Multi-mode transport through a quantum nanowire with two embedded dots

We investigate the conductance of a quantum wire with two embedded quantum dots using a T-matrix approach based on the Lippmann-Schwinger formalism. The quantum dots are represented by a quantum well with Gaussian shape and the wire is two-dimensional with parabolic confinement in the transverse direction. In a broad wire the transport can assume a strong nonadiabatic character and the conductance manifests effects caused by intertwined inter- and intra-dot processes that are identified by analysis of the ``nearfield'' probability distribution of the transported electrons.Comment: RevTeX, 7 pages with included postscript figure

Blood selenium levels and contribution of food groups to selenium intake in adolescent girls in Iceland.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.Significant changes have been reported in dietary habits and food availability in Iceland that would be expected to compromise selenium intake and status, especially among young people. These include substantial decreases in the consumption of fish and milk, as well as the selenium content of imported wheat. The aim of this study was to assess selenium in the diet and whole blood of adolescent girls, as well as define the most important foods contributing to intake and blood concentrations of selenium. The subjects were 96 randomly selected girls, aged 16-20, who answered a validated food frequency questionnaire (FFQ) for dietary assessment. Selenium intake from each food group was calculated in µg/day. Blood samples were collected for measurement of whole blood selenium. Mean dietary selenium was 51±25 µg/day. Milk/dairy products, including cheese, contributed 36±14% of total dietary selenium; fish 18±12%; and bread/cereal products 13±6%. Mean whole blood selenium was 117±12 µg/l (range 90-208); nearly 90% of subjects were above the optimal level of 100 µg/l. Fish and bread/cereal products were the only foods significantly correlated with selenium in blood (r=0.32; P=0.002 and r=0.22; P=0.04, respectively) while no correlation was found with milk and dairy products in spite of their greater contribution to total selenium intake. In this population of Icelandic adolescent girls, selenium intake and status seem acceptable. Judging from associations between intake and blood levels, fish and cereals may be the most important contributors to blood selenium.Landspitali University Hospital Research Fund Agricultural Productivity Fun

Coherent electronic transport in a multimode quantum channel with Gaussian-type scatterers

Coherent electron transport through a quantum channel in the presence of a general extended scattering potential is investigated using a T-matrix Lippmann-Schwinger approach. The formalism is applied to a quantum wire with Gaussian type scattering potentials, which can be used to model a single impurity, a quantum dot or more complicated structures in the wire. The well known dips in the conductance in the presence of attractive impurities is reproduced. A resonant transmission peak in the conductance is seen as the energy of the incident electron coincides with an energy level in the quantum dot. The conductance through a quantum wire in the presence of an asymmetric potential are also shown. In the case of a narrow potential parallel to the wire we find that two dips appear in the same subband which we ascribe to two quasi bound states originating from the next evanescent mode.Comment: RevTeX with 14 postscript figures include

Optical coherence tomography versus intravascular ultrasound to evaluate stent implantation in patients with calcific coronary artery disease

AIMS: Stent underexpansion and malapposition are associated with adverse outcomes following percutaneous coronary intervention, but detection and treatment can be challenging in the presence of extensive coronary artery calcification. Frequency domain optical coherence tomography (FD-OCT) is a novel intravascular imaging technique with greater spatial resolution than intravascular ultrasound (IVUS) but its role in the presence of extensive coronary calcification remains unclear. We sought to determine the utility of FD-OCT compared to IVUS imaging to guide percutaneous coronary intervention in patients with severe calcific coronary artery disease. METHODS: 18 matched IVUS and FD-OCT examinations were evaluated following coronary stent implantation in 12 patients (10 male; mean age 70±7 years) undergoing rotational atherectomy for symptomatic calcific coronary artery disease. RESULTS: In-stent luminal areas were smaller (minimum in-stent area 6.77±2.18 vs 7.19±2.62 mm(2), p<0.05), while reference lumen dimensions were similar with FD-OCT compared with IVUS. Stent malapposition was detected in all patients by FD-OCT and in 10 patients by IVUS. The extent of stent malapposition detected was greater (20% vs 6%, p<0.001) with FD-OCT compared to IVUS. Postdilation increased the in-stent luminal area (minimum in-stent area: 8.15±1.90 vs 7.30±1.62 mm(2), p<0.05) and reduced the extent of stent malapposition (19% vs 34%, p<0.005) when assessed by FD-OCT, but not IVUS. CONCLUSIONS: Acute stent malapposition occurs frequently in patients with calcific coronary disease undergoing rotational atherectomy and stent implantation. In the presence of extensive coronary artery calcification, FD-OCT affords enhanced stent visualisation and detection of malapposition, facilitating improved postdilation stent apposition and minimal luminal areas. TRIAL REGISTRATION NUMBER: NCT02065102

