| 1. |
- Ananthakrishnan, Gopal, et al.
(författare)
-
An acoustic analysis of lion roars. II : Vocal tract characteristics
- 2011
-
Ingår i: Proceedings from Fonetik 2011. - Stockholm : KTH Royal Institute of Technology. ; , s. 5-8, s. 5-8
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper makes the first attempt to perform an acoustic-to-articulatory inversion of a lion (Panthera leo) roar. The main problems that one encounters in attempting this, is the fact that little is known about the dimensions of the vocal tract, other than a general range of vocal tract lengths. Precious little is also known about the articulation strategies that are adopted by the lion while roaring. The approach used here is to iterate between possible values of vocal tract lengths and vocal tractconfigurations. Since there seems to be a distinct articulatory changes during the process of a roar, we find a smooth path that minimizes the error function between arecorded roar and the simulated roar using a variable length articulatory model.
|
|
| 2. |
- Anderson, Emma K., et al.
(författare)
-
Decays of excited silver-cluster anions Agn, n=4 to 7, in the Double ElectroStatic Ion Ring ExpEriment
- 2018
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 98:2
-
Tidskriftsartikel (refereegranskat)abstract
- Spontaneous decays of small, hot silver-cluster anions Ag-n(-), n = 4-7, have been studied using one of the rings of the Double ElectroStatic Ion Ring ExpEriment (DESIREE). Observation of these decays over very long time scales is possible due to the very low residual gas pressure (similar to 10(-14)) and cryogenic (13 K) operation of DESIREE. The yield of neutral particles from stored beams of Ag-6(-) and Ag-2(-) anions were measured for 100 milliseconds and were found to follow single power-law behavior with millisecond time-scale exponential cutoffs. The Ag-4(-) and Ag-5(-) anions were stored for 60 s and the observed decays show two-component power-law behaviors. We present calculations of the rate constants for electron detachment from and fragmentation of Ag-4(-) and Ag-5(-). In these calculations, we assume that the internal energy distribution of the clusters are flat and with this we reproduce the early steep parts of the experimentally measured decay curves for Ag-4(-) and Ag-5(-) which extends to tens and hundreds of milliseconds, respectively. The fact that the calculations reproduce the early slopes of Ag-4(-) and Ag-5(-), which differ for the two cases, suggests that it is the changes in fragmentation rates with internal cluster energies of Ag-4(-) and Ag-5(-) rather than conditions in the ion source that determine this behavior. Comparisons with the measurements strongly suggest that the neutral particles detected in these time domains originate from Ag-4(-) -> Ag-3(-) + Ag and Ag-5(-) -> Ag-3(-) +Ag-2 fragmentation processes.
|
|
| 3. |
|
|
| 4. |
- Anderson, Emma K., 1986-, et al.
(författare)
-
Fragmentation of and electron detachment from hot copper and silver dimer anions : A comparison
- 2023
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 107:6
-
Tidskriftsartikel (refereegranskat)abstract
- We measured the spontaneous decays of internally hot copper and silver dimer anions, and , stored in one of the two ion-beam storage rings of the Double Electrostatic Ion Ring Experiment (DESIREE) at Stockholm University. A coincidence detection technique was utilized enabling essentially background-free measurements of -> Cu + Cu- and -> Ag + Ag- fragmentation rates. Furthermore, the total rates of neutral decay products (monomers and dimers) were measured and the relative contributions of fragmentation and electron emission ( -> Cu2 + e- and -> Ag2 + e-) were deduced as functions of storage time. Fragmentation is completely dominant at early times. However, after about 20 ms of storage, electron emission is observed and becomes the leading decay path after 100 ms for both dimer anions. The branching ratios between fragmentation and electron emission (vibrationally assisted autodetachment processes) are very nearly the same for and Ag-2 throughout the present storage cycle of 10 seconds. This is surprising considering the difference between the electron affinities of the neutral dimers, Cu2 and Ag2, and the difference between the and the dissociation energies.
|
|
| 5. |
- Anderson, Emma K., et al.
(författare)
-
Spontaneous electron emission from hot silver dimer anions: Breakdown of the Born-Oppenheimer approximation
- 2020
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 124
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first experimental evidence of spontaneous electron emission from a homonuclear dimer anion through direct measurements of Ag−2 → Ag2 + e− decays on milliseconds and seconds timescales. This observation is very surprising as there is no avoided crossing between adiabatic energy curves to mediate such a process. The process is weak, yet dominates the decay signal after 100 ms when ensembles of internally hot Ag−2 ions are stored in the cryogenic ion-beam storage ring, DESIREE, for 10 s. The electron emission process is associated with an instantaneous, very large reduction of the vibrational energy of the dimer system. This represents a dramatic deviation from a Born-Oppenheimer description of dimer dynamics.
|
|
| 6. |
- Andersson, Daniel P., et al.
