Publications by authors named "Ragnar Olafsson"

Introduction: Interest in the use of psychedelics has increased following reports of their possible therapeutic potential. However, little is known about the knowledge of and attitudes towards the substances among health care professional who provide treatment for mental disorders in Iceland. An online survey was therefore conducted among members of the Icelandic associations of psychiatrists, general practitioners and psychologists.

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The EEG is suggested as a potential diagnostic and prognostic biomarker for seasonal affective disorder (SAD). As a pre-clinical form of SAD, seasonality is operationalized as seasonal variation in mood, appetite, weight, sleep, energy, and socializing. Importantly, both EEG biomarkers and seasonality interact with age.

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Depressive rumination has been conceptualized as a mental habit that is initiated automatically without conscious awareness, intent, or control in response to negative mood. However, it is unknown whether depression vulnerability is characterized by elevated levels of mood-reactive rumination at the level of short-term dynamics. Using mobile ecological momentary assessment, formerly depressed individuals with a recurrent history of depression ( = 94) and nonclinical controls ( = 55) recorded affect and rumination 10 times daily over 6 days, after completing baseline measures of trait ruminative brooding, early life stress, and habitual characteristics of negative thinking (e.

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It has been suggested that mental habits may underpin a heightened disposition to engage in rumination in response to negative mood. The aim of the current study was to assess the role of habit in the dynamic interplay between affect and ruminative thinking in the flow of daily life experiences. Using mobile ecological momentary assessment, 97 participants recorded affect and rumination ten times daily over six days, after completing measures of trait ruminative brooding and habitual characteristics of negative thinking (e.

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The aim of the present study was to test predictions derived from the habit-goal framework of depressive rumination and investigate its relevance to cognitive reactivity-another well-known vulnerability factor to depression. Formerly depressed (FD; n=20) and never depressed (ND; n=22) participants completed self-report measures of rumination, cognitive reactivity, and habitual characteristics of rumination (e.g.

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Trichotillomania (TTM; hair-pulling disorder) is characterized by an irresistible urge or desire to pull out one's own hair, and a sense of pleasure when hair is pulled out. Evidence from translational neuroscience has shown that 'wanting' (motivation to seek a reward) and 'liking' (enjoyment when reward is received) are each mediated by overlapping but distinct neural circuitry, and that 'wanting' contributes to addictive/compulsive behaviors more so than 'liking'. In the present study, we developed the Hair Pulling Reward Scale (HPRS), a self-report measure that consists of two subscales designed to assess (a) cue-triggered urges and appetitive motivation to pull hair (i.

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Background And Aims: Excoriation (skin-picking) disorder (SPD) is often conceptualized as a behavioral addiction in which aberrant reward processing may play an important role. The current study sought to develop a self-report instrument--the Skin Picking Reward Scale (SPRS)--that measures how strongly skin picking is 'liked' (i.e.

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Background And Objectives: Control of obsessive thoughts in Obsessive Compulsive Disorder (OCD) involves both avoidance and removal of undesirable intrusive thoughts. Thought suppression tasks tap both of these processes but experimental results have been inconsistent. Experimental tasks allowing more focused study of the processes involved in controlling intrusive thoughts may be needed.

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Introduction: The Icelandic health care system ranks favourably in international comparison but patients' experience of interaction with the health service has not been well studied. The goal of this study was to examine the satisfaction of patients admitted to the Acute Cardiac Unit (ACU) at Landspitali - The National University Hospital of Iceland.

Methods: A questionnaire based on the Patient Satisfaction Questionnaire III was mailed to patients admitted to the ACU between 1 January and 29 February 2012.

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Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure.

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This study examined relationships between physical appearance concerns (fear of fat, body image disturbance; BIDQ), disgust, and anti-fat prejudice (dislike, blame), and tested whether disgust mediates relationships between physical appearance concerns and anti-fat prejudice. Participants (N=1649; age=28 years) provided demographic data and completed measures of anti-fat prejudice, tendency to feel disgust, and physical appearance concerns. Univariate, multivariate, and mediation analyses were conducted.

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In the present study, we examined the psychometric properties of the Skin Picking Impact Scale (SPIS; Keuthen, Deckersbach, Wilhelm et al., 2001), a 10 item self-report questionnaire designed to assess the psychosocial impact of skin picking disorder (SPD). Participants were 650 individuals who met criteria for SPD in an online survey.

