| 1. |
- Barrau, Sophie, et al.
(författare)
-
Nanomorphology of Bulk Heterojunction Organic Solar Cells in 2D and 3D Correlated to Photovoltaic Performance
- 2009
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 42:13, s. 4646-4650
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Tidskriftsartikel (refereegranskat)abstract
- Control of the nanoscale morphology of the donor-acceptor material blends inorganic solar Cells is critical for optimizing the photovoltaic performances. The influence of intrinsic (acceptor materials) and extrinsic (donor:acceptor weight ratio, substrate, solvent) parameters was investigated, by atomic force microscopy (AFM) and electron tomography (ET), on the nanoscale phase separation of blends of a low-band-gap alternating polyfluorene copolymers (APFO-Green9) with [6,6]-phenyl-C-71-butyric acid methyl ester ([70]PCBM). The photovoltaic performances display an optimal efficiency for the device elaborated with a 1:3 APFO-Green polymer:[70][PCBM weight ratio and spin-coated from chloroform solution. The associated active layer morphology presents small phase-separated domains which is a good balance between as a large interfacial donor-acceptor area and Continuous paths of the donor and acceptor phases to the electrodes.
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| 2. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Cognitive-behavioral therapy with applied relaxation
- 2006. - 1
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Ingår i: Tinnitus treatment.. - New York : Thieme. - 1588901815 - 3131320710 - 9781588901811 ; , s. 96-115
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Most clinicians have little experience with tinnitus treatments, and are unsure of how to help a patient suffering from the condition. Filling a significant gap in literature, this book offers a variety of in-depth protocols to treat tinnitus. Beginning with a review of several neurophysiological and psychological models of tinnitus, the book goes on to cover evaluation tools; counseling options and methods; treatment with hearing aids, wearable and non-wearable noise generators, and music; tinnitus-related insomnia; quality-of-life issues; and much more. Highly experienced clinicians give you the practical strategies to apply such therapeutic modalities as cognitive-behavioral therapy, individual and group sessions, sound therapy, habituation therapy, and narrative therapy. You will also find sample handouts to allow for effective communication with patients. With key clinical information for implementing all current therapies, this text is an essential professional tool for audiologists, psychologists, and other practitioners involved in managing otologic disorders.Richard Tyler, PhD, is a professor in the Department of Otolaryngology-Head Neck Surgery and in the Department of Speech Pathology and Audiology at the University of Iowa. Tyler and Sergei Kochkin, PhD recently sat down to talk about the results of a survey they conducted about tinnitus treatment and the effectiveness of hearing aids, which was published in the December 2008 edition of The Hearing Review. Click here to learn more and to watch a podcast that examines the survey results: http://www.hearingreview.com/podcast/files/ST20081218.asp.
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| 3. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Development of a new approach to guided self-help via the Internet : The Swedish experience
- 2008
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Ingår i: Journal of technology in human services. - : Informa UK Limited. - 1522-8835 .- 1522-8991. ; 26:2-4, s. 161-181
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the development and empirical status of guided Internet-delivered self-help. The treatment approach combines the benefits of bibliotherapy with book-length text materials and the support given online via web pages and e-mail. Interactive features such as online registrations, tests, and online discussion forums are also included. Cognitive behavior therapy (CBT) guided the research and clinical implementations of this approach, as it lends itself more easily to the self-help format compared with other presently available psychotherapy approaches. We include an overview of the research, current issues and research in service delivery, lessons learned through a program of research, and directions for future investigations
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| 4. |
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| 5. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Dimensions of perfectionism and tinnitus distress
- 2005
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Ingår i: Psychology, Health & Medicine. - : Informa UK Limited. - 1354-8506 .- 1465-3966. ; 10:1, s. 78-87
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the relationship between perfectionism and tinnitus distress. In addition, associations between perfectionism, sleep problems and anxiety/depression were investigated. The study included 256 tinnitus patients who completed measures of perfectionism, tinnitus distress, anxiety, depression, and a measure of insomnia. Gender-differentiated multiple regression analyses showed that anxiety and depressive states were related to tinnitus distress for both genders. However, for the males, the perfectionism subscale Personal Standards was related to tinnitus distress, whereas in females, it was the Organization subscale that was most predictive of tinnitus distress.
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| 6. |
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| 7. |
- Andersson, Gerhard, et al.
