| 1. |
- Dey, Lankeswar, et al.
(författare)
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Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters
- 2018
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 866:1
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Tidskriftsartikel (refereegranskat)abstract
- Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole no-hair theorem at the 10% level.
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| 2. |
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| 3. |
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| 4. |
- Burmeister, Florian, et al.
(författare)
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Description and performance of an electron-ion coincidence TOF spectrometer used at the Brazilian synchrotron facility LNLS
- 2010
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 180:1-3, s. 6-13
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the characteristics and performance of a Time-of-Flight Mass Spectrometer (TOF-MS) for coincidence measurements between electrons and ions that has been developed jointly in Sweden and Brazil. The spectrometer, used for studies of inner-shell photoexcitation of molecules in the gas-phase, has been optimized by implementing ion and electron lenses to allow the use of relatively small diameter detectors. Simulations were performed to understand the lens performance and they show that ions (electrons) could be collected without angular discrimination with a maximum kinetic energy up to ten (two) times higher than without the lens actions. A rotary vacuum chamber allows the spectrometer axis to be positioned at different angles relative to the polarization vector of the excitation beam. An important characteristic of the apparatus is that the acquisition setup allows a multi-hit capability with 1 ns resolution. Hereby, Photoelectron-Photoion-Photoion Coincidence (PEPIPICO) measurements can be performed on molecules containing two or more atoms of equal mass. A method to obtain experimental detection efficiencies of a single ion and one of one, two or three electrons has been developed. A systematic study of the interaction region has been performed to determine the shape of the photon and gas beams. Measurements on molecular nitrogen demonstrate the spectrometer's ability to resolve fragments with the same charge to mass ratio arriving within only a few ns. Simulations and experimental results of fragmentation of two singly charged cation nitrogen atoms agree, confirming that the spectrometer performance is well understood. (C) 2010 Elsevier B.V. All rights reserved.
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| 5. |
- Carravetta, V., et al.
(författare)
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PH-dependent X-ray Photoelectron Chemical Shifts and Surface Distribution of Cysteine in Aqueous Solution
- 2019
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 123:17, s. 3776-3785
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Tidskriftsartikel (refereegranskat)abstract
- The distribution and protonation states of amino acids in water droplets are of considerable concern in studies on the formation of clouds in the atmosphere as well as in many biological contexts. In the present work we use the amino acid cysteine as a prototypical example and explore the protonation states of this molecule in aqueous solution, which are strongly affected by the acidity of the environment and also can show different distributions between surface and bulk. We use a combination of X-ray photoelectron chemical shift measurements, density functional theory calculations of the shifts, and reactive force field molecular dynamics simulations of the underlying structural dynamics. We explore how the photoelectron spectra distinctly reflect the different protonation states that are generated by variation of the solution acidity and how the distribution of these protonation states can differ between bulk and surface regions. At specific pH values, we find that the distribution of the cysteine species at the surface is quite different from that in bulk, in particular, for the appearance in the surface region of species which do not exist in bulk. Some ramifications of this finding are discussed.
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| 6. |
- Ergon, Mattias, et al.
