| 1. |
- Adell, Martin, 1976
(author)
-
Preparation and Characterization of the Magnetic Semiconductor (GaMn)As
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- The diluted ferromagnetic semiconductor (GaMn)As has been grown by low temperature molecular beam epitaxy and the effects of post growth treatments on the electronic, magnetic and structural properties have been studied. In situ low temperature annealing of (GaMn)As layers has been performed. A clear correlation between annealing temperature and the Fermi level position of the annealed layers is found by photoelectron spectroscopy. The Curie temperature is also seen to depend on the position of the Fermi level as is expected from mean field Zener model according to which it is predicted that TC∝p1/3, where p is the density of of holes in the magnetic layer.After these first annealing experiments in vacuum, much of the efforts have been devoted to an alternative method of heat treatments utilizing an amorphous arsenic capping layer as an effective sink for diffusing Mn interstitial (MnI) atoms. These MnI defects are known to act as double donors and to form antiferromagnetically coupled complexes with the substitutional Mn (MnGa) atoms and thereby causing a deterioration of the ferromagnetic state. Thus, by removing MnI by the present annealing procedure TC and the saturation magnetization are found to be considerably enhanced after only short heat treatments, ~3h, at low temperatures, ~180ºC. This short annealing time is also found to give optimal improvement of the magnetic state of the (GaMn)As layers independently of layer thickness.Several different techniques have been used to characterize the modifications of (GaMn)As layers annealed under As-capping. XRD and Hall effect measurements have given direct evidences for that MnI defects are effectively removed from the (GaMn)As and that this process primarily occurs at a time scale of only a few hours after which the rate of change is considerably slowed down. The surface reaction between the diffusing Mn atoms and arsenic from the capping layer has also been thoroughly investigated by several synchrotron radiation based spectroscopic techniques as well as by microscopy such as AFM and MFM. It is found that the number of available defects, i.e. primarily the (GaMn)As layer thickness, determines the character of the annealed surface. Upon annealing, initially a monolayer of epitaxial MnAs will be formed at the (GaMn)As/As-caping interface as the MnI reach the interface. Further out diffusion of MnI will also occur after the formation of this MnAs layer and will result in self organized quantum dots at the (GaMn)As surface. However, this process is much slower than the initial reaction forming the continuous MnAs layer. Keywords: UPS, XAS, Magnetic Semiconductor, (GaMn)As.
|
|
| 2. |
|
|
| 3. |
- Boito, Deneb, 1993-, et al.
(author)
-
Diffusivity-limited q-space trajectory imaging
- 2023
-
In: Magnetic Resonance Letters. - : KeAi Publishing Communications. - 2772-5162. ; 3:2, s. 187-196
-
Journal article (peer-reviewed)abstract
- Q-space trajectory imaging (QTI) allows non-invasive estimation of microstructural features of heterogeneous porous media via diffusion magnetic resonance imaging performed with generalised gradient waveforms. A recently proposed constrained estimation framework, called QTI+, improved QTI’s resilience to noise and data sparsity, thus increasing the reliability of the method by enforcing relevant positivity constraints. In this work we consider expanding the set of constraints to be applied during the fitting of the QTI model. We show that the additional conditions, which introduce an upper bound on the diffusivity values, further improve the retrieved parameters on a publicly available human brain dataset as well as on data acquired from healthy volunteers using a scanner-ready protocol.
|
|
| 4. |
- Boito, Deneb, 1993-, et al.
