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  • Beek, Jaap van de, et al. (författare)
  • A time and frequency synchronization scheme for multiuser OFDM
  • 1999
  • Ingår i: IEEE Journal on Selected Areas in Communications. - : IEEE - Institute of Electrical and Electronics Engineers Inc.. - 0733-8716 .- 1558-0008. ; 17:11, s. 1900-1914
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a multiuser synchronization scheme for tracking the mobile's uplink time and frequency offsets. It uses the redundancy introduced by the cyclic prefix and does not need additional pilots. We show performance results of an orthogonal frequency division multiplexing (OFDM)-based radio interface based on universal mobile telecommunication system (UMTS) parameters. For a UMTS-typical mobile channel environment, the performance of a coherent system employing the scheme is virtually indistinguishable from the performance of a perfectly synchronized system. In a differentially modulated system, synchronization errors decrease the system performance by about 0.7 dB compared to a perfectly synchronized system. Index Terms - Communication system, delay estimation, frequency estimation, multicarrier, multiuser system, orthogonal frequency division multiplexing (OFDM), synchronization, universal mobile telecommunication system (UMTS).
  • Niméus, Emma, et al. (författare)
  • Gene expression profiling in primary breast cancer distinguishes patients developing local recurrence after breast conservation surgery with or without postoperative radiotherapy
  • 2008
  • Ingår i: Breast Cancer Research. - : BioMed Central (BMC). - 1465-5411 .- 1465-542X. ; 10:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction Some patients with breast cancer develop local recurrence after breast-conservation surgery despite postoperative radiotherapy, whereas others remain free of local recurrence even in the absence of radiotherapy. As clinical parameters are insufficient for identifying these two groups of patients, we investigated whether gene expression profiling would add further information. Methods We performed gene expression analysis (oligonucleotide arrays, 26,824 reporters) on 143 patients with lymph node-negative disease and tumor-free margins. A support vector machine was employed to build classifiers using leave-one-out cross-validation. Results Within the estrogen receptor-positive (ER+) subgroup, the gene expression profile clearly distinguished patients with local recurrence after radiotherapy (n = 20) from those without local recurrence (n = 80 with or without radiotherapy). The receiver operating characteristic (ROC) area was 0.91, and 5,237 of 26,824 reporters had a P value of less than 0.001 (false discovery rate = 0.005). This gene expression profile provides substantially added value to conventional clinical markers (for example, age, histological grade, and tumor size) in predicting local recurrence despite radiotherapy. Within the ER- subgroup, a weaker, but still significant, signal was found (ROC area = 0.74). The ROC area for distinguishing patients who develop local recurrence from those who remain local recurrence-free in the absence of radiotherapy was 0.66 (combined ER+/ER-). Conclusion A highly distinct gene expression profile for patients developing local recurrence after breast-conservation surgery despite radiotherapy has been identified. If verified in further studies, this profile might be a most important tool in the decision making for surgery and adjuvant therapy.
  • Beek, Jaap van de, et al. (författare)
  • A conceptual study of OFDM-based multiple access schemes : Part 4: Tracking of time and frequency offset
  • 1996
  • Rapport (övrigt vetenskapligt)abstract
    • This paper is part of a conceptual study of a multiuser OFDM system. In previous reports we have examined requirements for the air interface and presented uncoded performance (in terms of bit error rate) for the uplink of such systems. In this report we adopt the user allocation structure from the previous parts of the study and examine the role of channel coding. We present performance simulations that illustrate the effects of a convolutional code exploiting channel diversity, and channel estimator performance exploiting the channel correlation.
  • Beek, Jaap van de, et al. (författare)
  • Synchronization of a TDMA-OFDM frequency hopping system
  • 1998
  • Ingår i: Pathway to a global wireless revolution. - Piscataway, NJ : IEEE Communications Society. - 0780343204 ; , s. 1290-1294
  • Konferensbidrag (refereegranskat)abstract
    • In this paper we present a Time Division Multiple Access-Orthogonal Frequency Division Multiplexing (TDMA-OFDM)-based radio interface proposal for the Universal Mobile Telecommunication System (UMTS). We focus on synchronization and present an implementable algorithm for the tracking of the mobiles' time and frequency offsets at the base station in the uplink. This algorithm is based on recently developed estimation methods that use redundancy introduced by the cyclic prefix. A modified Maximum Likelihood (ML) estimator for the Additive White Gaussian Noise (AWGN) channel is used to meet both implementational requirements and performance requirements for frequency-selective fading multiuser environments. Simulation results for a typical UMTS mobile channel environment show that the uncoded symbol error rate of a coherently modulated system using our synchronization scheme is virtually indistinguishable from that of a system with no time and frequency offset.