(författare)
-
Relation among hypertriglyceridaemia, cardiometabolic disease, and hereditary factors : design and rationale of the Stockholm hyperTRIglyceridaemia REGister study
- 2024
-
Ingår i: European Heart Journal Open. - : Oxford University Press. - 2752-4191. ; 4:2
-
Tidskriftsartikel (refereegranskat)abstract
- AimsHypertriglyceridaemia (hTG) is associated with atherosclerotic cardiovascular disease, pancreatitis, and non-alcoholic fatty liver disease (NAFLD) in large population-based studies. The understanding of the impact of hereditary hTG and cardiometabolic disease status on the development of hTG and its associated cardiometabolic outcomes is more limited. We aimed to establish a multigenerational cohort to enable studies of the relationship between hTG, cardiometabolic disease and hereditary factors.Methods and resultsThe population-based observational Stockholm hyperTRIglyceridaemia REGister (STRIREG) study includes 1 460 184 index individuals who have measured plasma triglycerides in the clinical routine in Region Stockholm, Sweden, between 1 January 2000 and 31 December 2021. The laboratory measurements also included basic haematology, blood lipid panel, liver function tests, and HbA1c. Using the Swedish Multi-Generation register, 2 147 635 parents and siblings to the indexes were identified to form the complete study cohort. Laboratory data from participants were combined with data from several national registers that provided information on the cause of death, medical diagnoses, dispensed medicines, and socioeconomic factors including country of birth, education level, and marital status.ConclusionThe multi-generational longitudinal STRIREG cohort provides a unique opportunity to investigate different aspects of hTG as well as heredity for other metabolic diseases. Important outcome measures include mortality, cardiovascular mortality, major cardiovascular events, development of incident diabetes, and NAFLD. The STRIREG study will provide a deeper understanding of the impact of hereditary factors and associated cardiometabolic complications.
|
|
| 7. |
|
|
| 8. |
- Barklem, Paul, et al.
(författare)
-
Mutual Neutralization in Li++H−/D− and Na++H−/D− Collisions : Implications of Experimental Results for Non-LTE Modeling of Stellar Spectra
- 2021
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 908:2
-
Tidskriftsartikel (refereegranskat)abstract
- Advances in merged-beams instruments have allowed experimental studies of the mutual neutralization (MN) processes in collisions of both Li+ and Na+ ions with D− at energies below 1 eV. These experimental results place constraints on theoretical predictions of MN processes of Li+ and Na+ with H−, important for non-LTE modeling of Li and Na spectra in late-type stars. We compare experimental results with calculations for methods typically used to calculate MN processes, namely the full quantum (FQ) approach, and asymptotic model approaches based on the linear combination of atomic orbitals (LCAO) and semiempirical (SE) methods for deriving couplings. It is found that FQ calculations compare best overall with the experiments, followed by the LCAO, and the SE approaches. The experimental results together with the theoretical calculations, allow us to investigate the effects on modeled spectra and derived abundances and their uncertainties arising from uncertainties in the MN rates. Numerical experiments in a large grid of 1D model atmospheres, and a smaller set of 3D models, indicate that neglect of MN can lead to abundance errors of up to 0.1 dex (26%) for Li at low metallicity, and 0.2 dex (58%) for Na at high metallicity, while the uncertainties in the relevant MN rates as constrained by experiments correspond to uncertainties in abundances of much less than 0.01 dex (2%). This agreement for simple atoms gives confidence in the FQ, LCAO, and SE model approaches to be able to predict MN with the accuracy required for non-LTE modeling in stellar atmospheres.
|
|
| 9. |
|
|
| 10. |
- Bull, James N., et al.
(författare)
-
Ultraslow radiative cooling of Cn- (n=3-5)
- 2019
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 151:11
-
Tidskriftsartikel (refereegranskat)abstract
- Ultraslow radiative cooling lifetimes and adiabatic detachment energies for three astrochemically relevant anions, Cn- (n = 3-5), are measured using the Double ElectroStatic Ion Ring ExpEriment (DESIREE) infrastructure at Stockholm University. DESIREE maintains a background pressure of approximate to 10(-14) mbar and temperature of approximate to 13 K, allowing storage of mass-selected ions for hours and providing conditions coined a molecular cloud in a box. Here, we construct two-dimensional (2D) photodetachment spectra for the target anions by recording photodetachment signal as a function of irradiation wavelength and ion storage time (seconds to minute time scale). Ion cooling lifetimes, which are associated with infrared radiative emission, are extracted from the 2D photodetachment spectrum for each ion by tracking the disappearance of vibrational hot-band signal with ion storage time, giving 1e cooling lifetimes of 3.1 +/- 0.1 s (C3-), 6.8 +/- 0.5 s (C4-), and 24 +/- 5 s (C5-). Fits of the photodetachment spectra for cold ions, i.e., those stored for at least 30 s, provide adiabatic detachment energies in good agreement with values from laser photoelectron spectroscopy on jet-cooled anions, confirming that radiative cooling has occurred in DESIREE. Ion cooling lifetimes are simulated using a simple harmonic cascade model, finding good agreement with experiment and providing a mode-by-mode understanding of the radiative cooling properties. The 2D photodetachment strategy and radiative cooling modeling developed in this study could be applied to investigate the ultraslow cooling dynamics of a wide range of molecular anions.
|
|
| 11. |
- Cederblad, Lars, et al.
