| 1. |
- Korablev, Oleg I., et al.
(författare)
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Infrared Spectrometer for ExoMars: A Mast-Mounted Instrument for the Rover
- 2017
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Ingår i: Astrobiology. - : Mary Ann Liebert. - 1531-1074 .- 1557-8070. ; 17:6-7, s. 542-564
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Tidskriftsartikel (refereegranskat)abstract
- ISEM (Infrared Spectrometer for ExoMars) is a pencil-beam infrared spectrometer that will measure reflected solar radiation in the near infrared range for context assessment of the surface mineralogy in the vicinity of the ExoMars rover. The instrument will be accommodated on the mast of the rover and will be operated together with the panoramic camera (PanCam), high-resolution camera (HRC). ISEM will study the mineralogical and petrographic composition of the martian surface in the vicinity of the rover, and in combination with the other remote sensing instruments, it will aid in the selection of potential targets for close-up investigations and drilling sites. Of particular scientific interest are water-bearing minerals, such as phyllosilicates, sulfates, carbonates, and minerals indicative of astrobiological potential, such as borates, nitrates, and ammonium-bearing minerals. The instrument has an ∼1° field of view and covers the spectral range between 1.15 and 3.30 μm with a spectral resolution varying from 3.3 nm at 1.15 μm to 28 nm at 3.30 μm. The ISEM optical head is mounted on the mast, and its electronics box is located inside the rover's body. The spectrometer uses an acousto-optic tunable filter and a Peltier-cooled InAs detector. The mass of ISEM is 1.74 kg, including the electronics and harness. The science objectives of the experiment, the instrument design, and operational scenarios are described.
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| 2. |
- Sushko, Iurii, et al.
(författare)
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Applicability Domains for Classification Problems : Benchmarking of Distance to Models for Ames Mutagenicity Set.
- 2010
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Ingår i: Journal of chemical information and modeling. - : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 50:12, s. 2094-2111
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Tidskriftsartikel (refereegranskat)abstract
- The estimation of accuracy and applicability of QSAR and QSPR models for biological and physicochemical properties represents a critical problem. The developed parameter of "distance to model" (DM) is defined as a metric of similarity between the training and test set compounds that have been subjected to QSAR/QSPR modeling. In our previous work, we demonstrated the utility and optimal performance of DM metrics that have been based on the standard deviation within an ensemble of QSAR models. The current study applies such analysis to 30 QSAR models for the Ames mutagenicity data set that were previously reported within the 2009 QSAR challenge. We demonstrate that the DMs based on an ensemble (consensus) model provide systematically better performance than other DMs. The presented approach identifies 30-60% of compounds having an accuracy of prediction similar to the interlaboratory accuracy of the Ames test, which is estimated to be 90%. Thus, the in silico predictions can be used to halve the cost of experimental measurements by providing a similar prediction accuracy. The developed model has been made publicly available at http://ochem.eu/models/1 .
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| 3. |
- Beiranvand, B., et al.
(författare)
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A distributed terahertz metasurface with cold-electron bolometers for cosmology missions
- 2021
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- We developed and tested a 2D periodic array of cold-electron bolometers arranged into a wideband frequency selective metasurface that absorbs more than 70% of the incident power in the frequency range 100–800 GHz. The array had 10 × 10 unit cells, each containing four bolometers incorporated into a ring. The chip with bolometers was mounted on the back side of the silicon lens without a back-reflector. Preliminary experiments demonstrated voltage responsivity as high as 10 V/W for the current-biased series array. Simulation of the noise performance shows realization of background noise-limited performance with NEP < NEP for the optical power load P > 15 pW. Results of numerical simulation made for the unit cell of the array are presented together with the equivalent diagram based on lumped network elements. The unit cell also was developed numerically to operate in two radiation modes.
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| 4. |
- Chefer, Vladimir, et al.
