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Schmidt, Anders, et al.
(författare)
Caffeine poisoning and lactate rise: an overlooked toxic effect?
2008
Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172. ; 52:7, s. 1012-1014
Tidskriftsartikel (refereegranskat) abstract
Severe caffeine poisoning is rare but associated with a high mortality. The symptoms are mainly attributable to hyperadrenergic stimulation, are relatively well known and described in the literature. Transient rises in plasma lactate levels may occur but are, however, less well described. We present a case of serious caffeine poisoning with a concomitant rise in lactate treated with a non-selective beta-blocker and discuss briefly the symptomatology, the management of caffeine poisoning and the association between lactate and metabolic acidosis.
4.
Verardo, Damiano, et al.
(författare)
Nanowires for Biosensing : Lightguiding of Fluorescence as a Function of Diameter and Wavelength
2018
Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:8, s. 4796-4802
Tidskriftsartikel (refereegranskat) abstract
Semiconductor nanowires can act as nanoscaled optical fibers, enabling them to guide and concentrate light emitted by surface-bound fluorophores, potentially enhancing the sensitivity of optical biosensing. While parameters such as the nanowire geometry and the fluorophore wavelength can be expected to strongly influence this lightguiding effect, no detailed description of their effect on in-coupling of fluorescent emission is available to date. Here, we use confocal imaging to quantify the lightguiding effect in GaP nanowires as a function of nanowire geometry and light wavelength. Using a combination of finite-difference time-domain simulations and analytical approaches, we identify the role of multiple waveguide modes for the observed lightguiding. The normalized frequency parameter, based on the step-index approximation, predicts the lightguiding ability of the nanowires as a function of diameter and fluorophore wavelength, providing a useful guide for the design of optical biosensors based on nanowires.
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Voss, Ulrikke
(författare)
Adapt, Survive or Die - Metabolic Imbalances and the Enteric Nervous System
2013
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Abstract: In this thesis the questions “do enteric neurons adapt to survive in conditions of obesity/type 2-diabetes (T2D) related metabolic imbalances? Or do they die?” are asked. Obese and T2D patients have high rates of gastrointestinal (GI) symptoms. The GI tract comprises the body’s largest surface to the outside environment; it performs diverse and complex roles in an ever changing external environment. It has evolved into a fine tuned sensory organ, with a complex network of sensory-, taste-, baro-, mehcano- and pathogen recognizing receptors (PRR). The presence of PRRs allows the GI tract to mediate and modulate immune responses, in response to both pathogens and toxins present in our microbiota. The microbiota is shaped by our diet, as well as our genetics. The fluid adaptation and control of the GI tract is mediated by the enteric nervous system (ENS). ENS is an extensive interconnected network of neurons and glia cells, controlling intestinal motility, secretion and blood flow. It harbors a neurotransmitter variety and receptor diversity enabling interactions with neurons, immune, endocrine and intestinal cells as well as with luminal factors. Results show that mice fed a high fat diet (HFD) for 6 months have a significant loss of enteric neurons. To evaluate metabolic factors known to be altered in the obese/T2D-condition (ODC), we used isolated enteric neurons. We noted that palmitic acid (PA), a lipid known to be increased in ODC caused a significant loss of enteric neurons, through mechanisms involving deranged energy metabolism and the purinergic P2Y13 receptor. In ODC an increased permeability of the intestinal barrier causes increased translocation of lipopolysaccharide (LPS) to the circulation and initiation of immune responses. We found that exposing cultured enteric neurons to LPS caused neuronal loss through activation of AMP activated protein kinase. Glucagon-like peptide (GLP) 1 and 2 are involved in satiety, insulin release and intestinal barrier function. Both GLPs are reduced in ODC. We showed a great neuroprotective potential of the hormones. Based on these findings, HFD-induced enteric neuronal loss is suggested to be a culmination of several factors, including increased PA- and LPS-exposures and a decreased GLP level, leading to dysregulation and altered function of enteric neurons.
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Huang, Fei, 1987-, et al.