(författare)
-
Classification of Hypoglycemic Events in Type 1 Diabetes Using Machine Learning Algorithms
- 2023
-
Ingår i: Diabetes Therapy. - : Springer Nature. - 1869-6953 .- 1869-6961. ; 14:6, s. 953-965
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionTo improve the utilization of continuous- and flash glucose monitoring (CGM/FGM) data we have tested the hypothesis that a machine learning (ML) model can be trained to identify the most likely root causes for hypoglycemic events.MethodsCGM/FGM data were collected from 449 patients with type 1 diabetes. Of the 42,120 identified hypoglycemic events, 5041 were randomly selected for classification by two clinicians. Three causes of hypoglycemia were deemed possible to interpret and later validate by insulin and carbohydrate recordings: (1) overestimated bolus (27%), (2) overcorrection of hyperglycemia (29%) and (3) excessive basal insulin presure (44%). The dataset was split into a training (n = 4026 events, 304 patients) and an internal validation dataset (n = 1015 events, 145 patients). A number of ML model architectures were applied and evaluated. A separate dataset was generated from 22 patients (13 ‘known’ and 9 ‘unknown’) with insulin and carbohydrate recordings. Hypoglycemic events from this dataset were also interpreted by five clinicians independently.ResultsOf the evaluated ML models, a purpose-built convolutional neural network (HypoCNN) performed best. Masking the time series, adding time features and using class weights improved the performance of this model, resulting in an average area under the curve (AUC) of 0.921 in the original train/test split. In the dataset validated by insulin and carbohydrate recordings (n = 435 events), i.e. ‘ground truth,’ our HypoCNN model achieved an AUC of 0.917.ConclusionsThe findings support the notion that ML models can be trained to interpret CGM/FGM data. Our HypoCNN model provides a robust and accurate method to identify root causes of hypoglycemic events.
|
|
| 12. |
- Chartkunchand, Kiattichart C., et al.
(författare)
-
Dianion diagnostics in DESIREE : High-sensitivity detection of C-n(2-) from a sputter ion source
- 2018
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 89:3
-
Tidskriftsartikel (refereegranskat)abstract
- A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, C-n(2-), with n = 7-24. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot C-n(2-) dianions injected into the ring yielded C-n(2-) anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a 90 degrees analyzing magnet on the ion injection line reflect the production of internally hot C-7(2-) - C-24(2-) dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of C-6(2-) was found while there was a clear C-7(2-) signal with the expected isotopic distribution. This is consistent with earlier experimental studies and with theoretical predictions. An upper limit is deduced for a C-6(2-) signal that is two orders-of-magnitude smaller than that for C-7(2-). In addition, CnO2- and CnCu2- dianions were detected.
|
|
| 13. |
- Chartkunchand, Kiattichart C., et al.
(författare)
-
Radiative lifetimes of the bound excited states of Pt-
- 2016
-
Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 94:3
-
Tidskriftsartikel (refereegranskat)abstract
- © 2016 American Physical Society.The intrinsic radiative lifetimes of the 5d106sS1/22 and 5d96s2 D3/22 bound excited states in the platinum anion Pt- have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying 5d106s S1/22 state was measured to be 2.54±0.10s, while only a lifetime in the range of 50-200 ms could be estimated for the 5d96s2 D3/22 fine-structure level. The storage lifetime of the Pt- ion beam was measured to be a little over 15 min at a ring temperature of 13K. The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.
|
|
| 14. |
- Dekkers, Koen, et al.
(författare)
-
An online atlas of human plasma metabolite signatures of gut microbiome composition.
- 2022
-
Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Human gut microbiota produce a variety of molecules, some of which enter the bloodstream and impact health. Conversely, dietary or pharmacological compounds may affect the microbiota before entering the circulation. Characterization of these interactions is an important step towards understanding the effects of the gut microbiota on health. In this cross-sectional study, we used deep metagenomic sequencing and ultra-high-performance liquid chromatography linked to mass spectrometry for a detailed characterization of the gut microbiota and plasma metabolome, respectively, of 8583 participants invited at age 50 to 64 from the population-based Swedish CArdioPulmonary bioImage Study. Here, we find that the gut microbiota explain up to 58% of the variance of individual plasma metabolites and we present 997 associations between alpha diversity and plasma metabolites and 546,819 associations between specific gut metagenomic species and plasma metabolites in an online atlas ( https://gutsyatlas.serve.scilifelab.se/ ). We exemplify the potential of this resource by presenting novel associations between dietary factors and oral medication with the gut microbiome, and microbial species strongly associated with the uremic toxin p-cresol sulfate. This resource can be used as the basis for targeted studies of perturbation of specific metabolites and for identification of candidate plasma biomarkers of gut microbiota composition.
|
|
| 15. |
|
|
| 16. |
- Eklund, Gustav, et al.
(författare)
-
Cryogenic merged-ion-beam experiments in DESIREE : Final-state-resolved mutual neutralization of Li+ and D-
- 2020
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 102:1
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed an experimental technique to study charge-and energy-flow processes in sub-eV collisions between oppositely charged, internally cold, ions of atoms, molecules, and clusters. Two ion beams are stored in separate rings of the cryogenic ion-beam storage facility DESIREE, and merged in a common straight section where a set of biased drift tubes is used to control the center-of-mass collision energy locally in fine steps. Here, we present measurements on mutual neutralization between Li+ and D- where a time-sensitive imaging-detector system is used to measure the three-dimensional distance between the neutral Li and D atoms as they reach the detector. This scheme allows for direct measurements of kinetic-energy releases, and here it reveals separate populations of the 3s state and the (3p + 3d) states in neutral Li while the D atom is left in its ground state 1s. The branching fraction of the 3s final state is measured to be 57.8 +/- 0.7% at a center-of-mass collision energy of 78 +/- 13 meV. The technique paves the way for studies of charge-, energy-, and mass-transfer reactions in single collisions involving molecular and cluster ions in well-defined quantum states.
|
|
| 17. |
- Eklund, Gustav, 1990-, et al.
