Consent bias in research: how to avoid it

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Between the scales: water from different perspectives

In der vorliegenden Arbeit werden verschiedene Wassermodelle in sogenannten Multiskalen-Computersimulationen mit zwei Auflösungen untersucht, in atomistischer Auflösung und in einer vergröberten Auflösung, die als "coarse-grained" bezeichnet wird. In der atomistischen Auflösung wird ein Wassermolekül, entsprechend seiner chemischen Struktur, durch drei Atome beschrieben, im Gegensatz dazu wird ein Molekül in der coarse-grained Auflösung durch eine Kugel dargestellt.rnrnDie coarse-grained Modelle, die in dieser Arbeit vorgestellt werden, werden mit verschiedenen coarse-graining Methoden entwickelt. Hierbei kommen hauptsächlich die "iterative Boltzmann Inversion" und die "iterative Monte Carlo Inversion" zum Einsatz. Beides sind struktur-basierte Ansätze, die darauf abzielen bestimmte strukturelle Eigenschaften, wie etwa die Paarverteilungsfunktionen, des zugrundeliegenden atomistischen Systems zu reproduzieren. Zur automatisierten Anwendung dieser Methoden wurde das Softwarepaket "Versatile Object-oriented Toolkit for Coarse-Graining Applications" (VOTCA) entwickelt.rnrnEs wird untersucht, in welchem Maße coarse-grained Modelle mehrere Eigenschaftenrndes zugrundeliegenden atomistischen Modells gleichzeitig reproduzieren können, z.B. thermodynamische Eigenschaften wie Druck und Kompressibilität oder strukturelle Eigenschaften, die nicht zur Modellbildung verwendet wurden, z.B. das tetraedrische Packungsverhalten, welches für viele spezielle Eigenschaft von Wasser verantwortlich ist.rnrnMit Hilfe des "Adaptive Resolution Schemes" werden beide Auflösungen in einer Simulation kombiniert. Dabei profitiert man von den Vorteilen beider Modelle:rnVon der detaillierten Darstellung eines räumlich kleinen Bereichs in atomistischer Auflösung und von der rechnerischen Effizienz des coarse-grained Modells, die den Bereich simulierbarer Zeit- und Längenskalen vergrössert.rnrnIn diesen Simulationen kann der Einfluss des Wasserstoffbrückenbindungsnetzwerks auf die Hydration von Fullerenen untersucht werden. Es zeigt sich, dass die Struktur der Wassermoleküle an der Oberfläche hauptsächlich von der Art der Wechselwirkung zwischen dem Fulleren und Wasser und weniger von dem Wasserstoffbrückenbindungsnetzwerk dominiert wird.rnWater is one of the most frequently studied fluids on earth. In this thesis, water was investigated at two resolutions using multi-scale computer simulation techniques. First, the atomistic and coarse-grained resolutions were studied separately. In the atomistic resolution, a~water molecule is described chemically by three atoms, while in the coarse-grained case, a~molecule is modeled by a~sphere.rnrnIn this work, various coarse-grained models have been developed using different coarse-graining techniques, mainly iterative Boltzmann inversion and iterative inverse Monte Carlo, which are structure-based approaches that aim to reproduce distributions, such as the pair distribution functions, of the atomistic model. In this context the Versatile Object-oriented Toolkit for Coarse-graining applications (VOTCA) was developed.rnrnIt was studied to which extent the coarse-grained models can simultaneously reproduce several properties of the underlying atomistic model, such as thermodynamic properties like pressure and compressibility or structural properties, which have not been used in the coarse-graining process, e.g. the tetrahedral packing behavior, which is responsible for many special properties of water.rnrnSubsequently, these two resolutions were combined using the adaptive resolution scheme, which combines the advantage of atomistic details in a~small cavity of high resolution with the computational efficiency of the coarse-grained model in order to access larger time and length scales. In this scheme, the introduced coarse-grained models were used to study the influence of the hydrogen bonds on the hydration of small fullerenes. It was found that the interface structure is more dependent on the nature of the interaction between the solute and water molecules than on the presence of the hydrogen bond network.r

Comment on "Electromagnetic dissociation of ^8B and the astrophysical S-factor for ^7Be(p,gamma)^8B"

Recently, Davids and Typel recommended a "low" value of S_{17}(0) based on fits to published direct and Coulomb dissociation data, in which they excluded the precise result of Junghans et al. We show that their statistical analysis is incorrect, due to a substantial underestimate of the experimental uncertainties, and leads to conclusions that are not supported by a proper analysis.Comment: submitted to Phys. Rev.

