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In recent years, the discovery of massive quasars at
has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.
A lasting legacy of the International Polar Year (IPY) 2007–2008 was the promotion of the Permafrost Young Researchers Network (PYRN), initially an IPY outreach and education activity by the International Permafrost Association (IPA). With the momentum of IPY, PYRN developed into a thriving network that still connects young permafrost scientists, engineers, and researchers from other disciplines. This research note summarises (1) PYRN’s development since 2005 and the IPY’s role, (2) the first 2015 PYRN census and survey results, and (3) PYRN’s future plans to improve international and interdisciplinary exchange between young researchers. The review concludes that PYRN is an established network within the polar research community that has continually developed since 2005. PYRN’s successful activities were largely fostered by IPY. With >200 of the 1200 registered members active and engaged, PYRN is capitalising on the availability of social media tools and rising to meet environmental challenges while maintaining its role as a successful network honouring the legacy of IPY.
We extend Følner’s amenability criterion to the realm of general topological groups. Building on this, we show that a topological group
is amenable if and only if its left-translation action can be approximated in a uniform manner by amenable actions on the set
. As applications we obtain a topological version of Whyte’s geometric solution to the von Neumann problem and give an affirmative answer to a question posed by Rosendal.
The transit of the planet orbiting HD209458 has been observed using VLT/UVES, in search for faint signatures of an extended envelope of gas possibly surrounding the planet, called exosphere. Preliminary results are shown and described. They show no evidence so far of exospheric signatures.
Empathy is a basic human ability, and patients with schizophrenia show
dysfunctional empathic abilities on the behavioural and neural level.
These dysfunctions may precede the onset of illness; thus, it seems
mandatory to examine the empathic abilities in individuals at clinical
high risk for psychosis.
Using functional magnetic resonance imaging, we measured 15 individuals
at clinical high risk of psychosis (CHR group) and compared their empathy
performance with 15 healthy volunteers and 15 patients with
Behavioural data analysis indicated no significant deficit in the CHR
group. Functional data analysis revealed hyperactivation in a
frontotemporoparietal network including the amygdala in the CHR group
compared with the other two groups.
Despite normal behavioural performance, the CHR group activated the
neural empathy network differently and specifically showed
hyperactivation in regions critical for emotion processing. This could
suggest a compensatory mechanism reflecting emotional hypersensitivity or
dysfunctional emotion regulation. Further investigations should clarify
the role of these neural alterations for development and exacerbation of
The aim of the present study was to examine the association between intake of five common antioxidative nutrients from supplements and medications (vitamin E, vitamin C, carotenoids, Se, and Zn) and levels of high-sensitivity C-reactive protein (hs-CRP) in the general population. For this purpose, a total of 2924 participants of the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 study (2006–8) were investigated cross-sectionally. Intake of dietary supplements and medication during the last 7 d was recorded in a personal interview, when participants were asked to show product packages of ingested preparations. Linear regression models were calculated; first, the exposure to regular nutrient intake was treated with a binary response (yes/no); then regularly ingested amounts were divided into quartiles to examine dose–response relationships. Effect of single v. combined supplementation of antioxidants was assessed through the inclusion of interaction terms into the models. Regular intake of any of the five investigated antioxidants per se was not associated with hs-CRP levels. However, dose–response analyses revealed that participants who regularly ingested more than 78 mg vitamin E/d, which corresponds to the upper quartile, had 22 % lower hs-CRP levels (95 % CI 0·63, 0·97) compared to those of persons who were not exposed to any vitamin E supplementation. Stratified analyses showed that this association was found only in persons who took vitamin E in combination with other antioxidants. The combined supplementation of vitamin E with other antioxidants could thus be a promising strategy for the prevention of inflammation-related diseases in the general population, if further studies could confirm that the proposed association is causal.