(författare)
Quantitative evaluation of thin-layer thickness and CO2 mass utilizing seismic complex decomposition at the Ketzin CO2 storage site, Germany
2016
Ingår i: Geophysical Journal International. - : Oxford University Press (OUP). - 0956-540X .- 1365-246X. ; 207:1, s. 160-173
Tidskriftsartikel (refereegranskat) abstract
Determining thin layer thickness is very important for reservoir characterization and CO2 quantification. Given its high time-frequency resolution and robustness, the complex spectral decomposition method was applied on time-lapse 3D seismic data from the Ketzin pilot site for CO2 storage to evaluate the frequency-dependent characteristics of thin layers at the injection level. Higher temporal resolution and more stratigraphic details are seen in the all-frequency and monochromatic reflectivity amplitude sections obtained by complex spectral decomposition compared to the stacked sections. The mapped geologic discontinuities within the reservoir are consistent with the preferred orientation of CO2 propagation. Tuning frequency mapping shows the thicknesses of the reservoir sandstone and gaseous CO2 is consistent with the measured thickness of the sandstone unit from well logging. An attempt to discriminate between pressure effects and CO2 saturation using the extracted tuning frequency indicates that CO2 saturation is the main contributor to the amplitude anomaly at the Ketzin site. On the basis of determined thickness of gaseous CO2 in the reservoir, quantitative analysis of the amount of CO2 was performed and shows a discrepancy between the injected and calculated CO2 mass. This may be explained by several uncertainties, like structural reservoir heterogeneity, a limited understanding of the complex subsurface conditions, error of determined tuning frequency, the presence of ambient noise and ongoing CO2 dissolution.
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Romenskyy, Maksym, et al.
(författare)
Tricritical points in a Vicsek model of self-propelled particles with bounded confidence
2014
Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - USA : American Physical Society. - 1539-3755 .- 1550-2376. ; 90:6
Tidskriftsartikel (refereegranskat) abstract
We study the orientational ordering in systems of self-propelled particles with selective interactions. To introduce the selectivity we augment the standard Vicsek model with a bounded-confidence collision rule: a given particle only aligns to neighbors who have directions quite similar to its own. Neighbors whose directions deviate more than a fixed restriction angle α are ignored. The collective dynamics of this system is studied by agent-based simulations and kinetic mean-field theory. We demonstrate that the reduction of the restriction angle leads to a critical noise amplitude decreasing monotonically with that angle, turning into a power law with exponent 32 for small angles. Moreover, for small system sizes we show that upon decreasing the restriction angle, the kind of the transition to polar collective motion changes from continuous to discontinuous. Thus, an apparent tricritical point with different scaling laws is identified and calculated analytically. We investigate the shifting and vanishing of this point due to the formation of density bands as the system size is increased. Agent-based simulations in small systems with large particle velocities show excellent agreement with the kinetic theory predictions. We also find that at very small interaction angles, the polar ordered phase becomes unstable with respect to the apolar phase. We derive analytical expressions for the dependence of the threshold noise on the restriction angle. We show that the mean-field kinetic theory also permits stationary nematic states below a restriction angle of 0.681π. We calculate the critical noise, at which the disordered state bifurcates to a nematic state, and find that it is always smaller than the threshold noise for the transition from disorder to polar order. The disordered-nematic transition features two tricritical points: At low and high restriction angle, the transition is discontinuous but continuous at intermediate α. We generalize our results to systems that show fragmentation into more than two groups and obtain scaling laws for the transition lines and the corresponding tricritical points. A numerical method to evaluate the nonlinear Fredholm integral equation for the stationary distribution function is also presented. This method is shown to give excellent agreement with agent-based simulations, even in strongly ordered systems at noise values close to zero.
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Siegbahn, HOG, et al.
(författare)
Structures at liquid surfaces studied by core electron spectroscopy
1995
Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. ; 76, s. 417-420
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt) abstract
Core electron spectroscopy has been applied to the study of a solution substrate of CsI in formamide. Gibbs monolayers are formed on the substrate by dissolution of ionic surfactants and the resulting ionic composition of the surface region is investigate
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