| 1. |
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| 2. |
- Bucin, Dragan, et al.
(författare)
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Heart transplantation across the antibodies against HLA and ABO
- 2006
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Ingår i: Transplant International. - : Frontiers Media SA. - 1432-2277 .- 0934-0874. ; 19:3, s. 239-244
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Tidskriftsartikel (refereegranskat)abstract
- We have intentionally performed heart transplantation in a 5-year-old child, despite the most unfavourable risk factors for patient survival; the presence of high level of antibodies against donor's human leucocyte antigen (HLA) class I/II and blood group antigens. Pretransplant treatment by mycophenolate mofetil, prednisolone, tacrolimus, intravenous immunoglobulin, rituximab, protein-A immunoadsorption (IA) and plasma exchange reduced antibody titres against the donor's lymphocytes from 128 to 16 and against the donor's blood group antigen from 256 to 0. The patient was urgently transplanted with a heart from an ABO incompatible donor (A(1) to O). A standard triple-drug immunosuppressive protocol was used. No hyperacute rejection was seen. Antibodies against the donor's HLA antigens remained at a low level despite three acute rejections. Rising anti-A(1) blood group antibodies preceded the second rejection and were reduced by two blood group-specific IAs and remained at a low level. The patient is doing well despite the persistence of donor-reactive antibodies.
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| 3. |
- Johansson, Björn, et al.
(författare)
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Distributed Model Predictive Consensus
- 2006
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Ingår i: Proceedings of the 17th International Symposium on Mathematical Theory of Networks and Systems. ; , s. 2438-2444
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider the problem of designing a distributed control strategy such that a linear combination of the states of a number of vehicles coincide at a given time. The vehicles are described by linear difference equations and are subject to convex input constraints. It is demonstrated how primal decomposition techniques and incremental subgradient methods allow us to find a solution in which each vehicle performs individual planning of its trajectory and exchanges critical information with neighbors only. We explore various communication, computation, and control structures, and demonstrate the performance of the algorithms by numerical examples.
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| 4. |
- Johansson, Björn, et al.
(författare)
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On decentralized negotiation of optimal consensus
- 2008
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 44:4, s. 1175-1179
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Tidskriftsartikel (refereegranskat)abstract
- A consensus problem consists of finding a distributed control strategy that brings the state or output of a group of agents to a common value, a consensus point. In this paper, we propose a negotiation algorithm that computes an optimal consensus point for agents modeled as linear control systems subject to convex input constraints and linear state constraints. By primal decomposition and incremental subgradient methods, it is shown that the algorithm can be implemented such that each agent exchanges only a small amount of information per iteration with its neighbors.
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| 5. |
- Johansson, Björn, et al.
(författare)
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Subgradient methods and consensus algorithms for solving convex optimization problems
- 2008
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Ingår i: Decision and Control, 2008. CDC 2008. 47th IEEE Conference on. - : IEEE. - 9781424431236 ; , s. 4185-4190
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Konferensbidrag (refereegranskat)abstract
- In this paper we propose a subgradient method for solving coupled optimization problems in a distributed way given restrictions on the communication topology. The iterative procedure maintains local variables at each node and relies on local subgradient updates in combination with a consensus process. The local subgradient steps are applied simultaneously as opposed to the standard sequential or cyclic procedure. We study convergence properties of the proposed scheme using results from consensus theory and approximate subgradient methods. The framework is illustrated on an optimal distributed finite-time rendezvous problem.
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| 6. |
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| 7. |
- Johansson, Håkan, et al.
(författare)
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What do we mean by active citizenship
- 2007
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Ingår i: Citizenship in Nordic welfare states: Dynamics of choice, duties and participation in a changing Europe. - : Routledge: London. - 9780415414890 ; , s. 32-51
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Bokkapitel (refereegranskat)
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| 8. |
- Andréasson, Sven, et al.
(författare)
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Behandling av alkohol- och narkotikaproblem : En evidensbaserad kunskapssammanställning
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Utvärderingens syfteMissbruk och beroende av alkohol är ett av de största folkhälsoproblemen. Narkotikamissbruk är mindre vanligt men har stora medicinska konsekvenser för de berörda. De sociala och juridiska aspekterna är betydande. En kritisk genomgång av litteraturen vad avser behandling av abstinens, protraherad abstinens, behandling i syfte att förhindra återfall, psykologiska och sociala behandlingar för att minska återfallsrisken, behandlingsprogram och institutionsvårdens roll, samt behandling av missbruk under graviditet. Dessutom en granskning av mini-intervention i primärvård och annan vård vars syfte är att minska konsumtionen hos högkonsumenter av alkohol. Nyligen gjorda meta-analyser inom området värderas och särskild vikt fästs vid interventioner som finns eller lätt kan introduceras i den svenska vårdorganisationen. Behandlingsprogram för patienter med samtidig annan psykisk störning värderas.Så kallat lågdosberoende av bensodiazepiner och andra lugnande medel eller sömnmedel behandlas inte. Inte heller belyses effekten av behandlingar vars primära mål är kroppsliga komplikationer av missbruket, och inte heller granskas metoder att minska tillgänglighet.TillvägagångssättStrukturerad översikt, kostnadsanalyser.Insamling av primärdataSystematisk sökning i relevanta databaser, litteraturlistor i påträffade studier samt i aktuella monografier. Ingen bakre tidsbegränsning och sökning i databaser till och med februari 1999.Utgångspunkt för urval av dataHuvudsakligen randomiserade, kontrollerade, dubbelblinda studier, samt metaanalyser som baseras på sådana studier. Vad gäller långtidsförlopp och ekonomiska analyser även kohortstudier och andra naturalistiska studier.Genomgång av publikationenSamtliga studier värderas med hjälp av en i gruppen utarbetad, och med övriga psykiatriprojekt gemensam, kvalitetsmall. Alla centrala studier läses av minst två i gruppen.Färdiga manuskript värderas av styrelse, expertgrupp samt externa granskare.
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| 9. |
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| 10. |
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| 11. |
- Engström, Ulrika, et al.