(author)
-
MRI with generalized diffusion encoding reveals damaged white matter in patients previously hospitalized for COVID-19 and with persisting symptoms at follow-up
- 2023
-
In: Brain Communications. - : Oxford University Press. - 2632-1297. ; 5:6
-
Journal article (peer-reviewed)abstract
- There is mounting evidence of the long-term effects of COVID-19 on the central nervous system, with patients experiencing diverse symptoms, often suggesting brain involvement. Conventional brain MRI of these patients shows unspecific patterns, with no clear connection of the symptomatology to brain tissue abnormalities, whereas diffusion tensor studies and volumetric analyses detect measurable changes in the brain after COVID-19. Diffusion MRI exploits the random motion of water molecules to achieve unique sensitivity to structures at the microscopic level, and new sequences employing generalized diffusion encoding provide structural information which are sensitive to intravoxel features. In this observational study, a total of 32 persons were investigated: 16 patients previously hospitalized for COVID-19 with persisting symptoms of post-COVID condition (mean age 60 years: range 41–79, all male) at 7-month follow-up and 16 matched controls, not previously hospitalized for COVID-19, with no post-COVID symptoms (mean age 58 years, range 46–69, 11 males). Standard MRI and generalized diffusion encoding MRI were employed to examine the brain white matter of the subjects. To detect possible group differences, several tissue microstructure descriptors obtainable with the employed diffusion sequence, the fractional anisotropy, mean diffusivity, axial diffusivity, radial diffusivity, microscopic anisotropy, orientational coherence (Cc) and variance in compartment’s size (CMD) were analysed using the tract-based spatial statistics framework. The tract-based spatial statistics analysis showed widespread statistically significant differences (P < 0.05, corrected for multiple comparisons using the familywise error rate) in all the considered metrics in the white matter of the patients compared to the controls. Fractional anisotropy, microscopic anisotropy and Cc were lower in the patient group, while axial diffusivity, radial diffusivity, mean diffusivity and CMD were higher. Significant changes in fractional anisotropy, microscopic anisotropy and CMD affected approximately half of the analysed white matter voxels located across all brain lobes, while changes in Cc were mainly found in the occipital parts of the brain. Given the predominant alteration in microscopic anisotropy compared to Cc, the observed changes in diffusion anisotropy are mostly due to loss of local anisotropy, possibly connected to axonal damage, rather than white matter fibre coherence disruption. The increase in radial diffusivity is indicative of demyelination, while the changes in mean diffusivity and CMD are compatible with vasogenic oedema. In summary, these widespread alterations of white matter microstructure are indicative of vasogenic oedema, demyelination and axonal damage. These changes might be a contributing factor to the diversity of central nervous system symptoms that many patients experience after COVID-19.
|
|
| 5. |
|
|
| 6. |
- Gullestad, Lars, et al.
(author)
-
Everolimus With Reduced Calcineurin Inhibitor in Thoracic Transplant Recipients With Renal Dysfunction: A Multicenter, Randomized Trial
- 2010
-
In: Transplantation. - : Williams and Wilkins. - 0041-1337 .- 1534-6080. ; 89:7, s. 864-872
-
Journal article (peer-reviewed)abstract
- Background. The proliferation signal inhibitor everolimus offers the potential to reduce calcineurin inhibitor (CNI) exposure and alleviate CNI-related nephrotoxicity. Randomized trials in maintenance thoracic transplant patients are lacking. Methods. In a 12-month, open-labeled, multicenter study, maintenance thoracic transplant patients (glomerular filtration rate greater than= 20 mL/min/1.73m(2) and less than90 mL/min/1.73 m(2)) greater than1 year posttransplant were randomized to continue their current CNI-based immunosuppression or start everolimus with predefined CNI exposure reduction. Results. Two hundred eighty-two patients were randomized (140 everolimus, 142 controls; 190 heart, 92 lung transplants). From baseline to month 12, mean cyclosporine and tacrolimus trough levels in the everolimus cohort decreased by 57% and 56%, respectively. The primary endpoint, mean change in measured glomerular filtration rate from baseline to month 12, was 4.6 mL/min with everolimus and -0.5 mL/min in controls (Pless than0.0001). Everolimus-treated heart and lung transplant patients in the lowest tertile for time posttransplant exhibited mean increases of 7.8 mL/min and 4.9 mL/min, respectively. Biopsy-proven treated acute rejection occurred in six everolimus and four control heart transplant patients (P=0.54). In total, 138 everolimus patients (98.6%) and 127 control patients (89.4%) experienced one or more adverse event (P=0.002). Serious adverse events occurred in 66 everolimus patients (46.8%) and 44 controls (31.0%) (P=0.02). Conclusion. Introduction of everolimus with CNI reduction offers a significant improvement in renal function in maintenance heart and lung transplant recipients. The greatest benefit is observed in patients with a shorter time since transplantation.
|
|
| 7. |
- Gullestad, L., et al.
