| 1. |
- di Bernardo, M., et al.
(författare)
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Bifurcations in Nonsmooth Dynamical Systems
- 2008
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Ingår i: SIAM Review. - : Society for Industrial & Applied Mathematics (SIAM). - 0036-1445 .- 1095-7200. ; 50:4, s. 629-701
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Forskningsöversikt (refereegranskat)abstract
- A review is presented of the one-parameter, nonsmooth bifurcations that occur in a variety of continuous-time piecewise-smooth dynamical systems. Motivated by applications, a pragmatic approach is taken to defining a discontinuity-induced bifurcation (DIB) as a nontrivial interaction of a limit set with respect to a codimension-one discontinuity boundary in phase space. Only DIBs that are local are considered, that is, bifurcations involving equilibria or a single point of boundary interaction along a limit cycle for flows. Three classes of systems are considered, involving either state jumps, jumps in the vector field, or jumps in some derivative of the vector field. A rich array of dynamics are revealed, involving the sudden creation or disappearance of attractors, jumps to chaos, bifurcation diagrams with sharp corners, and cascades of period adding. For each kind of bifurcation identified, where possible, a kind of "normal form" or discontinuity mapping (DM) is given, together with a canonical example and an application. The goal is always to explain dynamics that may be observed in simulations of systems which include friction oscillators, impact oscillators, DC-DC converters, and problems in control theory.
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| 2. |
- Bentayeb, Malek, et al.
(författare)
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Indoor air quality, ventilation and respiratory health in elderly residents Living in nursing homes in Europe
- 2015
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 45:5, s. 1228-1238
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Tidskriftsartikel (refereegranskat)abstract
- Few data exist on respiratory effects of indoor air quality and comfort parameters in the elderly. In the context of the GERIE study, we investigated for the first time the relationships of these factors to respiratory morbidity among elderly people permanently living in nursing homes in seven European countries. 600 elderly people from 50 nursing homes underwent a medical examination and completed a standardised questionnaire. Air quality and comfort parameters were objectively assessed in situ in the nursing home. Mean concentrations of air pollutants did not exceed the existing standards. Forced expiratory volume in 1 s/forced vital capacity ratio was highly significantly related to elevated levels of particles with a 50% cut-off aerodynamic diameter of <0.1 mu m (PM0.1) (adjusted OR 8.16, 95% CI 2.24-29.3) and nitrogen dioxide (aOR 3.74, 95% CI 1.06-13.1). Excess risks for usual breathlessness and cough were found with elevated PM10 (aOR 1.53 (95% CI 1.15-2.07) and aOR 1.73 (95% CI 1.17-10.3), respectively) and nitrogen dioxide (aOR 1.58 (95% CI 1.15-2.20) and aOR 1.56 (95% CI 1.03-2.41), respectively). Excess risks for wheeze in the past year were found with PM0.1 (aOR 2.82, 95% CI 1.15-7.02) and for chronic obstructive pulmonary disease and exhaled carbon monoxide with formaldehyde (aOR 3.49 (95% CI 1.17-10.3) and aOR 1.25 (95% CI 1.02-1.55), respectively). Breathlessness and cough were associated with higher carbon dioxide. Relative humidity was inversely related to wheeze in the past year and usual cough. Elderly subjects aged >= 80 years were at higher risk. Pollutant effects were more pronounced in the case of poor ventilation. Even at low levels, indoor air quality affected respiratory health in elderly people permanently living in nursing homes, with frailty increasing with age. The effects were modulated by ventilation.
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| 6. |
- Shul'ga, Marianna
(författare)
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Approximate symmetry of the nonlinear heat equation
- 1991
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Ingår i: Ukrainian Mathematical Journal. - 0041-5995 .- 1573-9376. ; 43:6, s. 833-
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Tidskriftsartikel (refereegranskat)abstract
- Using the Krylov-Bogolyubov-Mitropol0ski˘ı asymptotic methods, we study the approximate Galileian symmetry of a multidimensional nonlinear heat equation.
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| 9. |
- Dán, György, et al.
