Search

The lattice locations and electronic configurations of Fe in 57Co/57Fe implanted ZnO (to (5-6) × 1014 Fe/cm-2) have been studied by 57Fe Mössbauer emission spectroscopy. The spectra acquired upon room temperature implantation show ∼20% of the probe atoms as Fe2+ on perturbed Zn sites and the remaining fraction as Fe2+ in damage sites of interstitial character. After annealing at 773 K, ∼20% remain on crystalline sites, while the damage fraction has partly disappeared and instead a ∼30% fraction occurs as high-spin Fe3+, presumably in precipitates. This suggests that precipitation of Co/Fe in ZnO likely takes place at relatively low temperatures, thus explaining some of the discrepancies in the literature regarding magnetic properties of 3d metal-doped ZnO. [ABSTRACT FROM AUTHOR]

The valence state and annealing reactions of Mn/Fe in single crystalline α-AlO have been determined following low fluence (<10 cm) 60 keV implantations of Mn (T = 1.5 min) and emission Mössbauer spectroscopy on the Fe daughter nuclei in the temperature range from 110-700 K. At 110 K, most probe atoms are found in the Fe state in amorphous surroundings due to the implantation damage. A fraction of the Fe is found in cubic environment, possibly nano-precipitates of η-AlO. This site is found to disappear from the spectra above 500 K. Annealing of the damage sites at increasing temperatures leads first to increased incorporation of the probe atoms as Fe on Al sites, and, above room temperature, also as Fe. The Fe sub-spectrum is masked by slow paramagnetic relaxations following a T dependence, as expected for a two-phonon Raman process. Our data is consistent with data from Co and Fe implantations, suggesting a general increase in the average Fe valence state with lower implantation dose and negligible annealing reactions at room temperature. [ABSTRACT FROM AUTHOR]

Ion implantation provides a precise method of incorporating dopant atoms in semiconductors, provided lattice damage due to the implantation process can be annealed and the dopant atoms located on regular lattice sites. We have undertaken Fe emission Mössbauer spectroscopy measurements on GaAs and GaP single crystals following implantation of radioactive Mn ions, to study the lattice sites of the implanted ions, the annealing of implantation induced damage and impurity-vacancy complexes formed. The Mössbauer spectra were analyzed with four spectral components: an asymmetric doublet (D1) attributed to Fe atoms in distorted environments due to implantation damage, two single lines, S1 assigned to Fe on substitutional Ga sites, and S2 to Fe on interstitial sites, and a low intensity symmetric doublet (D2) assigned to impurity-vacancy complexes. The variations in the extracted hyperfine parameters of D1 for both materials at high temperatures ( T > 400 K) suggests changes in the immediate environment of the Fe impurity atoms and different bonding mechanism to the Mössbauer probe atom. The results show that the annealing of the radiation induced damage is more prominent in GaAs compared to GaP. [ABSTRACT FROM AUTHOR]

This preliminary study aims to investigate a M w 6.3 earthquake that occurred in South Iceland on Thursday 29 May 2008 at 15:45 UTC. The epicentre was in the Olfus District between the towns of Selfoss and Hveragerdi. This study examines the data recorded and the damage observed immediately after the event. Horizontal accelerations of up to 80%g were recorded in the epicentral region and there is visual evidence that the vertical acceleration exceeded 1 g. The PGA data is compared to a ground motion estimation model developed for the South Iceland earthquakes in June 2000. In general the basic properties of this event are found to be similar to the characteristics of the South Iceland earthquakes in June 2000. The duration of strong-motion is short and the intensity attenuates rapidly with increasing distance. The earthquake action resisted by buildings in the near fault area is inspected through evaluation of elastic as well as inelastic response spectra. The vast majority of structures seemed to withstand the strong-motion fairly competently and without significant visual damage due firstly to the low-rise, predominantly reinforced concrete or timber, style of buildings. Secondly, the short duration of strong-motion contributed to the endurance of structures. [ABSTRACT FROM AUTHOR]