(författare)
-
Experimental lifetime of the a1Δ electronically excited state of CH−
- 2022
-
Ingår i: Physical Review Research. - : American Physical Society (APS). - 2643-1564. ; 4:1
-
Tidskriftsartikel (refereegranskat)abstract
- By repeatedly probing the a1Δ excited state and the X3Σ− ground-state populations in a beam of CH− ions stored in a cryogenic ion-beam storage ring for 100 s, we extract an intrinsic lifetime of 14.9±0.5 s for this excited state. This is far longer than all earlier experimental and theoretical results, exposing large difficulties in measuring and calculating slow decays and the need for benchmark quality experiments.
|
|
| 18. |
- Eklund, Gustav, 1990-
(författare)
-
Experiments on mutual neutralization using storage rings with merged ion beams
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents work on merged-beams experiments using the DESIREE facility, which consists of two electrostatic ion-storage rings operated at cryogenic temperatures of about 13 K. The two storage rings have a common straight section, where oppositely charged ions can interact at sub-eV collision energies. The work consists of development of the experimental method, tools for data analysis, and simulations for interpretation of the experimental results. This development has led to the first results from merged-beams experiments at DESIREE. The experiments are performed on mutual neutralization, a collision process where an electron is transferred from a negatively charged ion to a positively charged ion, resulting in two neutral products. This reaction is investigated for three systems: Li+ with D−, Na+ with D−, and Mg+ with D−. The reactions studied are of astrophysical interest, in particular for modeling of stellar atmospheres. The detection of the reaction products is done by using a position- and time-sensitive detector, and from this information it is possible to determine the quantum states involved in the reaction. The branching fractions of the reaction channels are measured and compared to theoretical modeling.
|
|
| 19. |
|
|
| 20. |
- Eklund, Gustav, et al.
(författare)
-
Final-state-resolved mutual neutralization of Na+ and D-
- 2021
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 103:3
-
Tidskriftsartikel (refereegranskat)abstract
- The present paper reports on a merged-beam experiment on mutual neutralization between Na+ and D-. For this experiment, we have used the DESIREE ion-beams storage-ring facility. The reaction products are detected using a position- and time-sensitive detector, which ideally allows for determination of the population of each individual quantum state in the final atomic systems. Here, the 4s, 3d, and 4p final states in Na are observed and in all cases the D atom is in its ground state 1s S-2. The respective branching fractions of the states populated in Na are determined by fitting results from a Monte Carlo simulation of the experiment to the measured data. The center-of-mass collision energy is controlled using a set of biased drift tubes, and the branching fractions are measured for energies between 80 meV and 393 meV. The resulting branching fractions are found to agree qualitatively with the only available theoretical calculations for this particular system, which are based on a multichannel Landau-Zener approach using dynamic couplings determined with a linear combination of atomic orbitals model.
|
|
| 21. |
- Eklund, Gustav
(författare)
-
Rotationally cold molecular ions in DESIREE : Threshold photodetachment thermometry of OH− and OD−
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In experiments on molecular ions it is highly beneficial if the ions are in the electronic, vibrational and rotational ground state. Previous studies on these systems in ion traps or storage rings have been successful in preparing the molecular ions in the electronic and vibrational ground states, but the rotational degrees of freedom are experimentally more challenging due to their long relaxation times and the relatively small amounts of energy required for rotational excitations. Recent developments in electrostatic cryogenic storage devices have opened up possibilities of studying and controlling the rotational relaxation of molecular ions. This thesis presents experiments performed on the molecularions OH ̄ and OD ̄ stored in the cryogenic storage ring DESIREE at Stockholm University. The molecular ions are studied using a technique known as photodetachment thermometry, relying on detection of molecules neutralized through photodetachment as they are stored in the ring. By modeling the photodetachment cross section, we are able to measure the relative populations of rotational states and monitor the rotational relaxation of the molecular ions. The long storage times of DESIREE allow us to observe the rotational relaxation on timescales up to several relaxation lifetimes. From these measurements we are able to extract the intrinsic lifetime of the first excited rotational state of OH ̄ to be 183 ± 35 s. In addition to measuring the spontaneous rotational relaxation, we have also applied a selective photodetachment method to prepare an ensemble of ions at even lower internal temperature than what occurs spontaneously.
|
|
| 22. |
- Eklund, Robert, 1962-, et al.
(författare)
-
A comparative acoustic analysis of purring in four cheetahs
- 2012
-
Ingår i: Proceedings from FONETIK 2012. - Gothenburg : University of Gothenburg. - 9789163709852 ; , s. 41-44
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports results from a comparativeanalysis of purring in four tame cheetahs. Theresults exhibited individual variation forrelative phase duration and number of cyclesper phase, while egressive phases were louderand had higher fundamental frequency in allfour cheetahs.
|
|
| 23. |
- Eklund, Robert, 1962-, et al.
(författare)
-
A comparative acoustic analysis of purring in juvenile, subadult and adult cheetahs
- 2013
-
Ingår i: Proceedings of Fonetik 2013 The XXVIth Annual Phonetics Meeting, 12-13 June 2013, Linköping University, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789175195827 - 9789175195797 ; , s. 25-28
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Previous studies of cheetah purring havedescribed purring in adult cheetahs. This paperextends the cheetah purring research to includejuvenile and subadult cheetahs and analyzespurring data from cheetahs in ages rangingfrom 7 months to 7 years, and with weightsranging from 18 kilos to over 70 kilos. Resultsshow that while there is considerable variationacross most parameters analysed (amplitude,phase duration, cycles per phase andfundamental frequency), mainly attributable todegree of relaxation/agitation, previouslyreported observations that ingressive phasestend to be lower in frequency are largelyconfirmed, with one notable exception.
|
|
| 24. |
- Eklund, Robert, 1962-, et al.