(författare)
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Optical and near-infrared observations of SN 2011dh-The first 100 days
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 562, s. A17-
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Tidskriftsartikel (refereegranskat)abstract
- We present optical and near-infrared (NIR) photometry and spectroscopy of the Type IIb supernova (SN) 2011dh for the first 100 days. We complement our extensive dataset with Swift ultra-violet (UV) and Spitzer mid-infrared (MIR) data to build a UV to MIR bolometric lightcurve using both photometric and spectroscopic data. Hydrodynamical modelling of the SN based on this bolometric lightcurve have been presented in Bersten et al. (2012, ApJ, 757, 31). We find that the absorption minimum for the hydrogen lines is never seen below similar to 11 000 km s(-1) but approaches this value as the lines get weaker. This suggests that the interface between the helium core and hydrogen rich envelope is located near this velocity in agreement with the Bersten et al. (2012) He4R270 ejecta model. Spectral modelling of the hydrogen lines using this ejecta model supports the conclusion and we find a hydrogen mass of 0.01-0.04 M-circle dot to be consistent with the observed spectral evolution. We estimate that the photosphere reaches the helium core at 5-7 days whereas the helium lines appear between similar to 10 and similar to 15 days, close to the photosphere and then move outward in velocity until similar to 40 days. This suggests that increasing non-thermal excitation due to decreasing optical depth for the gamma-rays is driving the early evolution of these lines. The Spitzer 4.5 mu m band shows a significant flux excess, which we attribute to CO fundamental band emission or a thermal dust echo although further work using late time data is needed. The distance and in particular the extinction, where we use spectral modelling to put further constraints, is discussed in some detail as well as the sensitivity of the hydrodynamical modelling to errors in these quantities. We also provide and discuss pre- and post-explosion observations of the SN site which shows a reduction by similar to 75 percent in flux at the position of the yellow supergiant coincident with SN 2011dh. The B, V and r band decline rates of 0.0073, 0.0090 and 0.0053 mag day(-1) respectively are consistent with the remaining flux being emitted by the SN. Hence we find that the star was indeed the progenitor of SN 2011dh as previously suggested by Maund et al. (2011, ApJ, 739, L37) and which is also consistent with the results from the hydrodynamical modelling.
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| 7. |
- Feifel, R., et al.
(författare)
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"Hidden" vibrations in CO : Reinvestigation of resonant Auger decay for the C 1s → π* excitation
- 2002
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 65:5 A, s. 527011-527018
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Tidskriftsartikel (refereegranskat)abstract
- The higher vibrational levels of the C 1s→π* excitation in carbon monooxide (CO) were investigated by using resonant Auger electron spectroscopy. The absorption profile of the CO was recorded in the partial electron yield mode. The results showed that the vibrational states were not seen in a total yield absorption spectrum whereas they were shown to be discernable in a partial electron yield spectrum.
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| 8. |
- K. Wiesner, R. F. Fink, S. L. Sorensen, M. Andersson, R. Feifel, I. Hjelte, C. Miron, A. Naves de Brito, L. Rosenqvist, H. Wang, S. Svensson, O. Björneholm
(författare)
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Valence Photoionization and Resonant Core Excitation of Ozone - Experimental and Theoretical Study of the C-State of O3
- 2003
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Ingår i: Chem Phys. Lett.. ; :375, s. 76-
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Marinho, R. R.T., et al.
(författare)
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Interference between direct and resonant channels in near-resonance photoemission in argon
- 2001
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 63:3, s. 325141-325145
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Tidskriftsartikel (refereegranskat)abstract
- The photoelectron spectra of argon was demonstrated during resonant photoemissions. The interference effects of the photoelectron spectra of argon was monitored by following the intensity of final states through resonant and direct channels. The need for a unified one-description of the ionization through a direct and core-excitation mediated channel was described.
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| 10. |
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| 14. |
- Cockerill, W, et al.