(författare)
-
Future thinking in tinnitus patients
- 2007
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Ingår i: Journal of Psychosomatic Research. - : Elsevier BV. - 0022-3999 .- 1879-1360. ; 63:2, s. 191-194
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The purpose of the study was to investigate future thinking in a group of tinnitus patients. It was predicted that participants in the tinnitus group would report fewer positive future events. Methods: A cross-sectional design was used. Two groups of participants completed the test session: tinnitus patients (n=20) and healthy controls (n=20) without tinnitus. Participants completed measures of anticipation of future positive and negative experiences, anxiety and depression. In addition, participants with tinnitus completed a test of tinnitus annoyance. Results: Tinnitus participants generated a greater number of negative future events compared to the controls. There was no difference between the groups on positive future events or on self-reported anxiety, but the tinnitus group scored higher on a depression measure. Controlling for depression scores removed the group difference. Conclusions: While the groups differed on future thinking, the difference concerned negative events, which suggests that anxious information processing might be important in explaining tinnitus annoyance. Levels of depressive symptoms should, however, be considered.
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| 8. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Hyperacusi - ett outforskat område. Kognitiv beteendeterapi kan lindra besvären vid ljudöverkänslighet, ett tillstånd med många frågetecken
- 2005
-
Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 44, s. 3210-3212
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Tidskriftsartikel (refereegranskat)abstract
- Hyperacusis innebär extrem känslighet för vardagens ljud är ett problem som drabbar cirka 8% av befolkningen. I svåra fall uppstår undvikande av många situationer samt en vana att skydda öronen med hörselskydd även i situationer där det inte behövs. Orsakerna till hyperacusis är till viss del kända, men många frågetecken kvarstår. För hyperacusis finns ingen dokumenterat botande behandling, men kognitiv beteendeterapi, samt eventuellt även tinnitus retraining therapy med brusgenerator, kan minska besvären,. Gott omhändertagande och en multidisciplinär utredning är att rekommendera i svåra fall. En av de viktigaste uppgifterna för framtida forskning är att kartlägga naturalförloppet vad gäller hyperacusis, då detta är i stort okänt. Det finns även ett stort behov av kontrollerade behandlingsstudier.
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| 9. |
- Andersson, Gerhard, 1966-, et al.
(författare)
-
Internet-based self-help for depression : randomised controlled trial
- 2005
-
Ingår i: British Journal of Psychiatry. - : Royal College of Psychiatrists. - 0007-1250 .- 1472-1465. ; 187, s. 456-461
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Major depression can be treated by means of cognitive-behavioural therapy, but as skilled therapists are in short supply there is a need for self-help approaches. Many individuals with depression use the internet for discussion of symptoms and to share their experience.AIMS:To investigate the effects of an internet-administered self-help programme including participation in a monitored, web-based discussion group, compared with participation in web-based discussion group only.METHOD:A randomised controlled trial was conducted to compare the effects of internet-based cognitive-behavioural therapy with minimal therapist contact (plus participation in a discussion group) with the effects of participation in a discussion group only.RESULTS:Internet-based therapy with minimal therapist contact, combined with activity in a discussion group, resulted in greater reductions of depressive symptoms compared with activity in a discussion group only (waiting-list control group). At 6 months' follow-up, improvement was maintained to a large extent.CONCLUSIONS:Internet-delivered cognitive cognitive-behavioural therapy should be pursued further as a complement or treatment alternative for mild-to-moderate depression.
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| 10. |
- Andersson, Gerhard, 1966-, et al.
(författare)
-
Internet-based self-help treatment of tinnitus
- 2006. - 1
-
Ingår i: Tinnitus treatment.. - New York : Thieme. - 1588901815 - 3131320710 - 9781588901811 ; , s. 29-40
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Most clinicians have little experience with tinnitus treatments, and are unsure of how to help a patient suffering from the condition. Filling a significant gap in literature, this book offers a variety of in-depth protocols to treat tinnitus. Beginning with a review of several neurophysiological and psychological models of tinnitus, the book goes on to cover evaluation tools; counseling options and methods; treatment with hearing aids, wearable and non-wearable noise generators, and music; tinnitus-related insomnia; quality-of-life issues; and much more. Highly experienced clinicians give you the practical strategies to apply such therapeutic modalities as cognitive-behavioral therapy, individual and group sessions, sound therapy, habituation therapy, and narrative therapy. You will also find sample handouts to allow for effective communication with patients. With key clinical information for implementing all current therapies, this text is an essential professional tool for audiologists, psychologists, and other practitioners involved in managing otologic disorders
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| 11. |
|
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| 12. |
- Andersson, Gerhard, et al.
