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result(s) for
"Johansson, Max"
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Model-Based Design and Evaluation of State-of-the-Art Thermal Management Systems for Electrified Trucks
2025
Electric vehicle thermal management systems have in the last two decades grown to become complex systems. This development has come as a response to the unique challenges faced by electrified powertrains, particularly the driving range reduction in cold climate operation. The rapid increase in complexity makes the systems harder to design, control, and evaluate, and consequently, a need for systematic analysis and design tools has emerged. The key contribution of this work is a model-based simulation tool developed to enable the combined evaluation and control of state-of-the-art thermal management systems. To show how engineers may use the tool to solve industrially relevant problems, two simulation case studies are performed and presented. The first case study compares three thermal management system layouts of increasing complexity and shows how their performance varies as ambient temperature decreases. The second case study concerns the potential benefits of additional cooling radiators for fuel cell trucks under heavy load in hot climates.
Journal Article
Bioimpedance Sensor Array for Long-Term Monitoring of Wound Healing from Beneath the Primary Dressings and Controlled Formation of H2O2 Using Low-Intensity Direct Current
by
Kumar Joon, Narender
,
Bobacka, Johan
,
Viik, Jari
in
beneath the dressings
,
Biofilms
,
bioimpedance
2019
Chronic wounds impose a significant financial burden for the healthcare system. Currently, assessment and monitoring of hard-to-heal wounds are often based on visual means and measuring the size of the wound. The primary wound dressings must be removed before assessment can be done. We have developed a quasi-monopolar bioimpedance-measurement-based method and a measurement system to determine the status of wound healing. The objective of this study was to demonstrate that with an appropriate setup, long-term monitoring of wound healing from beneath the primary dressings is feasible. The developed multielectrode sensor array was applied on the wound area and left under the primary dressings for 142 h. The impedance of the wounds and the surrounding intact skin area was measured regularly during the study at 150 Hz, 300 Hz, 1 kHz, and 5 kHz frequencies. At the end of the follow-up period, the wound impedance had reached the impedance of the intact skin at the higher frequencies and increased significantly at the lowest frequencies. The measurement frequency affected the measurement sensitivity in wound monitoring. The skin impedance remained stable over the measurement period. The sensor array also enabled the administration of periodical low-intensity direct current (LIDC) stimulation in order to create an antimicrobial environment across the wound area via the controlled formation of hydrogen peroxide (H2O2).
Journal Article
The Electrochemical Commercial Vehicle (ECCV) Platform
2024
Several technological challenges delay the adoption of electrified powertrains in the heavy-duty transport sector. For fuel-cell hybrid electric trucks, key issues include slow cold start, reduced cooling power during high ambient temperatures, and uncertainties regarding durability. In addition, the engineers must handle the complexity of the system. In this article, a Matlab/Simulink library is introduced, which has been developed to aid engineers in the design and optimization of energy management systems and strategies of this complex system that consider mechanical, electrochemical, and thermal energy flows. The library is introduced through five example vehicle models, and through case studies that highlight the various kinds of analysis that can be performed using the provided models. All library code is open source, open for commercial use, and runs in Matlab/Simulink without any need for external libraries.
Journal Article
Estimating Mode Effects by Three Methods in the Swedish Survey on Income and Living Conditions
2025
The target estimate differences between the web and telephone respondents in the Swedish Survey on Income and Living Conditions can either be due to differences in compositions or measurement, known as selection effects and measurement effects respectively. Three methods are reviewed and used to estimate the selection and measurement effects for 133 target variables of the survey in this thesis. The assumptions of the methods are also discussed in relation to the situation under investigation. The number of significant selection effects and measurement effects varies by method. The two calibration methods that use weights lead to the conclusion that the majority of target variables are affected by selection effects and measurement effects. A minority of target variables are affected by either effect according to the third method that does not use weights. All methods share the conclusion that 23 target variables are affected by measurement effects, and that 33 are not affected. All methods share the conclusion that 28 variables are affected by selection effects, and that 12 variables are not affected. The largest estimated measurement effect is 18.77 %, and the largest selection effect is -14.36 %.