(författare)
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Health-related quality of life and radiographic vertebral fracture
- 2004
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 15:2, s. 113-119
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Tidskriftsartikel (refereegranskat)abstract
- Background: Vertebral fractures are associated with back pain and disability; however, relatively little is known about the impact of radiographic vertebral fractures on quality of life in population samples. The aim of this study was to determine the impact of a recent radiographic vertebral fracture on health-related quality of life (HRQoL). Methods: Men and women aged 50 years and over were recruited from population registers in 12 European centers. Subjects completed an interviewer-administered questionnaire and had lateral spine radiographs performed. Subjects in these centers were followed prospectively and had repeat spinal radiographs performed a mean of 3.8 years later. Prevalent deformities were defined using established morphometric criteria, and incident vertebral fractures by both morphometric criteria and qualitative assessment. For each incident fracture case, three controls matched for age, gender, and center were selected: one with a prevalent deformity (at baseline) and two without prevalent deformities. All subjects were interviewed or completed a postal questionnaire instrument which included Short Form 12 (SF-12), the EQ-5D (former EuroQol), and the quality of life questionnaire of the International Osteoporosis Foundation (QUALEFFO). The median time from the second spinal radiograph until the quality of life survey was 1.9 years. Comparison between cases and their matched controls was undertaken using the signed rank test. Results: 73 subjects with incident vertebral fracture (cases), mean age 64.8 years (of whom 23 had a baseline deformity), and 196 controls, mean age 63.9 years (of whom 60 had a baseline deformity), were studied. There were strong correlations between the domain scores for each of the three instruments. There was no statistically significant difference in any of the domain scores between cases and those controls with a prevalent deformity. However, compared with the controls without a prevalent deformity the cases had significantly impaired quality of life as determined using the total QUALEFFO score (38.2 vs 33.7), the physical component score of the SF-12 (39.9 vs 43.7) and the health status score of the EQ-5D (62.3 vs 69.9). When the analysis was repeated after stratification of the cases by baseline deformity status (i.e., cases with and without a prevalent deformity at baseline), cases with a prevalent deformity had impaired quality of life compared with their matched controls, both with and without a prevalent deformity. In contrast there was no significant difference in quality of life among the cases without a prevalent deformity and either control group. Conclusion: In this population-based study a recent vertebral fracture was associated with impairment in quality of life, though this was mainly among those who had sustained a previous vertebral deformity.
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| 15. |
- da Silva, Aderson Miranda, et al.
(författare)
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Surface-Altered Protonation Studied by Photoelectron Spectroscopy and Reactive Dynamics Simulations
- 2015
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 6:5, s. 807-811
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Tidskriftsartikel (refereegranskat)abstract
- The extent to which functional groups are protonated at aqueous interfaces as compared to bulk is deemed essential to several areas in chemistry and biology. The origin of such changes has been the source of intense debate. We use X-ray photoelectron spectroscopy and all-atom reactive molecular dynamics simulations as two independent methods to probe, at the molecular scale, both bulk and surface distributions of protonated species of cysteine in an aqueous solution. We show that the distribution of the cysteine species at the surface is quite different from that in the bulk. We argue that this finding, however, cannot be simply related to a change in the extent of proton sharing between the two conjugate acid/base pairs that may occur between these two regions. The present theoretical simulations identify species at the surface that are not present in the bulk.
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| 16. |
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| 17. |
- Fernandez-Martin, JL, et al.
(författare)
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COSMOS: the dialysis scenario of CKD-MBD in Europe
- 2013
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Ingår i: Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. - : Oxford University Press (OUP). - 1460-2385. ; 28:7, s. 1922-1935
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Tidskriftsartikel (refereegranskat)
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| 18. |
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| 19. |
- Guimaraes, Drielle D., et al.
(författare)
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Dietary Nitrate Reduces Blood Pressure in Rats With Angiotensin II-Induced Hypertension via Mechanisms That Involve Reduction of Sympathetic Hyperactivity
- 2019
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Ingår i: Hypertension. - : Lippincott Williams & Wilkins. - 0194-911X .- 1524-4563. ; 73:4, s. 839-848
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Tidskriftsartikel (refereegranskat)abstract
- Several experimental and clinical studies have shown that dietary nitrate supplementation can increase nitric oxide bioavailability. In the oral cavity, commensal bacteria reduce nitrate to nitrite, which is subsequently absorbed into the circulation where reduction to nitric oxide by enzymatic systems occur. Although it is well-known that boosting the nitrate-nitrite-nitric oxide pathway can improve cardiovascular, renal, and metabolic functions and that sympathoexcitation contributes to the development of the same disorders, the potential effects of dietary nitrate on sympathetic activity remain to be elucidated. In this study, we hypothesized that treatment with inorganic nitrate could prevent the increase in sympathetic nerve activity in an experimental model of Ang II (angiotensin II)-induced hypertension. Multiple in vivo approaches were combined, that is, Wistar rats orally treated with the nitric oxide synthase inhibitor L-NAME (N(G)-nitro-L-arginine methyl ester, 0.5 g/L) and implanted with subcutaneous osmotic minipump for continuous delivery of Ang II (120 ng/kg per minute; 14 days). Simultaneously, rats were supplemented with sodium nitrate (10 mmol/L) or placebo (sodium chloride; 10 mmol/L) in the drinking water. Blood pressure, heart rate, and renal sympathetic nerve activity were recorded. In placebo-treated rats, Ang II+ L-NAME treatment-induced arterial hypertension, which was linked with reduced spontaneous baroreflex sensitivity and increased renal sympathetic nerve activity, as well as upregulation of AT 1 Rs (Ang II type-1 receptors) in the rostral ventrolateral medulla. Supplementation with nitrate normalized the expression of AT 1 Rs in rostral ventrolateral medulla and reduced sympathetic nerve activity, which was associated with attenuated development of hypertension. In conclusion, chronic dietary nitrate supplementation blunted the development of hypertension via mechanisms that involve reduction of sympathetic outflow.
