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Detection and quantification of differentially expressed genes requires valid and reliable references to control for error variability introduced by preparatory procedures or efficiency of reverse transcription and polymerase chain reaction (PCR) amplification conditions. So-called housekeeping genes are frequently used as endogenous standards, based on the assumption that they are constitutively expressed and independent of experimental conditions. However, if the influence of experimental stimuli is to be analyzed, it cannot a priori be assumed that their expression is unaffected by stimulation. In the present study, the authors studied the expression of different housekeeping genes in the vascular endothelium of intact conduit vessels perfused in a unique biomechanical perfusion model. Ten control gene candidates were investigated by microarray expression analysis. Further, five of these genes were systematically analyzed by real-time reverse transcriptase (RT)-PCR gene quantification and their suitability as reference genes were evaluated. On the basis of these findings, the authors suggest criteria for evaluation of endogenous control genes in vascular perfusion studies.
N/A / Link / Doroudi , Roya / 2005

N/A / Link / Strandberg , Erling / 2011

N/A / Link / Andersson , Björn / 2007

A scheme for estimating T-CONT bandwidth demand within dynamic bandwidth allocation (DBA) for next-generation passive optical network (NG-PON) is proposed and evaluated. Estimating T-CONT bandwidth demand is considered as a main challenge in gigabit-capable passive optical network (GPON) DBA. The proposed minimum guaranteed T-CONT content (MGTC) scheme allows for a more conservative estimate of bandwidth demand. It is shown that at high load significant improvements in delay, jitter and bandwidth utilization can be achieved with the proposed scheme. For light loads the conventional scheme shows better delay performance. However, this may be overcome by controlled overgranting in the MGTC scheme.
978-081948035-4 / Link / Skubic , Björn / 2009

BACKGROUND: In the construction of a Kock reservoir for continent urinary diversion, 70 cm of the distal ileum are used. Impaired absorption of bile acids in these patients might cause diarrhoea. Data on the absorption of bile acids in different parts of the human intestine are limited. METHODS: Biopsies were taken during endoscopy from the duodenum, the terminal ileum or the right colon, and during surgery 10, 50, 100 and 150 cm proximally to the ileo-caecal valve using standard endoscopy biopsy forceps. The biopsy specimens were incubated in vitro with radio-labelled taurocholic acid at 37 degrees C for 22 or 45 min The radioactivity was determined using the liquid scintillation technique. RESULTS: A linear increase in the uptake was observed, with increased concentrations of taurocholic acid between 100 and 500 microm in all specimens tested, that represented passive uptake or unspecific binding. The active uptake could be calculated from the intercept of the line representing passive uptake with the ordinate. The active uptake in the terminal ileum was 3-4 times greater than 100 cm proximal to the valve. CONCLUSIONS: The active absorption of bile acids in humans can be determined in small biopsy specimens taken using standard biopsy forceps during endoscopy or surgery. This method is suitable for clinical studies of bile acid absorption. Active uptake of bile acids not only takes place in the very distal part of the ileum but also to a considerable degree 100 cm proximally to the ileo-colonic valve. This should be taken into account when selecting the ileal segment for continent urinary diversion.
N/A / Link / Ung , Kjell-Arne / 2002

Colloidal-sized hematite spheroids exposed to aqueous NaCl solutions were investigated by X-ray photoelectron spectroscopy using the fast-frozen technique. The O 1s region provided evidence for (de)protonation reactions of surface (hydr)oxo groups of OH-enriched/O-depleted hematite Surfaces. These results were also correlated to changes in sodium (Na 1s) and chloride (Cl 2p) contents with pH. Electrolyte ion surface loadings were successfully predicted using a classic thermodynamic adsorption model normalized for surface site density. These efforts pointed to ion-specific inner-Helmholtz plane capacitances.
N/A / Link / Boily , Jean-Francois / 2010

N/A / Link / O'Shea , J. N. / 2000

Luleå tekniska universitet Övrigt
978-1-615-67816-7 / Link / Wårell , Linda / 2009

Uppsala universitet Övrigt
This paper is a study of the phase content and morphology of Al2O3 grown by the AlCl3/H-2/CO2 process on a chemical vapour deposition (CVD) TiO layer. The results were compared with the results of CVD of Al2O3 on Ti2O3, Ti3O5 and TiO2 from an earlier inv
N/A / Link / FREDRIKSSON , E / 1995

The speciation of ammonium at the hematite/water interface was probed by cryogenic X-ray photoelectron spectroscopy. Wet pastes of colloidal hematite spheroids equilibrated in aqueous solutions of 50 mM NH4Cl exhibit distinctive pH-sensitive N 1s peaks for both NH4+ (401.7 eV) and NH3 (400.1 eV), yet total N/Fe ratios remain relatively invariant (0.029 ± 0.006) throughout the pH 2.2−10.5 range. Both NH4+ and NH3 species coexist throughout most of the tested pH range. NH4+ is most likely stabilized at the interface by hydrogen bonding with surface (hydr)oxo groups. A cationic sorption edge for NH3 is driven by proton abstraction of NH4+ by (hydr)oxo groups, forming surface complexes of the type ≡Fe−OH···NH3. These interactions shift the NH4+/NH3 equilibrium from pKa = 9.3 in water to 8.4 at the interface. Removal of excess water by vacuum dehydration induces, on the other hand, formation of NH2 directly bound to surface Fe atoms. These results underscore distinct ammonium species in contact with mineral surfaces and should be considered in understanding environmental and catalytic reactions in this medium.
N/A / Link / Shimizu , Kenichi / 2011