(författare)
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Repeated exposure to moderate doses of ethanol augments hippocampal glutamate neurotransmission by increasing release
- 2011
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 16:2, s. 229-237
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Tidskriftsartikel (refereegranskat)abstract
- The present study used conventional and quantitative microdialysis to assess glutamatergic and GABAergic neurotransmission in the hippocampal CA3 area of the rat following a moderate-dose ethanol treatment regimen. Male Wistar rats received 3.4 g/kg of ethanol or water for 6 days via gastric gavage. Microdialysis experiments commenced 2 days later. Basal and depolarization-induced glutamate overflow were significantly elevated in ethanol-treated animals. Basal and depolarization-induced gamma-aminobutyric acid (GABA) overflow were unaltered. Quantitative no-net-flux microdialysis was used to determine if changes in dialysate glutamate levels following ethanol administration are due to an increase in release or a decrease in uptake. To confirm the validity of this method for quantifying basal glutamate dynamics, extracellular concentrations of glutamate and the extraction fraction, which reflects changes in analyte clearance, were quantified in response to retro-dialysis of the glutamate uptake blocker trans-pyrrolidine-2,4-dicarboxylic acid (tPDC). tPDC significantly decreased the extraction fraction for glutamate, resulting in augmented extracellular glutamate concentrations. Repeated ethanol administration did not alter the glutamate extraction fraction. However, extracellular glutamate concentrations were significantly elevated, indicating that glutamate release is increased as a consequence of repeated ethanol administration. These data demonstrate that repeated bouts of moderate ethanol consumption alter basal glutamate dynamics in the CA3 region of the dorsal hippocampus. Basal glutamate release is augmented, whereas glutamate uptake is unchanged. Furthermore, they suggest that dysregulation of glutamate transmission in this region may contribute to the previously documented deficits in cognitive function associated with moderate dose ethanol use.
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| 5. |
- Edström, Alexander, et al.
(författare)
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Magnetic properties of (Fe1-xCox)(2)B alloys and the effect of doping by 5d elements
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 92:17
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Tidskriftsartikel (refereegranskat)abstract
- We have explored, computationally and experimentally, the magnetic properties of (Fe1-xCox)(2)B alloys. Calculations provide a good agreement with experiment in terms of the saturation magnetization and the magnetocrystalline anisotropy energy with some difficulty in describing Co2B, for which it is found that both full potential effects and electron correlations treated within dynamical mean field theory are of importance for a correct description. The material exhibits a uniaxial magnetic anisotropy for a range of cobalt concentrations between x = 0.1 and x = 0.5. A simple model for the temperature dependence of magnetic anisotropy suggests that the complicated nonmonotonic behavior is mainly due to variations in the band structure as the exchange splitting is reduced by temperature. Using density functional theory based calculations we have explored the effect of substitutionally doping the transition metal sublattice by the whole range of 5d transition metals and found that doping by Re or W elements should significantly enhance the magnetocrystalline anisotropy energy. Experimentally, W doping did not succeed in enhancing the magnetic anisotropy due to formation of other phases. On the other hand, doping by Ir and Re was successful and resulted in magnetic anisotropies that are in agreement with theoretical predictions. In particular, doping by 2.5 at.% of Re on the Fe/Co site shows a magnetocrystalline anisotropy energy which is increased by 50% compared to its parent (Fe0.7Co0.3)(2)B compound, making this system interesting, for example, in the context of permanent magnet replacement materials or in other areas where a large magnetic anisotropy is of importance.
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| 6. |
- Henriksson, Richard, et al.
