| 98551. |
- Lindqvist, Elisabet
(författare)
-
Rheumatoid Arthritis in a 10-Year Perspective, Outcome for Patients Followed from Early Disease
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rheumatoid arthritis (RA) is characterized by persistent inflammation, progressive joint damage and disability. This thesis describes the outcome after 10 years in a cohort of 183 RA patients (116 women, 67 men) recruited 1985-89. The mean age was 51 years and symptom duration 11 months at inclusion. Standardized clinical, biochemical and radiographic assessments were performed annually. Health status, disease process, damage and mortality were evaluated and early factors predicting outcome were investigated. After 10 years: -94% preserved independence in daily life, 47% were mildly disabled, as evaluated by HAQ, however disability increased significantly. -18% were in remission, 17% had undergone large joint replacement and 8% had developed extra-articular manifestations. -Joint damage in hands and feet developed and progressed most markedly during the first 3 years and affected 96% of the patients. -Mortality was not increased. -Initial HAQ predicted disability after 10 years correctly to 70%, while remission, extra-articular manifestations and mortality were not predictable. -ESR, COMP, IgA-RF, anti-CCP and anti-IL-1alpha at inclusion were prognostic for future joint damage in an additive fashion. -In the disablement process, disease activity and joint damage contributed most to the development of body function impairments. Disease activity and body function impairments subsequently led to activity limitations (HAQ). The outcome has improved compared with earlier studies, especially for disability and mortality. Continued follow-up of these patients will provide information on the long-term consequences of RA and the cohort will be useful for the evaluation of novel prognostic markers.
|
|
| 98552. |
|
|
| 98553. |
|
|
| 98554. |
- Lindqvist, Fredrik, et al.
(författare)
-
Detection and localization of load coils from one-port measurements
- 2010
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456. ; 59:7, s. 1972-1982
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThis paper deals with detection and localization of load coils in the copper access network. The load coil is a legacy device that must be removed before deploying broadband services on twisted-pair transmission lines. The proposed methods do not require dedicated hardware but utilize the already installed transceivers for one-port measurements of the line input impedance. The number of load coils is detected by counting the number of resonance peaks in the line impedance spectrum. An approximative model of the symmetric loaded line is presented, from which a low-complexity load coil locator is derived. For nonsymmetric lines, a load coil locator using model-based optimization is proposed. The two methods are compared and evaluated by computer simulations and by laboratory measurements on real transmission lines. The estimation results indicate that up to five load coils can be robustly detected and located with the proposed methods.
|
|
| 98555. |
- Lindqvist, Fredrik
(författare)
-
Estimation and detection of transmission line characteristics in the copper access network
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The copper access-network operators face the challenge of developing and maintaining cost-effective digital subscriber line (DSL) services that are competitive to other broadband access technologies. The way forward is dictated by the demand of ever increasing data rates on the twisted-pair copper lines. To meet this demand, a relocation of the DSL transceivers in cabinets closer to the customers are often necessary combined with a joint expansion of the accompanying optical-fiber backhaul network. The equipment of the next generation copper network are therefore becoming more scattered and geographically distributed, which increases the requirements of automated line qualification with fault detection and localization. This scenario is addressed in the first five papers of this dissertation where the focus is on estimation and detection of transmission line characteristics in the copper access network. The developed methods apply model-based optimization with an emphasis on using low-order modeling and a priori information of the given problem. More specifically, in Paper I a low-order and causal cable model is derived based on the Hilbert transform. This model is successfully applied in three contributions of this dissertation. In Paper II, a class of low-complexity unbiased estimators for the frequency-dependent characteristic impedance is presented that uses one-port measurements only. The so obtained characteristic impedance paves the way for enhanced time domain reflectometry (a.k.a. TDR) on twisted-pair lines. In Paper III, the problem of estimating a nonhomogeneous and dispersive transmission line is investigated and a space-frequency optimization approach is developed for the DSL application. The accompanying analysis shows which parameters are of interest to estimate and further suggests the introduction of the concept capacitive length that overcomes the necessity of a priori knowledge of the physical line length. In Paper IV, two methods are developed for detection and localization of load coils present in so-called loaded lines. In Paper V, line topology identification is addressed with varying degree of a priori information. In doing so, a model-based optimization approach is employed that utilizes multi-objective evolutionary computation based on one/two-port measurements. A complement to transceiver relocation that potentially enhances the total data throughput in the copper access network is dynamic spectrum management (DSM). This promising multi-user transmission technique aims at maximizing the transmission rates, and/or minimizing the power consumption, by mitigating or cancelling the dominating crosstalk interference between twisted-pair lines in the same cable binder. Hence the spectral utilization is improved by optimizing the transmit signals in order to minimize the crosstalk interference. However, such techniques rely on accurate information of the (usually) unknown crosstalk channels. This issue is the main focus of Paper VI and VII of this dissertation in which Paper VI deals with estimation of the crosstalk channels between twisted-pair lines. More specifically, an unbiased estimator for the square-magnitude of the crosstalk channels is derived from which a practical procedure is developed that can be implemented with standardized DSL modems already installed in the copper access network. In Paper VII the impact such a non-ideal estimator has on the performance of DSM is analyzed and simulated. Finally, in Paper VIII a novel echo cancellation algorithm for DMT-based DSL modems is presented.