Dissertation
iSWAP-type geometric gates induced by paths on Schmidt sphere
2024
We propose iSWAP-type quantum gates based on geometric phases purely associated with paths on the Schmidt sphere [Phys. Rev. A 62, 022109 (2000)]. These geometric Schmidt gates can entangle qubit pairs to an arbitrary degree; in particular, they can create maximally entangled states from product states by an appropriate choice of base point on the Schmidt sphere. We identify Hamiltonians that generate pure paths on the Schmidt sphere by reverse engineering and demonstrate explicitly that the resulting Hamiltonians can be implemented in systems of transmon qubits. The geometric Schmidt gates are characterized by vanishing dynamical phases and are complementary to geometric single-qubit gates that take place on the Bloch sphere.
Bioimpedance Sensor Array for Long-Term Monitoring of Wound Healing from Beneath the Primary Dressings and Controlled Formation of H 2 O 2 Using Low-Intensity Direct Current
2019
Chronic wounds impose a significant financial burden for the healthcare system. Currently, assessment and monitoring of hard-to-heal wounds are often based on visual means and measuring the size of the wound. The primary wound dressings must be removed before assessment can be done. We have developed a quasi-monopolar bioimpedance-measurement-based method and a measurement system to determine the status of wound healing. The objective of this study was to demonstrate that with an appropriate setup, long-term monitoring of wound healing from beneath the primary dressings is feasible. The developed multielectrode sensor array was applied on the wound area and left under the primary dressings for 142 h. The impedance of the wounds and the surrounding intact skin area was measured regularly during the study at 150 Hz, 300 Hz, 1 kHz, and 5 kHz frequencies. At the end of the follow-up period, the wound impedance had reached the impedance of the intact skin at the higher frequencies and increased significantly at the lowest frequencies. The measurement frequency affected the measurement sensitivity in wound monitoring. The skin impedance remained stable over the measurement period. The sensor array also enabled the administration of periodical low-intensity direct current (LIDC) stimulation in order to create an antimicrobial environment across the wound area via the controlled formation of hydrogen peroxide (H
O
).
Journal Article
One-loop matrix elements of effective superstring interactions: α′-expanding loop integrands
by
Edison, Alex
,
Guillen, Max
,
Johansson, Henrik
in
Amplitudes
,
Classical and Quantum Gravitation
,
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
2021
A
bstract
In the low-energy effective action of string theories, non-abelian gauge interactions and supergravity are augmented by infinite towers of higher-mass-dimension operators. We propose a new method to construct one-loop matrix elements with insertions of operators
D
2
k
F
n
and
D
2
k
R
n
in the tree-level effective action of type-I and type-II superstrings. Inspired by ambitwistor string theories, our method is based on forward limits of moduli-space integrals using string tree-level amplitudes with two extra points, expanded in powers of the inverse string tension
α′
. Similar to one-loop ambitwistor computations, intermediate steps feature non-standard linearized Feynman propagators which eventually recombine to conventional quadratic propagators. With linearized propagators the loop integrand of the matrix elements obey one-loop versions of the monodromy and KLT relations. We express a variety of four- and five-point examples in terms of quadratic propagators and formulate a criterion on the underlying genus-one correlation functions that should make this recombination possible at all orders in
α′
. The ultraviolet divergences of the one-loop matrix elements are crosschecked against the non-separating degeneration of genus-one integrals in string amplitudes. Conversely, our results can be used as a constructive method to determine degenerations of elliptic multiple zeta values and modular graph forms at arbitrary weight.
