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- Yannuzzi, M., et al.
(författare)
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TEFIS: A Single Access Point for Conducting Multifaceted Experiments on Heterogeneous Test Facilities
- 2014
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Ingår i: Computer Networks. - : Elsevier BV. - 1389-1286 .- 1872-7069. ; 63, s. 147-172
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Tidskriftsartikel (refereegranskat)abstract
- A few years ago, an experimental facility composed of networking gear and simulation tools was sufficient for testing the main features of a prototype before the final product could be launched to the Internet market. This paradigm has certainly changed, but the lack of platforms enabling the realistic assessment of the different facets of a product, including cross-cutting trials across different testbeds, poses strong limitations for researchers and developers. In light of this, we present an open platform that offers a versatile combination of heterogeneous experimental facilities called “TEstbed for Future Internet Services” (TEFIS). TEFIS provides a single access point for conducting cutting-edge experiments on testbeds that supply different capabilities, including testbeds dedicated to network performance, software performance, grid computing, and living labs. We shall show that TEFIS covers the entire life-cycle of a multifaceted experiment, with the advantage that a single testrun can seamlessly execute across different experimental facilities. In order to demonstrate the potential and versatility of the TEFIS platform, we describe the deployment of four distinct experiments and provide a set of results highlighting the benefits of using TEFIS. The experiments described in this article cover: i) the experimentation with an open API called OPENER (which is an open and programmable environment for managing experimentation with SDN applications); ii) an application for skiers and tourists at the Megève ski resort in France; iii) an application that can dynamically adapt the Quality of Experience (QoE) of multimedia services for mobile users; and iv) an augmented reality workspace for remote education and learning purposes based on videoconferencing.
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| 3. |
- Carlström, Mattias, et al.
(författare)
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SOD1-Deficiency Causes Salt-Sensitivity and Aggravates Hypertension in Hydronephrosis
- 2009
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 297:1, s. R82-R92
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Tidskriftsartikel (refereegranskat)abstract
- Background: Hydronephrosis causes renal dysfunction and salt-sensitive hypertension, which is associated with NO-deficiency and abnormal tubuloglomerular feedback (TGF) response. We investigated the role of oxidative stress for salt-sensitivity and for hypertension in hydronephrosis. Methods: Hydronephrosis was induced in SOD1-transgenic (SOD1-tg), SOD1-deficient (SOD1-ko) and wild-type mice and in rats. In mice, telemetric measurements were performed during normal (0.7% NaCl) and high sodium (4% NaCl) diets and with chronic Tempol supplementation. 8-iso-prostaglandin-F2alpha (F2-IsoPs) and protein excretion profiles and histology were investigated. The acute effects of Tempol on blood pressure and TGF were studied in rats. Results: In hydronephrosis, wild-type mice developed salt-sensitive hypertension (114+/-1 to 120+/-2 mmHg) which was augmented in SOD1-ko (125+/-3 to 135+/-4 mmHg), but abolished in SOD1-tg (109+/-3 to 108+/-3 mmHg). SOD1-ko controls displayed salt-sensitive blood pressure (108+/-1 to 115+/-2 mmHg), which was not found in wild-types or SOD1-tg. Chronic Tempol treatment reduced blood pressure in SOD1-ko controls (-7 mmHg) and in hydronephrotic wild-types (-8 mmHg) and SOD1-ko mice (-16 mmHg), but had no effect on blood pressure in wild-type or SOD1-tg controls. SOD1-ko controls and hydronephrotic wild-type and SOD1-ko mice exhibited increased fluid excretion associated with increased F2-IsoPs and protein excretion. The renal histopathological changes found in hydronephrotic wild-types were augmented in SOD1-ko and diminished in SOD-tg mice. Tempol attenuated blood pressure and normalized TGF response in hydronephrosis (DeltaPSF: 15.2+/-1.2 to 9.1+/-0.6 mmHg, TP: 14.3+/-0.8 to 19.7+/-1.4 nl/min). Conclusion: Oxidative stress due to SOD1-deficiency causes salt-sensitivity and plays a pivotal role for the development of hypertension in hydronephrosis. Increased superoxide formation may enhance TGF response and thereby contribute to hypertension.
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| 4. |
- Kumar, Arun, 1991, et al.
(författare)
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Improved Predictive Model of Drivers’ Subjective Perception of Vehicle Reaction under Aerodynamic Excitations
- 2023
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Ingår i: International Journal of Automotive Technology. - 1976-3832 .- 1229-9138. ; 24:6, s. 1655-1664
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Tidskriftsartikel (refereegranskat)abstract
- In vehicle development, rating vehicle reactions to external disturbances such as aerodynamic excitations are important for improving safety and comfort of passengers. Vehicle motion reactions under such conditions are dependent on both disturbance and drivers’ steering actions. A predictive model has been developed to correctly anticipate the drivers’ ability to identify unexpected external disturbances for straight-line, high-speed driving in a driving simulator. The measured variables were band-pass filtered to desired frequency ranges. Excess yaw and roll velocities, defined as the difference between actual rotations and rotations predicted with a dynamic model from the cause of actual steering, were calculated. The standard deviations of the measured variables in a time window around disturbances were used in a regression model to predict the driver responses. Replacing actual rotations with excess rotations reduced the importance of steering input as a predictor by approximately 2/3, thus improving the accuracy of the predictive model. The model showed the change in driver sensitivity to rotations at different frequency intervals. It also showed that only driver input in around 1 ∼ 2 Hz reduces driver sensitivity and that drivers are not necessarily sensitive to high rotational accelerations, but rather to large differences between actual vehicle yaw and roll and expected vehicle yaw and roll responses from the steering input The result from this study were later compared to succeeding on-road tests which confirmed that the predictive model was improved with the use of excess motion variables.