(författare)
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Multi-beam antennas in a PMP system : An up-link carrier to interference ratio performance evaluation
- 2001
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Ingår i: IEEE 54TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2001. - 0780370058 ; , s. 338-342
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Konferensbidrag (refereegranskat)abstract
- The performed study is an up-link carrier-to-interference (C/I) performance evaluation of narrow multi-beam and wide sector-beam node antennas in a PMP system. It is shown that the introduction of three-beam node antennas improves up-link C/I with 5 dB compared with wide-beam sector antenna. The replacement of wide-beam antennas can be made on a sector by sector basis. Simulations have shown that it is possible to get significant interference improvement in a 5x3-hub network by replacing 20% of the wide-beam antennas with multi-beam antennas.
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| 12. |
- Johansson, Björn, et al.
(författare)
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A RANDOMIZED INCREMENTAL SUBGRADIENT METHOD FOR DISTRIBUTED OPTIMIZATION IN NETWORKED SYSTEMS
- 2009
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Ingår i: SIAM Journal on Optimization. - 1052-6234 .- 1095-7189. ; 20:3, s. 1157-1170
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Tidskriftsartikel (refereegranskat)abstract
- We present an algorithm that generalizes the randomized incremental subgradient method with fixed stepsize due to Nedic and Bertsekas [SIAM J. Optim., 12 (2001), pp. 109-138]. Our novel algorithm is particularly suitable for distributed implementation and execution, and possible applications include distributed optimization, e.g., parameter estimation in networks of tiny wireless sensors. The stochastic component in the algorithm is described by a Markov chain, which can be constructed in a distributed fashion using only local information. We provide a detailed convergence analysis of the proposed algorithm and compare it with existing, both deterministic and randomized, incremental subgradient methods.
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| 13. |
- Johansson, Björn, et al.
(författare)
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A simple peer-to-peer algorithm for distributed optimization in sensor networks
- 2007
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Ingår i: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL. ; , s. 5402-5407
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Konferensbidrag (refereegranskat)abstract
- We propose a distributed algorithm that solves a special class of optimization problems using only peer-to-peer communication. One application is parameter estimation problems in sensor networks. Current decentralized algorithms for solving this class of optimization problems typically rely on passing around a parameter estimate in a ring consisting of all network nodes. In our algorithm, which extends the randomized incremental subgradient method with fixed stepsize due to Nedic and Bertsekas, nodes maintain individual estimates and need to exchange information only with their neighbors. We establish approach of the solution to an interval around the optimum value. We illustrate the algorithm's performance, in terms of convergence rate and communication cost relative to alternative schemes, through several numerical examples.
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| 14. |
- Johansson, Björn, et al.
(författare)
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Bilateral same day phacoemulsification : 220 Cases retrospectively reviewed
- 2003
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Ingår i: British Journal of Ophthalmology. - : BMJ. - 0007-1161 .- 1468-2079. ; 87:3, s. 285-290
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Tidskriftsartikel (refereegranskat)abstract
- Background/aims: The relative frequency, basic patient data, results, and complications of planned same day bilateral phacoemulsification were studied from April 1999 to May 2001 at the Department of Ophthalmology, Linköping University Hospital, Sweden. Methods: Retrospective study of patient records (n=220) regarding preoperative and postoperative visual acuity, applied indications, concurrent disease, preoperative, peroperative, and postoperative complications, and number of unplanned postoperative visits. The monthly rate of bilateral phacoemulsification to all cataract procedures was monitored. Results: Mean corrected preoperative visual acuity was 0.27 (worse eye) and 0.39 (better eye), and postoperatively (all eyes) 0.71. Visual acuity was 0.5 or better in 78% of eyes. Preoperative considerations included type of cataract, to avoid anisometropia, social circumstances, and concurrent eye disease. Reasons for unplanned postoperative visits included secondary cataract (n=10), iritis (n=6), corneal oedema (n=3), cortex in the anterior chamber (n=2), and unilateral endophthalmitis (n=2). During the study period, 10.5% of patients were operated upon bilaterally on the same day. Conclusions: Same day bilateral phacoemulsification was found to be a safe and cost effective way of rapidly rehabilitating selected cataract patients. The patient must be informed of the added potential risks as well as the benefits of the procedure.
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| 15. |
- Johansson, Björn, et al.
(författare)
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Distributed non-smooth resource allocation over a network
- 2009
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Ingår i: IEEE Conference on Decision and Control. ; , s. 1678-1683
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Konferensbidrag (refereegranskat)abstract
- Networked systems are common and crucial. Oneof the canonical problems in such systems is distributed resourceallocation. From this rather broad class of problems, weconsider a convex non-smooth resource allocation problem witha global resource constraint. Specifically, the objective functionis separable and consists of a sum of convex functions, eachassociated with a node in a given network. Each component ofthe objective depends on a single variable local to the associatednode and the sum of all local variables must remain constantat all times. For scalability, we constrain the nodes to onlycommunicate and exchange resources with their immediateneighbors. We propose an algorithm that combines subgradientoptimization with distributed averaging. Starting the algorithmfrom a feasible point, the nodes iteratively exchange resourceswith their neighbors to get close to the optimal set whilesatisfying the total resource constraint at all times.We show thatunder mild technical conditions the algorithm converges in anepsilon-sense, as long as the stepsize is chosen sufficiently smalland the distributed averaging process is sufficiently accurate.We derive expressions for how the stepsize and the number ofconsensus iterations affect the accuracy of the final result.
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| 16. |
- Johansson, Björn, 1978-
(författare)
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Distributed resource allocation in networked systems using decomposition techniques
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Internet and power distribution grids are examples of ubiquitous systems that are composed of subsystems that cooperate using a communication network. We loosely define such systems as networked systems. These systems are usually designed by using trial and error. With this thesis, we aim to fill some of the many gaps in the diverse theory of networked systems. Therefore, we cast resource allocation in networked systems as optimization problems, and we investigate a versatile class of optimization problems. We then use decomposition methods to devise decentralized algorithms that solve these optimization problems. The thesis consists of four main contributions: First, we review decomposition methods that can be used to devise decentralized algorithms for solving the posed optimization problems. Second, we consider cross-layer optimization of communication networks. Network performance can be increased if the traditionally separated network layers are jointly optimized. We investigate the interplay between the data sending rates and the allocation of resources for the communication links. The communication networks we consider have links where the data transferring capacity can be controlled. Decomposition methods are applied to the design of fully distributed protocols for two wireless network technologies: networks with orthogonal channels and network-wide resource constraints, as well as wireless networks using spatial-reuse time division multiple access. Third, we consider the problem of designing a distributed control strategy such that a linear combination of the states of a number of vehicles coincide at a given time. The vehicles are described by linear difference equations and are subject to convex input constraints. It is demonstrated how primal decomposition techniques and incremental subgradient methods allow us to find a solution in which each vehicle performs individual planning of its trajectory and exchanges critical information with neighbors only. We explore various communication, computation, and control structures. Fourth, we investigate the resource allocation problem for large-scale server clusters with quality-of-service objectives, in which key functions are decentralized. Specifically, the problem of selecting which services the servers should provide is posed as a discrete utility maximization problem. We develop an efficient centralized algorithm that solves this problem, and we propose three suboptimal schemes that operate with local information.
