes in ion channel number and activity are needed to maintain proper cardiac function at variable temperatures. The rapid component of the delayed rectifier K+ current (IKr) is important for repolarization of cardiac action potential and, therefore, crucial for regulation of cellular excitability and heart rate. To examine temperature plasticity of cardiac IKr, we cloned the ether-à-go-go-related gene (ERG) channel and measured its electrophysiological properties in thermally acclimated rainbow trout (Oncorhynchus mykiss; omERG).

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The noncovalent complexation of tetraethyl and tetraphenyl resorcinarenes with mono-, di-, and oligosaccharides was studied with negative-polarization electrospray ionization quadrupole ion trap and electrospray ionization Fourier-transform ion cyclotron resonance mass-spectrometric analysis. The saccharides formed 1:1 complexes with deprotonated resorcinarenes, which exhibited clear size and structure selectivity in their complexation. In the case of the monosaccharides, hexoses formed much more abundant and kinetically stable complexes than pentoses or deoxyhexoses.

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We report an analysis of the pH-dependent dissociation of a multimeric metalloprotein, xylose isomerase from Streptomyces rubiginosus (XI), by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Xylose isomerases are industrially significant enzymes that catalyze interconversion of aldose and ketose sugars. XI is biologically active as a approximately 173-kDa tetrameric complex, comprised of four identical approximately 43-kDa subunits and eight metal cations, unequivocally identified as the Mg(2+) cations in this work.

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The transport and bioavailability of sediment-associated contaminants are often controlled by the contaminants' desorbing behaviour. This study examines the desorption kinetics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), diphenyl ethers (PCDEs) and hydroxydiphenyl ethers (HO-PCDEs) from the highly contaminated River Kymijoki sediment in Finland. The desorption kinetics data were generated using Tenax((R)) extraction, and a first-order three-compartment kinetic model was fitted to the data.

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Sensor for the detection of local contrast gloss of products.

Opt Lett

April 2008

Department of Physics and Mathematics, University of Joensuu, Joensuu, Finland.

We introduce a sensor for providing information on the local contrast gloss (or luster) of products. The sensor also provides information of the local specular gloss of the object. The signals of this sensor are produced by diffractive optical elements from fields that are scattered in the diffuse and specular directions from the object.

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The complex formation of a tetraammonium C1-resorcinarene (R+4HCl) was studied using electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Although R+4HCl easily loses its counter ions in the ESI process, a neutral self-assembled structure with an intramolecular circular hydrogen-bonded 16-membered -N(+)-H ..

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The wetting properties of polypropylene (PP) surfaces were modified by adjusting the dimensions of the surface nanostructure. The nanostructures were generated by injection molding with nanoporous anodized aluminum oxide (AAO) as the mold insert. Atomic layer deposition (ALD) of molybdenum nitride film was used to control the pore diameters of the AAO inserts.

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Bioaccumulation of atrazine and chlorpyrifos to Lumbriculus variegatus from lake sediments.

Ecotoxicol Environ Saf

November 2008

Faculty of Biosciences, Laboratory of Aquatic Ecology and Ecotoxicology, University of Joensuu, Yliopistokatu 7, P.O. Box 111, 80101 Joensuu, Finland.

The bioaccumulation of the pesticides chlorpyrifos and atrazine to the benthic oligochaeta Lumbriculus variegatus from four diverse artificially contaminated lake sediments (OC 0.13-21.5%) was studied in the laboratory.

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Asymmetric transmission gratings operating in the resonance domain are designed by modeling of the dose-controlled electron-beam lithography process with Gaussian convolution. We aim to exceed some efficiency limit eta(s) over a specified spectral range and to maximize eta(s). The resultant continuous-profile gratings are fabricated by electron-beam lithography and proportional reactive-ion etching into SiO(2).

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The desorption and bioavailability of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) were studied in spiked natural sediments at six concentrations. The desorption kinetics were measured in a sediment-water suspension using Tenax resin extraction, and the bioavailability was measured by exposing Lumbriculus variegatus (Oligochaeta) to PCB 77-spiked sediment in a 14-d kinetic study. In addition, freely dissolved pore-water concentrations were measured using the polyoxymethylene solid-phase extraction method.

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The mountain hare (Lepus timidus) is a year-round active herbivore adapted to survive the boreal winter. Captive mountain hares (N=4) were implanted with intraabdominal thermosensitive loggers to record their core body temperature (T(b)) for a year and during food deprivation (8-48h) in summer and winter. The average T(b) was 38.

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Strong dark self-enhancement, the increase in diffraction efficiency after irradiation, has been reported previously for dichromated-gelatin gratings. Here a more-detailed study of this self-enhancement effect is presented. The self-enhancement in dichromated-gelatin gratings was of the order of 10-100, depending on the pH and on the dichromate concentration of the solution used for the preparation of dichromated-gelatin films.

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Experimental results concerning the real-time hologram recording process in dichromated poly(vinyl alcohol) are presented. Self-enhancement, the increase in diffraction efficiency of the holographic gratings in the dark after recording, is also presented. The influence of the recording parameters (pH, exposure energy, dichromate concentration) on the self-enhancement gain is shown.

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Fast and memory efficient implementation of the exact PNN.

IEEE Trans Image Process

June 2010

Department of Computer Science, University of Joensuu, FIN-80101 Joensuu, Finland.

Straightforward implementation of the exact pairwise nearest neighbor (PNN) algorithm takes O(N3) time, where N is the number of training vectors. This is rather slow in practical situations. Fortunately, much faster implementation can be obtained with rather simple modifications to the basic algorithm.

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Acceleration of flowering would be beneficial for breeding trees with a long juvenile phase; conversely, inhibition of flowering would prevent the spread of transgenes from the genetically modified trees. We have previously isolated and characterized several MADS genes from silver birch (Betula pendula Roth). In this study, we investigated the more detailed function of one of them, BpMADS4, a member of the APETALA1/FRUITFULL group of MADS genes.

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