| 1. |
- Lui, Hoi-Shun, 1980, et al.
(author)
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Mutual Coupling Compensation of Compact Antenna Array for Direction-of-Arrivals Estimations
- 2010
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In: 4th International Conference on Signal Processing and Communication Systems. - 9781424479078 ; , s. 1-10
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Conference paper (peer-reviewed)abstract
- Mutual coupling is well known as an undesirable effect as it degrades the performance of most array signal processing algorithm. Such undesirable effect becomes significant when the antenna element spacing becomes small, which is the case for compact antenna array. Throughout the years, extensive studies from signal processing and communication society have been conducted to compensate such undesirable effect. In this paper, a new method for the determination of receiving mutual impedances of omni-directional antenna elements is proposed. The new method is able to compensate such undesirable effect for compact array. Numerical examples of using the new method for the determinations receiving mutual impedances for some monopole arrays are given, which aims to show the differences between the old and new methods. DOA estimation examples with better accuracies demonstrate the superior mutual coupling characterization performance of the new receiving mutual impedance determination method over existing methods.
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| 2. |
- Lui, Hoi-Shun, 1980, et al.
(author)
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Mutual Coupling Compensation for Direction-of-Arrival Estimations Using the Receiving-Mutual-Impedance Method
- 2010
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In: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2010
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Journal article (peer-reviewed)abstract
- A short review of the receiving-mutual-impedance method (RMIM) for mutual coupling compensation in direction finding applications using linear array is conducted. The differences between the conventional-mutual-impedance method (CMIM) and RMIM, as well as the three different determination methods for receiving mutual impedance (RMI), will be discussed in details. As an example, direction finding with better accuracies is used for demonstrating the superiority of mutual coupling compensation using RMIM.
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| 3. |
- Last, Torben, et al.
(author)
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3D-Printing Enables Fabrication of Swirl Nozzles for Fast Aerosolization of Water-Based Drugs
- 2021
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In: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 30:2, s. 181-183
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Journal article (peer-reviewed)abstract
- Portable inhalers are used for delivering drugs to the lung in the form of aerosols and form the standard treatment for diseases such as Asthma, COPD, and cystic fibrosis. However, for aqueous drug formulations, spray nozzle chips have so far been restricted to cleanroom manufacture due to their small feature sizes. Here we present a spring-actuated 3D-printed swirl nozzle that sprays an aqueous drug solution, matching propellant-containing inhalers in aerosolization time. The use of two-photon polymerization enables the small nozzle feature size of 100 mu m and device print times of only 4 min, making serial mass-fabrication a viable option. Our 35 bar spring-operated swirl nozzle prototype achieves mean volumetric particle sizes of 12.5 mu m on doses of 100 mu l, aerosolized in 270 ms, as fast as a propellant-driven inhaler. [2021-0002]
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| 6. |
- Maraste, Rauni, et al.
(author)
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Anxiety and depression in breast cancer patients at start of adjuvant radiotherapy : Relations to age and type of surgery
- 1992
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In: Acta Oncologica. - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 31:6, s. 641-643
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Journal article (peer-reviewed)abstract
- Using a self-report questionnaire, the Hospital Anxiety and Depression (HAD) scale, feelings of anxiety and depression were assessed in 133 breast cancer patients referred for adjuvant radiotherapy following surgical treatment. Eighteen patients (14% had scores indicating morbid anxiety. Significant depression was recorded for only 2 patients (1.5% Severe anxiety was recorded for 10 out of 54 mastectomized patients (19% and for 8 out of 79 patients treated with breast conserving surgery (10% The difference was not significant (p = 0.13). In a subgroup aged 50-59 years, morbid anxiety was significantly more common among mastectomized patients than among patients operated conservatively, 4 out of 9 (44% vs. 1 out of 23 (4% (p = 0.01). Such a pattern was not discernable in the patients <50 years of age or those ≥ 60 years old. The results suggest that, at start of adjuvant radiotherapy, emotional distress is characterized by anxiety rather than depression and the risk of morbid anxiety is especially large for mastectomized women in their fifties.