|
|
| 98556. |
|
|
| 98557. |
- Lindqvist, Fredrik
(författare)
-
Estimation of line properties in the copper access network
- 2009
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The copper access-network operators face the challenge of developing and maintaining cost-effective digital subscriber line (DSL) services that are competitive to other broadband access technologies. The way forward is dictated by the demand of ever increasing data rates on the twisted-pair copper lines. This forces a deployment of the DSL transceivers in cabinets closer to the customers with a joint expansion of the accompanying optical-fiber backhaul network. The equipment of the next generation copper network is therefore becoming more scattered and geographically distributed, which often leads to increased maintenance for the operator. Another challenge for the operators is to maintain high quality of service even when the signal-to-noise-ratio margin is reduced in favor of higher bit-rates, required by new services such as IP-TV and high-definition TV (HD-TV). Moreover, the emerging multi-user techniques for increasing the total throughput in the copper network utilize spectrum management, which relies on accurate information of the usually unknown crosstalk channels in the cable binders. What these challenges have in common is the need of an efficient tool for estimating the properties and the states of the transmission lines. A viable solution is to use the already installed DSL transceivers for line qualification and monitoring, combined with rapid fault detection and localization, in order to prevent unnecessary and costly manual intervention. This thesis addresses estimation of various kinds of line properties based on one-port or two-port measurements. For the purpose of line qualification and fault detection, the focus is on: low-order and causal cable modeling (Paper I), estimation of the characteristic impedance (Paper II), detection and localization of load coils (Paper III), and estimation of line topology (Paper IV). For the application of dynamic spectrum management (DSM), the focus is on: estimation of the crosstalk channels (Paper V) and the impact of estimation errors on the DSM performance (Paper VI). Finally, estimation of the echo transfer function for echo cancellation is addressed (Paper VII).
|
|
| 98558. |
- Lindqvist, Fredrik, et al.
(författare)
-
Estimation of Nonhomogeneous and Multi-Section Twisted-Pair Transmission-Line Parameters
- 2015
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 63:11, s. 3568-3578
-
Tidskriftsartikel (refereegranskat)abstract
- In emerging and future copper access networks, the trend goes towards exploiting higher transmission bandwidths on shorter twisted-pair cables. Methods to accurately determine relevant transmission-line parameters are a prerequisite to exploit the potential of these short-to-medium range access lines. In this paper, we propose a model-based space-frequency optimization approach initially developed for microwave applications. By utilizing the concept of capacitive length, two major advances are achieved. First, we overcome the requirement of a priori information of physical line length. Second, the number of parameters is reduced compared to prior art. We introduce two estimators to illustrate the concept. A low-complexity estimator with only two parameters per spatial unit primarily targets higher frequencies. A wideband estimator with three parameters per spatial unit extends to the lower frequencies used by operational digital subscriber line services. Performance and limitations of the approach are illustrated by both computer simulations and measurements.
|
|
| 98559. |
- Lindqvist, Fredrik, et al.
(författare)
-
Low-order and causal twisted-pair cable modeling by means of the Hilbert transform
- 2008
-
Ingår i: AIP Conference Proceedings. - : AIP. ; , s. 301-310
-
Konferensbidrag (refereegranskat)abstract
- A new low-order and causal twisted-pair cable model for the copper access network is derived. From the serial resistance of the widely used, but non-causal, BT0 model, the serial inductance is computed via the Hilbert transform. By doing so, a causal cable model is obtained containing fewer parameters compared to the BT0 model. The deviation between the two models is evaluated for the standardized ETSI cables.
|
|
| 98560. |
- Lindqvist, Gunilla, et al.
(författare)
-
Informal home caregiving in a gender perspective : A selected literature review
- 2004
-
Ingår i: Vård i Norden. - 0107-4083 .- 1890-4238. ; 24:4, s. 26-30
-
Tidskriftsartikel (refereegranskat)abstract
- An informal home caregiver is a person (family member or friends) who takes care of or participates to some degree in the care of a person in the home. This study provides a selected review of literature published 1982-2003 of the informal home caregiving from a gender perspective. A computer-aided search using MEDLINE and CINAHL was carried out. The final number of articles was 45. The main findings were that there are differences in informal caregiving due to gender. Gender differences were found in categories such as affected lifeworld, health problems, managing ability and caregivers experience from caring for a care receiver with different diseases. It is of importance that the informal caregiver is involved in the planning and that a planning act takes place. If society involves the informal home caregiver we can avoid the caregiver being the hidden victim of illness and disability. It is known that burdensome caregiving can result in encroachment due to exhaustion.
|
|