Prompted by the generally poor understanding of the nature of magnetic phenomena in 3d-metal doped ZnO, we have undertaken on-line 57Fe Mössbauer spectroscopy on ZnO single crystals in an external magnetic field of 0.6 T, following the implantation of radioactive 57Mn ions at room temperature. The Mössbauer spectra of the dilute Fe impurities are dominated by sextets whose angular dependence rules out an ordered magnetic state (which had been previously proposed) but are well accounted for on the basis of Fe3+ paramagnetic centers on substitutional Zn sites with unusually long relaxation times (>20 ns). [ABSTRACT FROM AUTHOR]

The lattice sites, valence states, resulting magnetic behaviour and spin–lattice relaxation of Fe ions in GaN and AlN were investigated by emission Mössbauer spectroscopy following the implantation of radioactive 57 Mn + ions at ISOLDE/CERN. Angle dependent measurements performed at room temperature on the 14.4 keV γ -rays from the 57 Fe Mössbauer state (populated from the 57 Mn β − decay) reveal that the majority of the Fe ions are in the 2+ valence state nearly substituting the Ga and Al cations, and/or associated with vacancy type defects. Emission Mössbauer spectroscopy experiments conducted over a temperature range of 100–800 K show the presence of magnetically split sextets in the “wings” of the spectra for both materials. The temperature dependence of the sextets relates these spectral features to paramagnetic Fe 3+ with rather slow spin–lattice relaxation rates which follow a T 2 temperature dependence characteristic of a two-phonon Raman process. [ABSTRACT FROM AUTHOR]

Abstract: 57Fe Mössbauer spectroscopy studies, following implantation of radioactive , have been conducted on InP and n- and p-type InAs at temperatures above 300K. The ions are produced at the ISOLDE facility at CERN, ionized and accelerated to 60keV energy and implanted with fluences of into single crystal samples. Mössbauer spectra were collected with a parallel plate avalanche counter. Analysis of the Mössbauer spectra required three components: an asymmetric doublet attributed to Fe atoms in implantation induced damaged environments, a single line assigned to Fe on substitutional In sites and a weak symmetric doublet assigned to impurity–vacancy complexes. In InP the substitutional Fe component becomes significant above 400K; while in InAs the fraction is already appreciable (>30%) after implantation at room temperature. The asymmetric doublet dominates the spectra of all samples but shows significant reduction in intensity with increasing temperatures. The radiation damage shows strong annealing above 400K in the InAs samples and above 450K in InP; the Fe-defect complex dissociates at 500K, and the component dominates the spectra at higher temperatures. There was no evidence of any magnetic components in the spectra, indicating that at the low concentrations used in our measurements, the Fe ions were predominantly in the state. [Copyright &y& Elsevier]

Background: Atrial fibrillation (AF) is a highly morbid condition which requires long-term adherence to oral anticoagulation and may be associated with adverse quality of life and health care utilization. We developed a relational agent-an interactive smartphone-based intervention accessible regardless of digital or health literacy-to assist individuals residing in rural, Western Pennsylvania, with AF with chronic disease self-management., Methods: The "Mobile health intervention for rural atrial fibrillation" is a single center, parallel-arm randomized clinical trial for adults with AF funded by the National Institute of Health's National Heart, Lung, and Blood Institute to enroll 264 participants. All participants receive a smartphone with data plan: The intervention is a 4 month relational agent coupled with the AliveCor Kardia for heart rate and rhythm monitoring provided by smartphone, and the control a pre-installed, smartphone-based application for health-related information (WebMD). The study uses remote recruitment and engagement to enroll individuals who would otherwise be unlikely to participate in clinical research due to rurality. The primary outcome of the trial is adherence to oral anticoagulation, determined by proportion of days covered, as measured at 12 months. The secondary outcomes are quality of life, both AF-specific and general, and health care utilization. The study entails a baseline visit, a 4 month intervention phase, and 8 and 12 month follow-up visits., Conclusions: This mobile health trial tests the effectiveness of a smartphone-based relational agent to improve clinical and patient-reported outcomes in rural-dwelling individuals., Competing Interests: Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Inc.)