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We tested whether suppressing disgust related thoughts, compared with no suppression, differentially affected target thought frequency and emotional responses, and whether this was related to participants' cognitive inhibition abilities. We also tested whether different control instructions during a thought control task would affect performance on a subsequent behavioural avoidance task involving disgust related stimuli. Sixty university students, pre-selected on their level of disgust propensity/sensitivity, were instructed to either suppress or not to suppress all target-related thoughts following viewing of a disgust-related film fragment.

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Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information during a routine breast exam for cancer. PAI enhances contrast between blood vessels and background tissue, which can help characterize suspicious lesions. However, most PAI systems are either not compatible with commercial ultrasound systems or inefficiently deliver light to the region of interest, effectively reducing the sensitivity of the technique.

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Ultrasound current source density imaging (UCSDI) exploits the acoustoelectric (AE) effect, an interaction between ultrasound pressure and electrical resistivity, to map electrical conduction in the heart. The conversion efficiency for UCSDI is determined by the AE interaction constant K, a fundamental property of all materials; K directly affects the magnitude of the detected voltage signal in UCSDI. This paper describes a technique for measuring K in biological tissue, and reports its value for the first time in cadaver hearts.

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Pathological skin picking (PSP) is often recognized as an impulse control disorder. The current study sought to investigate the relationship between PSP and different forms of impulsivity. University students that met criteria for PSP (n = 55) and university students without history of PSP (n = 55) answered a multidimensional impulsivity questionnaire (the UPPS Impulsive Behavior Scale) and completed 2 neurocognitive tasks that assess impulsivity (the Stop Signal Task and the Information Sampling Task).

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The Attentional Control Scale (ACS) is a self-report questionnaire that has been developed to measure individual differences in attentional control. Despite its fairly widespread use, little is known about the psychometric properties of the scale in adult samples. In the present study, factor structure of the ACS and its relationship with symptoms of anxiety and depression was investigated in a total sample of 728 Icelandic university students.

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Understanding the tumor microenvironment is critical to characterizing how cancers operate and predicting their response to treatment. We describe a novel, high-resolution coregistered photoacoustic (PA) and pulse echo (PE) ultrasound system used to image the tumor microenvironment. Compared to traditional optical systems, the platform provides complementary contrast and important depth information.

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Ultrasound strain imaging has been proposed to quantitatively assess myocardial contractility. Cross-correlation-based 2-D speckle tracking (ST) and auto-correlation-based tissue Doppler imaging (TDI) [often called Doppler tissue imaging (DTI)] are competitive ultrasound techniques for this application. Compared with 2-D ST, TDI, as a 1-D method, is sensitive to beam angle and suffers from low strain signal-to-noise ratio because a high pulse repetition frequency is required to avoid aliasing in velocity estimation.

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A clinical ultrasound scanner and 14 MHz linear array collected real-time photoacoustic images (PAI) during an injection of gold nanorods (GNRs) near the region of a mature PC-3 prostate tumor in mice implanted with a skin flap window chamber. Three dimensional spectroscopic PAI (690-900 nm) was also performed to investigate absorption changes near the tumor and enhance specific detection of GNRs. Whereas GNRs improved PAI contrast (+18 dB), the photoacoustic spectrum was consistent with the elevated near infrared absorption of GNRs.

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Pathological skin picking (PSP) is characterized by excessive picking of the skin, resulting in significant distress or functional impairment. The aim of the present study was to investigate the emotion regulation hypothesis of PSP. University students with PSP (n = 55) and without history of PSP (n = 55) were asked to retrospectively rate the intensity of affective states before, during, and after skin picking episodes.

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Ultrasound strain imaging using 2-D speckle tracking has been proposed to quantitatively assess changes in myocardial contractility caused by ischemia. Its performance must be demonstrated in a controlled model system as a step toward routine clinical application. In this study, a well-controlled 2-D cardiac elasticity imaging technique was developed using two coplanar and orthogonal linear probes simultaneously imaging an isolated retroperfused rabbit heart.

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We describe the first mapping of biological current in a live heart using ultrasound current source density imaging (UCSDI). Ablation procedures that treat severe heart arrhythmias require detailed maps of the cardiac activation wave. The conventional procedure is time-consuming and limited by its poor spatial resolution (5-10 mm).

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Correlation-based speckle tracking methods are commonly used in elasticity imaging to estimate displacements. In the presence of local strain, a larger window size results in larger displacement error. To reduce tracking error, we proposed a short correlation window followed by a correlation coefficient filter.

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