Meals, Microbiota and Mental Health in Children and Adolescents (MMM-Study) : A protocol for an observational longitudinal case-control study

Funding Information: This manuscript was partially funded by grant European Union's Horizon 2020 research and innovation program, grant GEMMA 825033 as well as by the University of Iceland Research Fund and The Landspitali University Hospital Scientific Fund. Publisher Copyright: © 2022 Asbjornsdottir et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Recent studies indicate that the interplay between diet, intestinal microbiota composition, and intestinal permeability can impact mental health. More than 10% of children and adolescents in Iceland suffer from mental disorders, and rates of psychotropics use are very high. The aim of this novel observational longitudinal case-control study, “Meals, Microbiota and Mental Health in Children and Adolescents (MMM-Study)” is to contribute to the promotion of treatment options for children and adolescents diagnosed with mental disorders through identification of patterns that may affect the symptoms. All children and adolescents, 5-15 years referred to the outpatient clinic of the Child and Adolescent Psychiatry Department at The National University Hospital in Reykjavik, Iceland, for one year (n≈150) will be invited to participate. There are two control groups, i.e., sex-matched children from the same postal area (n≈150) and same parent siblings (full siblings) in the same household close in age +/- 3 years (n<150). A three-day food diary, rating scales for mental health, and multiple questionnaires will be completed. Biosamples (fecal-, urine-, saliva-, blood samples, and buccal swab) will be collected and used for 16S rRNA gene amplicon sequencing of the oral and gut microbiome, measurements of serum factors, quantification of urine metabolites and host genotype, respectively. For longitudinal follow-up, data collection will be repeated after three years in the same groups. Integrative analysis of diet, gut microbiota, intestinal permeability, serum metabolites, and mental health will be conducted applying bioinformatics and systems biology approaches. Extensive population-based data of this quality has not been collected before, with collection repeated in three years' time, contributing to the high scientific value. The MMM-study follows the “Strengthening the Reporting of Observational Studies in Epidemiology” (STROBE) guidelines. Approval has been obtained from the Icelandic National Bioethics Committee, and the study is registered with Clinicaltrials.gov. The study will contribute to an improved understanding of the links between diet, gut microbiota and mental health in children through good quality study design by collecting information on multiple components, and a longitudinal approach. Furthermore, the study creates knowledge on possibilities for targeted and more personalized dietary and lifestyle interventions in subgroups.Peer reviewe

UPRIGHT, a resilience-based intervention to promote mental well-being in schools: study rationale and methodology for a European randomized controlled trial