(författare)
-
Obituary. Jeff Richards.
- 2005
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Ingår i: Cognitive Behaviour Therapy. - 1650-6073 .- 1651-2316. ; 34, s. 128-128
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Andersson, Gerhard, 1966-, et al.
(författare)
-
Stroop facilitation in tinnitus patients : An experiment conducted via the World Wide Web
- 2005
-
Ingår i: Cyberpsychology & Behavior. - : Mary Ann Liebert Inc. - 1094-9313 .- 1557-8364. ; 8:1, s. 32-38
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive mechanisms have been proposed to play an important role in tinnitus. In the present study, tinnitus participants were administered an emotional Stroop test via the Internet, incorporating words related to tinnitus concerns. In line with previous research using this Web-based version of the emotional Stroop test, faster color naming was demonstrated for concern-relevant words relative to neutral words. The present results thus provided support for a role for cognitive factors that are important for the understanding of tinnitus. However, future research is warranted in order to clarify the precise mechanisms involved in tinnitus-related Stroop effects. 1© Mary Ann Liebert, Inc.
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| 14. |
- Andersson, Gerhard, et al.
(författare)
-
Stroop facilitation in tinnitus patients: an experiment conducted via the world wide web
- 2005
-
Ingår i: Cyberpsychology and behavior. ; 8:1, s. 32-38
-
Tidskriftsartikel (refereegranskat)abstract
- Cognitive mechanisms have been proposed to play an important role in tinnitus. In the present study, tinnitus participants were administered an emotional Stroop test via the Internet, incorporating words related to tinnitus concerns. In line with previous research using this Web-based version of the emotional Stroop test, faster colour naming was demonstrated for concern-relevant words relative to neutral words. The present results thus provided supported for a role of cognitive factors that are important for the understanding of tinnitus. However, future research is warranted in order to clarify the precise mechanisms involved in tinnitus-related Stroop effects.
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| 15. |
- Andersson, Gerhard, et al.
(författare)
-
Tinnitus and short-term serial recall in stable versus intermittent masking conditions
- 2009
-
Ingår i: Scandinavian Journal of Psychology. - : Wiley. - 0036-5564 .- 1467-9450. ; 50:5, s. 517-522
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Tidskriftsartikel (refereegranskat)abstract
- The relation between tinnitus and short-term memory performance in varying background sounds is not well understood. In the present study a sample of 18 persons with tinnitus completed a serial recall test in three conditions, silence, masking and intermittent masking. The performance of a matched control group without tinnitus was also investigated. Based on the literature on the "irrelevant sound effect" we expected that the tinnitus group would perform worse during intermittent masking and that they would score lower overall compared to the control group. Results revealed no statistically significant differences between the groups, nor any group interaction within sound conditions for the serial recall test. Groups did however differ regarding subjective measures of concentration problems, anxiety and depression. Results are discussed in relation to thought suppression and distraction from tinnitus.
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| 16. |
- Andersson, Gerhard, 1966-, et al.
(författare)
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Treatment of tinnitus in the elderly : A controlled trial of cognitive behavior therapy
- 2005
-
Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 44:11, s. 671-675
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate the effects of cognitive behavioral therapy (CBT) in elderly people with tinnitus (<65 years). Thirty-seven patients were called in for a structured interview. Following exclusion, twenty-three participated in the trial. All participants underwent medical ear, nose, and throat (ENT) examination, audiometry, and tinnitus matchings. A randomized controlled design with a waiting list control group was used. A CBT treatment package was delivered in six weekly two hour group sessions. Outcome was measured using validated self-report inventories and daily diary ratings of annoyance, loudness and sleep quality for one week pre-treatment, post-treatment. A three month follow-up was included at which time all participants had received treatment, but in a shorter format for the control group. Results showed statistically significant reductions of tinnitus-related distress. Thus, CBT was better than no treatment, but the particular aspects of CBT that contributed to the effects can not be established. In conclusion, the findings give some support for the use of group CBT for elderly people with tinnitus. © 2005 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.
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| 17. |
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| 18. |
- Andersson, Viktor, et al.
(författare)
-
An optical spacer is no panacea for light collection in organic solar cells
- 2009
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:4, s. 043302-
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Tidskriftsartikel (refereegranskat)abstract
- The role of an optical spacer layer has been examined by optical simulations of organic solar cells with various bandgaps. The simulations have been performed with the transfer matrix method and the finite element method. The results show that no beneficial effect can be expected by adding an optical spacer to a solar cell with an already optimized active layer thickness.