Background: Prior studies have demonstrated the safety risks when patients and consumers use conversational assistants such as Apple's Siri and Amazon's Alexa for obtaining medical information., Objective: The aim of this study is to evaluate two approaches to reducing the likelihood that patients or consumers will act on the potentially harmful medical information they receive from conversational assistants., Methods: Participants were given medical problems to pose to conversational assistants that had been previously demonstrated to result in potentially harmful recommendations. Each conversational assistant's response was randomly varied to include either a correct or incorrect paraphrase of the query or a disclaimer message-or not-telling the participants that they should not act on the advice without first talking to a physician. The participants were then asked what actions they would take based on their interaction, along with the likelihood of taking the action. The reported actions were recorded and analyzed, and the participants were interviewed at the end of each interaction., Results: A total of 32 participants completed the study, each interacting with 4 conversational assistants. The participants were on average aged 42.44 (SD 14.08) years, 53% (17/32) were women, and 66% (21/32) were college educated. Those participants who heard a correct paraphrase of their query were significantly more likely to state that they would follow the medical advice provided by the conversational assistant (χ 2 1 =3.1; P=.04). Those participants who heard a disclaimer message were significantly more likely to say that they would contact a physician or health professional before acting on the medical advice received (χ 2 1 =43.5; P=.001)., Conclusions: Designers of conversational systems should consider incorporating both disclaimers and feedback on query understanding in response to user queries for medical advice. Unconstrained natural language input should not be used in systems designed specifically to provide medical advice., (©Timothy W Bickmore, Stefán Ólafsson, Teresa K O'Leary. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 09.11.2021.)

The change in the Curie temperature of single crystalline garnet Y 3 Fe 5 O 12 (YIG) sample due to lattice damage induced by ion implantation has been investigated in 57 Fe emission Mössbauer Spectroscopy (eMS) following implantation of 57 Mn (T ½  = 1.5 min). The Mössbauer spectra analysis reveal high spin Fe 3+ ions substituted on both the octahedral and the tetrahedral sites. Measurements in the temperature range 298 K-798 K show that average values of the magnetic hyperfine field are decreased by the implantation-induced damage on the local lattice structure of the YIG. The Curie temperature, however, is determined to be 651 ± 5 K, considerably higher than the value of bulk YIG (559 K). This is most likely due to lattice damage-induced changes on the spin configurations of YIG through a Fe A -O-Fe D distortion scheme., Competing Interests: Declaration of competing interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background & Aims: In Iceland a nationwide program has been launched offering direct-acting antiviral (DAA) treatment for everyone living with hepatitis C virus (HCV). We estimate (i) the time and treatment scale-up required to achieve the World Health Organization's HCV elimination target of an 80% reduction in incidence; and (ii) the ongoing frequency of HCV testing and harm reduction coverage among people who inject drugs (PWID) required to minimize the likelihood of future HCV outbreaks occurring., Methods: We used a dynamic compartmental model of HCV transmission, liver disease progression and the HCV cascade of care, calibrated to reproduce the epidemic of HCV in Iceland. The model was stratified according to injecting drug use status, age and stage of engagement. Four scenarios were considered for the projections., Results: The model estimated that an 80% reduction in domestic HCV incidence was achievable by 2030, 2025 or 2020 if a minimum of 55/1,000, 75/1,000 and 188/1,000 PWID were treated per year, respectively (a total of 22, 30 and 75 of the estimated 400 PWID in Iceland per year, respectively). Regardless of time frame, this required an increased number of PWID to be diagnosed to generate enough treatment demand, or a 20% scale-up of harm reduction services to complement treatment-as-prevention incidence reductions. When DAA scale-up was combined with annual antibody testing of PWID, the incidence reduction target was reached by 2024. Treatment scale-up with no other changes to current testing and harm reduction services reduced the basic reproduction number of HCV from 1.08 to 0.59, indicating that future outbreaks would be unlikely., Conclusion: HCV elimination in Iceland is achievable by 2020 with some additional screening of PWID. Maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that outbreaks are unlikely to occur once elimination targets have been reached., Lay Summary: In Iceland, a nationwide program has been launched offering treatment for the entire population living with hepatitis C virus (HCV). A mathematical model was used to estimate the additional health system requirements to achieve the HCV elimination targets of the World Health Organization (WHO), as well as the year that this could occur. With some additional screening of people who inject drugs, Iceland could reach the WHO targets by 2020, becoming one of the first countries to achieve HCV elimination. The model estimated that once elimination targets were reached, maintaining current monitoring and harm reduction services while providing ongoing access to DAA therapy for people diagnosed with HCV would ensure that future HCV outbreaks are unlikely to occur., (Copyright © 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