Multiple rotation averaging is an important problem in computer vision. The problem is challenging because of the nonlinear constraints required to represent the set of rotations. To our knowledge no one has proposed any globally optimal solution for the case of simultaneous updates of the rotations. In this paper we propose a simple procedure based on Lagrangian duality that can be used to verify global optimality of a local solution, by solving a linear system of equations. We show experimentally on real and synthetic data that unless the noise levels are extremely high this procedure always generates the globally optimal solution.
978-3-642-37431-9 (online) / Link / Fredriksson , Johan / 2013

The objective of the investigation is to study the interference of different background noises on speech processing. For this purpose speech recognition with the Hagerman test and a test battery with speech comprehension tasks (SVIPS) were performed in speech-weighted background noises varying in temporal structure, signal-to-noise ratio (SNR), and meaningfulness. With different test criteria and a score of perceived effort, the aim was to get a more complete picture of speech comprehension under adverse listening situations. Twenty-four subjects, aged 56-83 years, with a bilateral sensorineural hearing impairment, participated in the study. Differences in performance between the different background noises varied depending on the speech processing task, SNR, and on quantitative versus qualitative outcome measures. Age effects were seen in the Hagerman test and especially in background conditions of modulated noises (speech and reversed speech). Findings are discussed in relation to a hypothesis suggesting that masking and distraction interference from background noises on speech processing at peripheral, central auditory, and cognitive levels depends on the SNR used and the noise type and the listening task.
N/A / Link / Larsby , Birgitta / 2008

N/A / Link / Chau , Pei Pei / 2007

Halide anion (F–, Cl–, Br–, and I–) adsorption and its impact on sodium adsorption at the hematite/water interface were studied by cryogenic X-ray photoelectron spectroscopy (XPS). Measurements were carried out on frozen, centrifuged wet hematite pastes that were previously equilibrated in 50 mM electrolytic solutions in the pH 2–11 range. XPS-derived halide ion surface loadings decreased in the order F– > I– ≈ Cl– > Br–, whereas sodium loadings were in the order Na(F) > Na(I) > Na(Br) > Na(Cl). The greater sodium loadings in NaF and in NaI resulted from larger anion loadings in these systems. Bromide ion had the lowest loading among all halide ions despite having a charge-to-size ratio that is intermediate between those of Cl– and I–. This unexpected result may have arisen from specific properties of the hematite/water interface, such as water structure and electric double layer thickness. Fluoride ion adsorption proceeded via the formation of hydrogen bonds with the surface hydroxo groups (e.g., ≡Fe–OH2···F– or ≡Fe–OH···F–). Surface-bound fluoride ions exert a greater charge-screening effect than the other halide anions, as demonstrated by considerably small zeta potential values. Fe–F bond formation was excluded as a possible interfacial process as the F 1s peak binding energy (684.2 eV) was more comparable to that of NaF (684.6 eV) than FeF3 (685.4 eV). Overall, these findings motivate further refinements of existing thermodynamic adsorption models for predicting the ionic composition of hematite particle surfaces contacted with sodium halide aqueous solutions.
N/A / Link / Shimizu , Kenichi / 2013

A scheme for estimating T-CONT bandwidth demand within dynamic bandwidth allocation (DBA) for next-generation passive optical network (NG-PON) is proposed and evaluated. Estimating T-CONT bandwidth demand is considered as a main challenge in gigabit-capable passive optical network (GPON) DBA. The proposed minimum guaranteed T-CONT content (MGTC) scheme allows for a more conservative estimate of bandwidth demand. It is shown that at high load significant improvements in delay, jitter and bandwidth utilization can be achieved with the proposed scheme. For light loads the conventional scheme shows better delay performance. However, this may be overcome by controlled over-granting in the MGTC scheme.
978-155752877-3 / Link / Skubic , Björn / 2009