(författare)
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Quality differentiation with source shaping and forward error correction
- 2003
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Ingår i: Interactive Multimedia On Next Generation Networks. - 3540205349 ; , s. 222-233
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Konferensbidrag (refereegranskat)abstract
- The transmission of video traffic over the Internet is a fundamental issue of network design. Video applications require quality of service guarantees from the network in terms of limited packet loss, end-to-end delay, and delay variation. The question of today's research and development is how to provide these guarantees considering the architecture of the present Internet. In the last years a variety of admission control schemes based on per-hop or end-to-end measurements has been suggested to control delay and loss sensitive streams with very little or no support at the routers. Most of these solutions, however, have to apply the same acceptance threshold for all streams, a significant limitation considering the diverse quality requirements of the applications. In this work we investigate how source shaping and forward error correction (FEC) can be used together to achieve application specific quality differentiation in terms of end-to-end delay and packet loss probability. While source shaping and FEC have been proposed independently to decrease the probability of packet loss due to buffer overflow, their joint use has not been studied before. As the two control functions use the same scarce resource, end-node delay, and their efficiency to decrease loss probability is proportional to the introduced delay but with a decreasing marginal gain, combining the two a better performance can be achieved than by using only one of them. The performance evaluation focuses on the optimal delay allocation for shaping and FEC, such that the loss probability is minimized. We investigate how shaping can be used to substitute FEC redundancy and the sensitivity of the quality differentiation to the background traffic characteristics.
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| 12. |
- Scott, Felipe, et al.
(författare)
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Corn stover semi-mechanistic enzymatic hydrolysis model with tight parameter confidence intervals for model-based process design and optimization
- 2015
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 177, s. 255-265
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Tidskriftsartikel (refereegranskat)abstract
- Uncertainty associated to the estimated values of the parameters in a model is a key piece of information for decision makers and model users. However, this information is typically not reported or the confidence intervals are too large to be useful. A semi-mechanistic model for the enzymatic saccharification of dilute acid pretreated corn stover is proposed in this work, the model is a modification of an existing one providing a statistically significant improved fit towards a set of experimental data that includes varying initial solid loadings (10 to 25 % w/w) and the use of the pretreatment liquor and washed solids with or without supplementation of key inhibitors. A subset of 8 out of 17 parameters was identified, showing sufficiently tight confidence intervals to be used in uncertainty propagation and model analysis, without requiring interval truncation via expert judgment.
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| 15. |
- Varshney, Ambuj, et al.
(författare)
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Battery-free VisibleLight Sensing
- 2017
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Ingår i: Proceeding VLCS '17 Proceedings of the 4th ACM Workshop on Visible Light Communication Systems. Snowbird, Utah, USA — October 16 - 16, 2017. - New York, NY, USA : ACM. ; , s. 3-8, s. 3-8
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Konferensbidrag (refereegranskat)abstract
- We present the design of the first Visible Light Sensing (VLS) system that consumes only tens of μWs of power to sense and communicate. Unlike most existing VLS systems, we require no modification to the existing light infrastructure since we use unmodulated light as a sensing medium. We achieve this by designing a novel mechanism that uses solar cells to achieve a sub-μW power consumption for sensing. Further, we devise an ultra-low power transmission mechanism that backscatters sensor readings and avoids the processing and computational overhead of existing sensor systems. Our initial results show the ability to detect and transmit hand gestures or presence of people up to distances of 330m at a peak power of μWs. Further, we demonstrate that our system can operate in diverse light conditions (100 lx to 80 klx) where existing VLS designs fail due to saturation of the transimpedance amplifier (TIA).
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| 16. |
- Varshney, Ambuj, et al.
(författare)
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Coordination of Wireless Sensor Networks using Visible Light
- 2015
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Ingår i: SenSys '15 Proceedings of the 13th ACM Conference on Embedded Networked Sensor Systems. - New York, NY, USA : ACM. - 9781450336314 ; , s. 421-422
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Konferensbidrag (refereegranskat)abstract
- Wireless sensor networks are often deployed indoors where artificial lighting is present. Indoor lighting is increasingly being composed of Light Emitting Diodes (LEDs) that offer the ability to precisely control the intensity and the frequency of the light carrier. This can be used to coordinate wireless sensor networks (WSN). The periodic variations in the light intensity can synchronise the clocks on the sensor nodes, while the ability to modulate the light carrier enables the transmission of control information like channel assignment or transmission schedules.We present Guidelight, a simple mechanism that uses controlled fluctuations in the light intensity to coordinate sensor nodes. Guidelight can wake-up or time synchronise sensor nodes or even send small bits of control information to them. All of these have separate dedicated solutions in WSN. Guidelight aims to provide a single solution to all these problems. Our initial experiments demonstrate the ability of Guidelight to trigger sensor nodes. We demonstrate Guidelight is able to trigger sensor nodes selectively at a mean error of 21 μ s.