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| 20. |
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| 21. |
- Ismail, AA, et al.
(författare)
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Incidence of limb fracture across Europe: Results from the European Prospective Osteoporosis Study (EPOS)
- 2002
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 13:7, s. 565-571
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this population-based prospective study was to determine the incidence of limb fracture by site and gender in different regions of Europe. Men and women aged 50-79 years were recruited from population registers in 31 European centers. Subjects were invited to attend for an interviewer-administered questionnaire and lateral spinal radiographs. Subjects were subsequently followed up using an annual postal questionnaire which included questions concerning the occurrence of new fractures. Self-reported fractures were confirmed where possible by radiograph, attending physician or subject interview. There were 6451 men and 6936 women followed for a median of 3.0 years. During this time there were 140 incident limb fractures in men and 391 in women. The age-adjusted incidence of any limb fracture was 7,3/1000 person-years [pyrs] in men and 19 per 1000 pyrs in women, equivalent to a 2,5 times excess in women. Among women, the incidence of hip, humerus and distal forearm fracture, though not 'other' limb fracture, increased with age, while in men only the incidence of hip and humerus fracture increased with age. Among women, there was evidence of significant variation in the occurrence of hip, distal forearm and humerus fractures across Europe, with incidence rates higher in Scandinavia than in other European regions. though for distal forearm fracture the incidence in east Europe was similar to that observed in Scandinavia. Among men, there was no evidence of significant geographic variation in the occurrence of these fractures. This is the first large population-based study to characterize the incidence of limb fracture in men and women over 50 years of age across Europe. There are substantial differences in the descriptive epidemiology of limb fracture by region and gender.
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| 22. |
- Kirschner, Johannes, et al.
(författare)
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The molecular structure of the surface of water-ethanol mixtures
- 2021
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 23:19, s. 11568-11578
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Tidskriftsartikel (refereegranskat)abstract
- Mixtures of water and alcohol exhibit an excess surface concentration of alcohol as a result of the amphiphilic nature of the alcohol molecule, which has important consequences for the physico-chemical properties of water-alcohol mixtures. Here we use a combination of intensity vibrational sum-frequency generation (VSFG) spectroscopy, heterodyne-detected VSFG (HD-VSFG), and core-level photoelectron spectroscopy (PES) to investigate the molecular properties of water-ethanol mixtures at the air-liquid interface. We find that increasing the ethanol concentration up to a molar fraction (MF) of 0.1 leads to a steep increase of the surface density of the ethanol molecules, and an increased ordering of the ethanol molecules at the surface. When the ethanol concentration is further increased, the surface density of ethanol remains more or less constant, while the orientation of the ethanol molecules becomes increasingly disordered. The used techniques of PES and VSFG provide complementary information on the density and orientation of ethanol molecules at the surface of water, thus providing new information on the molecular-scale properties of the surface of water-alcohol mixtures over a wide range of compositions. This information is invaluable in understanding the chemical and physical properties of water-alcohol mixtures.