(author)
-
Galectin-3 predicts response to statin therapy in the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA)
- 2012
-
In: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 33:18, s. 2290-2296
-
Journal article (peer-reviewed)abstract
- To investigate whether plasma galectin-3, a mediator of fibrogenesis, can identify patients with chronic heart failure (HF) for whom statins are effective. Patients with ischaemic systolic HF enrolled in the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA) were randomly assigned to 10 mg/day of rosuvastatin or placebo. Galectin-3 was measured in plasma. The primary outcome was cardiovascular death, myocardial infarction, or stroke. Of 1492 patients, 411 had a primary event during a median follow-up of 32.8 months. There was an interaction between baseline galectin-3 and rosuvastatin on the primary endpoint (P-value for interaction 0.036). Among patients with below the median plasma concentrations of galectin-3 (19.0 ng/mL), those assigned to rosuvastatin had a lower primary event rate [hazard ratio (HR) 0.65; 95 confidence interval (CI), 0.460.92; P 0.014], lower total mortality (HR 0.70; 95 CI, 0.500.98; P 0.038), and lower event rate of all-cause mortality and HF hospitalizations (HR 0.72; 95 CI, 0.540.98; P 0.017) compared with placebo, but no benefit was observed in patients with higher levels of galectin-3. The combination of concurrently low concentrations of galectin-3 and N-terminal pro-B-type natriuretic peptide (102.7 pmol/L) identified patients with a large benefit with rosuvastatin (HR 0.33; 95 CI, 0.160.67; P 0.002). Patients with systolic HF of ischaemic aetiology who have galectin-3 values 19.0 ng/mL may benefit from rosuvastatin treatment. However, the data from this post hoc analysis should be interpreted with caution since the overall results of the CORONA study did not show a significant effect on the primary endpoint.
|
|
| 8. |
- Gulliksen, Jan, et al.
(author)
-
Accessibility and Public Policy in Sweden
- 2010
-
In: interactions. - : Association for Computing Machinery (ACM). - 1072-5520 .- 1558-3449. ; 17:3, s. 26-29
-
Journal article (peer-reviewed)abstract
- Principles and guidelines will become more important, due to the development of accessibility policies and the harmonization with Europe in Sweden is discussed. Public policy is the body of principles that underpin the operation of legal systems in a state, which address the social, moral, and economic values that tie a society together. Accessibility policies often start at the international level. Many countries currently have different regulations for interface accessibility. In Sweden the transparency of the public sector is one of the foundations of democracy and the development of an accessible society and is manifested by a duty to publish and promote openness. Public policy and legislation play an important role in contributing to increased accessibility. Sweden is a country of negotiation and transparency, not binding legislation. Involving groups with impairments may not only provide increased accessibility but also increase innovation.
|
|
| 9. |
- Gulliksen, J, et al.
(author)
-
Accessibility through Standardisation
- 2001
-
In: In Proceedings of the 1st international conference on Universal Access of Human-Computer Interfaces, UAHCI 2001, New Orleans.
-
Conference paper (peer-reviewed)
|
|
| 10. |
- Gulliksen, Jan, 1965-, et al.
(author)
-
Accomplishing universal access through system reachability : a management perspective
- 2004
-
In: Universal Access in the Information Society. - : Springer Berlin/Heidelberg. - 1615-5289 .- 1615-5297. ; 3:1, s. 96-101
-
Journal article (peer-reviewed)abstract
- The aim of this paper is to describe the need of a method by which we can estimate the return on accessibility investments in information technology (IT) systems. This paper reveals some of the reasons why accessibility still is a secondhand criterion when designing digital services. It also describes the authors experiences regarding the concept of accessibility and how it must develop in order to obtain the status of a basic business criterion for the benefit of disabled people who are currently excluded from public services and labour markets. The paper also questions the need of a separate accessibility standard. Additionally, we discuss some of the hindering in the market and limiting perspectives that are blocking further development. One of the problems in the market seems to be that accessibility as a concept has been more of an issue about creating equal opportunities and therefore probably does not have the quality of a business criterion. In order to bridge that gap, we argue for replacing accessibility with reachability, which is a concept based on a measure used by media when estimating the reached percentage of a population or target group.
|
|
