Role of the spin-orbit splitting and the dynamical fluctuations in the Si(557)-Au surface

Our it ab initio calculations show that spin-orbit coupling is crucial to understand the electronic structure of the Si(557)-Au surface. The spin-orbit splitting produces the two one-dimensional bands observed in photoemission, which were previously attributed to spin-charge separation in a Luttinger liquid. This spin splitting might have relevance for future device applications. We also show that the apparent Peierls-like transition observed in this surface by scanning tunneling microscopy is a result of the dynamical fluctuations of the step-edge structure, which are quenched as the temperature is decreased

Structural models for the Si(553)-Au atomic chain reconstruction

Recent photoemission experiments on the Si(553)-Au reconstruction show a one-dimensional band with a peculiar ~1/4 filling. This band could provide an opportunity for observing large spin-charge separation if electron-electron interactions could be increased. To this end, it is necessary to understand in detail the origin of this surface band. A first step is the determination of the structure of the reconstruction. We present here a study of several structural models using first-principles density functional calculations. Our models are based on a plausible analogy with the similar and better known Si(557)-Au surface, and compared against the sole structure proposed to date for the Si(553)-Au system [Crain JN et al., 2004 Phys. Rev. B 69 125401 ]. Results for the energetics and the band structures are given. Lines for the future investigation are also sketched

First-principles study of the atomic and electronic structure of the Si(111)-(5x2-Au surface reconstruction

We present a systematic study of the atomic and electronic structure of the Si(111)-(5x2)-Au reconstruction using first-principles electronic structure calculations based on the density functional theory. We analyze the structural models proposed by Marks and Plass [Phys. Rev. Lett.75, 2172 (1995)], those proposed recently by Erwin [Phys. Rev. Lett.91, 206101 (2003)], and a completely new structure that was found during our structural optimizations. We study in detail the energetics and the structural and electronic properties of the different models. For the two most stable models, we also calculate the change in the surface energy as a function of the content of silicon adatoms for a realistic range of concentrations. Our new model is the energetically most favorable in the range of low adatom concentrations, while Erwin's "5x2" model becomes favorable for larger adatom concentrations. The crossing between the surface energies of both structures is found close to 1/2 adatoms per 5x2 unit cell, i.e. near the maximum adatom coverage observed in the experiments. Both models, the new structure and Erwin's "5x2" model, seem to provide a good description of many of the available experimental data, particularly of the angle-resolved photoemission measurements

Long-term clinical and economic outcomes in previously untreated paediatric patients with severe haemophilia A : A nationwide real-world study with 700 person-years

AimFor previously untreated patients (PUPs) with severe haemophilia A in Finland for the past 2 decades, the standard practice has been to start early primary prophylaxis. We evaluated the long-term clinical outcomes and costs of treatment with high-dose prophylaxis in PUPs from birth to adolescence, including immune tolerance induction (ITI). MethodsFrom the medical records of all PUPs born between June 1994 and May 2013 in Finland, we retrospectively extracted data on clinical outcomes and healthcare use. Using linear mixed models, we analysed longitudinal clinical outcome data. To analyse skewed cost data, including zero costs, we applied hurdle regression. ResultsAll 62 patients received early regular prophylaxis; totally, they have had treatment for nearly 700 patient-years. The median age of starting home treatment was 1.1years. The mean (SD) annual treatment costs (Europerkg) were 4391Euro (3852). For ages 1-3, ITI comprised over half of the costs; in other groups, prophylactic FVIII treatment dominated. With these high costs, however, clinical outcomes were desirable; median (IQR) ABR was low at 0.19 (0.07-0.46) and so was AJBR at 0.06 (0-0.24). Thirteen (21%) patients developed a clinically significant inhibitor, 10 (16%) with a high titre. All ITIs were successful. The mean costs for ITI were 383448Euro (259085). The expected ITI payback period was 1.81 (95% CI 0.62-12.12) years. ConclusionsEarly high-dose prophylaxis leads to excellent long-term clinical outcomes, and early childhood ITI therapy seems to turn cost-neutral generally already in 2years.Peer reviewe

Plasmon tunability in metallodielectric metamaterials

The dielectric properties of metamaterials consisting of periodically arranged metallic nanoparticles of spherical shape are calculated by rigorously solving Maxwell's equations. Effective dielectric functions are obtained by comparing the reflectivity of planar surfaces limiting these materials with Fresnel's formulas for equivalent homogeneous media, showing mixing and splitting of individual-particle modes due to inter-particle interaction. Detailed results for simple cubic and fcc crystals of aluminum spheres in vacuum, silver spheres in vacuum, and silver spheres in a silicon matrix are presented. The filling fraction of the metal f is shown to determine the position of the plasmon modes of these metamaterials. Significant deviations are observed with respect to Maxwell-Garnett effective medium theory for large f, and multiple plasmons are predicted to exist in contrast to Maxwell-Garnett theory.Comment: 6 pages, 4 figure

High-k GaAs metal insulator semiconductor capacitors passivated by ex-situ plasma-enhanced atomic layer deposited AlN for Fermi-level unpinning

This paper examines the utilization of plasma-enhanced atomic layer deposition grown AlN in the fabrication of a high-kinsulator layer on GaAs. It is shown that high-kGaAsMIS capacitors with an unpinned Fermi level can be fabricated utilizing a thin ex-situ deposited AlNpassivation layer. The illumination and temperature induced changes in the inversion side capacitance, and the maximum band bending of 1.2 eV indicates that the MIS capacitor reaches inversion. Removal of surface oxide is not required in contrast to many common ex-situ approaches.Peer reviewe

Luotanko vai enkö luota? Nuorten luottamus sosiaalisessa mediassa leviävään informaatioon ja siihen liittyviä tekijöitä.