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| 23. |
- Le Guen, K., et al.
(författare)
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H2S ultrafast dissociation probed by energy-selected resonant Auger electron–ion coincidence measurements
- 2007
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 127:11, s. 114315-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the ultrafast dissociation of the H2S molecule upon S 2p(3/2)-> 6a(1) inner-shell excitation by combining high-resolution resonant Auger spectroscopy and energy-selected Auger electron-ion coincidence measurements. Auger final states have been correlated to the different fragmentation pathways (S+, HS+, and H2S+ ions). As an original result, we evidence a three-step mechanism to describe the resonant production of S+: the Auger recombination in the HS* fragment is followed for the A (3)Pi and c (1)Pi states by the S++H fragmentation mechanism.
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| 24. |
- Marinho, Ricardo R. T., et al.
(författare)
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Ethanol Solvation in Water Studied on a Molecular Scale by Photoelectron Spectroscopy
- 2017
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 121:33, s. 7916-7923
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Tidskriftsartikel (refereegranskat)abstract
- Because of the amphiphilic properties of alcohols, hydrophobic hydration is important in the alcohol water system. In the present paper we employ X-ray photoelectron spectroscopy (XPS) to investigate the bulk and surface molecular structure of ethanol water mixtures from 0.2 to 95 mol %. The observed XPS binding energy splitting between the methyl C is and hydroxymethyl C is groups (BES_[CH3-CH2OH]) as a function of the ethanol molar percentage can be divided into different regions: one below 35 mol % with higher values (about 1.53 eV) and one starting at 60 mol % up to 95 mol % with 1.49 eV as an average value. The chemical shifts agree with previous quantum mechanics/molecular mechanics (QM/MM) calculations [Loytynoja, T.; et al. J. Phys. Chem. B 2014, 118, 13217]. According to these calculations, the BES_[CH3-CH2OH] is related to the number of hydrogen bonds between the ethanol and the surrounding molecules. As the ethanol concentration increases, the average number of hydrogen bonds decreases from 2.5 for water-rich mixtures to 2 for pure ethanol. We give an interpretation for this behavior based on how the hydrogen bonds are distributed according to the mixing ratio. Since our experimental data are surface sensitive, we propose that this effect may also be manifested at the interface. From the ratio between the XPS C is core lines intensities we infer that below 20 mol % the ethanol molecules have their hydroxyl groups more hydrated and possibly facing the solution's bulk. Between 0.1 and 14 mol %, we show the formation of an ethanol monolayer at approximately 2 mol %. Several parameters are derived for the surface region at monolayer coverage.
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| 25. |
- Miron, C., et al.
(författare)
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Nuclear motion driven by the Renner-Teller effect as observed in the resonant Auger decay to the X̃2Π electronic ground state of N2O
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:2, s. 864-869
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear dynamics in the Nt 1s→π* in nitrous oxide was studied using the high resolution resonant Auger spectroscopy and ab initio quantum chemical calculations. For probing the nuclear motion of the system in the core-excited state, the frequency detuning technique was used. The results showed changes in vibrational structure for the Auger decay spectra and a strong influence of nuclear motion on the electronic decay.
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| 26. |
- Rosenqvist, L., et al.
(författare)
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Femtosecond dissociation of ozone studied by the Auger Doppler effect
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:8, s. 3614-3620
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Tidskriftsartikel (refereegranskat)abstract
- The peaks arising from the decay of the excited oxygen atom were studied. Fast dissociation of core-excited ozone was confirmed by the presence of Auger emission from atomic oxygen in the decay spectrum from the ozone OT 1s-σ*(7a1) state. No such emission was observed after excitation of the corresponding state on the central oxygen atom. An angle-dependent energy shift of the atomic lines was observed. Analysis of the energy shift revealed that the kinetic energy released in the dissociation process is approximately 3.3 ± 0.3eV. An energy release of 8.45 was found by application of a Born-Haber cycle.
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| 27. |
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| 28. |
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