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| 17. |
- Johansson, Björn, et al.
(författare)
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Distributed resource allocation strategies for achieving quality of service in server clusters
- 2006
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Ingår i: PROCEEDINGS OF THE 45TH IEEE CONFERENCE ON DECISION AND CONTROL. ; , s. 1990-1995
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Konferensbidrag (refereegranskat)abstract
- We investigate the resource allocation problem for large-scale server clusters with quality-of-service objectives, where key functions are decentralized. Specifically, the optimal service selection is posed as a discrete utility maximization problem that reflects management objectives and resource constraints. We develop an efficient centralized algorithm that solves this problem, and we propose three suboptimal schemes that operate with local information. The performance of the suboptimal schemes is evaluated in simulations, both under idealized conditions and in a full-scale system simulator.
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| 18. |
- Johansson, Björn, et al.
(författare)
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Faster Linear Iterations for Distributed Averaging
- 2008
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Ingår i: Proceedings of the 17th IFAC World Congress, 2008.
-
Konferensbidrag (refereegranskat)abstract
- Distributed averaging problems are a subclass of distributed consensus problems,which have received substantial attention from several research communities. Although many ofthe proposed algorithms are linear iterations, they vary both in structure and state dimension.In this paper, we investigate the performance benefits of adding extra states to distributedaveraging iterations. We establish conditions for convergence and discuss possible ways ofoptimizing the convergence rates. By numerical examples, it is shown that the performance canbe significantly increased by adding extra states. Finally, we provide necessary and sufficientconditions for convergence of a more general version of distributed averaging iterations.
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| 19. |
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| 20. |
- Johansson, Björn, 1978-
(författare)
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On Distributed Optimization in Networked Systems
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Numerous control and decision problems in networked systems can be posed as optimization problems. Examples include the framework of network utility maximization for resource allocation in communication networks, multi-agent coordination in robotics, and collaborative estimation in wireless sensor networks (WSNs). In contrast to classical distributed optimization, which focuses on improving computational efficiency and scalability, these new applications require simple mechanisms that can operate under limited communication. In this thesis, we develop several novel mechanisms for distributed optimization under communication constraints, and apply these to several challenging engineering problems. In particular, we devise three tailored optimization algorithms relying only on nearest neighbor, also known as peer-to-peer, communication. Two of the algorithms are designed to minimize a non-smooth convex additive objective function, in which each term corresponds to a node in a network. The first method is an extension of the randomized incremental subgradient method where the update order is given by a random walk on the underlying communication graph, resulting in a randomized peer-to-peer algorithm with guaranteed convergence properties. The second method combines local subgradient iterations with consensus steps to average local update directions. The resulting optimization method can be executed in a peer-to-peer fashion and analyzed using epsilon-subgradient methods. The third algorithm is a center-free algorithm, which solves a non-smooth resource allocation problem with a separable additive convex objective function subject to a constant sum constraint. Then we consider cross-layer optimization of communication networks, and demonstrate how optimization techniques allow us to engineer protocols that mimic the operation of distributed optimization algorithms to obtain an optimal resource allocation. We describe a novel use of decomposition methods for cross-layer optimization, and present a flowchart that can be used to categorize and visualize a large part of the current literature on this topic. In addition, we devise protocols that optimize the resource allocation in frequency-division multiple access (FDMA) networks and spatial reuse time-division multiple access (TDMA) networks, respectively. Next we investigate some variants of the consensus problem for multi-robot coordination, for which it is usually standard to assume that agents should meet at the barycenter of the initial states. We propose a negotiation strategy to find an optimal meeting point in the sense that the agents' trajectories to the meeting point minimize a quadratic cost criterion. Furthermore, we also demonstrate how an augmented state vector can be used to boost the convergence rate of the standard linear distributed averaging iterations, and we present necessary and sufficient convergence conditions for a general version of these iterations. Finally, we devise a generic optimization software component for WSNs. To this end, we implement some of the most promising optimization algorithms developed by ourselves and others in our WSN testbed, and present experimental results, which show that the proposed algorithms work surprisingly well.
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| 21. |
- Johansson, Björn, et al.
(författare)
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On Distributed Optimization using Peer-to-Peer Communications in Wireless Sensor Networks
- 2008
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Ingår i: Proceedings of IEEE SECON. ; , s. 497-505
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Konferensbidrag (refereegranskat)abstract
- We describe and evaluate a suite of distributed and computationally efficient algorithms for solving a class of convex optimization problems in wireless sensor networks. The problem class has wide applications in estimation, detection, localization, coordination and resource sharing. We focus on peer-to-peer algorithms where nodes only exchange data with their immediate neighbors, and consider three distinct alternatives: a dual-based broadcast algorithm, a novel stochastic unicast algorithm, and a linear broadcast algorithm tailored for least-squares problems. We implement the algorithms in the network simulator NS2 and present extensive simulation results for random topologies.
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| 22. |
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| 23. |
- Johansson, Björn, et al.
(författare)
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Primal and Dual Approaches to Distributed Cross-layer Optimization
- 2005
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. ; , s. 113-118
-
Konferensbidrag (refereegranskat)abstract
- Several approaches for cross-layer design, e.g., coordinating the traditionally separated layers in wireless networks, have been proposed. However, protocols that are close to achieving the performance bounds are still lacking. We propose three distributed algorithms for joint congestion control and resource allocation in networks with variable capacities subject to a global resource constraint. Examples include spectrum assignment in wireless networks and wavelength allocation in optical networks. For scalability, we impose the additional constraint that nodes can only negotiate and exchange resources with their neighbors. The proposed algorithms consist of two complementary approaches based on decomposition techniques, in which congestion control and resource allocations are performed on different time-scales. Two of the algorithms can be shown to converge without network delays. Copyright 2005 IFAC
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| 24. |
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| 25. |
- Johansson, Gunvi, et al.