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| 17. |
- Yen, Hsin-Yung, et al.
(författare)
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Electrospray ionization of native membrane proteins proceeds via a charge equilibration step
- 2022
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 12:16, s. 9671-9680
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Tidskriftsartikel (refereegranskat)abstract
- Electrospray ionization mass spectrometry is increasingly applied to study the structures and interactions of membrane protein complexes. However, the charging mechanism is complicated by the presence of detergent micelles during ionization. Here, we show that the final charge of membrane proteins can be predicted by their molecular weight when released from the non-charge reducing saccharide detergents. Our data indicate that PEG detergents lower the charge depending on the number of detergent molecules in the surrounding micelle, whereas fos-choline detergents may additionally participate in ion–ion reactions after desolvation. The supercharging reagent sulfolane, on the other hand, has no discernible effect on the charge of detergent-free membrane proteins. Taking our observations into the context of protein-detergent interactions in the gas phase, we propose a charge equilibration model for the generation of native-like membrane protein ions. During ionization of the protein-detergent complex, the ESI charges are distributed between detergent and protein according to proton affinity of the detergent, number of detergent molecules, and surface area of the protein. Charge equilibration influenced by detergents determines the final charge state of membrane proteins. This process likely contributes to maintaining a native-like fold after detergent release and can be harnessed to stabilize particularly labile membrane protein complexes in the gas phase.
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| 18. |
- Christersson, Christina, et al.
(författare)
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Tissue factor and IL8 production by P-selectin-dependent platelet-monocyte aggregates in whole blood involves phosphorylation of Lyn and is inhibited by IL10
- 2008
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 6:6, s. 986-994
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: P-selectin and CD40L expressed by activated platelets induce tissue factor (TF) and inflammatory cytokines in monocytes, but little is known of the cellular signaling pathways involved. The anti-inflammatory cytokine IL10 reduces atherosclerotic plaque formation. OBJECTIVES: To evaluate the importance of P-selectin upon platelet-monocyte aggregate (PMA) formation in thrombin receptor activator peptide (TRAP) stimulated whole blood, the P-selectin-P-selectin glycoprotein ligand (PSGL)-1-induced cellular signaling pathway, and the effects of IL10 on these functions. METHODS: TF, IL8, and monocyte chemotactic protein-1 (MCP-1) production, PMAs and phosphorylation of Lyn were analyzed in whole blood, purified monocytes, and vitamin D(3)-differentiated U-937 cells stimulated with TRAP or P-selectin with or without IL10. Anti-P-selectin or anti-CD40L antibodies (Abs), Src-kinases inhibitors, SU6656 or PP2, were added in some experiments. RESULTS: TRAP and P-selectin increased TF, IL8, and MCP-1 mRNA in whole blood and purified monocytes. Anti-P-selectin Ab reduced TRAP-induced PMA formation by 80 +/- 2% (P = 0.001) and production of TF (P = 0.04) and IL8 (P = 0.01). IL10 and SU6656 had no effect on PMA formation, although both significantly reduced TF (P = 0.002 and P = 0.02) and IL8 (P = 0.009 and P = 0.001) mRNA upon TRAP and P-selectin stimulation. Induced Lyn phosphorylation in monocytes was diminished by SU6656 (P = 0.02), anti-P-selectin Ab (P = 0.02), and IL10 (P = 0.03) upon TRAP or P-selectin stimulation. These results were confirmed in the vitamin D(3)-differentiated U-937 cells. CONCLUSIONS: The formation of PMAs in whole blood was P-selectin-dependent in the long term. P-selectin-PSGL-1-induced TF and IL8 expression through Lyn phosphorylation, and part of the inhibitory effect of IL10 depends on reduced phosphorylation.
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