| 1. |
- Aazh, H, et al.
(författare)
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Influence of ear canal occlusion and static pressure difference on bone conduction thresholds: Implications for mechanisms of bone conduction
- 2005
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Ingår i: International Journal of Audiology. - : Informa Healthcare. - 1499-2027 .- 1708-8186. ; 44:5, s. 302-306
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Tidskriftsartikel (refereegranskat)abstract
- The effect of air pressure change on bone conduction (BC) hearing thresholds in the occluded ear was investigated. The pump manometer system of an impedance bridge was used to change the air pressure in the ear canal of twenty-two normally hearing subjects. BC thresholds were measured with: (1) open ear; (2) the ear canal occluded with a probe tube and application of 0 daPa air pressure; and (3) the ear canal occluded with a probe tube and application of -350 daPa air pressure. Thresholds were lower in condition 2 than in condition 1, the difference decreasing from 27 dB at 2500 Hz to 4.5 dB at 2000 Hz. Thresholds were higher in condition 3 than in condition 2. The results are interpreted in terms of changes in the relative contribution of the three routes of transmission for BC sound produced by occlusion and by a static pressure difference.
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| 2. |
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| 3. |
- Abuhasanein, Suleiman, et al.
(författare)
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A novel model of artificial intelligence based automated image analysis of CT urography to identify bladder cancer in patients investigated for macroscopic hematuria
- 2024
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Ingår i: Scandinavian Journal of Urology. - : Medical Journal Sweden AB. - 2168-1805 .- 2168-1813. ; 59, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate whether artificial intelligence (AI) based automatic image analysis utilising convolutional neural networks (CNNs) can be used to evaluate computed tomography urography (CTU) for the presence of urinary bladder cancer (UBC) in patients with macroscopic hematuria. METHODS: Our study included patients who had undergone evaluation for macroscopic hematuria. A CNN-based AI model was trained and validated on the CTUs included in the study on a dedicated research platform (Recomia.org). Sensitivity and specificity were calculated to assess the performance of the AI model. Cystoscopy findings were used as the reference method. RESULTS: The training cohort comprised a total of 530 patients. Following the optimisation process, we developed the last version of our AI model. Subsequently, we utilised the model in the validation cohort which included an additional 400 patients (including 239 patients with UBC). The AI model had a sensitivity of 0.83 (95% confidence intervals [CI], 0.76-0.89), specificity of 0.76 (95% CI 0.67-0.84), and a negative predictive value (NPV) of 0.97 (95% CI 0.95-0.98). The majority of tumours in the false negative group (n = 24) were solitary (67%) and smaller than 1 cm (50%), with the majority of patients having cTaG1-2 (71%). CONCLUSIONS: We developed and tested an AI model for automatic image analysis of CTUs to detect UBC in patients with macroscopic hematuria. This model showed promising results with a high detection rate and excessive NPV. Further developments could lead to a decreased need for invasive investigations and prioritising patients with serious tumours.
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| 4. |
- Ahlström, Christer, 1977-, et al.
(författare)
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The impact of driver sleepiness on fixation-related brain potentials
- 2020
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- The effects of driver sleepiness are often quantified as deteriorated driving performance, increased blink durations and high levels of subjective sleepiness. Driver sleepiness has also been associated with increasing levels of electroencephalogram (EEG) power, especially in the alpha range. The present exploratory study investigated a new measure of driver sleepiness, the EEG fixation-related lambda response. Thirty young male drivers (23.6 +/- 1.7 years old) participated in a driving simulator experiment in which they drove on rural and suburban roads in simulated daylight versus darkness during both the daytime (full sleep) and night-time (sleep deprived). The results show lower lambda responses during night driving and with longer time on task, indicating that sleep deprivation and time on task cause a general decrement in cortical responsiveness to incoming visual stimuli. Levels of subjective sleepiness and line crossings were higher under the same conditions. Furthermore, results of a linear mixed-effects model showed that low lambda responses are associated with high subjective sleepiness and more line crossings. We suggest that the fixation-related lambda response can be used to investigate driving impairment induced by sleep deprivation while driving and that, after further refinement, it may be useful as an objective measure of driver sleepiness.
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| 5. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
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Inventory study of an early pandemic COVID- 19 cohort in South-Eastern Sweden, focusing on neurological manifestations
- 2023
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 18:1 January
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Tidskriftsartikel (refereegranskat)abstract
- Background Neurological manifestations in patients with COVID-19 have been reported previously as outcomes of the infection. The purpose of current study was to investigate the occurrence of neurological signs and symptoms in COVID-19 patients, in the county ofÖstergötland in southeastern Sweden. Methods This is a retrospective, observational cohort study. Data were collected between March 2020 and June 2020. Information was extracted from medical records by a trained research assistant and physician and all data were validated by a senior neurologist. Results Seventy-four percent of patients developed at least one neurological symptom during the acute phase of the infection. Headache (43%) was the most common neurological symptom, followed by anosmia and/or ageusia (33%), confusion (28%), hallucinations (17%), dizziness (16%), sleep disorders in terms of insomnia and OSAS (Obstructive Sleep Apnea) (9%), myopathy and neuropathy (8%) and numbness and tingling (5%). Patients treated in the ICU had a higher male presentation (73%). Several risk factors in terms of co-morbidities, were identified. Hypertension (54.5%), depression and anxiety (51%), sleep disorders in terms of insomnia and OSAS (30%), cardiovascular morbidity (28%), autoimmune diseases (25%), chronic lung diseases (24%) and diabetes mellitus type 2 (23%) founded as possible risk factors. Conclusion Neurological symptoms were found in the vast majority (74%) of the patients. Accordingly, attention to neurological, mental and sleep disturbances is warranted with involvement of neurological expertise, in order to avoid further complications and long-term neurological effect of COVID-19. Furthermore, risk factors for more severe COVID-19, in terms of possible co-morbidities that identified in this study should get appropriate attention to optimizing treatment strategies in COVID-19 patients.
