| 21. |
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Att välja trä
- 2020. - 10
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)
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| 22. |
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| 23. |
- Bejhed, Johan, 1973-
(författare)
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Fluidic Microsystems for Micropropulsion Applications in Space
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Spacecraft on interplanetary missions or advanced satellites orbiting the Earth all require propulsion systems to complete their missions. Introducing microelectromechanical systems technology to the space industry will not only reduce size and weight of the propulsion system, but can also increase the performance of the mission.Fluid handling systems are used in chemical and electric propulsion. Some components incorporated in a fluidic handling system are presented and evaluated in this work.Microsystems are very sensitive to contamination. Reliable, robust, and easily integrated filters were modeled, manufactured, and experimentally verified.A fluid connector, designed to withstand large temperature variations and aggressive propellants was manufactured and characterized. Similar designs was also be used as a thermally activated minute valve.The feasibility of a cold gas system for precise attitude control has been demonstrated. Steps towards improving the performance (from specific im-pulse 45 s) have been taken, by the integration of suspended heater elements.For electric propulsion, two thermally regulated flow restrictors have been characterized. These devices can fine-tune the propellant flow to e.g. an ion engine.A single-use valve using a soldered seal has also been successfully dem-onstrated within a pressure range of 5 to 100 bar.The microsystem-based propulsion systems of tomorrow’s spacecraft need to be demonstrated in space, in order to gain necessary credibility.
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| 26. |
- Bejhed, Johan, et al.
(författare)
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Numerical modeling and verification of gas flow through a network of crossed narrow v-grooves
- 2006
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 16:10, s. 2006-2013
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Tidskriftsartikel (refereegranskat)abstract
- The gas flow through a network of crossing thin micro-machined channels has been successfully modeled and simulated. The crossings are formed by two sets of v-grooves that intersect as two silicon wafers are bonded together. The gas is distributed from inlets via a manifold of channels to the narrow v-grooves. The narrow v-grooves could work as a particle filter. The fluidic model is derived from the Navier–Stokes equation and assumes laminar isothermal flow and incorporates small Knudsen number corrections and Poiseuille number calculations. The simulations use the finite element method. Several elements of the full crossing network model are treated separately before lumping them together: the straight v-grooves, a single crossing in an infinite set and a set of exactly four crossings along the flow path. The introduction of a crossing effectively corresponds to a virtual reduction of the length of the flow path, thereby defining a new effective length. The first and last crossings of each flow path together contribute to a pressure drop equal to that from three ordinary crossings. The derived full network model has been compared to previous experimental results on several differently shaped crossed v-groove networks. Within the experimental errors, the model corresponds to the mass flow and pressure drop measurements. The main error source is the uncertainty in v-groove width which has a profound impact on the fluidic behavior.
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| 27. |
- Bergemalm, Daniel, 1977-, et al.
(författare)
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Systemic Inflammation in Preclinical Ulcerative Colitis
- 2021
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Ingår i: Gastroenterology. - : AGA Institute. - 0016-5085 .- 1528-0012. ; 161:5, s. 1526-1539.e9
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Preclinical ulcerative colitis is poorly defined. We aimed to characterize the preclinical systemic inflammation in ulcerative colitis, using a comprehensive set of proteins.Methods: We obtained plasma samples biobanked from individuals who developed ulcerative colitis later in life (n = 72) and matched healthy controls (n = 140) within a population-based screening cohort. We measured 92 proteins related to inflammation using a proximity extension assay. The biologic relevance of these findings was validated in an inception cohort of patients with ulcerative colitis (n = 101) and healthy controls (n = 50). To examine the influence of genetic and environmental factors on these markers, a cohort of healthy twin siblings of patients with ulcerative colitis (n = 41) and matched healthy controls (n = 37) were explored.Results: Six proteins (MMP10, CXCL9, CCL11, SLAMF1, CXCL11 and MCP-1) were up-regulated (P < .05) in preclinical ulcerative colitis compared with controls based on both univariate and multivariable models. Ingenuity Pathway Analyses identified several potential key regulators, including interleukin-1β, tumor necrosis factor, interferon-gamma, oncostatin M, nuclear factor-κB, interleukin-6, and interleukin-4. For validation, we built a multivariable model to predict disease in the inception cohort. The model discriminated treatment-naïve patients with ulcerative colitis from controls with leave-one-out cross-validation (area under the curve = 0.92). Consistently, MMP10, CXCL9, CXCL11, and MCP-1, but not CCL11 and SLAMF1, were significantly up-regulated among the healthy twin siblings, even though their relative abundances seemed higher in incident ulcerative colitis.Conclusions: A set of inflammatory proteins are up-regulated several years before a diagnosis of ulcerative colitis. These proteins were highly predictive of an ulcerative colitis diagnosis, and some seemed to be up-regulated already at exposure to genetic and environmental risk factors.
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| 28. |
- Bergström, Göran, 1964, et al.
(författare)
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Body weight at age 20 and in midlife is more important than weight gain for coronary atherosclerosis: Results from SCAPIS.
- 2023
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 373, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Elevated body weight in adolescence is associated with early cardiovascular disease, but whether this association is traceable to weight in early adulthood, weight in midlife or to weight gain is not known. The aim of this study is to assess the risk of midlife coronary atherosclerosis being associated with body weight at age 20, body weight in midlife and body weight change.We used data from 25,181 participants with no previous myocardial infarction or cardiac procedure in the Swedish CArdioPulmonary bioImage Study (SCAPIS, mean age 57 years, 51% women). Data on coronary atherosclerosis, self-reported body weight at age 20 and measured midlife weight were recorded together with potential confounders and mediators. Coronary atherosclerosis was assessed using coronary computed tomography angiography (CCTA) and expressed as segment involvement score (SIS).The probability of having coronary atherosclerosis was markedly higher with increasing weight at age 20 and with mid-life weight (p < 0.001 for both sexes). However, weight increase from age 20 until mid-life was only modestly associated with coronary atherosclerosis. The association between weight gain and coronary atherosclerosis was mainly seen in men. However, no significant sex difference could be detected when adjusting for the 10-year delay in disease development in women.Similar in men and women, weight at age 20 and weight in midlife are strongly related to coronary atherosclerosis while weight increase from age 20 until midlife is only modestly related to coronary atherosclerosis.
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| 29. |
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| 30. |
- Betancourt, Lazaro Hiram, et al.
(författare)
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The human melanoma proteome atlas-Defining the molecular pathology
- 2021
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Ingår i: Clinical and Translational Medicine. - : Wiley. - 2001-1326. ; 11:7, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The MM500 study is an initiative to map the protein levels in malignant melanoma tumor samples, focused on in-depth histopathology coupled to proteome characterization. The protein levels and localization were determined for a broad spectrum of diverse, surgically isolated melanoma tumors originating from multiple body locations. More than 15,500 proteoforms were identified by mass spectrometry, from which chromosomal and subcellular localization was annotated within both primary and metastatic melanoma. The data generated by global proteomic experiments covered 72% of the proteins identified in the recently reported high stringency blueprint of the human proteome. This study contributes to the NIH Cancer Moonshot initiative combining detailed histopathological presentation with the molecular characterization for 505 melanoma tumor samples, localized in 26 organs from 232 patients.
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