The increasing role that social media plays as a source of news and information has both positive and negative effects from the viewpoint of democratic societies. As sharing information on social media is easy, it has also become easier to spread false information. False news, which can render manipulation of people’s views and thoughts remarkably easy, can be extremely challenging to detect. We approached youngsters’ trust in social media content as a potential risk factor; trust can reduce uncertainty and suspicion of information and thus predict the spread of disinformation and conspiracy theories. This may have negative effects on societal security. We aimed to examine what factors explain Finnish youngsters’ (15–19 years) trust in news and information in social media. The analysis was based on a survey (N=800) collected in 2019– 2020. Using regression analysis we found four factors that were positively associated with youngsters’ trust in news and information in social media; trust in traditional media, daily use of social media, following social media influencers, and the belief that approval ratings predict the trustworthiness of news. In addition, the belief that social media gives a distorted view of other people’s lives was negatively connected to trust in news and information. From a national security perspective, youngsters’ social media use is often harmless. However, as their identities and worldviews are still developing, they may act as a target group for information campaigns which aim to undermine the stability of society and disrupt national security. Therefore, it is crucial to understand more about youngsters’ trust in social media content and their ability to detect false information

Low-Load Metal-Assisted Catalytic Etching Produces Scalable Porosity in Si Powders

The recently discovered low-load metal-assisted catalytic etching (LL-MACE) creates nanostructured Si with controllable and variable characteristics that distinguish this technique from the conventional high-load variant. LL-MACE employs 150 times less metal catalyst and produces porous Si instead of Si nanowires. In this work, we demonstrate that some of the features of LL-MACE cannot be explained by the present understanding of MACE. With mechanistic insight derived from extensive experimentation, it is demonstrated that (1) the method allows the use of not only Ag, Pd, Pt, and Au as metal catalysts but also Cu and (2) judicious combinations of process parameters such as the type of metal, Si doping levels, and etching temperatures facilitate control over yield (0.065−88%), pore size (3−100 nm), specific surface area (20−310 m2·g−1), and specific pore volume (0.05−1.05 cm3·g−1). The porous structure of the product depends on the space-charge layer, which is controlled by the Si doping and the chemical identity of the deposited metal. The porous structure was also dependent on the dynamic structure of the deposited metal. A distinctive comet-like structure of metal nanoparticles was observed after etching with Cu, Ag, Pd, and, in some cases, Pt; this structure consisted of 10−50 nm main particles surrounded by smaller (\u3c5 nm) nanoparticles. With good scalability and precise control of structural properties, LL-MACE facilitates Si applications in photovoltaics, energy storage, biomedicine, and water purification

Keratoendotheliitis Fugax Hereditaria : A Novel Cryopyrin-Associated Periodic Syndrome Caused by a Mutation in the Nucleotide-Binding Domain, Leucine-Rich Repeat Family, Pyrin Domain-Containing 3 (NLRP3) Gene

PURPOSE: To describe the phenotype and the genetic defect in keratoendotheliitis fugax hereditaria, an autosomal dominant keratitis that periodically affects the corneal endothelium and stroma, leading in some patients to opacities and decreased visual acuity. DESIGN: Cross-sectional, hospital-based study. METHODS: PATIENT POPULATION: Thirty affected and 7 unaffected subjects from 7 families, and 4 sporadic patients from Finland. OBSERVATION PROCEDURES: Ophthalmic examination and photography, corneal topography, specular microscopy, and optical coherence tomography in 34 patients, whole exome sequencing in 10 patients, and Sanger sequencing in 34 patients. MAIN OUTCOME MEASURES: Clinical phenotype, disease causing genetic variants. RESULTS: Unilateral attacks of keratoendotheliitis typically occurred 1-6 times a year (median, 2.5), starting at a median age of 11 years (range, 5-28 years), and lasted for 1-2 days. The attacks were characterized by cornea pseudoguttata and haze in the posterior corneal stroma, sometimes with a mild anterior chamber reaction, and got milder and less frequent in middle age. Seventeen (50%) patients had bilateral stroma! opacities. The disease was inherited as an autosomal dominant trait. A likely pathogenic variant c.61G > C in the NLRP3 gene, encoding cryopyrin, was detected in all 34 tested patients and segregated with the disease. This variant is present in both Finnish and non-Finnish European populations at a frequency of about 0.02% and 0.01%, respectively. CONCLUSION: Keratoendotheliitis fugax hereditaria is an autoinflammatory cryopyrin-associated periodic syndrome caused by a missense mutation c.61G > C in exon 1 of NLRP3 in Finnish patients. It is additionally expected to occur in other populations of European descent. ((c) 2018 The Author(s). Published by Elsevier Inc.Peer reviewe

Ion beam shaping and downsizing of nanostructures

We report a new approach for progressive and well-controlled downsizing of nanostructures below the 10 nm scale. Low energetic ion beam (Ar+) is used for gentle surface erosion, progressively shrinking the dimensions with ~ 1 nm accuracy. The method enables shaping of nanostructure geometry and polishing the surface. The process is clean room / high vacuum compatible being suitable for various applications. Apart from technological advantages, the method enables study of various size phenomena on the same sample between sessions of ion beam treatment.Comment: 14 pages, 6 figure