(författare)
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Measuring oral health from a public health perspective
- 2008
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Ingår i: Swedish Dental Journal. - Stockholm : Swedish Dental Journal. - 0347-9994. ; 32:3, s. 125-137
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Tidskriftsartikel (refereegranskat)abstract
- The paper aims to analyse measures of oral health-related quality of life (OHQOL) from a Public Health perspective. Twenty-two measures were analysed conceptually as to their mirroring of the Public Health principles: empowerment, participation, holism and equity. Elements of empowerment were found in connection with application of the measures. Participation was found in using lay opinions during development in 12 measures. All measures analysed had elements of a holistic approach so far that they were not wholly biological. Two measures captured positive health effects. Measures were available for all ages, various languages and populations, an element of equity. No measure was wholly compatible with Public Health. They were based on a utilitarian theory not in full accordance with modern health promotion. There is a need to develop measures that more obviously capture the positive aspects of health and health as a process, as well as the personal perspective of oral health.
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| 26. |
- Johansson, Gunvi, et al.
(författare)
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Measuring oral health from a public health perspective
- 2008
-
Ingår i: Swedish Dental Journal. - Stockholm : Swedish Dental Association. - 0347-9994. ; 32:3, s. 125-137
-
Tidskriftsartikel (refereegranskat)abstract
- The paper aims to analyse measures of oral health-related quality of life (OHOOL) from a Public Health perspective. Twenty-two measures were analysed conceptually as to their mirroring of the Public Health principles: empowerment, participation, holism and equity. Elements of empowerment were found in connection with application of the measures. Participation was found in using lay opinions during development in 12 measures. All measures analysed had elements of a holistic approach so far that they were not wholly biological. Two measures captured positive health effects. Measures were available for all ages, various languages and populations, an element of equity. No measure was wholly compatible with Public Health. They were based on a utilitarian theory not in full accordance with modern health promotion. There is a need to develop measures that more obviously capture the positive aspects of health and health as a process, as well as the personal perspective of oral health.
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| 27. |
- Johansson, Gunvi, 1950-
(författare)
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Oral health-related quality of life and young adults
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims were to describe and analyse measures for oral health-related quality of life (OHRQOL) from a Public Health perspective and to determine young adults' views on dental care. The methods used included one literature review (Paper I) and one empirical study with qualitative design (Paper II). In Paper I, twenty-two measures for oral healthrelated quality of life (OHRQOL) were analysed from a public health perspective as to the mirroring of the health promotion principles empowerment, participation, holism and equity. In Paper II, regular dental attenders in Sweden aged 21-30 were interviewed about their views on dental care. Data from eleven interviews were analysed in accordance with the constant comparative method. The results in Paper I showed, that elements of the public health principles were found in the OHRQOL measures. There were measures developed for different ages but no measures were specifically adapted to young adults. In Paper II, two principal views in young adults’ views on dental care were discerned: patients’ attitudes to dental care costs and attitudes to given functions within dental care. Dental care costs, as well as the patients’ views on the treatment, however not expressed to the dental staff, were deemed important. Young adults were found to have specific views and demands on received dental care that was not mirrored in the instruments. An urgent task would therefore be to explore young adults’needs and expectations regarding their OHRQOL and dental care.
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| 28. |
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| 29. |
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| 30. |
- Johansson, Marcus, 1992, et al.
(författare)
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A TEST IMPLEMENTATION OF THE CORE MANUFACTURING SIMULATION DATA SPECIFICATION
- 2007
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Ingår i: Proceedings of the 2007 Winter Simulation Conference in Washington D.C. USA, December 9-12 2007. ; , s. 1673-1681
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Konferensbidrag (refereegranskat)abstract
- This paper describes an effort of testing the Core Manufacturing Simulation Data (CMSD) information model as a neutral data interface for a discrete event simulation model developed using Enterprise Dynamics. The implementation is based upon a model of a paint shop at a Volvo Car Corporation plant in Sweden. The model is built for a Swedish research project (FACTS), which focuses on the work procedure of developing new and modified production systems. FACTS has found standardized simulation data structures to be of high interest to achieve efficient data collection in conceptual stages of production development programs. For the CMSD-development team, implementations serve as an approach to validate the structures in CMSD and to gather requirements for future enhancements. CMSD was originally developed to support job shops, but the results of this implementation indicate a good possibility to extend CMSD to also support flow shops.
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| 31. |
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| 32. |
- Johansson, Veronica, et al.
(författare)
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A path analysis of contract and fee-for-service care
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: In Swedish dentistry, the traditional patient financial system is fee-for-service care (FFS). Since 1999, the public dental health service (PDHS) in the county of Värmland offers an alternative system, contract care (CC). Here, the patient pays a set fee for a fixed period of time, and receives oral health care as specified by a contract, without additional costs. Previously, an association between patient financial system and oral health-related quality of life (OHRQoL) was found. The aim was to model direct and indirect effects with path analysis, to study if there were different underlying mechanisms in the patient financial systems. Material and methods: In 2003, a questionnaire was sent to randomly selected patients enrolled in CC (n=1,200) and FFS (n=1,200) in the PDHS in Värmland. The study was approved by the ethical board in the Southern region of Sweden. Response rate was 57%. Data without internal non-response (n=1,044; CC: 57%, FFS: 43%) were analysed with a multiple group path analysis. The interactions of four variables were of central interest: OHRQoL, the respondents’ perceptions of the dental caregiver’s humanistic (patient-, as opposed to disease-centred) qualities, what the respondents were prepared to pay, and what they had paid for dental care the previous year. Results: The underlying mechanisms in the systems were similar. However, there were differences regarding the central variables: the perceived humanism of the caregiver affected OHRQoL only in FFS, while what the respondents were prepared to pay for dental care was affecting the perception of humanism only in CC. Conclusions: The findings indicated that the perception of the caregiver’s humanistic qualities were important for oral health for respondents in FFS, while financial considerations were important for how the caregiver’s qualities were perceived by respondents in CC. Funding: The study was financed by the Swedish Research Council.
