| 621. |
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| 622. |
- Madsen, N, et al.
(författare)
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Search for trapped antihydrogen in ALPHA
- 2011
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Ingår i: Canadian journal of physics (Print). - 0008-4204 .- 1208-6045. ; 89:1, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- Antihydrogen spectroscopy promises precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe. Antihydrogen is, however, difficult to synthesize and is produced only in small quantities. The ALPHA collaboration is therefore pursuing a path towards trapping cold antihydrogen to permit the use of precision atomic physics tools to carry out comparisons of antihydrogen and hydrogen. ALPHA has addressed these challenges. Control of the plasma sizes has helped to lower the influence of the multipole field used in the neutral atom trap, and thus lowered the temperature of the created atoms. Finally, the first systematic attempt to identify trapped antihydrogen in our system is discussed. This discussion includes special techniques for fast release of the trapped anti-atoms, as well as a silicon vertex detector to identify antiproton annihilations. The silicon detector reduces the background of annihilations, including background from antiprotons that can be mirror trapped in the fields of the neutral atom trap. A description of how to differentiate between these events and those resulting from trapped antihydrogen atoms is also included.
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| 623. |
- Madsen, Pernille M, et al.
(författare)
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Genetic ablation of soluble tumor necrosis factor with preservation of membrane tumor necrosis factor is associated with neuroprotection after focal cerebral ischemia.
- 2015
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - 1559-7016.
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Tidskriftsartikel (refereegranskat)abstract
- Microglia respond to focal cerebral ischemia by increasing their production of the neuromodulatory cytokine tumor necrosis factor, which exists both as membrane-anchored tumor necrosis factor and as cleaved soluble tumor necrosis factor forms. We previously demonstrated that tumor necrosis factor knockout mice display increased lesion volume after focal cerebral ischemia, suggesting that tumor necrosis factor is neuroprotective in experimental stroke. Here, we extend our studies to show that mice with intact membrane-anchored tumor necrosis factor, but no soluble tumor necrosis factor, display reduced infarct volumes at one and five days after stroke. This was associated with improved functional outcome after experimental stroke. No changes were found in the mRNA levels of tumor necrosis factor and tumor necrosis factor-related genes (TNFR1, TNFR2, TACE), pro-inflammatory cytokines (IL-1β, IL-6) or chemokines (CXCL1, CXCL10, CCL2); however, protein expression of TNF, IL-1β, IL-6 and CXCL1 was reduced in membrane-anchored tumor necrosis factor(Δ/Δ) compared to membrane-anchored tumor necrosis factor(wt/wt) mice one day after experimental stroke. This was paralleled by reduced MHCII expression and a reduction in macrophage infiltration in the ipsilateral cortex of membrane-anchored tumor necrosis factor(Δ/Δ) mice. Collectively, these findings indicate that membrane-anchored tumor necrosis factor mediates the protective effects of tumor necrosis factor signaling in experimental stroke, and therapeutic strategies specifically targeting soluble tumor necrosis factor could be beneficial in clinical stroke therapy.
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| 624. |
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| 625. |
- Madsen, Steffen S., et al.
(författare)
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Sexual maturation and changes in water and salt transport components in the kidney and intestine of three-spined stickleback (Gasterosteus aculeatus L.)