(författare)
-
An acoustic analysis of agonistic sounds in wild cheetahs
- 2012
-
Ingår i: <em>Proceedings from FONETIK 2012</em>. - Gothenburg : University of Gothenburg. - 9789163709852 ; , s. 37-40
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The cheetah ranks among the more vocal felids,and is above all a prominent purrer. However,the cheetah also produces a wide variety ofother sounds, and this paper takes a closer lookat a category of sounds produced by wildcheetahs, agonistic vocalizations, that can bedivided into moaning, growling, hissing andspitting sounds.
|
|
| 25. |
- Eklund, Robert, 1962-, et al.
(författare)
-
An acoustic analysis of lion roars. I: Data collection and spectrogramand waveform analyses
- 2011
-
Ingår i: <em>Quarterly Progress and Status Report TMH-QPSR, Volume 51, 2011. Proceedings from Fonetik 2011</em>. Royal Institute of Technology, Stockholm, Sweden, 8–10 June 2011, pp. 1–4.. - Stockholm : Universitetsservice. ; 51:1, s. 1-4
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes the collection of lion roar data at two different locations, anoutdoor setting at Antelope Park in Zimbabwe and an indoor setting at Parken Zooin Sweden. Preliminary analyses of spectrographic and waveform data are provided.
|
|
| 26. |
|
|
| 27. |
- Gau, Rémi, et al.
(författare)
-
Brainhack : Developing a culture of open, inclusive, community-driven neuroscience
- 2021
-
Ingår i: Neuron. - : Elsevier. - 0896-6273 .- 1097-4199. ; 109:11, s. 1769-1775
-
Tidskriftsartikel (refereegranskat)abstract
- Brainhack is an innovative meeting format that promotes scientific collaboration and education in an open, inclusive environment. This NeuroView describes the myriad benefits for participants and the research community and how Brainhacks complement conventional formats to augment scientific progress.
|
|
| 28. |
|
|
| 29. |
- Grumer, Jon, et al.
(författare)
-
State-Resolved Mutual Neutralization of Mg+ and D-
- 2022
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 128:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present experimental final-state distributions for Mg atoms formed in Mg+ + D- mutual neutralization reactions at center-of-mass collision energies of 59 +/- 12 meV by using the merged-beams method. Comparisons with available full-quantum results reveal large discrepancies and a previously underestimated total rate coefficient by up to a factor of 2 in the 0-1 eV (< 10(4) K) regime. Asymptotic model calculations arc shown to describe the process much better and we recommend applying this method to more complex iron group systems; data that is of urgent need in stellar spectral modeling.
|
|
| 30. |
- Grumer, Jon, et al.
(författare)
-
State-Resolved Mutual Neutralization of Mg+ and D−
- 2022
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 128:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present experimental final-state distributions for Mg atoms formed in Mg++D− mutual neutralization reactions at center-of-mass collision energies of 59±12 meV by using the merged-beams method. Comparisons with available full-quantum results reveal large discrepancies and a previously underestimated total rate coefficient by up to a factor of 2 in the 0–1 eV (<104 K) regime. Asymptotic model calculations are shown to describe the process much better and we recommend applying this method to more complex iron group systems; data that is of urgent need in stellar spectral modeling.
|
|
| 31. |
- Hansen, Klavs, 1958, et al.
(författare)
-
Spontaneous decay of small copper-cluster anions Cun− (n=3–6), on long time scales
- 2017
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 95:2
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the spontaneous neutral particle emission from copper-cluster anions (Cun −, n = 3–6) stored at cryogenic temperatures in one of the electrostatic ion storage rings of the Double ElectroStatic Ion Ring ExpEriment facility at Stockholm University. The measured rate of emission from the stored Cu3 − ions follows a single power-law decay for about 1 ms but then decreases much more rapidly with time. The latter behavior may be due to a decrease in the density of available final states in Cu3 as the excitation energies of the decaying ions approach the electron detachment threshold. The emissions from Cu4 −, Cu5−, and Cu6− are well described by sums of two power laws that are quenched by radiative cooling of the stored ions with characteristic times between a few and hundreds of milliseconds. We relate these two-component behaviors to populations of stored ions with higher and lower angular momenta. In a separate experiment, we studied the laser-induced decay of Cu6− ions that were excited by 1.13- or 1.45-eV photons after 46 ms of storage.
|
|
| 32. |
- Hägg, Gustav, et al.