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| 6. |
- Ait Ali, Abderrahman, et al.
(författare)
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Evaluating the mix of maintenance activities on railway crossings with respect to life-cycle costs
- 2024
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Ingår i: European Journal of Transport and Infrastructure Research. - : TU Delft OPEN Publishing. - 1567-7141 .- 1567-7133. ; 24:1, s. 1-29
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Tidskriftsartikel (refereegranskat)abstract
- Switches & crossings (S&Cs) are vital assets as they allow for increased railway capacity by introducing flexibility and connectivity in railway networks. At the same time, this makes them critical since they can cause costly delays and disruptions if they are not well maintained. This motivates studies to improve maintenance strategies of S&Cs, considering both the life-cycle costs (LCCs) of the assets and socio-economic transportation costs for passengers and freight customers. In this paper, the interdependence between deterioration mechanisms, maintenance activities, and expected LCC (including transportation costs) for the crossing panel – an S&C subsystem – is investigated using a combination of mechanical and econometric modelling. The interrelation between the degradation of contact geometry and track settlement is analysed using simulations of dynamic vehicle– turnout interaction. Long-term mechanical degradation of the crossing panel is simulated for different maintenance strategies that correspond to different timing of the associated maintenance measures (crossing repair welding and tamping). This provides the basis for analysing the interdependence between preventive and corrective activities using econometric modelling. Based on a case study of a common type of S&Cs in the Swedish infrastructure, the impact of different maintenance strategies on LCC and transportation costs is analysed. Opportunities and challenges in the development of more economically effective maintenance strategies of S&Cs are discussed.
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| 7. |
- Alexander-Webber, J. A., et al.
(författare)
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Giant quantum Hall plateaus generated by charge transfer in epitaxial graphene
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology.
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| 8. |
- Alexander-Webber, J. A., et al.
(författare)
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Phase Space for the Breakdown of the Quantum Hall Effect in Epitaxial Graphene
- 2013
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 111:9, s. e096601-
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Tidskriftsartikel (refereegranskat)abstract
- We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (Ic) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (ρxx=0) shows a [1-(T/Tc)2] dependence and persists up to Tc>45 K at 29 T. With magnetic field Ic was found to increase ∝B3/2 and Tc∝B2. As the Fermi energy approaches the Dirac point, the ν=2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density.
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| 9. |
- Allard, Alexandra, 1994-, et al.
(författare)
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The N-shaped environmental Kuznets curve : an empirical evaluation using a panel quantile regression approach
- 2018
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Ingår i: Environmental Science and Pollution Research. - Heidelberg : Springer Verlag. - 0944-1344 .- 1614-7499. ; 25:6, s. 5848-5861
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Tidskriftsartikel (refereegranskat)abstract
- We evaluate the N-shaped environmental Kuznets curve (EKC) using panel quantile regression analysis. We investigate the relationship between CO2 emissions and GDP per capita for 74 countries over the period of 1994–2012. We include additional explanatory variables, such as renewable energy consumption, technological development, trade, and institutional quality. We find evidence for the N-shaped EKC in all income groups, except for the upper-middle-income countries. Heterogeneous characteristics are, however, observed over the N-shaped EKC. Finally, we find a negative relationship between renewable energy consumption and CO2 emissions, which highlights the importance of promoting greener energy in order to combat global warming.
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| 10. |
- Alling, Björn, et al.
(författare)
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Dynamic and structural stability of cubic vanadium nitride
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X .- 2469-9950 .- 2469-9969. ; 91:5, s. 054101-
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Tidskriftsartikel (refereegranskat)abstract
- Structural phase transitions in epitaxial stoichiometric VN/MgO(011) thin films are investigated using temperature-dependent synchrotron x-ray diffraction (XRD), selected-area electron diffraction (SAED), resistivity measurements, high-resolution cross-sectional transmission electron microscopy, and ab initio molecular dynamics (AIMD). At room temperature, VN has the B1 NaCl structure. However, below T-c = 250 K, XRD and SAED results reveal forbidden (00l) reflections of mixed parity associated with a noncentrosymmetric tetragonal structure. The intensities of the forbidden reflections increase with decreasing temperature following the scaling behavior I proportional to (T-c - T)(1/2). Resistivity measurements between 300 and 4 K consist of two linear regimes resulting from different electron/phonon coupling strengths in the cubic and tetragonal-VN phases. The VN transport Eliashberg spectral function alpha F-2(tr)(h omega), the product of the phonon density of states F(h omega) and the transport electron/phonon coupling strength alpha(2)(tr)(h omega), is determined and used in combination with AIMD renormalized phonon dispersion relations to show that anharmonic vibrations stabilize the NaCl structure at T greater than T-c. Free-energy contributions due to vibrational entropy, often neglected in theoretical modeling, are essential for understanding the room-temperature stability of NaCl-structure VN, and of strongly anharmonic systems in general.
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