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| 19. |
- Andersson, Viktor, et al.
(författare)
-
Comparative study of organic thin film tandem solar cells in alternative geometries
- 2008
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 104:12, s. 124508-
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Tidskriftsartikel (refereegranskat)abstract
- Optical modeling of one folded tandem solar cell and four types of stacked tandem solar cells has been performed using the finite element method and the transfer matrix method for the folded cell and the stacked cells, respectively. The results are analyzed by comparing upper limits for short circuit currents and power conversion efficiencies. In the case of serial connected tandems all of the five cell types may be compared, and we find that the folded cells are comparable to stacked tandem cells in terms of currents and power conversion efficiencies.
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| 20. |
- Andersson, Viktor, et al.
(författare)
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Imaging of the 3D Nanostructure of a Polymer Solar Cell by Electron Tomography
- 2009
-
Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:2, s. 853-855
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Tidskriftsartikel (refereegranskat)abstract
- Electron tomography has been used for analyzing the active layer in a polymer solar cell, a bulk heterojunction of an alternating copolymer of fluorene and a derivative of fullerene. The method supplies a three-dimensional representation of the morphology of the film, where domains with different scattering properties may be distinguished. The reconstruction shows good contrast between the two phases included in the film and demonstrates that electron tomography is an adequate tool for investigations of the three-dimensional nanostructure of the amorphous materials used in polymer solar cells.
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| 21. |
- Andersson, Viktor, et al.
(författare)
-
Optical modeling of a folded organic solar cell
- 2008
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:9, s. 094520-
-
Tidskriftsartikel (refereegranskat)abstract
- The optical behavior of a reflective tandem solar cell (V cell) is modeled by means of finite element method (FEM) simulations. The absorption of solar light in the active material as well as in both electrode layers is calculated. The FEM solves the electromagnetic wave equation on the entire defined geometry, resulting in the consideration of interference effects, as well as effects of refraction and reflection. Both single cells and tandem cells are modeled and confirmed to be in accordance with reflectance measurements. Energy dissipation in the active layers is studied as a function of layer thickness and folding angle, and the simulations clearly display the advantage of the light trapping feature of folded cells. This is especially prominent in cells with thinner active layers, where folding induces absorption in the active layer equivalent to that of much thicker cells.
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| 22. |
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| 23. |
- Carlbring, Per, 1972-, et al.
(författare)
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Treatment of Panic Disorder : Live Therapy vs. Self-Help via Internet
- 2005
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Ingår i: Behaviour Research and Therapy. - : Elsevier BV. - 0005-7967 .- 1873-622X. ; 43:10, s. 1321-1333
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Tidskriftsartikel (refereegranskat)abstract
- A randomized trial was conducted comparing 10 individual weekly sessions of cognitive behaviour therapy for panic disorder (PD) with or without agoraphobia with a 10-module self-help program on the Internet. After confirming the PD diagnosis with an in-person structured clinical interview (SCID) 49 participants were randomized. Overall, the results suggest that Internet-administered self-help plus minimal therapist contact via e-mail can be equally effective as traditional individual cognitive behaviour therapy. Composite within-group effect sizes were high in both groups, while the between-group effect size was small (Cohen's d=16). One-year follow-up confirmed the results, with a within-group effect size of Cohen's d=0.80 for the Internet group and d=0.93 for the live group. The results from this study generally provide evidence to support the continued use and development of Internet-distributed self-help programs.
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| 24. |
- Kaldo, Viktor, 1973-
(författare)
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Cognitive Behavioural Therapy as Guided Self-help to Reduce Tinnitus Distress
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tinnitus is common, and some individuals with tinnitus display high levels of distress. Cognitive behavioural therapy (CBT) is effective in reducing tinnitus distress, but is rarely available. CBT-based self-help, with or without guidance, has yielded positive results in other problem areas, and one initial randomized controlled trial (RCT) has shown promising results for tinnitus.This thesis is based on four studies;Study I showed that Internet-based self-help treatment with e-mail guidance alleviated tinnitus distress among consecutive patients and was rated as credible as traditional treatments. Active participation in treatment predicted outcome.Study II, an RCT, showed that an extended and more interactive version of the Internet-based self-help treatment with e-mail therapist support appeared to be equally effective as a group treatment. In study III, another RCT, a self-help book with weekly telephone support was superior to a wait-list control group. No strong evidence for the importance of telephone contact on outcome was found. In both study II and III, the positive outcome remained after one year and self-help approaches appeared more therapist time-effective compared to group treatment. Also, the received treatment-dose for patients in guided self-help was not lower than in the group treatment.Study IV found that the ‘Stages of Change’, from the transtheoretical model, are probably not the right theoretical framework to use with tinnitus patients. Predictors of outcome were found, but they were not in line with the theory behind the Stages of Change. The predictors were better understood when conceptualized as coping, showing that helplessness and less coping before treatment correlated with better outcome.In sum, guided cognitive behavioural self-help can decrease tinnitus distress. It appears to be therapist time-effective and shows effects comparable to or slightly below traditional CBT for tinnitus. Effects remain one year after treatment and generalize to a routine clinical setting.