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| 33. |
- Johansson, Veronica, et al.
(författare)
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Contract and fee-for-service care - regression modelling of oral health-related quality of life
- 2007
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In 1999, the public dental health service (PDHS) in the county of Värmland, Sweden, implemented contract care alongside the traditional patient financial system of fee-for-service care. In contract care, the patient pays a fixed sum annually for dental care and then receives basic dental care without additional costs. Aim The aim was to study the relation between patient financial system and oral health-related quality of life (OHRQoL). Methods In 2003, a questionnaire was sent to 2,400 consecutively selected patients in the PDHS in Värmland, 1,200 from each patient financial system. The questionnaire was answered by 1,324 participants (57% of those who could be reached). The questionnaire contained questions about willingness to pay for dental care, how much one had paid for dental care the previous year, OHRQoL (measured with the OHIP-14), dental anxiety, humanism of caregiver, general health (measured with the SF-36), multidimensional health locus of control, sense of coherence, self-esteem and demographics. Data on patient financial system, gender and age were obtained from the sampling frame. The data were analysed with a block method of multiple linear regression, adding blocks of variables in six steps: financial system, economic factors, individual factors, social factors, psychological factors and health factors. The threshold for statistical significance was set at p≤0.05. Results OHRQoL was affected by the financial system of the respondent: those in fee-for-service care had a worse OHRQoL than those in contract care. OHRQoL was also affected by health, sense of coherence and to some extent by psychological and economical factors. Of the social variables, only being foreign born had a significant effect on OHRQoL. Conclusions OHRQoL was found to be affected by patient financial system. Acknowledgements The study was financed by the Swedish Research Council.
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| 34. |
- Johansson, Veronica, et al.
(författare)
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Financial systems' impact on dental care : a review of fee-for-service and capitation systems
- 2007
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Ingår i: Community Dental Health. - 0265-539X. ; 24:1, s. 12-20
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Tidskriftsartikel (refereegranskat)abstract
- Objective This review covers the impact of financial systems on dental care. Background Remuneration in fee-for-service (FFS) is done per service provided and in capitation (CAP) per patient enrolled. It may be expected that dentists’ incentive in CAP is to keep the number of services provided at a minimum, while in FFS it is to keep the number of services at a maximum. This should lead to a different impact on care, with the dentists in CAP focusing more on prevention and dentists in FFS more on restorative treatment. Six questions were put: Does CAP increase or decrease caries incidence? Does CAP increase or decrease restorative treatments? Does CAP increase preventive care? Does CAP increase or decrease productivity? Does CAP increase or decrease the dentist’s satisfaction with his/her work? Does CAP increase or decrease the patients’ satisfaction with the oral care provided? Methods Literature was obtained through searches in databases. A format was developed to define the literature of interest. Results CAP decreases restorative treatment and there is a tendency of decreased caries incidence. “Supervised neglect” cannot be established. CAP increases preventive care. A conclusion regarding productivity was not possible. The results on dentist’s satisfaction with work were inconclusive, as were the results regarding patient satisfaction. Conclusions CAP has a different impact on provided care than FFS. More research is needed in this area and focus on efficiency is of importance. This review was funded by the Swedish Research Council.
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| 35. |
- Johansson, Veronica, et al.
(författare)
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Oral B's Nordic Report on Oral Health : Caries prevalence among children, adolescents and adults, and periodontal conditions among adults in Denmark, Finland, Norway and Sweden
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this report was to compare the oral health in the Nordic countries of Denmark, Finland, Norway and Sweden, from existing national clinical data. The conditions of interest were caries prevalence and periodontal conditions. The groups of interest were children and adolescents up to the age of 19, and adults up to 60 years old. Further, socio-economic and ethnic differences, as well as differences in relation to living area were also of interest. There are indications of similar trends in caries prevalence among children and adolescents in the Nordic countries, with a continuing decrease in caries prevalence during the past 20-30 years, and tendencies of a levelling out at the turn of the century. The WHO goal of a mean DMFT for 12-year-olds at 1.5 or below before the year 2020 (Petersen 2003), is already fulfilled in all four countries. However, it seems there is still work to do to attain the goal of at least 80% caries free 6-year-olds in 2020. The available data do not distinguish differences between urban and rural areas, nor ethnic and socio-economic differences. The most important finding regarding both caries prevalence and periodontal conditions in adults is that there is a lack of national data from Norway and Sweden. Although interpretations should be cautious, there are indications of slightly higher caries prevalence in Finland, compared to Denmark, among adult men. Data on educational level indicate similar patterns of associations between higher levels of education and lower figures of caries prevalence. There is a lack of data on ethnic differences in caries prevalence in adults. There is also a lack of data regarding differences between urban and rural living areas, which only were available for Denmark. The results regarding periodontal conditions indicate that bleeding is widespread in both Denmark and Finland, while both shallow and deep pockets seem to be more common in Finland. Data on educational level indicate similar patterns of associations between higher levels of education and lower prevalence of shallow and deep pockets. There is a lack of data on ethnic differences in periodontal conditions in adults. There is also a lack of data regarding differences between urban and rural living areas, which only were available for Denmark. From the available data, no interpretations regarding aggressive periodontitis, i.e. rapid deterioration of bone loss and periodontal ligaments, nor probability of developing it, can be made. A recommendation for the future is to conduct more national clinical assessments of oral health in adults. National clinical research is needed in order to estimate what actions need to be taken to improve oral health. Without national assessments, political reforms cannot be evaluated and conclusions regarding their effectiveness cannot be drawn.
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| 36. |
- Johansson, Veronica, et al.