Journal Article
Tumor-matched and unmatched cancer associated fibroblasts exhibit differential effect on proliferation and FMOD and MMP9 gene expression in head and neck squamous cell carcinoma cells when cocultured in spheroids
by
Rademaekers, Max
,
Johansson, Emil Oliver
,
Roberg, Karin
in
3D cultures
,
Antibodies
,
Biomedical and Life Sciences
2024
Background
Cancer-associated fibroblasts (CAFs) are the major cellular component of the tumor microenvironment and are known to affect tumor growth and response to various treatments. This study was undertaken to investigate the crosstalk between tumor-matched or unmatched CAFs and head and neck squamous cell carcinoma (HNSCC) cells regarding tumor growth and treatment response.
Methods
Three HNSCC cell lines (LK0412, LK0902 and LK0923), were cocultured in 2D or in 3D with their tumor-matched CAFs, site matched CAFs from other tumors or normal oral fibroblasts (NOFs). Cell proliferation was assessed as the amount of Ki67 positive cells/ spheroid area in formalin-fixed- paraffin-embedded 3D spheroids stained with Ki67 antibody. Viability after seven days of cisplatin treatment was measured with CellTiter-Glo 3D Viability Assay. The mRNA expression of CAF-associated markers (
ACTA2, COL1A2, FAP, PDGFRα, PDGFRβ, PDPN, POSTN
and
S100A4
) in CAFs before and after coculture with tumor cells as well as mRNA expression of CAF-induced genes (
MMP1
,
MMP9
and
FMOD
) in tumor cells separated from CAFs after co-culture was measured with RT-qPCR. The expression of selected protein biomarkers was validated with immunohistochemistry based on previous mRNA expression results.
Results
The proliferation of the LK0412 and LK0902 tumor spheroids varied significantly when cocultured with different CAFs and NOFs as shown by Ki-67 positive cells. RT‒qPCR analysis revealed different molecular profile of the analyzed HNSCC-derived CAFs concerning the expression of CAF-associated markers. The interaction between CAFs and HNSCC cells was more pronounced after coculture with unmatched CAFs as shown by changes in mRNA expression pattern of CAF-specific markers. Additionally, the unmatched CAFs significantly upregulated the mRNA expression of
MMP1
,
MMP9
and
FMOD
in tumor cells compared to tumor-matched CAFs.
Conclusion
Our results indicate that tumor-matched CAFs are unique for each tumor and affect the proliferation and the gene/protein expression of tumor cells in a distinct manner. The interaction between tumor unmatched CAFs and HNSCC cells in the tumor spheroids is associated with significant changes in the mRNA expression of CAF-specific markers and significant increases in FMOD and MMP9 in tumor cells compared to when cocultured with tumor-matched CAFs. Taken together, our results show how important the selection of CAFs is to get a reliable in vitro model that mimics the patients’ tumor.
Journal Article
Refinement of Swedish Administrative Registers to Monitor Stroke Events on the National Level
2013
Background: Routinely collected databases are kept for administrative purposes. We have refined the analyses of the Swedish National Patient Register and the Cause of Death Register and explored their validity to monitor stroke at the population level. Methods: First-ever strokes (incident cases) and all stroke events were measured by combining the two administrative registers and adding refinements. The administrative registers were validated against the Northern Sweden MONICA, a well-validated population-based epidemiological stroke register. Positive predictive values (PPVs) and sensitivity were calculated. Results: After refinements (restriction to first-ever strokes and additional minor delineations), the PPV of the two administrative registers combined was 94% and sensitivity 92% when compared with all MONICA stroke categories together. For stroke attacks (first and recurrent events together), the PPV in the administrative registers was 85% and sensitivity 91%. The PPV was higher in women than in men, whereas the sensitivity was similar. The PPV was lower but sensitivity higher in people below compared with those above 75 years of age. Both PPV and sensitivity were lower among fatal cases than among cases that survived 28 days. Conclusions: After refinement, Swedish national administrative registers may, with some caveats, be used as a low-resource-consuming alternative to crudely monitor stroke incidence rates at the national level. If further accuracy is strived for, high-quality conventional epidemiological registers are required.
Journal Article