- 2015
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 188, s. 107-119
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Tidskriftsartikel (refereegranskat)abstract
- Mature three-spined stickleback males use spiggin threads secreted from their kidney to glue together nest material. This requires strongly hypertrophied renal proximal tubular cells, which compromises renal osmoregulatory function during the breeding period. Experimental evidence suggests that the intestine takes over hypotonic fluid secretion at that stage but the mechanism is unexplored. To unravel the molecular mechanism we analyzed and compared transcript levels of several membrane proteins involved in water and salt transport in intestinal and renal tissues, in non-mature males (NM), mature males (MM), and mature females (MF). Aquaporin paralogs aqp1a, -30, -8aa, -8ab, -10a, and -10b, two Na+,K+-ATPase alpha-1 subunit isoforms (nka547, nka976), Na+,K+,2C1(-)-, and Na+,CI--cotransporters (nkcc1a, nkcc2,ncc), the cystic fibrosis transmembrane conductance regulator (cftr) and two claudin isoforms (cldn2, cldn15a) were expressed in the intestine and kidney in all groups. There were no differences in aqp and cldn expression between intestines of NM and MM; nkcc2 was lower and nka levels tended to be higher in intestines of MM than in NM. In the kidney, aqp1 and aqp8ab levels were lower in MM than in NM, whereas aqp3a, nkcc1a, cldn15a, and spiggin were markedly elevated. This was accompanied by marked hypertrophy of kidney tubules in MM. The data support an altered kidney function in terms of water handling in mature males, whereas there was no support for modified trans-epithelial water permeability or salt-secretory activity in the intestine of mature males. Salt-absorptive activity in the intestine may, however, be down-regulated during male maturation.
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| 626. |
- Mahendran, Srinivasan, 1989, et al.
(författare)
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Quantitative Predictions of the Thermal Conductivity in Transition Metal Dichalcogenides: Impact of Point Defects in MoS 2 and WS 2 Monolayers
- 2024
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Ingår i: Journal of Physical Chemistry C. - 1932-7447 .- 1932-7455. ; 128:4, s. 1709-1716
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Tidskriftsartikel (refereegranskat)abstract
- Transition metal dichalcogenides are investigated for various applications at the nanoscale because of their unique combination of properties and dimensionality. For many of the anticipated applications, heat conduction plays an important role. At the same time, these materials often contain relatively large amounts of point defects. Here, we provide a systematic analysis of the impact of intrinsic and selected extrinsic defects on the lattice thermal conductivity of MoS2 and WS2 monolayers. We combine Boltzmann transport theory and Green’s function-based T-matrix approach for the calculation of scattering rates. The force constants for the defect configurations are obtained from density functional theory calculations via a regression approach, which allows us to sample a rather large number of defects at a moderate computational cost and to systematically enforce both the translational and rotational acoustic sum rules. The calculated lattice thermal conductivity is in quantitative agreement with the experimental data for heat transport and defect concentrations for both MoS2 and WS2. Crucially, this demonstrates that the strong deviation from a 1/T temperature dependence of the lattice thermal conductivity observed experimentally can be fully explained by the presence of point defects. We furthermore predict the scattering strengths of the intrinsic defects to decrease in the sequence VMo ≈ V2S= > V2S⊥ > VS > Sad in both materials, while the scattering rates for the extrinsic (adatom) defects decrease with increasing mass such that Liad > Naad > Kad. Compared with earlier work, we find that both intrinsic and extrinsic adatoms are relatively weak scatterers. We attribute this difference to the treatment of the translational and rotational acoustic sum rules, which, if not enforced, can lead to spurious contributions in the zero-frequency limit.
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| 627. |
- Martin, T., et al.
(författare)
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Inversion of hydraulic conductivity from Induced Polarisation, Part B: field examples from five countries
- 2021
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Ingår i: Conference Proceedings, NSG2021 1st Conference on Hydrogeophysics. - : European Association of Geoscientists & Engineers. ; 2021
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Konferensbidrag (refereegranskat)abstract
- The knowledge about the hydraulic conductivity of the subsurface is crucial to know as it is a main parameter for groundwater flow characterization within an aquifer. The geophysical method time-domain Induced Polarisation has been shown to be useful for estimating the hydraulic conductivity. By using a new inversion approach, where we directly invert for hydraulic properties as inversion parameters, the estimation of the hydraulic conductivity can be improved. We have measured at several test sites across five European countries, all characterized by unconsolidated sediments, but with differences in terms of the water electrical conductivity. In particular, at the Zeeland site in the Netherlands, a strong gradient in the water electrical conductivity is present since a freshwater lens is overlaying the sea water. A very good agreement between the hydraulic conductivity values from the inversion with the present hydraulic model can be observed, despite of the high water electrical conductivity, which makes it challenging to identify the clay layers at the site. Similar results were achieved for the other tests sites. Therewith, this new methodology might open the way for reliable, cost-effective geophysical estimation of hydraulic conductivity in the field.