(författare)
-
Fungerar entreprenörskapsutbildning på universitetsnivå? Ett balanserat lärande för att utveckla kunskaper att företa sig entreprenöriella karriärer
- 2019
-
Ingår i: Entreprenörskapsutbildning : Går det att lära ut entreprenörskap? - Går det att lära ut entreprenörskap?. - 9789189301047
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I kapitel 4 utforskar Gustav Hägg hur väl entreprenörskapsutbildningar fung- erar och varför vi överhuvudtaget ska satsa på utbildning i entreprenörskap. Kapitelförfattaren lyfter inledningsvis att entreprenören ofta associeras med enhör- ningen och att det inte sällan är framgångsrika individer som lyfts fram. Enligt Hägg är detta missvisande då entreprenören kommer i alla möjliga skepnader och finns inom samtliga näringar i samhället. Från den enskilda näringsidkaren till tech-entreprenörerna såväl som förändringsagenterna inom stora företag som IKEA och H&M, men även inom kommuner och landsting. Faktum är att majoriteten av samhällets entreprenörer snarare, enligt Hägg, kan liknas vid den nordsvenska brukshästen. Hägg påpekar, med ett citat från Fayolle, att ”det är möjligt att under- visa samt lära sig entreprenörskap. Men precis som andra ämnesområden är det omöjligt att på förhand garantera en positiv utgång för de aktioner som företas”. Det kan således argumenteras att det inte på förhand går att förutse vem som blir nästa enhörning. Därför är optimering av den nordsvenska brukshästen en bättre grogrund för kommande generationers företagsamhet. Dagens samhälle ställer höga krav på individers förändringsbenägenhet och entreprenörerna är viktiga för att möta morgondagens samhällsutmaningar. Enligt Hägg bör därför satsningar på entreprenörskapsutbildning ges hög prioritet. Forskningsdiskussionen har tidigare både adresserat entreprenörskap som ämne men även som pedagogisk ansats. Det har väckt många frågor kring vad kärnan i en entreprenörskapsutbildning är och bör vara. Hägg pekar på att forskningen inte ger tydliga svar vilket för med sig utmaningar vad gäller att utvärdera lärande såväl som effekterna av entreprenörskapsutbildning. Syftet med kapitlet är att dels diskutera entreprenörskapsutbildningens utveckling över tid, eftersom historien påverkar hur vi förstår morgondagen. Dels att besvara de inledande frågorna: huruvida entrepre- nörskapsutbildning fungerar och varför vi bör utbilda entreprenörer.
|
|
| 33. |
- Karlgren, Jussi
(författare)
-
The Interaction of Discourse Modality and User Expectations in Human-Computer Dialog
- 1992
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study discusses the behavior of people towards natural language interfaces. It draws parallels to the behavior of people towards other people, and discusses how far these parallels can be stretched. A small experimental study of users performing tasks using a natural language interface to a database is presented, and the results related to the discussion.The main points made are1) that new modalities like the one used in typical human computer interaction - written interactive communication - are problematic for new users, from lack of conventions; and2) that users' attitudes towards computers and of the system's linguistic and other competence shape much of the interaction, and that these attitudes change, and that thus the important factor to take into account in system design is not what the initial attitudes are but rather what the process of changing them is and how to utilize the process of change to teach the user the system language and interaction modality.
|
|
| 34. |
- Kristiansson, Moa K., et al.
(författare)
-
Experimental and theoretical studies of excited states in Ir
- 2021
-
Ingår i: Physical Review A. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 103:6
-
Tidskriftsartikel (refereegranskat)abstract
- The properties of atomic negative ions are to a large extent determined by electron-electron correlation which makes them an ideal testing ground for atomic many-body physics. In this paper, we present a detailed experimental and theoretical study of excited states in the negative ion of iridium. The ions were stored at cryogenic temperatures using the double electrostatic ion ring experiment facility at Stockholm University. Laser photodetachment was used to monitor the relaxation of three bound excited states belonging to the [Xe] 4f(14)5d(8)6s(2) ionic ground configuration. Our measurements show that the first excited state has a lifetime much longer than the ion-beam storage time of 1230 +/- 100 s. The binding energy of this state was measured to be 1.045 +/- 0.002 eV. The lifetimes of the second and third excited states were experimentally determined to be 133 +/- 10 and 172 +/- 35 ms, respectively. Multiconfiguration Dirac-Hartree-Fock calculations were performed in order to extract binding energies and lifetimes. These calculations predict the existence of the third excited bound state that was detected experimentally. The computed lifetimes for the three excited bound states agree well with the experimental results and allow for a clear identification of the detected levels.
|
|
| 35. |
|
|
| 36. |
- Kristiansson, Moa K., 1989-, et al.
(författare)
-
High-precision electron affinity of oxygen
- 2022
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Negative ions are important in many areas of science and technology, e.g., in interstellar chemistry, for accelerator-based radionuclide dating, and in anti-matter research. They are unique quantum systems where electron-correlation effects govern their properties. Atomic anions are loosely bound systems, which with very few exceptions lack optically allowed transitions. This limits prospects for high-resolution spectroscopy, and related negative-ion detection methods. Here, we present a method to measure negative ion binding energies with an order of magnitude higher precision than what has been possible before. By laser-manipulation of quantum-state populations, we are able to strongly reduce the background from photodetachment of excited states using a cryogenic electrostatic ion-beam storage ring where keV ion beams can circulate for up to hours. The method is applicable to negative ions in general and here we report an electron affinity of 1.461 112 972(87) eV for O-16. High-precision measurements are useful to find isotopic shifts and electron correlation. Here the authors measure electron affinity and hyperfine splitting of atomic oxygen with higher precision than previous studies.
|
|
| 37. |
- Mårback, Sebastian, et al.