All-oral direct-acting antiviral drugs (DAAs) for hepatitis C virus, which have response rates of 95% or more, represent a major clinical advance. However, the high list price of DAAs has led many governments to restrict their reimbursement. We reviewed the availability of, and national criteria for, interferon-free DAA reimbursement among countries in the European Union and European Economic Area, and Switzerland. Reimbursement documentation was reviewed between Nov 18, 2016, and Aug 1, 2017. Primary outcomes were fibrosis stage, drug or alcohol use, prescriber type, and HIV co-infection restrictions. Among the 35 European countries and jurisdictions included, the most commonly reimbursed DAA was ombitasvir, paritaprevir, and ritonavir, with dasabuvir, and with or without ribavirin (33 [94%] countries and jurisdictions). 16 (46%) countries and jurisdictions required patients to have fibrosis at stage F2 or higher, 29 (83%) had no listed restrictions based on drug or alcohol use, 33 (94%) required a specialist prescriber, and 34 (97%) had no additional restrictions for people co-infected with HIV and hepatitis C virus. These findings have implications for meeting WHO targets, with evidence of some countries not following the 2016 hepatitis C virus treatment guidelines by the European Association for the Study of Liver., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The persistence of common, heritable psychiatric disorders that reduce reproductive fitness is an evolutionary paradox. Here, we investigate the selection pressures on sequence variants that predispose to schizophrenia, autism, bipolar disorder, major depression and attention deficit hyperactivity disorder (ADHD) using genomic data from 150,656 Icelanders, excluding those diagnosed with these psychiatric diseases. Polygenic risk of autism and ADHD is associated with number of children. Higher polygenic risk of autism is associated with fewer children and older age at first child whereas higher polygenic risk of ADHD is associated with having more children. We find no evidence for a selective advantage of a high polygenic risk of schizophrenia or bipolar disorder. Rare copy-number variants conferring moderate to high risk of psychiatric illness are associated with having fewer children and are under stronger negative selection pressure than common sequence variants.

The common charge states of Sn are 2+  and 4+. While charge neutrality considerations favour 2+  to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+  state instead. In order to investigate the charge states, lattice sites, and the effect of the ion implantation process of dilute Sn atoms in ZnO, we have performed 119 Sn emission Mössbauer spectroscopy on ZnO single crystal samples following ion implantation of radioactive 119 In (T ½   =  2.4 min) at temperatures between 96 K and 762 K. Complementary perturbed angular correlation measurements on 111m Cd implanted ZnO were also conducted. Our results show that the 2+  state is the natural charge state for Sn in defect free ZnO and that the 4+  charge state is stabilized by acceptor defects created in the implantation process.