In this study, Vickers indentation was used to investigate the two-way shape-memory effect (TWSME) in an austenitic Ti-50.9 at.% Ni alloy, exposed to different heat treatments. Three aging treatments were used to manipulate the size of Ti3Ni4 precipitates. All samples were Vickers indented, and the indent depth was investigated as function of thermal cycling. The TWSME was found only in the material aged at 400 °C, which contained coherent precipitates. Thermal cycling shows stable TWSME, however, heating well above the austenite finish temperature lead to permanent austenitic protrusions. The results indicate that stabilized martensite plays a critical role in creating TWSME surfaces.
The objectives were to conduct a meta-analysis in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards to determine effect sizes (Cohen's d) for cognitive dysfunction in adults with type 2 diabetes, relative to nondiabetic controls, and to obtain effect sizes for the most commonly reported neuropsychological tests within domains. Twenty-four studies, totaling 26,137 patients (n = 3351 with diabetes), met study inclusion criteria. Small to moderate effect sizes were obtained for five of six domains: motor function (3 studies, n = 2374; d = −0.36), executive function (12 studies, n = 1784; d = −0.33), processing speed (16 studies, n = 3076; d = −0.33), verbal memory (15 studies, n = 4,608; d = −0.28), and visual memory (6 studies, n = 1754; d = −0.26). Effect size was smallest for attention/concentration (14 studies, n = 23,143; d = −0.19). The following tests demonstrated the most notable performance decrements in diabetes samples: Grooved Pegboard (dominant hand) (d = −0.60), Rey Auditory Verbal Learning Test (immediate) (d = −0.40), Trails B (d = −0.39), Rey-Osterreith Complex Figure (delayed) (d = −0.38), Trails A (d = −0.34), and Stroop Part I (d = −0.28). This study provides effect sizes to power future epidemiological and clinical diabetes research studies examining cognitive function and to help inform the selection of neuropsychological tests. (JINS, 2014, 20, 1–14)
A layered composite coating material with favorable properties for application as a transparent conductor is presented. It is composed of layers of three nanoscopic materials, namely zinc oxide nanoparticles, single wall nanotubes, and graphene oxide nanosheets. The electrically conducting layer consists of single wall nanotubes (SWNTs). The layer of zinc oxide nanoparticles acts as a primer. It increases the adhesion and the stability of the films against mechanical stresses. The top layer of graphene oxide enhances the conductivity of such coatings. Such three-layer composite coatings show better conductivity (without compromising transparency) and improved mechanical stability compared to pure SWNT films. The processes used in the preparation of such coatings are easily scalable.
Now that most countries have harmonized intellectual property right (IPR) legislation as a consequence of signing the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPs), the dispute about the optimal level of IPR protection has shifted toward IPR enforcement. This paper develops an endogenous growth framework with two open economies satisfying the classical North–South assumptions to study (a) the regions' incentives to enforce IPRs in a decentralized game, (b) the desired IPR enforcement of the two regions in negotiation rounds on global harmonization, and (c) the constrained efficient enforcement level. We show how the different solutions relate to each other and how the results depend on the research productivity in the North and the regions' relative market sizes. Although growth rates increase substantially when IPR enforcement is harmonized at the North's desired level, our numerical simulation suggests that the South may also benefit in terms of long-run welfare.
Four acrylate-based networks were developed such that they possessed similar glass transition temperature (~− 37 °C) but varied in material stiffness at room temperature by an order of magnitude (2–12 MPa). Thermo-mechanical and adhesion testing were performed to investigate the effect of elastic modulus on adhesion profiles of the developed samples. Adhesion experiments with a spherical probe revealed no dependency of the pull-off force on material modulus as predicted by the Johnson, Kendall, and Roberts theory. Results obtained using a flat probe showed that the pull-off force increases linearly with an increase in the material modulus, which matches very well with Kendall's theory.
We analyzed the contact mechanisms of bioinspired microfibrillar adhesives using in situ scanning electron microscopy. During adhesion tests we observed that (i) the superior adhesion of mushroom-shaped fibrils is assisted by the stochastic nature of detachment, (ii) the aspect ratio of microfibrils influences the bending/buckling behavior and the contact reformation, and (iii) the backing layer deformation causes the microfibrils to elastically interact with each other. These studies give new insights into the mechanisms responsible for adhesion of bioinspired fibrillar adhesives.