(författare)
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Elevated synaptophysin I in the prefrontal cortex of human chronic alcoholics
- 2008
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Ingår i: Synapse. - : Wiley. - 0887-4476 .- 1098-2396. ; 62:11, s. 829-33
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Tidskriftsartikel (refereegranskat)abstract
- Convergent lines of evidence suggest potentiation of glutamatergic synapses after chronic ethanol exposure, and indicate that the presynaptic effect hereof is on modulators of synaptic strength rather than on executors of glutamate release. To address this hypothesis in the context of ethanol dependence in humans, we used semiquantitative immunoblotting to compare the immunoreactivities of synaptophysin I, syntaxin 1A, synaptosome-associated protein 25, and vesicle-associated membrane protein in the prefrontal and motor cortices between chronic alcoholics and control subjects. We found a region-specific elevation in synaptophysin I immunoreactivity in the prefrontal cortex of alcoholics, but detected no significant differences between the groups in the immunoreactivities of the other three proteins. Our findings are consistent with an effect of repeated ethanol exposure on modulators of synaptic strength but not on executors of glutamate release, and suggest a role for synaptophysin I in the enduring neuroplasticity in the prefrontal cortical glutamate circuitry that is associated with ethanol dependence.
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| 7. |
- Johansson, Sofia, et al.
(författare)
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Dysregulation of cell death machinery in the prefrontal cortex of human alcoholics
- 2009
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Ingår i: International Journal of Neuropsychopharmacology. - 1461-1457 .- 1469-5111. ; 12:1, s. 109-115
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Tidskriftsartikel (refereegranskat)abstract
- In human alcoholics, the cell density is decreased in the prefrontal cortex (PFC) and other brain areas. This may be due to persistent activation of cell death pathways. To address this hypothesis, we examined the status of cell death machinery in the dorsolateral PFC in alcoholics. Protein and mRNA expression levels of several key pro- and anti-apoptotic genes were compared in post-mortem samples of 14 male human alcoholics and 14 male controls. The findings do not support the hypothesis. On the contrary, they show that several components of intrinsic apoptotic pathway are decreased in alcoholics. No differences were evident in the motor cortex, which is less damaged in alcoholics and was analysed for comparison. Thus, cell death mechanisms may be dysregulated by inhibition of intrinsic apoptotic pathway in the PFC in human alcoholics. This inhibition may reflect molecular adaptations that counteract alcohol neurotoxicity in cells that survive after many years of alcohol exposure and withdrawal.
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| 8. |
- Kuzmin, Alexander, et al.
(författare)
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Effects of subunit selective nACh receptors on operant ethanol self-administration and relapse-like ethanol-drinking behavior
- 2009
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Ingår i: Psychopharmacology. - : Springer Science and Business Media LLC. - 0033-3158 .- 1432-2072. ; 203:1, s. 99-108
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: The sensitivity to ethanol central effects is partially determined by the subunit composition of brain nicotinic acetylcholine receptors (nAChRs). Thus, the effects of intraventral tegmental area (VTA) administration of the nicotinic subunit-specific antagonist, alpha-conotoxin MII (alphaCtxMII, alpha(3)beta(2)*, beta(3)*, alpha(6)*), were compared to those of systemic mecamylamine (MEC, an allosteric negative modulator of the nAChR), dihydro-beta-erythroidine (DHbetaE, alpha(4)beta(2)*), and methyllycaconitine (MLA, alpha(7)*) to elucidate involvement of different subunits of nAChRs in operant ethanol self-administration and relapse-like activation of ethanol consumption after ethanol deprivation in rats. METHODS: The effects of drugs were studied in rats trained for operant oral self-administration of ethanol (FR = 1). For ethanol deprivation, trained animals were subjected to a period of alcohol deprivation for 10 days. alphaCtxMII was given directly into the VTA through implanted permanent intracranial cannulae, whereas MEC, DHbetaE, and MLA were administered systemically. RESULTS: alphaCtxMII reduced operant ethanol self-administration and blocked the deprivation-induced relapse-like ethanol consumption. MEC reduced operant ethanol self-administration and inhibited the deprivation-induced increase in alcohol consumption. DHbetaE did not alter ethanol self-administration in the lower-dose range but inhibited ethanol intake at a higher dose (4 mg/kg), although this effect might have been nonspecific. MLA failed to block self-administration of ethanol and relapse-like drinking after deprivation. CONCLUSIONS: Our results indicate that nAChRs are involved in the modulation of operant alcohol self-administration and relapse-like alcohol drinking behavior in rats. Our observations support the working hypothesis that systemically active selective ligands for nAChR alpha(3)beta(2)*, beta(3), and/or alpha(6)* receptor subunits might be of therapeutic value for the treatment of alcoholism.