Context. It is well established that the winds of carbon-rich AGB stars (carbon stars) can be driven by radiation pressure on grains of amorphous carbon and collisional transfer of momentum to the gas. This has been demonstrated convincingly by different numerical wind models that include time-dependent dust formation. To simplify the treatment of dust opacities, radiative cross sections are usually computed using the assumption that the dust grains are small compared to wavelengths around the stellar flux maximum. Considering the typical grain sizes that result from these models, however, the applicability of this small-particle limit (SPL) seems questionable.Aims. We explore grain size effects on wind properties of carbon stars, using a generalized description of radiative cross sections valid for particles of arbitrary sizes. The purpose of the study is to investigate under which circumstances the SPL may give acceptable results, and to quantify the possible errors that may occur when the SPL does not hold.Methods. The time-dependent description of grain growth in our detailed radiation-hydrodynamical models gives information about dust particle radii in every layer at every instant of time. Theses grain radii are used for computing opacities and determining the radiative acceleration of the dust-gas mixture. From the large number of models presented in the first paper of this series (based on SPL dust opacities) we selected two samples, i.e., a group of models with strong, well-developed outflows that are probably representative of the majority of wind-forming models, and another group, close to thresholds in stellar parameter space for dust-driven winds, which are referred to as critical cases.Results. We show that in the critical cases the effect of the generalized description of dust opacities can be significant, resulting in more intense mass loss and higher wind velocities compared to models using SPL opacities. For well-developed winds, however, grain size effects on mass-loss rates and wind velocities are found to be small. Both groups of models tend towards lower degrees of dust condensation compared to corresponding SPL models, owing to a self-regulating feedback between grain growth and radiative acceleration. Consequently, the "dust-loss rates" are lower in the models with the generalized treatment of grain opacities.Conclusions. We conclude that our previous results on mass-loss rates obtained with SPL opacities are reliable within a wide region of stellar parameter space, except for critical cases close to thresholds of dust-driven outflows where SPL models will tend to underestimate the mass-loss rates and wind velocities.
N/A / Link / Mattsson , Lars / 2011

When core-hole decay develops along two different paths, i.e. by a direct Auger-transition path and by an indirect path passing via two-hole–one-particle excitation and de-excitation, the screening of the direct Auger-transition matrix element by the particle–hole (de-)excitations leads to a pronounced interference effect in the Auger-electron emission. The manifestation of the interference effect in the Auger-photoelectron coincidence spectroscopy spectrum is discussed in the light of the unique capabilities of the coincidence measurements.
N/A / Link / Ohno , Masahide / 2003

The Pb-Zn-Ba(-Ag-Au) mineralization in the Triades and Galana mine areas is hosted in 2.5-1.4 Ma pyroclastic rocks, and structurally controlled mostly by NE-SW or N-S trending brittle faults. Proximal pervasive silica and distal pervasive sericite-illite alteration are the two main alteration types present at the surface. The distribution of mineralization-alteration in the district suggests at least two hydrothermal events or that hydrothermal activity lasted longer at Galana. The Sr isotope signature of sphalerite and barite (87Sr/86Sr = 0.709162 to 0.710214) and calculated oxygen isotope composition of a fluid in equilibrium with barite and associated quartz at temperatures of around 230°C are suggestive of a seawater hydrothermal system and fluid/rock interaction. Lead isotope ratios of galena and sphalerite (206Pb/204Pb from 18.8384 to 18.8711; 207Pb/204Pb from 15.6695 to 15.6976; 208Pb/204Pb from 38.9158 to 39.0161) are similar to those of South Aegean Arc volcanic and Aegean Miocene plutonic rocks, andcompatible with Pb derived from an igneous source. Galena and sphalerite from Triades-Galana have δ34SVCDT values ranging from +1 to +3.6‰, whereas barite sulfate shows δ34SVCDT values from +22.8 to +24.4‰. The sulfur isotope signatures of these minerals are explained by seawater sulfate reduction processes. The new analytical data are consistent with a seawater-dominated hydrothermal system and interaction of the hydrothermal fluid with the country rocks, which are the source of the ore metals.
N/A / Link / Marschik , Robert / 2010

N/A / Link / Strandberg , Christer / 2003

Linköpings universitet Tvärvetenskapliga Forskningsområden
N/A / Link / Andersson , Lars / 1990

The purpose of this study was to investigate the relative importance of mechanisms behind the effect of food on the intestinal absorption and bioavailability for low solubility compounds by applying a porcine single-pass perfusion model. Nanoparticle suspensions of the model compounds, danazol and cyclosporine were perfused through the jejunum in isotonic fluid alone (control) and isotonic fluid with a P-glycoprotein (P-gp) inhibitor (verapamil) or dietary and endogenous lipids added. The drugs were also administered as saturated solutions in the isotonic fluid containing lipids. Administration of cyclosporine together with verapamil increased the absorption compared to the control (1.6 times) suggesting an effect on jejunal permeability. However, addition of dietary lipids to the media led to a 50% reduction in the absorption of cyclosporine indicating lack of major effects by P-gp inhibition by lipids in vivo. The absorption of danazol was increased (2.6 times) when administered as a nanosuspension in lipid containing media compared to the control, but decreased (60%) when administered as a solution in the same media. This shows how important dissolution of the drug nanoparticles is in drug absorption. The difference in the effect of lipids in the absorption of cyclosporine and danazol when administered as nanosuspensions may be due to different distribution to the colloidal structures present in the media, thereby rendering the drugs' different diffusion rates in the perfused segment. In conclusion, solubilisation seems to be a more important factor than P-gp inhibition as an explanation for the food-drug interaction observed for several low solubility drugs. In addition, the partition into different colloidal structures seems to play a major role in the dissolution and absorption of poorly soluble drugs.
N/A / Link / Persson , Eva M. / 2008