The mechanical properties of thin metal films as compared to their bulk counterparts have been in the focus of materials science in the recent years. Owing to their technological importance, almost only metals with a face centered cubic structure like copper and aluminum have attracted scientific interest. Thin films made of bcc metals, on the other hand, have been largely neglected.
However, from a scientific point of view, the mechanical properties of bcc metals are of special interest. As an example, the yield stress of bcc metals is strongly temperature dependent for low temperatures, while it shows a behavior similar to fcc metals for higher temperatures. This is often referred to as the brittle to ductile transition (BDT). Despite intense research the underlying mechanisms leading to this phenomenon are still not understood in full detail. A major problem is the understanding of dislocation dynamics on the microscopic scale, which is different from that of fcc metals because of the special symmetry of the crystal system.
A first step is to verify in thin films that for temperatures above the BDT the thermomechanical behavior of bcc metals resembles that of fcc metals. As a model system we chose iron with a BDT temperature slightly above room temperature. We deposited iron by means of an MBE system on sapphire substrates. The so-produced epitaxial thin iron films with thicknesses above 50 nm were then thermally cycled from room temperature to 540°C in a vacuum substrate curvature apparatus to test their thermomechanical behavior.
We will present the results of substrate curvature measurements performed with iron films of different thicknesses and discuss similarities and differences to results obtained for metals with fcc crystal structures.
Micro-Raman spectroscopy is used to measure stress distributions in 1.5 µm thick polycrystalline silicon thin film solar cells on glass. These measurements are combined with transmission electron microscopy and atomic force microscopy to assign the measured local stresses to the sample's microstructure. Expansion and contraction of the silicon lattice in the layer and the borosilicate glass substrate during the thermal processing of the solar cell as well as quartz beads of µm size that reside on the glass substrate for light-trapping purposes induce internal stresses that locally vary with structural features. While the thermal processing induces an average tensile stress in the silicon layer originating from the thermal mismatch between glass and silicon, the latter results in lateral stress gradients up to 208 ± 12 MPa in the mapped area.
Cu(In, Ga)Se2 (CIGS) solar cells have been fabricated on different metal foil substrates. Preferred foils with regard to costs and physical properties were stainless steel, titanium and Kovar® (Fe/Ni/Co alloy). SiOx films prepared by PECVD and sol/gel methods were deposited as barrier layers on these metal foil substrates. Both film types showed good suitability as diffusion barriers for substrate elements. In the SiOx:Na (sol/gel) barrier sodium could be incorporated to provide the Na-supply to the CIGS absorber. With relatively low sodium concentrations in these films (6% Na2O) large amounts of Na in the absorber have been found. Using a combination of SiOx (PECVD) and SiOx:Na (sol/gel) layers AM 1.5 cell efficiencies of 13.1% on titanium foil substrates have been achieved. With a newly implemented insulation test based on electrolysis measurements pinholes in the barrier layers could be localized and conclusions on their origin could be drawn.
In this work, different set-ups as well as different transducer materials have been investigated in order to develop a hydrogen peroxide (H2O2) sensor for the gas phase. The sensor is based on a combined physical/chemical transduction mechanism and should be able to detect high H2O2 concentrations up to 10 Vol.%. Different sensor arrangements are presented that are based on a “three sensor” cell and a diffusion cell. As transducer materials manganese oxide and copper alloys have been investigated. For the reference part of the sensor set-up, Teflon and enamel have been tested as passivating material.
Compression tests with varying loading rates were performed on  and  oriented small-scale bcc Mo and Nb pillars to determine the contribution of thermally activated screw dislocation motion during deformation. Calculated activation volumes were shown to be in the range of 2 - 9 b3 and by further examination were found to decrease with pillar diameter. This suggests that the kink-pair nucleation of screw dislocations is enhanced by surface effects in the micron and submicron range.