Only a few common variants in the sequence of the genome have been shown to impact cognitive traits. Here we demonstrate that polygenic scores of educational attainment predict specific aspects of childhood cognition, as measured with IQ. Recently, three sequence variants were shown to associate with educational attainment, a confluence phenotype of genetic and environmental factors contributing to academic success. We show that one of these variants associating with educational attainment, rs4851266-T, also associates with Verbal IQ in dyslexic children (P = 4.3 × 10 -4 , β = 0.16 s.d.). The effect of 0.16 s.d. corresponds to 1.4 IQ points for heterozygotes and 2.8 IQ points for homozygotes. We verified this association in independent samples consisting of adults (P = 8.3 × 10 -5 , β = 0.12 s.d., combined P = 2.2 x 10 -7 , β = 0.14 s.d.). Childhood cognition is unlikely to be affected by education attained later in life, and the variant explains a greater fraction of the variance in verbal IQ than in educational attainment (0.7% vs 0.12%,. P = 1.0 × 10 -5 )., Competing Interests: B.G., G.A.J., G.B., P.S., S.K., B.Ke., O.G., H.H., P.I., S.O., M.F., G.Þ., S.A., B.S., U.Th., A.K., D.F.G., H.S., B.V.H. and K.S. are employees of deCODE Genetics/Amgen.

Background/aims: Liver transplantation is an important treatment option for end-stage liver disease. Since liver transplantation is not performed in Iceland, patients are sent abroad for this procedure. The aim of this study was to investigate indications and results of liver transplantations for Icelandic patients., Materials and Methods: The study was retrospective and included all patients in Iceland who had undergone liver transplantation from the first transplantation in 1984 to the end of 2012. Information was gathered from medical records. The study period was divided into three subperiods in order to evaluate changes in frequency of transplantation and survival., Results: During the period, 45 liver transplantations, thereof five retransplantations, were performed. Of 40 patients 16 were males, 18 females, mean age 40 years. There were six children, 2 girls and 4 boys with an age range of 0.4-12 years. Number of transplantation per million inhabitants increased significantly (2.40 during 1984-1996; 5.18 during 1997-2006 and 8.90 during 2007-2013; p<0.01). The main indication for transplantation was cirrhosis with complications in 26 patients (65%), acute liver failure in 6 (15%), cirrhosis and hepatocellular carcinoma in three (8%), and hemangioendothelioma in two (5%). The most common underlying liver diseases were primary biliary cirrhosis in 8 (20%), autoimmune hepatitis in four (10%), alcoholic cirrhosis in three (7.5%) and primary sclerosing cholangitis in three (7.5%). The mean waiting time for transplantation was 5.9 months (median 3.2). Survial was 84% in one year and 63% in 5 years. Survival increased during the study period., Conclusions: The number of liver transplantations has increased significantly in recent years. Survival has improved and is comparable to survival in countries where liver transplantations are performed.

Background: The study was carried out in order to examine the effect of unemployment on the incidence of disability pension in Iceland by examining changes in this relationship from 1992 to 2007., Methods: The annual incidence of disability pension for the period 1992-2007 was calculated. Correlations and significance tests for the relationship between unemployment rates and disability pension incidence rates were calculated. The relationship was examined for different disease groups., Results: Two big fluctuations occurred in the unemployment rate during the study period with an upswing in unemployment from 1993 to 1995 and in 2002 and 2003. In both cases, there were corresponding increases in the incidence of disability pension. The incidence of disability pension declined again when the level of unemployment went down, even though not to the same extent., Conclusions: Health and mental and physical capability determine the overall incidence of disability pension, but marginal fluctuations over time seem to be related to environmental conditions in the labour market, especially the unemployment rate. The observed disability pension incidence pattern in the two unemployment cycles of the study period indicates mainly that people with impaired health are forced out of the labour market in times of increasing unemployment rather than pointing towards a negative effect of unemployment on health. Our findings indicate that there is a need to strengthen the vocational rehabilitation system in Iceland as well as the support system for employment and social participation.