Abstract
The new elements from
Z
= 107 to 112 were synthesized in cold fusion reactions based on targets of lead and bismuth. The principle physical concepts are presented which led to the ...application of this reaction type in search experiments for new elements. Described are the technical developments from early mechanical devices to experiments with recoil separators. An overview is given of present experiments which use cold fusion for systematic studies and synthesis of new isotopes. Perspectives are also presented for the application of cold fusion reactions in synthesis of elements beyond element 113, the so far heaviest element produced in a cold fusion reaction. Further, the transition of hot fusion to cold fusion is pointed out, which occurs in reactions for synthesis of elements near
Z
= 126 using actinide targets and beams of neutron rich isotopes of elements from iron to germanium.
Some evidence suggests that heart rate variability (HRV) biofeedback might be an effective way to treat anxiety and stress symptoms. To examine the effect of HRV biofeedback on symptoms of anxiety ...and stress, we conducted a meta-analysis of studies extracted from PubMed, PsycINFO and the Cochrane Library.
The search identified 24 studies totaling 484 participants who received HRV biofeedback training for stress and anxiety. We conducted a random-effects meta-analysis.
The pre-post within-group effect size (Hedges' g) was 0.81. The between-groups analysis comparing biofeedback to a control condition yielded Hedges' g = 0.83. Moderator analyses revealed that treatment efficacy was not moderated by study year, risk of study bias, percentage of females, number of sessions, or presence of an anxiety disorder.
HRV biofeedback training is associated with a large reduction in self-reported stress and anxiety. Although more well-controlled studies are needed, this intervention offers a promising approach for treating stress and anxiety with wearable devices.
•Strongly non-linear load-deflection behaviour was observed for the DCB-specimen.•An effective stiffness was introduced in order to correlate results with LEFM.•GIC was significantly increasing with ...crack propagation.•Compliance calibration methods from test standards are not recommended for C/C-SiC.•Crack onset loads were predicted by FEA for varying initial crack lengths.
Delaminations are critical defects to the structural integrity of ceramic matrix composite (CMC) structures. They may be induced during processing due to differing shrinkage of fibres and matrix.
The focus of this work is on the crack onset in order to determine conservative load limits for locally delaminated samples and components. Therefore, the critical energy release rate is determined for carbon fibre reinforced silicon carbide, C/C-SiC, at varying initial crack lengths.
Double cantilever beam testing and a number of data reduction methods are applied on the fabric-reinforced C/C-SiC material. The resulting critical energy release rates are compared. The validation of the experimental energy release rate is done by cohesive zone modelling, using an average critical energy release rate in combination with a maximum stress criterion and a linear softening rule. A good agreement of numerical and experimental crack onset loads was obtained for varying initial crack lengths.
Anxiety disorders are highly prevalent. Fear conditioning and extinction learning in animals often serve as simple models of fear acquisition and exposure therapy of anxiety disorders in humans. This ...article reviews the empirical and theoretical literature on cognitive processes in fear acquisition, extinction, and exposure therapy. It is concluded that exposure therapy is a form of cognitive intervention that specifically changes the expectancy of harm. Implications for therapy research are discussed.
The rich phenomenology of twisted bilayer graphene (TBG) near the magic angle is believed to arise from electron correlations in topological flat bands. An unbiased approach to this problem is highly ...desirable, but also particularly challenging, given the multiple electron flavors, the topological obstruction to defining tight-binding models, and the long-ranged Coulomb interactions. While numerical simulations of realistic models have thus far been confined to zero temperature, typically excluding some spin or valley species, analytic progress has relied on fixed point models away from the realistic limit. Here, we present unbiased Monte Carlo simulations of realistic models of magic-angle TBG at charge neutrality. We establish the absence of a sign problem for this model in a momentum-space approach and describe a computationally tractable formulation that applies even on breaking chiral symmetry and including band dispersion. Our results include (i) the emergence of an insulating Kramers intervalley coherent ground state in competition with a correlated semimetal phase, (ii) detailed temperature evolution of order parameters and electronic spectral functions that reveal a “pseudogap” regime, in which gap features are established at a higher temperature than the onset of order, and (iii) predictions for electronic tunneling spectra and their evolution with temperature. Our results pave the way towards uncovering the physics of magic-angle graphene through exact simulations of over a hundred electrons across a wide temperature range.