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| 25. |
- Kaldo, Viktor, et al.
(författare)
-
Internet versus group cognitive-behavioral treatment of distress associated with tinnitus : A randomized controlled trial
- 2008
-
Ingår i: Behavior Therapy. - : Elsevier BV. - 0005-7894 .- 1878-1888. ; 39:4, s. 348-359
-
Tidskriftsartikel (refereegranskat)abstract
- Tinnitus distress can be reduced by means of cognitive-behavior therapy (CBT), and the treatment can be delivered in different ways. The most recent format is Internet-based self-help. The aim of this study was to compare this treatment (n = 26) with standard group-based CBT (n = 25) in a randomized controlled trial. Outcomes on self-report inventories measuring tinnitus distress were evaluated immediately after and 1 year after treatment. Results showed that both groups had improved, and there were few differences between them. The effect size for the Internet treatment was d = 0.73 (95% CI = 0.16-1.30) and for the group treatment was d = 0.64 (95% CI = 0.07-1.21). The Internet treatment consumed less therapist time and was 1.7 times as cost-effective as the group treatment. At pretreatment patients rated the Internet treatment as less credible than the group treatment. In conclusion, Internet treatment for tinnitus distress merits further investigation, as the outcomes achieved are promising.
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| 26. |
- Kaldo, Viktor, et al.
(författare)
-
Tinnitus Stages of Change Questionnaire : Psychometric development and validation
- 2006
-
Ingår i: Psychology, Health & Medicine. - : Informa UK Limited. - 1354-8506 .- 1465-3966. ; 11:4, s. 483-497
-
Tidskriftsartikel (refereegranskat)abstract
- This study describes the development of the Tinnitus Stages of Change Questionnaire (TSOCQ), which aims to assess the readiness of tinnitus patients to change their behaviors and attitudes in relation to tinnitus. Its ability to predict treatment outcome was also investigated. One hundred and fifty-one patients with tinnitus completed the questionnaire. Through repeated principal component analyses, together with judgments of the factors' theoretical relevance, empirically and clinically meaningful scales were derived. A factor solution in accordance with the transtheoretical model (TTM) and with acceptable psychometric properties was found with the five scales of the TSOCQ labeled Precontemplation (Medical Solution), Precontemplation (Helplessness), Contemplation, Preparation and Action/Maintenance. Participants scoring high on Precontemplation (Helplessness) and low on Action/Maintenance had better treatment outcomes. In conclusion, the TSOCQ had some ability to predict treatment success, but further research is required into the utility of the TTM for understanding the rehabilitation process in tinnitus patients. © 2006 Taylor & Francis.
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| 27. |
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| 28. |
- Kaldo, Viktor, et al.
(författare)
-
Use of a self-help book with weekly therapist contact to reduce tinnitus distress : a randomized controlled trial
- 2007
-
Ingår i: Journal of Psychosomatic Research. - : Elsevier BV. - 0022-3999 .- 1879-1360. ; 63:2, s. 195-202
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Tinnitus distress can be reduced by means of cognitive-behavior therapy (CBT). To compensate for the shortage of CBT therapists, we aimed, in this study, to investigate the effects of a CBT-based self-help book guided by brief telephone support. Methods: Seventy-two patients were randomized either to a self-help book and seven weekly phone calls or to a wait-list control condition, later on receiving the self-help book with less therapist support. The dropout rate was 7%. Follow-up data 1 year after completion of treatment were also collected (12% dropout). The Tinnitus Reaction Questionnaire (TRQ) was the main outcome measure, complemented with daily ratings of tinnitus and measures of insomnia, anxiety, and depression. Results: On the TRQ, significant reductions were found in the treatment group both immediately following treatment and at 1-year follow-up. In the treatment group, 32% reached the criteria for clinical significance (at least 50% reduction of the TRQ) compared to 5% in the wait-list group. Directly after treatment, two out of five measures showed significant differences in favor of the treatment with more therapist support compared with the group who, after their waiting period, received little therapist support. The self-help treatment was estimated to be 2.6 (seven phone calls) and 4.8 (one phone call) times as cost-effective as regular CBT group treatment. Conclusions: Guided self-help can serve as an alternative way to administer CBT for tinnitus. Preliminary results cast some doubts on the importance of weekly therapist contact. The effect size was somewhat smaller than for regular CBT, but on the other hand, the self-help seems far more cost-effective. Future studies should compare treatment modalities directly and explore cost-effectiveness more thoroughly.