Background: Adolescence is crucial period for laying the foundations for healthy development and mental wellbeing. The increasing prevalence of mental disorders amongst adolescents makes promotion of mental well-being and prevention interventions at schools important. UPRIGHT (Universal Preventive Resilience Intervention Globally implemented in schools to improve and promote mental Health for Teenagers) is designed as a whole school approach (school community, students and families) to promote a culture of mental well-being and prevent mental disorders by enhancing resilience capacities. The present article aims at describing the rationale, conceptual framework, as well as methodology of implementation and evaluation of the UPRIGHT intervention.Methods: UPRIGHT project is a research and innovation project funded by the European Union's Horizon 2020 Research and Innovation programme under grant agreement No. 754919 (Duration: 48 months). The theoretical framework has been developed by an innovative and multidisciplinary approach using a co-creation process inside the UPRIGHT Consortium (involving seven institutions from Spain, Italy, Poland, Norway, Denmark, and Iceland). Resulted is the UPRIGHT programme with 18 skills related to 4 components: Mindfulness, Coping, Efficacy and Social and Emotional Learning. Among the five Pan-European regions, 34 schools have been currently involved (17 control; 17 intervention) and around 6000 adolescents and their families are foreseen to participate along a 3-year period of evaluation. Effectiveness of the intervention will be evaluated as a randomized controlled trial including quantitative and qualitative analysis in the five Pan-European regions representative of the cultural and socioeconomic diversity. The cost-effectiveness assessment will be performed by simulation modelling methods.Discussion: We expect a short- to medium-term improvement of mental well-being in adolescents by enhancing resilience capacities. The study may provide robust evidence on intrapersonal, familiar and social environmental resilience factors promoting positive mental well-being.Trial registration: ClinicalTrials.gov Identifier: NCT03951376. Registered 15 May 2019

Safety of the Deferral of Coronary Revascularization on the Basis of Instantaneous Wave-Free Ratio and Fractional Flow Reserve Measurements in Stable Coronary Artery Disease and Acute Coronary Syndromes

OBJECTIVES The aim of this study was to investigate the clinical outcomes of patients deferred from coronary revascularization on the basis of instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements in stable angina pectoris (SAP) and acute coronary syndromes (ACS). BACKGROUND Assessment of coronary stenosis severity with pressure guidewires is recommended to determine the need for myocardial revascularization. METHODS The safety of deferral of coronary revascularization in the pooled per-protocol population (n = 4,486) of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) and iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trials was investigated. Patients were stratified according to revascularization decision making on the basis of iFR or FFR and to clinical presentation (SAP or ACS). The primary endpoint was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. RESULTS Coronary revascularization was deferred in 2,130 patients. Deferral was performed in 1,117 patients (50%) in the iFR group and 1,013 patients (45%) in the FFR group (p <0.01). At 1 year, the MACE rate in the deferred population was similar between the iFR and FFR groups (4.12% vs. 4.05%; fully adjusted hazard ratio: 1.13; 95% confidence interval: 0.72 to 1.79; p = 0.60). A clinical presentation with ACS was associated with a higher MACE rate compared with SAP in deferred patients (5.91% vs. 3.64% in ACS and SAP, respectively; fully adjusted hazard ratio: 0.61 in favor of SAP; 95% confidence interval: 0.38 to 0.99; p = 0.04). CONCLUSIONS Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year. (C) 2018 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.Peer reviewe

Physical and cognitive impact following SARS-CoV-2 infection in a large population-based case-control study

© 2023. The Author(s).BACKGROUND: Persistent symptoms are common after SARS-CoV-2 infection but correlation with objective measures is unclear. METHODS: We invited all 3098 adults who tested SARS-CoV-2 positive in Iceland before October 2020 to the deCODE Health Study. We compared multiple symptoms and physical measures between 1706 Icelanders with confirmed prior infection (cases) who participated, and 619 contemporary and 13,779 historical controls. Cases participated in the study 5-18 months after infection. RESULTS: Here we report that 41 of 88 symptoms are associated with prior infection, most significantly disturbed smell and taste, memory disturbance, and dyspnea. Measured objectively, cases had poorer smell and taste results, less grip strength, and poorer memory recall. Differences in grip strength and memory recall were small. No other objective measure associated with prior infection including heart rate, blood pressure, postural orthostatic tachycardia, oxygen saturation, exercise tolerance, hearing, and traditional inflammatory, cardiac, liver, and kidney blood biomarkers. There was no evidence of more anxiety or depression among cases. We estimate the prevalence of long Covid to be 7% at a median of 8 months after infection. CONCLUSIONS: We confirm that diverse symptoms are common months after SARS-CoV-2 infection but find few differences between cases and controls in objective parameters measured. These discrepancies between symptoms and physical measures suggest a more complicated contribution to symptoms related to prior infection than is captured with conventional tests. Traditional clinical assessment is not expected to be particularly informative in relating symptoms to a past SARS-CoV-2 infection.Peer reviewe