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| 5. |
- Kumar, Arun, 1991, et al.
(författare)
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Prediction of Drivers’ Subjective Evaluation of Vehicle Reaction Under Aerodynamic Excitations
- 2024
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Ingår i: Human Factors. - : SAGE Publications. - 1547-8181 .- 0018-7208. ; 66:5, s. 1600-1615
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objectives are to determine which quantities are important to measure to determine how drivers perceive vehicle stability, and to develop a regression model to predict which induced external disturbances drivers are able to feel. Background: Driver experience of a vehicle’s dynamic performance is important to auto manufacturers. Test engineers and test drivers perform several on-road assessments to evaluate the vehicle’s dynamic performance before sign-off for production. The presence of external disturbances such as aerodynamic forces and moments play a significant role in the overall vehicle assessment. As a result, it is important to understand the relation between the subjective experience of the drivers and these external disturbances acting on the vehicle. Method: A sequence of external yaw and roll moment disturbances of varying amplitudes and frequencies is added to a straight-line high-speed stability simulation test in a driving simulator. The tests are performed with both common and professional test drivers, and their evaluations to these external disturbances are recorded. The sampled data from these tests are used to generate the needed regression model. Results: A model is derived for predicting which disturbances drivers can feel. It quantifies difference in sensitivity between driver types and between yaw and roll disturbances. Conclusion: The model shows a relationship between steering input and driver sensitivity to external disturbances in a straight-line drive. Drivers are more sensitive to yaw disturbance than roll disturbance and increased steering input lowers sensitivity. Application: Identify the threshold above which unexpected disturbances such as aerodynamic excitations can potentially create unstable vehicle behaviour.
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| 6. |
- Kumar, Arun, 1991, et al.
(författare)
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Predictive Model of Driver's Perception of Vehicle Stability under Aerodynamic Excitation
- 2023
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Ingår i: SAE Technical Papers. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- In vehicle development, a subjective evaluation of the vehicle's behavior at high speeds is usually conducted by experienced drivers with the objective of assessing driving stability. To avoid late design changes, it is desirable to predict and resolve perceived instabilities early in the development phase. In this study, a mathematical model is developed from measurements during on-road tests to predict the driver's ability to identify vehicle instabilities under excitations such as aerodynamic excitations. A vehicle is fitted with add-ons to create aerodynamic excitations and is driven by multiple drivers on a high-speed track. Drivers' evaluation, responses, cabin motion, and crosswind conditions are recorded. The influence of yaw and roll rates, lateral acceleration, and steering angle at various frequency ranges when predicting the drivers' evaluation of induced excitation is demonstrated. The drivers' evaluation of vehicle behavior is influenced by driver-vehicle interactions. Excess rotational rates, defined as the part of rotational rates that are not the result of steering action, reduce the importance of steering as a predictor and improve the accuracy of the predictive model. The present model is compared with an earlier developed model derived from data from a driving simulator under preconditioned aerodynamic excitations.
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| 7. |
- Rosenquist, R, et al.
(författare)
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Clonal evolution as judged by immunoglobulin heavy chain gene rearrangements in relapsing precursor-B acute lymphoblastic leukemia.
- 1999
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Ingår i: European Journal of Haematology. - 0902-4441 .- 1600-0609. ; 63:3, s. 171-9
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Tidskriftsartikel (refereegranskat)abstract
- Oligoclonality and ongoing clonal evolution are common features in patients with precursor-B (pre-B) acute lymphoblastic leukemia (ALL), as judged by immunoglobulin heavy chain (IgH) gene rearrangement analysis. These features are considered to be results of secondary rearrangements after malignant transformation or emergence of new tumor clones. In the present study we analyzed the IgH gene rearrangement status in 18 cases with relapsing pre-B ALL using variable heavy chain (V(H)) gene family specific polymerase chain reaction (PCR) amplification and single stranded conformation polymorphism (SSCP) analysis. Clonal IgH rearrangements were displayed in all leukemias but one, and altered rearrangement patterns occurred in five cases (29%), which were selected for detailed nucleotide sequence analysis. In one case, multiple subclones at diagnosis were suggested to be derived from a progenitor clone through joining of different V(H) germline gene segments to a pre-existing D-J(H) complex (V(H) to D-J(H) joining). Evidence for V(H) gene replacement with identical N-sequences at the V(H)-D junction and a common D-J(H) region was observed in one case. Diversification at the V(H)-D junction consisting of heterogeneous N-sequences were observed in one case. This molecular modification of the V(H)-D region could fit a hypothesized "open-and-shut" mechanism. Nevertheless, despite these ongoing events at least one IgH rearrangement remained unchanged throughout the disease in most patients, indicating that the immunoglobulin heavy chain locus can be a suitable marker for detection of minimal residual disease (MRD).
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