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| 9. |
- Kuzmin, Alexander, et al.
(författare)
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Expression of pronociceptin and its receptor is downregulated in the brain of human alcoholics
- 2009
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993 .- 1872-6240. ; 1305:Suppl. 1, s. S80-85
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Tidskriftsartikel (refereegranskat)abstract
- Animal studies demonstrated a role of neuropeptide nociceptin (NC) and its receptor (opiate receptor like-1, OPRL1) in ethanol-induced reward; activation of the OPRL1 by natural or synthetic ligands reduced ethanol self-administration and prevented relapse to ethanol drinking. The endogenous NC may function in neuronal circuits involved in reinforcing or conditioning effects of ethanol as a "brake" to limit ethanol intake (Roberto, M., Siggins, G.R. 2006. Nociceptin/orphanin FQ presynaptically decreases GABAergic transmission and blocks the ethanol-induced increase of GABA release in central amygdala. Proc. Natl. Acad. Sci. USA 103. 9715-9720), whereas repeated ethanol intake may downregulate the endogenous NC/OPRL1 system resulting in activation of ethanol consumption. To address this hypothesis, we evaluated whether expression of the pronociceptin (PNOC) and OPRL1 genes is altered in human alcoholics. mRNAs transcribed from these genes were analyzed by quantitative RT-PCR in the prefrontal and orbitofrontal cortices, central amygdala and hippocampal dentate gyrus, structures controlling alcohol consumption. Reduction in PNOC mRNA (1.7-fold) was found in the hippocampus of alcoholics, whereas OPRL1 mRNA levels were decreased (1.4-fold) in the central amygdala. No changes in expression of these genes in other brain areas analyzed were evident. We hypothesise that chronic ethanol intake downregulates PNOC and OPRL1 gene expression in the hippocampus and amygdala, respectively. The findings may be also interpreted as inherited molecular differences between alcoholics and controls. The PNOC/OPRL1 downregulation may underlie impairment of cognitive control over alcohol seeking in alcoholics. Stimulation of the OPRL1 receptors with synthetic agonists may increase threshold for activation of ethanol-related behaviour by environmental cues, and thus may reduce cue- or stress-primed relapse to ethanol consumption.
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| 10. |
- Kuzmin, Alexander, et al.
(författare)
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Repeated moderate-dose ethanol bouts impair cognitive function in Wistar rats
- 2012
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 17:1, s. 132-140
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Tidskriftsartikel (refereegranskat)abstract
- The effects of repeated, intermittent administration of a moderate dose of ethanol (3.4 g/kg/day × 6 days, intragastrically via gavages) on cognitive function were examined in male Wistar rats. No significant differences in weight gain between the ethanol- and water-treated rats were found. Analysis of physical dependence revealed no signs of spontaneous withdrawal, whereas withdrawal signs exacerbated by Ro15-4513, an inverse benzodiazepine agonist, were apparent 5 hours but not 24 hours after the cessation of ethanol treatment. Spatial learning and memory, as assessed in the Barnes maze, were impaired 3-6 days following the treatment but recovered by the 11th-14th days. Reversal learning, however, was impaired throughout the 2-week observation period. Thus, bouts of moderate-dose ethanol administration transiently impair spatial learning and memory, and promote cognitive inflexibility. The employed ethanol exposure paradigm may provide a model of human cognitive deficits associated with alcohol binge drinking.
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