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| 29. |
- Kamae, Tuneyoshi, et al.
(författare)
-
PoGOLite - A high sensitivity balloon-borne soft gamma-ray polarimeter
- 2008
-
Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 30:2, s. 72-84
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200 mCrab point-like sources between 25 and 80 keV in one 6-h flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. Synchrotron radiation, inverse Compton scattering and propagation through high magnetic fields are likely to produce high degrees of polarisation in the energy band of the instrument. We demonstrate, through tests at accelerators, with radioactive sources and through computer simulations, that PoGOLite will be able to detect degrees of polarisation as predicted by models for several classes of high energy sources. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles while securing a large effective area has been the greatest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow Held of view (FWHM = 1.25 msr, 2.0 deg x 2.0 deg) obtained with detector cells and the use of thick background shields warrant a large effective area for polarisation measurements (similar to 228 cm(2) at E = 40 keV) without sacrificing the signal-to-noise ratio. Simulation studies for an atmospheric overburden of 3-4 g/cm(2) indicate that neutrons and gamma-rays entering the PDC assembly through the shields are dominant backgrounds. Off-line event selection based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a similar to 100 mCrab source between 25 and 50 keV. A 6-h observation of the Crab pulsar will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5 sigma significance; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. Long-duration flights will measure the dependence of the polarisation across the cyclotron absorption line in Hercules X-1. A scaled-down instrument will be flown as a pathfinder mission from the north of Sweden in 2010. The first science flight is planned to take place shortly thereafter.
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| 30. |
- Sundqvist, Kristina, et al.
(författare)
-
Receptor Modeling of PCDD/FS in Sediment of the Sundsvall Bay, Sweden
- 2008
-
Ingår i: Organohalogen Compounds. ; 70:1641-4
-
Tidskriftsartikel (refereegranskat)abstract
- In the Sundsvall Bay area, located in the southern Bothnian Sea (a sub-basin of the Baltic Sea), industrial history have included a large variety of activities, from small sawmills to large pulp and paper mills as well as chloralkali production. Previously, several sawmills in the area used chlorophenol formulations for wood preservation, and these were contaminated by PCDD/Fs. Chloralkali production using graphite electrodes and bleaching of pulp using chlorine are manufacturing processes also known to have caused PCDD/Fs emissions. A chemical industry has been active in the area since the 1930s and an aluminum smelter was built in 1942. Aluminum production, like many high temperature processes, is known to produce PCDD/Fs.The aim of this study was to investigate the possibility of using receptor modeling for identification and apportioning of the major sources of PCDD/Fs in the Sundsvall Bay. The Sundsvall Bay was chosen as the first study area of this modeling technique along the Swedish coast since there are several possible sources of PCDD/Fs in the area and a relatively large number of sediment samples have been analyzed. Current PCDD/F emissions have been investigated by sampling river water, industrial effluent entering the bay and, in addition, soil from two contaminated sawmill sites.
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| 31. |
- Tvingstedt, Kristofer, 1976-, et al.
(författare)
-
Folded reflective tandem polymer solar cell doubles efficiency
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:12, s. 123514-
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Tidskriftsartikel (refereegranskat)abstract
- Conjugated polymers are promising materials for the production of inexpensive and flexible photovoltaic cells. Organic materials display tunable optical absorption within a large spectral range. This enables the construction of organic tandem photovoltaic cells. The authors here demonstrate a reflective tandem cell where single cells are reflecting the nonabsorbed light upon another adjacent cell. By folding two planar but spectrally different cells toward each other, spectral broadening and light trapping are combined to give an enhancement of power conversion efficiency of a factor of 1.8±0.3.
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