(författare)
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Patients' health in contract and fee-for-service care : I. A descriptive comparison
- 2007
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Ingår i: Swedish Dental Journal. - : Swedish dental association. - 0347-9994. ; 31:1, s. 27-34
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Tidskriftsartikel (refereegranskat)abstract
- Fee-for-service care, paying afterwards for services provided, is the traditional adult patient financial system in dentistry in Sweden. The public dental health service (PDHS) in the county of Värmland has since 1999 also an alternative system, contract care. There, a fixed sum of money is paid annually for dental care, which then is received without additional costs. This study compares the demographics, general health and oral health-related quality of life (OHRQoL) in the patient financial systems fee-for-service and contract care in the PDHS in Värmland. A questionnaire was answered by 1,324 patients, response rate 57%. A non-response analysis was undertaken. The non-response analysis showed that the likelihood for answering the questionnaire was higher for women, for respondents in contract care and for increasing age. Further analyses revealed that the non-respondents were healthier than the respondents and that experience of pain in the mouth was the only variable increasing the likelihood of response. General health was studied with the SF-36 and OHRQoL with the OHIP-14. The demographics studied were gender, age, birth country, marital status, education and social network. The results showed that there were differences in patients' health between the patient financial systems. Respondents in contract care had better OHRQoL than those in fee-for-service care. They also had better general health in four of the dimensions of SF-36, were younger, better educated, born in Sweden and were married/living with somebody to a larger extent than fee-for-service care respondents. Fee-for-service care respondents experienced higher social affinity with their housing area. In conclusion, patients in contract care had better general health and OHRQoL than patients in fee-for-service care. There were social differences in choice of financial system and biased non-response.
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| 37. |
- Johansson, Veronica, et al.
(författare)
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Patients' health in contract and fee-for-service care : a descriptive analysis
- 2006
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Ingår i: Community Dental Health. - 0265-539X. ; 23:3, s. 187-188
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- AIM Fee-for-service, paying afterwards for services provided, is the traditional patient financial system in dentistry in Sweden. The public dental health service (PDHS) in Värmland has since 1999 also an alternative system: contract care, where a fixed sum of money is paid annually for dental care, which is then received without additional cost. This study describes demographic as well as general and oral health-related characteristics among patients in a service study comparing the two patient financial systems, fee-for-service and contract care, in the PDHS in Värmland. METHODS A questionnaire was answered by 1,324 patients (response rate 57%). Of the respondents, 52% were in contract care and 48% in fee-for-service. A non-response analysis and a special study of the non-respondents were undertaken. General health was studied with SF-36, measuring health in eight dimensions: physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, and mental health. Oral health was studied with OHIP-14, measuring oral health in seven dimensions (functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability and handicap) and as an index. The demographic factors included gender, age, birth country, marital status, education, and social affinity with neighbourhood and housing area. The data were analysed with contingency tables, Chi-square tests, t-tests, Mann-Whitney non-parametric tests and logistic regression analyses. RESULTS The non-response analysis revealed that the likelihood for answering the questionnaire was higher for women (OR=1.27), for respondents in contract care (OR=1.43) and for each year of life (OR=1.02). A short telephone interview with 40 non-respondents in each financial system indicated that the non-respondents had better oral health than the respondents. The non-respondents had experienced less pain in the mouth, less difficulties doing their usual jobs and had found life more satisfying than the respondents. There were no significant differences in gender or age. In the study population, differences in health were observed between the financial systems. Respondents in contract care had better oral health than those in fee-for-service (p=0.019). They had also better general health in half of the dimensions of SF-36 (physical functioning: p<0.001; role-physical: p=0.002; general health: p<0.001; social functioning: p=0.045), were younger (p<0.001), better educated (p< 0.001), were born in Sweden more often (p<0.001) and were more often married/living with somebody (p=0.011) than were the fee-for-service respondents. The fee-for-service respondents experienced higher social affinity with their housing area (p=0.049). CONCLUSION There was bias in nonresponse. Contract care patients had better general and oral health than patients in fee-for-service. Acknowledgement: The study was financed by the Swedish Research Council.
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| 38. |
- Kressner, Marit, et al.
(författare)
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The impact of hospital volume on surgical outcome in patients with rectal cancer.
- 2009
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Ingår i: Diseases of the colon and rectum. - 1530-0358 .- 0012-3706. ; 52:9, s. 1542-9
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: This study was designed to investigate, in a population-based setting, the surgical outcome in patients with rectal cancer according to the hospital volume. METHODS: Since 1995 all patients with rectal cancer have been registered in the Swedish Rectal Cancer Registry. Hospitals were classified, according to number treated per year, as low-volume, intermediate-volume, or high-volume hospitals (<11, 11-25, or >25 procedures per year). Postoperative mortality, reoperation rate within 30 days, local recurrence rate, and overall five-year survival were studied. For postoperative morbidity and mortality the whole cohort from 1995 to 2003 (n = 10,425) was used. For cancer-related outcome only, those with five-year follow-ups, from 1995 to 1998, were used (n = 4,355). RESULTS: In this registry setting the postoperative mortality rate was 3.6% in low-volume hospitals, and 2.2% in intermediate-volume and high-volume hospitals (P = 0.002). The reoperation rate was 10%, with no differences according to volume. The overall local recurrence rates were 9.4%, 9.3%, and 7.5%, respectively (P = 0.06). Significant difference was found among the nonirradiated patients (P = 0.004), but not among the irradiated patients (P = 0.45). No differences were found according to volume in the absolute five-year survival. CONCLUSION: Postoperative mortality and local recurrence in nonirradiated patients were lower in high-volume hospitals. No difference was seen between volumes in reoperation rates, overall local recurrence, or absolute five-year survival.
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| 39. |
- Kull, Inger, et al.
(författare)
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Astma/KOL-mottagningar i primärvård ger effektivt omhändertagande
- 2008
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 105:42, s. 2937-2940
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Tidskriftsartikel (refereegranskat)abstract
- Astma och KOL (kroniskt obstruktiv lungsjukdom) har blivit allt vanligare, och möjligheterna till både korrekt diagnos och förbättrad behandling har ökat under det senaste decenniet, vilket ställer nya krav på hälso- och sjukvården. Korrekt diagnos, adekvat patientutbildning och rökslutarstöd är högt prioriterade åtgärder. Ett strukturerat omhändertagande med en välfungerande astma/KOL-mottagning i primärvården underlättar och förbättrar vården av denna stora patientgrupp. I artikeln föreslås nya kriterier för astma/KOL-mottagningar i primärvård.
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| 40. |
- Lanke, E., et al.