Successful percutaneous treatment of a mycotic right coronary to right ventricle fistula.

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Acute myocardial infarction in young adultsincidence, risk factors and prognosis

INNGANGUR Nýgengi bráðs hjartadreps hefur lækkað í almennu þýði á undanförnum áratugum en margt bendir til þess að þetta eigi ekki við um yngstu aldurshópana. Markmið þessarar rannsóknar var að kanna nýgengi, áhættuþætti og horfur eftir brátt hjartadrep meðal ungra einstaklinga hér á landi. EFNIVIÐUR OG AÐFERÐIR Rannsóknin var afturskyggn gagnarannsókn. Gögn fengust úr gagnagrunni SCAAR-SWEDEHEART, sjúkraskrám Landspítala og Dánarmeinaskrá landlæknis. Í rannsóknarþýðinu var faraldsfræði milli kvenna ≤55 ára og karla ≤50 ára sem greindust með brátt hjartadrep (STEMI/NSTEMI) á Íslandi á árunum 2014-2020 borin saman við eldri sjúklinga. NIÐURSTÖÐUR Af öllum STEMI- og NSTEMI-tilfellum á Íslandi á tímabilinu (2852) voru 344 sjúklingar (12%) ungir. Ekki var sýnt fram á breytingu á nýgengi bráðs hjartadreps meðal yngri aldurshópsins á tímabilinu. Hlutfall STEMI var hærra meðal yngri sjúklinga samanborið við eldri (52% á móti 35%, p30 kg/m2) (47% á móti 36%, p ÁLYKTANIR Á rannsóknartímabilinu var ekki sýnt fram á breytingu á nýgengi bráðs hjartadreps meðal yngri einstaklinga. Yngri einstaklingar með brátt hjartadrep hafa aðra áhættuþætti en þeir eldri, þeir hafa lægra dánarhlutfall en sömu líkur á endurteknu hjartadrepi ári eftir áfallið. INTRODUCTION: The incidence of acute myocardial infarction (AMI) might not be decreasing as much among young adults as in the general population in recent years. The goal of our study was to explore incidence, risk factors and prognosis of AMI among young patients in Iceland. MATERIAL AND METHODS: This was a retrospective case control study. The data was obtained from the SCAAR-SWEDEHEART database, medical records from Landspitali University Hospital and the death register from the Directorate of Health. The epidemiology of women ≤55 years and men ≤50 years diagnosed with AMI (STEMI/NSTEMI) in Iceland in 2014-2020 was compared with older patients. RESULTS: Of all the cases (2852), 344 patients (12%) were young. No change was demonstrated in the incidence of AMI in the young patients during the study period. The proportion of STEMI was higher among young patients (52% vs. 35%, p30 kg/m2)(47% vs. 36%, p<0.01) were more prevalent in younger patiens compared to the older. Older patients were more likely to die in the year following the AMI, both from all-cause (7% vs. 3%, p<0.05) and cardiovascular mortality (7% vs. 3%, p<0.05). A difference in recurrent AMI between the young and older patients was not demonstrated (2% vs. 3%, p=0.3). CONCLUSION: During the research period, a change in the incidence of AMI among young patients, was not demonstrated. Younger patients with AMI have different risk factors than older patients, they have lower mortality rate but the same risk of recurrent AMI.Peer reviewe