  • Blom Johansson, Monica, 1965- (författare)
  • Aphasia and Communication in Everyday Life : Experiences of persons with aphasia, significant others, and speech-language pathologists
  • 2012
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The aims of this thesis were to describe the experiences of persons with aphasia and their significant others of their conversations and use of communication strategies, examine current practice of family-oriented speech-language pathology (SLP) services, and test a family-oriented intervention in the early phase of rehabilitation.The persons with aphasia valued having conversations despite perceiving their aphasia as a serious social disability. They acknowledged the importance of the communication partners’ knowledge and understanding of aphasia and their use of supporting conversation strategies. Their own use of communication strategies varied considerably. The persons with aphasia longed to regain language ability and to be active participants in society.A majority of the significant others perceived their conversations with the person with aphasia as being less stimulating and enjoyable than conversations before stroke onset. Aphasia was considered a serious problem. The significant others took on increased communicative responsibility, where two thirds had changed their communicative behaviour to facilitate conversations. Type and severity of aphasia were especially related to the communicative experiences of the significant others and their motivation to be involved in SLP services.Thirty percent of the speech-language pathologists worked with people with aphasia and typically met with their families. They considered the involvement of significant others in SLP services as very important, especially in providing information about aphasia and communication partner training (CPT). However, involvement of significant others was restricted because of a time shortage and perceived limited skills and knowledge. In addition, there were national differences regarding aphasia rehabilitation services.The intervention consisted of three sessions directed to significant others (primarily emotional support and information) and three directed to the dyads (a person with aphasia and a significant other) (primarily CPT). All six participants (three dyads) felt that their knowledge and understanding of aphasia had increased and that their conversations had improved. These improvements were also evident to some extent with formal assessments.These results suggest the following: CPT should be an integral part of SLP services, national clinical guidelines are needed, and further education of speech-language pathologists and implementation of new knowledge into clinical practice requires consideration.
  • Blom Johansson, Monica, 1965-, et al. (författare)
  • Self-reported changes in everyday life and health of significant others of people with aphasia : a quantitative approach
  • 2020
  • Ingår i: Aphasiology. - : Routledge. - 0268-7038 .- 1464-5041.
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Changes in the everyday life and health of the significant others (SOs) of people living with stroke sequalae have been widely investigated. However, information regarding the frequency of the changes in daily life and the variables most associated with these perceived life changes is limited.Aims: To examine the extent to which SOs of persons with aphasia (PWAs) experience changes in everyday life and health after the stroke event and how they evaluate these changes and to identify which variables are associated with these perceived life changes.Methods & Procedures: A study-specific questionnaire about perceived changes in everyday life and health was completed by 173 SOs of PWAs living in Sweden (response rate 67.8%). The items concerned the SO’s working and financial situation, leisure time and social life, relationship with the PWA, household work and responsibility, and health and quality of life.Outcomes & Results: The everyday life and health of the SOs were greatly affected by the stroke event. The changes the SOs experienced were mainly appraised negatively. The relationships with the PWA and immediate family were least affected by the stroke. The perceived existence and severity of physical, cognitive, and language impairments of the PWA were the variables most strongly associated with the everyday life situation of the participants. The sex and age of the participants and the nature of the relationship with the PWA were only marginally associated with the experience of the situation.Conclusions: SOs’ perceptions of the PWA’s stroke-related disabilities and need for assistance may be a key factor in identifying SOs who may require support and guidance to help them cope with their new life situation.