(författare)
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Co-segregation of the PROS1 locus and protein S deficiency in families having no detectable mutations in PROS1
- 2004
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell. - 1538-7933 .- 1538-7836. ; 2:11, s. 1918-1923
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Tidskriftsartikel (refereegranskat)abstract
- Inherited deficiency of protein S constitutes an important risk factor of venous thrombosis. Many reports have demonstrated that causative mutations in the protein S gene are found only in approximately 50% of the cases with protein S deficiency. It is uncertain whether the protein S gene is causative in all cases of protein S deficiency or if other genes are involved in cases where no mutation is identified. The aim of the current study was to determine whether haplotypes of the protein S gene cosegregate with the disease phenotype in cases where no mutations have been found. Eight protein S-deficient families comprising 115 individuals where previous DNA sequencing had failed to detect any causative mutations were analyzed using four microsatellite markers in the protein S gene region. Co-segregation between microsatellite haplotypes and protein S deficiency was found in seven of the investigated families, one family being uninformative. This suggests that the causative genetic defects are located in or close to the protein S gene in a majority of such cases where no mutations have been found.
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| 41. |
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| 42. |
- Leong, Swee, et al.
(författare)
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A real world pilot implementation of the Core Manufacturing Simulation Data model
- 2008
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Ingår i: ; , s. 334-341
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Konferensbidrag (refereegranskat)abstract
- While software for discrete event simulation (DES) has emerged into sophisticated tools for decision support in a wide range of contexts, the need to integrate DES tools with other applications is increasing. In the industrial engineering context, simulation engineers strive to use real world data, e.g., logs of machine breakdown, to make behavior of DES models imitate reality. However, the format used for describing simulation data is often specialized to the current situation. The Core Manufacturing Simulation Data (CMSD) is a collaborative effort with academia and industry to standardize the format used for simulation data, to facilitate data exchange among simulation and manufacturing applications. This paper describes the results from a pilot implementation study at Volvo Trucks, where CMSD was utilized as the data exchange format between two data systems and two DES models. The DES tools used were commercial software packages Unigraphics Plant Simulation and InControl Enterprise Dynamics. Generic and reusable interfaces for CMSD-file communication were developed for each of these tools. The CMSD interfaces were successfully connected to a model in each simulation tool describing the same manufacturing process. A stand alone application was developed to collect and analyze raw data and to create the CMSD file being used as input data for both models. The result is a system including raw data analysis, data reformatting, CMSD interfacing, and model execution. Based on the result, a generic methodology for CMSD interface development in DES tools has evolved. The most important conclusion is that CMSD data can be interpretable by both Plant Simulation and Enterprise Dynamics, and that it saves engineering development time during the model building phase.
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| 43. |
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| 44. |
- Mu, Xiangkui, et al.
(författare)
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Does electron and proton therapy reduce the risk of radiation induced cancer after spinal irradiation for childhood medulloblastoma? A comparative treatment planning study.
- 2005
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Ingår i: Acta oncologica (Stockholm, Sweden). - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 44:6, s. 554-62
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this treatment planning comparison study was to explore different spinal irradiation techniques with respect to the risk of late side-effects, particularly radiation-induced cancer. The radiotherapy techniques compared were conventional photon therapy, intensity modulated x-ray therapy (IMXT), conventional electron therapy, intensity/energy modulated electron therapy (IMET) and proton therapy (IMPT).CT images for radiotherapy use from five children, median age 8 and diagnosed with medulloblastoma, were selected for this study. Target volumes and organs at risk were defined in 3-D. Treatment plans using conventional photon therapy, IMXT, conventional electron therapy, IMET and IMPT were set up. The probability of normal tissue complication (NTCP) and the risk of cancer induction were calculated using models with parameters-sets taken from published data for the general population; dose data were taken from dose volume histograms (DVH).Similar dose distributions in the targets were achieved with all techniques but the absorbed doses in the organs-at-risk varied significantly between the different techniques. The NTCP models based on available data predicted very low probabilities for side-effects in all cases. However, the effective mean doses outside the target volumes, and thus the predicted risk of cancer induction, varied significantly between the techniques. The highest lifetime risk of secondary cancers was estimated for IMXT (30%). The lowest risk was found with IMPT (4%). The risks associated with conventional photon therapy, electron therapy and IMET were 20%, 21% and 15%, respectively.This model study shows that spinal irradiation of young children with photon and electron techniques results in a substantial risk of radiation-induced secondary cancers. Multiple beam IMXT seems to be associated with a particularly high risk of secondary cancer induction. To minimise this risk, IMPT should be the treatment of choice. If proton therapy is not available, advanced electron therapy may provide a better alternative.
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| 45. |
- Naucler, Pontus, et al.
(författare)
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Efficacy of HPV DNA testing with cytology triage and/or repeat HPV DNA testing in primary cervical cancer screening.
- 2009
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 1460-2105 .- 0027-8874. ; 101:2, s. 88-99
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Tidskriftsartikel (refereegranskat)abstract
- Primary cervical screening with both human papillomavirus (HPV) DNA testing and cytological examination of cervical cells with a Pap test (cytology) has been evaluated in randomized clinical trials. Because the vast majority of women with positive cytology are also HPV DNA positive, screening strategies that use HPV DNA testing as the primary screening test may be more effective.
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| 46. |
- Sampogna, Francesca, et al.
(författare)
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A multilevel analysis of factors affecting the difference in dental patients' and caregivers' evaluation of oral quality of life
- 2008
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Ingår i: European Journal of Oral Sciences. - : Wiley. - 0909-8836 .- 1600-0722. ; 116:6, s. 531-537
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Tidskriftsartikel (refereegranskat)abstract
- In a previous study, we observed that the concordance between patients' and caregivers' evaluation of oral health-related quality of life (OHRQoL) was low. The aim of this study was to use multilevel analysis to investigate the possible determinants of the low concordance, taking into account different patients' demographic and clinical variables, the financial system used by patients to pay for dental treatment, and the role of the different caregivers and clinics. The OHRQoL of patients was assessed both by the patients and by their caregivers, using the Oral Health Impact Profile (OHIP)-14. Data were collected in four clinics, and patients were evaluated by one of 27 caregivers. We tested eight multilevel models, using the difference (caregivers OHIP - patients OHIP) as the dependent variable. Data were complete for 432 patients. The mean difference was 4.4 (standard deviation = 8.2; higher scores indicated a higher impact on OHRQoL). The variance due to patients was partly explained by their age, gender, and number of teeth, with a greater OHIP difference for older vs. younger patients, for women than for men, and in patients with fewer teeth. Almost 30% of the variance was due to caregivers, while the effect of clinics was not significant. It is important to study the possible causes of the different judgments concerning patients' OHRQoL by patients and caregivers, in order to improve the patients' satisfaction with care.