(författare)
-
Uhm... What's going on? An EEG study on perception of filled pauses in spontaneous Swedish speech
- 2009
-
Ingår i: Proceedings of the 22nd Swedish Phonetics Conference. ; , s. 92-95, s. 92-95
-
Konferensbidrag (refereegranskat)abstract
- Filled pauses have been shown to play a significant role in comprehension and long-term storage of speech. Behavioral and neurophysiological studies suggest that filled pauses can help mitigate semantic and/or syntactic incongruity in spoken language. The purpose of the present study was to explore how filled pauses affect the processing of spontaneous speech in the listener. Brain activation of eight subjects was measured by electroencephalography (EEG), while they listened to recordings of Wizard-of-Oz travel booking dialogues.The results show a P300 component in the Primary Motor Cortex, but not in the Broca or Wernicke areas. A possible interpretation could be that the listener is preparing to engage in speech. However, a larger sample is currently being collected.
|
|
| 38. |
- Navarro-Navarrete, José E., 1988-, et al.
(författare)
-
High-resolution measurement of the electron affinity of cesium
- 2024
-
Ingår i: PHYSICAL REVIEW A. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 109:2
-
Tidskriftsartikel (refereegranskat)abstract
- Negative ions are unique quantum systems where electron correlation plays a decisive role in determining their properties. The lack of optically allowed transitions prevents traditional optical spectroscopy and the electron affinity is, therefore, for most elements, the only atomic quantity that can be determined with high accuracy. In this work, we present a high-precision experimental determination of the electron affinity of cesium. A collinear laser-ion beam apparatus was used to investigate the partial photodetachment cross section for the cesium anion, leaving the neutral atom in the 6p 2P3/2 excited state. A resonance ionization scheme was used to obtain final-state selectivity, which enabled the investigation of a sharp onset of the cross section associated with a Wigner s-wave threshold behavior. The electron affinity was determined to be 0.471 598 3(38) eV.
|
|
| 39. |
|
|
| 40. |
- Nilsonne, Gustav, et al.
(författare)
-
”Sluta betala för att få publicera forskning”
- 2023
-
Ingår i: Svenska Dagbladet. - 1101-2412. ; :2023-03-28
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Vetenskapliga tidskrifter som gömmer sina forskningsresultat bakom betalväggar har spelat ut sin roll. Nu har vi chansen att få 500 miljoner mer till forskning – bara genom att säga nej till tidskrifterna, skriver debattörer.
|
|
| 41. |
- Poline, Mathias, et al.
(författare)
-
Mutual neutralisation of O+ with O− : investigation of the role of metastable ions in a combined experimental and theoretical study
- 2021
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 23:43, s. 24607-24616
-
Tidskriftsartikel (refereegranskat)abstract
- The mutual neutralisation of O+ with O− has been studied in a double ion-beam storage ring with combined merged-beams, imaging and timing techniques. Branching ratios were measured at the collision energies of 55, 75 and 170 (± 15) meV, and found to be in good agreement with previous single-pass merged-beams experimental results at 7 meV collision energy. Several previously unidentified spectral features were found to correspond to mutual neutralisation channels of the first metastable state of the cation (O+(2Do), τ ≈ 3.6 hours), while no contributions from the second metastable state (O+(2Po), τ ≈ 5 seconds) were observed. Theoretical calculations were performed using the multi-channel Landau–Zener model combined with the anion centered asymptotic method, and gave good agreement with several experimentally observed channels, but could not describe well observed contributions from the O+(2Do) metastable state as well as channels involving the O(3s 5So) state.
|
|
| 42. |
- Sayols-Baixeras, Sergi, et al.
(författare)
-
Streptococcus Species Abundance in the Gut Is Linked to Subclinical Coronary Atherosclerosis in 8973 Participants From the SCAPIS Cohort
- 2023
-
Ingår i: Circulation. - : Lippincott Williams & Wilkins. - 0009-7322 .- 1524-4539. ; 148:6, s. 459-472
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Gut microbiota have been implicated in atherosclerotic disease, but their relation with subclinical coronary atherosclerosis is unclear. This study aimed to identify associations between the gut microbiome and computed tomography-based measures of coronary atherosclerosis and to explore relevant clinical correlates.Methods: We conducted a cross-sectional study of 8973 participants (50 to 65 years of age) without overt atherosclerotic disease from the population-based SCAPIS (Swedish Cardiopulmonary Bioimage Study). Coronary atherosclerosis was measured using coronary artery calcium score and coronary computed tomography angiography. Gut microbiota species abundance and functional potential were assessed with shotgun metagenomics sequencing of stool, and associations with coronary atherosclerosis were evaluated with multivariable regression models adjusted for cardiovascular risk factors. Associated species were evaluated for association with inflammatory markers, metabolites, and corresponding species in saliva.Results: The mean age of the study sample was 57.4 years, and 53.7% were female. Coronary artery calcification was detected in 40.3%, and 5.4% had at least 1 stenosis with >50% occlusion. Sixty-four species were associated with coronary artery calcium score independent of cardiovascular risk factors, with the strongest associations observed for Streptococcus anginosus and Streptococcus oralis subsp oralis (P<1×10-5). Associations were largely similar across coronary computed tomography angiography-based measurements. Out of the 64 species, 19 species, including streptococci and other species commonly found in the oral cavity, were associated with high-sensitivity C-reactive protein plasma concentrations, and 16 with neutrophil counts. Gut microbial species that are commonly found in the oral cavity were negatively associated with plasma indole propionate and positively associated with plasma secondary bile acids and imidazole propionate. Five species, including 3 streptococci, correlated with the same species in saliva and were associated with worse dental health in the Malmö Offspring Dental Study. Microbial functional potential of dissimilatory nitrate reduction, anaerobic fatty acid β-oxidation, and amino acid degradation were associated with coronary artery calcium score.Conclusions: This study provides evidence of an association of a gut microbiota composition characterized by increased abundance of Streptococcus spp and other species commonly found in the oral cavity with coronary atherosclerosis and systemic inflammation markers. Further longitudinal and experimental studies are warranted to explore the potential implications of a bacterial component in atherogenesis.
|
|
| 43. |
- Sayols-Baixeras, Sergi, et al.