  • Hägglund, Patricia, 1989- (författare)
  • Swallowing dysfunction among older people in short-term care : prevalence, effect of intervention, and risk of mortality
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Objectives: Swallowing dysfunction (dysphagia) is a common, but often neglected condition among geriatric patients that can cause severe complications such as malnutrition, aspiration pneumonia and death. The aims of this thesis were to (i) describe the study design and method of the multidisciplinary and multicenter project SOFIA (Swallowing function, Oral health, and Food Intake in old Age), (ii) study the prevalence of and the relationship between swallowing dysfunction and risk of undernutrition among older individuals in short-term care, (iii) study the effect of oral neuromuscular training on swallowing dysfunction among older individuals, and (iv) to investigate the association between poor oral health, swallowing dysfunction and mortality.Methods: This thesis includes four original papers that are all part of the SOFIA project. Paper Iis the study protocol. In total, 391 individuals aged 65 or older, from 36 short-term care units were included in the project. At baseline the participants’ status regarding swallowing function (assessed with the Timed Water Swallow Test, TWST), oral health (using the Revised Oral Assessment Guide, ROAG) and nutrition (assessed with the Minimal Eating Observation and Nutrition Form-version II, MEONF-II) were assessed and collected by calibrated professionals. Clinical data were also collected. Paper IIwas a cross-sectional study where the baseline assessments of the participants’ swallowing function and nutritional status were obtained and the relationship analyzed. Paper IIIwas a cluster randomized, controlled trial (cRCT) that included 116 participants identified with swallowing dysfunction in paper II. These participants were randomly assigned to either usual care (control group) or oral neuromuscular training (intervention group). All participants were assessed at baseline, after five weeks’ training and six months after end-of-treatment, regarding swallowing function and swallowing-related quality of life (QOL). Paper IVwas a prospective cohort study where all participants were followed-up 1-year after inclusion to investigate risk factors for mortality by analysis of the associations between swallowing dysfunction, poor oral health, and 1-year survival. Results: Paper II:The median age of the 391 participants was 84 years (Interquartile range [IQR] 11) and 209 (53%) were females. In total, 248 of the 385 (64%) participants showed swallowing dysfunction, and risk of undernutrition was observed in 91 of 390 (23%) participants. The adjusted logistics regression model revealed that participants with swallowing dysfunction had significantly higher odds of undernutrition than those with normal swallowing (Odds ratio [OR]: 1.74, 95% Confidence interval [CI] 1.04 to 2.92, P=0.034).Paper III: At end-of-treatment, a linear mixed model showed significant between-group differences of changes in swallowing efficacy between baseline and after completed treatment period (Ratio 1.60, 95% CI 1.15 to 2.29, P=0.007); indicating a 60% higher swallowing efficacy in the intervention group compared with the control group. Paper IV: A mixed effects Cox model showed that swallowing dysfunction and poor oral health were both independently associated with 1-year mortality (adjusted Hazard Ratio [aHR]: 1.67, 95% CI 1.02 to 2.75,P=0.041 and aHR: 1.98, 95% CI 1.07 to 3.65, P=0.029, respectively). In addition, swallowing dysfunction and poor oral health in combination predicted the highest mortality rate (35%, P<0.001).Conclusion: Swallowing dysfunction is highly prevalent and a risk factor for undernutrition among older people in short-term care. Oral neuromuscular training improves swallowing dysfunction and is thus a promising method of swallowing rehabilitation for older people with impaired swallowing. Swallowing dysfunction and poor oral health are independent risk factors for 1-year morality among older people in short-term care. Therefore, systematic screening and intervention to improve swallowing dysfunction and poor oral health are important to achieve healthy aging and to prevent undernutrition and early death.
  • Ambjörnsson, Helene Almlöf, et al. (författare)
  • Enzyme pretreatment of dissolving pulp as a way to improve the following dissolution in NaOH/ZnO
  • 2014
  • Ingår i: Holzforschung. - : Walter de Gruyter. - 0018-3830 .- 1437-434X. ; 68:4, s. 385-391
  • Tidskriftsartikel (refereegranskat)abstract
    • The dissolution of a softwood dissolving pulp in a NaOH/ZnO system was improved by means of a three-stage pretreatment with an initial xylanase treatment, followed by an alkaline extraction, and finally an endoglucanase stage. The solubility of the pulp increased from 29% to 81%, although the crystallinity and the specific surface area of the pulp did not change during the enzymatic treatment.
  • Beek, Jaap van de, et al. (författare)
  • A conceptual study of OFDM-based multiple access schemes : Part 2: Channel estimation in the uplink
  • 1996
  • Rapport (övrigt vetenskapligt)abstract
    • This paper deals with the design of channel estimators in the uplink of an OFDM based multi-user system. First, we propose a user allocation scheme that is based on the aim to use the correlation of the radio channel for channel estimation purposes. Further, we present the linear MMSE channel estimator based on a few pilot tones. We present an error analysis that proves valuable in the evaluation of linear channel estimators under mismatch. Finally, we present some results on the design of linear channel estimators and pilot patterns, showing by means of examplesthe importance of careful pilot positioning.
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