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| 47. |
- Sampogna, Francesca, et al.
(författare)
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A multilevel analysis of factors affecting the difference in patients’ and providers’ evaluation of oral quality of life
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Background It is important for dentists and hygienists to evaluate the oral health-related quality of life (OHRQoL) of patients, in order to depict with accuracy the burden of the disease on them, and thus to reach their specific needs. In a previous study, we observed that caregivers tended to overestimate the burden of dental conditions on patients’ life. Aim of the study In the present study, we further analysed those data using multilevel analysis, to investigate the possible determinants of the low concordance between patients’ and caregivers’ evaluation of OHRQoL, taking into account the role of the different caregivers and clinics. Methods This study consisted of a simultaneous assessment of patients’ oral quality of life, performed both by patients themselves and by their caregivers. Data were collected in four clinics, and patients were evaluated by 27 caregivers (15 dentists and 12 hygienists). OHRQoL was measured using the OHIP-14, that contains measures of physical, psychological and social abilities, general physical function, ability of speech and eating, symptoms of pain and discomfort, and appearance and social embarrassment. We tested eight multilevel models, using the OHIP difference as the dependent variable. In each model, the variance for the fixed effect (i.e., the levels) and the random effects (i.e., the intercept and other variables) was estimated. Results Data were complete for 432 patients. The mean difference between the caregivers’ OHIP and the patients’ OHIP was 4.4 (SD=8.2). The variance due to patients was partly explained by their age (higher OHIP difference in elderly vs young patients), gender (higher OHIP difference in women vs men), and number of teeth (higher OHIP difference in patients with less teeth). Almost 30% of variance was due to caregivers, while the effect of clinics was not significant. Conclusions The differences in caregivers’ evaluation could depend on the different caregivers’ experience, or their personal ability to empathize with the patient, or at least in part descend from different conceptual models of dental disease among caregivers. It is important to study the possible causes of the different judgments concerning patients’ OHRQoL by patients and caregivers, in order to improve the patients’ satisfaction of care, and to help patients to reach a well-informed decision about the treatment. Acknowledgement. The study was supported by the Swedish Research Council. DA is supported, in part, by funds from the "Progetto Ricerca Corrente" of the Italian Ministry of Health, Rome, Italy.
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| 48. |
- Sampogna, Francesca, et al.
(författare)
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Quality of life in patients with dental conditions : comparing patients' and providers' evaluation
- 2009
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Ingår i: Community Dental Health. - 0265-539X. ; 26:4, s. 234-238
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To measure the agreement between patients and their caregivers in evaluating patients’ oral quality of life. Basic research design. Cross-sectional study. Clinical setting. Data collected in four Swedish dental clinics in 2004. Participants. Consecutive patients. Data were completed for 444 patients. Fifteen dentists and 12 dental hygienists agreed to participate. Interventions. For each patient, the patient him/herself and his/her caregiver completed the 14-item Oral Health Impact Profile (OHIP-14), a specific instrument used to measure quality of life in oral conditions, with higher scores indicating a worse quality of life. Information on personal and clinical characteristics of patients were also collected. Main outcome measures. Median OHIP-14 scores given by caregivers and patients were calculated and compared in different subgroups of patients. Cohen’s kappa was calculated to measure the agreement between the evaluation of patients and caregivers. Results. OHIP-14 scores median values were 3.0 among patients and 9.0 among caregivers. Caregivers always gave a higher score than patients, especially in older patients and patients with lower education. The concordance between patients’ and caregivers’ evaluation was very low (for different OHIP-14 cutoffs: Cohen’s kappa from 0.10 to 0.15). Conclusions. In this study, great discrepancies were observed between patients and caregivers in the evaluation of patients’ oral quality of life, with caregivers overestimating the burden of dental conditions on patients. It is important to improve patient-caregiver communication, in order to increase patient satisfaction and provide better care. A good patient-caregiver relationship is essential for the patients’ well-being and their adherence to treatment.
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| 49. |
- Soldati, Pablo, et al.
(författare)
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Distributed optimization of end-to-end rates and radio resources in WiMax single-carrier networks
- 2006
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Ingår i: GLOBECOM - IEEE Global Telecommunications Conference. - 9781424403561
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of joint end-to-end band-width allocation and radio resource management in WiMax single-carrier wireless networks. The design problem is posed as a utility maximization problem subject to link rate constraints which involve transmission scheduling and power allocation. Inspired by a centralized algorithm for solving the associated optimization problem, we proceed systematically in our development of distributed resource allocation mechanisms. Contrary to the centralized algorithm, the proposed solution is distributed and of low computational complexity, generates schedules of finite length and with fixed time-slot durations, and acts on local neighborhood information only. Although the final scheme is suboptimal, we isolate and quantify the performance losses incurred and demonstrate strong performance in examples.
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| 50. |
- Soldati, Pablo, et al.
(författare)
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Proportionally fair allocation of end-to-end bandwidth in STDMA wireless networks
- 2006
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Ingår i: Proceedings of the International Symposium on Mobile Ad Hoc Networking and Computing. - New York, NY, USA : ACM. - 9781595933683 ; , s. 286-297
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of designing distributed mechanisms for joint congestion control and resource allocation in spatial-reuse TDMA wireless networks. The design problem is posed as a utility maximization subject to link rate constraints that involve both power allocation and transmission scheduling over multiple time-slots. Starting from the performance limits of a centralized optimization based on global network information, we proceed systematically in the development of distributed and transparent protocols. In the process, we introduce a novel decomposition method for convex optimization, establish its convergence for the utility maximization problem and demonstrate how it suggests a distributed solution based on flow control optimization and incremental updates of the transmission schedule. We develop a two-step procedure for finding the schedule updates and suggest two schemes for distributed channel reservation and power control under realistic interference models. Although the final protocols are suboptimal, we isolate and quantify the performance losses incurred by each simplification and demonstrate strong performance in examples.
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