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| 628. |
- Mathisen, J., et al.
(författare)
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Associations between psychosocial work environment factors and first-time and recurrent treatment for depression : a prospective cohort study of 24,226 employees
- 2024
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Ingår i: Epidemiology and Psychiatric Sciences. - 2045-7960 .- 2045-7979. ; 33
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Adverse factors in the psychosocial work environment are associated with the onset of depression among those without a personal history of depression. However, the evidence is sparse regarding whether adverse work factors can also play a role in depression recurrence. This study aimed to prospectively examine whether factors in the psychosocial work environment are associated with first-time and recurrent treatment for depression.Methods. The study included 24,226 participants from the Danish Well-being in Hospital Employees study. We measured ten individual psychosocial work factors and three theoretical constructs (effort–reward imbalance, job strain and workplace social capital). We ascertained treatment for depression through registrations of hospital contacts for depression (International Statistical Classification of Diseases and Related Health Problems version 10 [ICD-10]: F32 and F33) and redeemed prescriptions of antidepressant medication (Anatomical Therapeutic Chemical [ATC]: N06A) in Danish national registries. We estimated the associations between work factors and treatment for depression for up to 2 years after baseline among those without (first-time treatment) and with (recurrent treatment) a personal history of treatment for depression before baseline. We excluded participants registered with treatment within 6 months before baseline. In supplementary analyses, we extended this washout period to up to 2 years. We applied logistic regression analyses with adjustment for confounding.Results. Among 21,156 (87%) participants without a history of treatment for depression, 350 (1.7%) had first-time treatment during follow-up. Among the 3070 (13%) participants with treatment history, 353 (11%) had recurrent treatment during follow-up. Those with a history of depression generally reported a more adverse work environment than those without such a history. Baseline exposure to bullying (odds ratio [OR] = 1.72, 95% confidence interval [95% CI]: 1.30–2.32), and to some extent also low influence on work schedule (OR = 1.27, 95% CI: 0.97–1.66) and job strain (OR = 1.24, 95% CI: 0.97–1.57), was associated with first-time treatment for depression during follow-up. Baseline exposure to bullying (OR = 1.40, 95% CI: 1.04–1.88), lack of collaboration (OR = 1.31, 95% CI: 1.03–1.67) and low job control (OR = 1.27, 95% CI: 1.00–1.62) were associated with recurrent treatment for depression during follow-up. However, most work factors were not associated with treatment for depression. Using a 2-year washout period resulted in similar or stronger associations.Conclusions. Depression constitutes a substantial morbidity burden in the working-age population. Specific adverse working conditions were associated with first-time and recurrent treatment for depression and improving these may contribute to reducing the onset and recurrence of depression.
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| 629. |
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| 630. |
- Michiels, R., et al.
(författare)
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Enhancement of above Threshold Ionization in Resonantly Excited Helium Nanodroplets
- 2021
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 127
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Tidskriftsartikel (refereegranskat)abstract
- Clusters and nanodroplets hold the promise of enhancing high-order nonlinear optical effects due to their high local density. However, only moderate enhancement has been demonstrated to date. Here, we report the observation of energetic electrons generated by above-threshold ionization (ATI) of helium (He) nanodroplets which are resonantly excited by ultrashort extreme ultraviolet (XUV) free-electron laser pulses and subsequently ionized by near-infrared (NIR) or near-ultraviolet (UV) pulses. The electron emission due to high-order ATI is enhanced by several orders of magnitude compared with He atoms. The crucial dependence of the ATI intensities with the number of excitations in the droplets suggests a local collective enhancement effect.
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