(författare)
-
Streptococcus Species Abundance in the Gut Is Linked to Subclinical Coronary Atherosclerosis in 8973 Participants From the SCAPIS Cohort
- 2023
-
Ingår i: Circulation. - : American Heart Association. - 0009-7322 .- 1524-4539. ; 148:6, s. 459-472
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Gut microbiota have been implicated in atherosclerotic disease, but their relation with subclinical coronary atherosclerosis is unclear. This study aimed to identify associations between the gut microbiome and computed tomography–based measures of coronary atherosclerosis and to explore relevant clinical correlates.METHODS: We conducted a cross-sectional study of 8973 participants (50 to 65 years of age) without overt atherosclerotic disease from the population-based SCAPIS (Swedish Cardiopulmonary Bioimage Study). Coronary atherosclerosis was measured using coronary artery calcium score and coronary computed tomography angiography. Gut microbiota species abundance and functional potential were assessed with shotgun metagenomics sequencing of fecal samples, and associations with coronary atherosclerosis were evaluated with multivariable regression models adjusted for cardiovascular risk factors. Associated species were evaluated for association with inflammatory markers, metabolites, and corresponding species in saliva.RESULTS: The mean age of the study sample was 57.4 years, and 53.7% were female. Coronary artery calcification was detected in 40.3%, and 5.4% had at least 1 stenosis with >50% occlusion. Sixty-four species were associated with coronary artery calcium score independent of cardiovascular risk factors, with the strongest associations observed for Streptococcus anginosus and Streptococcus oralis subsp oralis (P<1×10–5). Associations were largely similar across coronary computed tomography angiography–based measurements. Out of the 64 species, 19 species, including streptococci and other species commonly found in the oral cavity, were associated with high-sensitivity C-reactive protein plasma concentrations, and 16 with neutrophil counts. Gut microbial species that are commonly found in the oral cavity were negatively associated with plasma indole propionate and positively associated with plasma secondary bile acids and imidazole propionate. Five species, including 3 streptococci, correlated with the same species in saliva and were associated with worse dental health in the Malmö Offspring Dental Study. Microbial functional potential of dissimilatory nitrate reduction, anaerobic fatty acid β-oxidation, and amino acid degradation were associated with coronary artery calcium score.CONCLUSIONS: This study provides evidence of an association of a gut microbiota composition characterized by increased abundance of Streptococcus spp and other species commonly found in the oral cavity with coronary atherosclerosis and systemic inflammation markers. Further longitudinal and experimental studies are warranted to explore the potential implications of a bacterial component in atherogenesis.
|
|
| 44. |
- Schmidt, Henning T., et al.
(författare)
-
Rotationally Cold OH- Ions in the Cryogenic Electrostatic Ion-Beam Storage Ring DESIREE
- 2017
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:7
-
Tidskriftsartikel (refereegranskat)abstract
- We apply near-threshold laser photodetachment to characterize the rotational quantum level distribution of OH- ions stored in the cryogenic ion-beam storage ring DESIREE at Stockholm University. We find that the stored ions relax to a rotational temperature of 13.4 +/- 0.2 K with 94.9 +/- 0.3% of the ions in the rotational ground state. This is consistent with the storage ring temperature of 13.5 +/- 0.5 K as measured with eight silicon diodes but in contrast to all earlier studies in cryogenic traps and rings where the rotational temperatures were always much higher than those of the storage devices at their lowest temperatures. Furthermore, we actively modify the rotational distribution through selective photodetachment to produce an OH- beam where 99.1 +/- 0.1% of approximately one million stored ions are in the J = 0 rotational ground state. We measure the intrinsic lifetime of the J = 1 rotational level to be 145 +/- 28 s.
|
|
| 45. |
- Schmidt-May, Alice F., 1988-, et al.
(författare)
-
Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen
- 2023
-
Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 108:4
-
Tidskriftsartikel (refereegranskat)abstract
- We report on mutual neutralization measurements between 7Li+ and 1H- at effective center-of-mass collision energies in the range of 100 to 350 meV. We find that final states of lithium with principal quantum number n = 3 dominate with 3s separated from the unresolved 3p and 3d states. We measure the 3s branching fraction to be 0.665(12) at 100(16) meV and no significant dependence on collision energy is observed in the studied range. Comparing to previous results on mutual neutralization between 7Li+ and 2H- [G. Eklund et al., Phys. Rev. A 102, 012823 (2020)], we find that 7Li+ collisions with 1H- result in a significantly higher 3s branching fraction than collisions with 2H-. The difference is 0.087(14). The 3s branching fraction of 7Li+ + 1H- and the determined isotope difference are in agreement with results from extended full quantum calculations based on the same input data and numerical method as in Croft et al. [H. Croft, A. S. Dickinson, and F. X. Gadea, J. Phys. B 32, 81 (1999)]. These calculations reveal strong Stueckelberg oscillations of the 3s branching fraction for both isotopes.
|
|
| 46. |
|
|