The effects of antidepressants for treating depressive disorders have been overestimated because of selective publication of positive trials. Reanalyses that include unpublished trials have yielded ...reduced effect sizes. This in turn has led to claims that antidepressants have clinically insignificant advantages over placebo and that psychotherapy is therefore a better alternative. To test this, we conducted a meta-analysis of studies comparing psychotherapy with pill placebo.
Ten 10 studies comparing psychotherapies with pill placebo were identified. In total, 1240 patients were included in these studies. For each study, Hedges' g was calculated. Characteristics of the studies were extracted for subgroup and meta-regression analyses.
The effect of psychotherapy compared to pill placebo at post-test was g = 0.25 95% confidence interval (CI) 0.14-0.36, I² = 0%, 95% CI 0-58. This effect size corresponds to a number needed to treat (NNT) of 7.14 (95% CI 5.00-12.82). The psychotherapy conditions scored 2.66 points lower on the Hamilton Depression Rating Scale (HAMD) than the placebo conditions, and 3.20 points lower on the Beck Depression Inventory (BDI). Some indications for publication bias were found (two missing studies). We found no significant differences between subgroups of the studies and in meta-regression analyses we found no significant association between baseline severity and effect size.
Although there are differences between the role of placebo in psychotherapy and pharmacotherapy research, psychotherapy has an effect size that is comparable to that of antidepressant medications. Whether these effects should be deemed clinically relevant remains open to debate.
This article reviews the current state of knowledge concerning the use of powder-based three-dimensional printing (3DP) for the synthesis of bone tissue engineering scaffolds. 3DP is a solid ...free-form fabrication (SFF) technique building up complex open porous 3D structures layer by layer (a bottom-up approach). In contrast to traditional fabrication techniques generally subtracting material step by step (a top-down approach), SFF approaches allow nearly unlimited designs and a large variety of materials to be used for scaffold engineering. Today’s state of the art materials, as well as the mechanical and structural requirements for bone scaffolds, are summarized and discussed in relation to the technical feasibility of their use in 3DP. Advances in the field of 3DP are presented and compared with other SFF methods. Existing strategies on material and design control of scaffolds are reviewed. Finally, the possibilities and limiting factors are addressed and potential strategies to improve 3DP for scaffold engineering are proposed.
Nano-structured silicon anodes are attractive alternatives to graphitic carbons in rechargeable Li-ion batteries, owing to their extremely high capacities. Despite their advantages, numerous issues ...remain to be addressed, the most basic being to understand the complex kinetics and thermodynamics that control the reactions and structural rearrangements. Elucidating this necessitates real-time in situ metrologies, which are highly challenging, if the whole electrode structure is studied at an atomistic level for multiple cycles under realistic cycling conditions. Here we report that Si nanowires grown on a conducting carbon-fibre support provide a robust model battery system that can be studied by (7)Li in situ NMR spectroscopy. The method allows the (de)alloying reactions of the amorphous silicides to be followed in the 2nd cycle and beyond. In combination with density-functional theory calculations, the results provide insight into the amorphous and amorphous-to-crystalline lithium-silicide transformations, particularly those at low voltages, which are highly relevant to practical cycling strategies.
An auxiliary optimal control problem is formulated that provides with its unique solution, a continuous representation of the global error of a numerical approximation to the solution of a linear ...quadratic optimal control problem. The resulting error functions are characterized as the unique solutions to an optimality system that is reformulated as a boundary value problem. With this formulation, reliable pointwise error estimates can be generated utilizing well-established techniques of defect control. A novel algorithm based on defect correction and defect control is presented that generates pointwise approximations to the global error of numerical optimal control solutions on a uniform grid. It is proven and numerically validated that this algorithm can generate pointwise estimates that approximate the true global error with a prescribed accuracy.
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