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| 7. |
- Nordenström, Anna
(author)
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Congenital adrenal hyperplasia, CYP21 deficiency, screening and clinical aspects
- 2001
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Doctoral thesis (other academic/artistic)abstract
- Congenital adrenal hyperplasia (CAH) is a group of recessively inherited disorders. More than 90% of all cases of CAB are caused by 21-hydroxylase deficiency. This enzyme deficiency results in reduced ability to synthesize cortisol and aldosterone and at the same time increased secretion of androgens. There is a wide spectrum of severity of the disease. The most severe forms of CAH are life-threatening, with the risk of a salt crisis in the neonatal period. CAH has special implications for girls since it causes virilization of the external genitalia, sometimes to the extent that they are assigned the wrong gender. Patients with milder forms of the disease do not show signs of prenatal virilization at birth but develop symptoms of excess androgen production later in life. A limited number of mutations in the 21-hydroxylase gene (CYP21) are responsible for around 95% of all affected Scandinavian CYP21 alleles. There is a clear genotype-phenotype correlation. Neonatal screening for CAH started in Sweden in 1986. Elevated blood levels of 17-hydroxy progesterone (17OHP) are used as an indicator of CAR The outcome for patients diagnosed with CAH before and after the screening program was initiated was studied. Screening resulted in earlier diagnoses and thereby prevented salt crises and led to earlier correct gender assignment in affected girls. We concluded that there are clear benefits of neonatal screening for CAR Neonatal screening is complicated by the fact that there is a spectrum of the severity of the disease. Screening 17-OHP levels were correlated with the CYP21 genotypes. We were able to show that the screening 17-OBP level provides some information on disease severity on a group level, but it cannot be used to predict disease severity in an individual case. Genotyping can be used to predict disease severity in children who are diagnosed through screening before any signs of salt loss have developed. In addition, genotyping can be used to distinguish between false and true positive cases with slightly elevated 17OHP. In order to investigate whether the screening can be optimized for preterm infants, we correlated screening 17OHP levels with gestational age in pretem infants. We compared direct measurements of 17-OHP and values after ether extraction, and the number of recalls that would result from different putative cut-off levels were calculated. The possible effects of influencing factors, such as prenatal glucocorticoid treatment, mode of delivery, and neonatal asphyxia, on the screening results were studied. We concluded that with direct measurements of 17-OHP, we can detect patients with salt-wasting CAH born Preterm and obtain the results faster (which is essential to prevent salt crises) without increasing the number of recalls. New recall procedures for the screening of preterm infants were implemented in Sweden based on these findings. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activates cortisone to cortisol. A patient with insufficient response to treatment with cortisone-acetate was found to have an apparent 11beta-HSD1 deficiency with a greatly increased ratio of cortisone to cortisol metabolites. Treatment with hydrocortisone resulted in normalization of 17-OHP, reduced pregnanetriole excretion as well as the ratio of cortisone to cortisol metabolites. We could not detect any mutations in the 11 beta-HSD I gene. Some patients with CAH seem to be unable to activate cortisone to cortisol due to deficient 11beta-HSD1; hence, hydrocortisone should be the drug of choice in these patients. Further studies are needed to investigate the prevalence as well as the mechanisms behind the inter-individual differences in the activity of this enzyme. Girls with CAH were studied in a structured play situation, using masculine, feminine, and neutral toys. They were videotaped when playing alone and when playing with a parent. CAH girls played more with masculine toys than the controls did. The degree of masculinization in toy play correlated with disease severity, i.e. the level of prenatal exposure to androgen, as assessed by CYP21 genotyping. The CAH girls played somewhat less with the masculine toys when a parent was present, indicating that the presence of the parent influenced them to behave in a less masculine fashion. Our results point to a direct, causative effect of prenatal androgens as an explanation for the differences in sex-typed behavior that can be seen between girls affected with CAH and controls. An increased knowledge of the specific situation for girls with CAH is important for improving the care of the patients. An increased understanding of the girl's preferences is also valuable to the families.
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| 8. |
- Pigot, Harry
(author)
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Afterload system design for functional donor heart assessment
- 2024
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Doctoral thesis (other academic/artistic)abstract
- Heart transplantation is a life-saving procedure for patients with end-stage heart failure. However, conservative acceptance criteria result in most donated hearts being discarded. Enabling clinicians to assess heart function after organ procurement can pave the way for the safe use of hearts that are currently rejected. This thesis focuses on improving techniques for the direct, controlled assessment of a recovered heart's hemodynamic performance. The first paper reviews ex situ working heart models and cardiac afterload devices, discussing challenges in emulating cardiac afterload and detailing an experimental method for a working porcine heart model. Paper II analyzes Windkessel models, which are the standard cardiac afterload model. It assesses their applicability and limitations, and presents a method for identifying model parameters from sampled data. The analysis concludes that complex models like the 4-element Windkessel model are not identifiable from relevant experimental data. The third paper reformulates traditional Windkessel models for a more accurate representation of hemodynamic responses. Using power as model input, the paper offers a more physiological representation of the hemodynamic response to various afterloads, aiding in afterload device design. In Paper IV, the efficacy of a pneumatic afterload device creating a range of physiological loading conditions is investigated in six porcine hearts. The experiments show the concept's utility in testing hearts under multiple conditions. Paper V introduces an actively controlled variable flow resistance, demonstrating its ability to reproduce a wide range of afterload dynamics while enforcing safe pressure limits for heart assessment. The afterload concept, outlined in Paper I, is investigated in silico using the methods from Paper III. A physical prototype and pilot experiments led to a patent submission for the design. These papers advance functional heart assessment by both refining Windkessel-model-based simulation tools (Papers II and III) and exploring novel afterload device concepts (Papers I, IV, and V). Together, they constitute a step towards clinical implementation of technology that can safely enable more transplantations by providing an improved basis for decision-making.
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