Recruiting patients to medical research: double blind randomised trial of "opt-in" versus "opt-out" strategies

Objective To evaluate the effect of opt-in compared with opt-out recruitment strategies on response rate and selection bias. Design Double blind randomised controlled trial. Setting Two general practices in England. Participants 510 patients with angina. Intervention Patients were randomly allocated to an opt-in (asked to actively signal willingness to participate in research) or opt-out (contacted repeatedly unless they signalled unwillingness to participate) approach for recruitment to an observational prognostic study of patients with angina. Main outcome measures Recruitment rate and clinical characteristics of patients. Results The recruitment rate, defined by clinic attendance, was 38% (96/252) in the opt-in arm and 50% (128/258) in the opt-out arm (P = 0.014). Once an appointment had been made, non-attendance at the clinic was similar (20% opt-in arm v 17% opt-out arm; P = 0.86). Patients in the opt-in arm had fewer risk factors (44% v 60%; P = 0.053), less treatment for angina (69% v 82%; P = 0.010), and less functional impairment (9% v 20%; P = 0.023) than patients in the opt-out arm. Conclusions The opt-in approach to participant recruitment, increasingly required by ethics committees, resulted in lower response rates and a biased sample. We propose that the opt-out approach should be the default recruitment strategy for studies with low risk to participants

Classical-path integral adaptive resolution in molecular simulation: towards a smooth quantum-classical coupling

Simulations that couple different classical molecular models in an adaptive way by changing the number of degrees of freedom on the fly, are available within reasonably consistent theoretical frameworks. The same does not occur when it comes to classical-quantum adaptivity. The main reason for this is the difficulty in describing a continuous transition between the two different kind of physical principles: probabilistic for the quantum and deterministic for the classical. Here we report the basic principles of an algorithm that allows for a continuous and smooth transition by employing the path integral description of atoms.Comment: 8 pages 4 figure

Localised anti-branes in non-compact throats at zero and finite T

We investigate the 3-form singularities that are typical to anti-brane solutions in supergravity and check whether they can be cloaked by a finite temperature horizon. For anti-D3-branes in the Klebanov-Strassler background, this was already shown numerically to be impossible when the branes are partially smeared. In this paper, we present analytic arguments that also localised branes remain with singular 3-form fluxes at both zero and finite temperature. These results may have important, possibly fatal, consequences for constructions of meta-stable de Sitter vacua through uplifting.Comment: 18 + 9 page

A neutral low-coordinate heterocyclic bismuth-tin species

The reaction of distannadiazane bearing bulky RAr*-groups (RAr* = C6H2{C(H)Ph2}2R-2,6,4; R = iPr, tBu) with ECl3 (E = Sb, Bi) was studied resulting in the isolation of previously unknown N,N-bis(dichloropnictino)amines (3) and a novel heterocyclic carbenoid bismuth species (4) bearing a Bi(III) and a Sn(IV) center. The structure and bonding was investigated by means of X-ray structure elucidations and DFT calculations

Learning from the universal, proactive outreach of the Brazilian Community Health Worker model: impact of a Community Health and Wellbeing Worker initiative on vaccination, cancer screening and NHS health check uptake in a deprived community in the UK

Background Delays in preventative service uptake are increasing in the UK. Universal, comprehensive monthly outreach by Community Health and Wellbeing Workers (CHW), who are integrated at the GP practice and local authority, offer a promising alternative to general public health campaigns as it personalises health promotion and prevention of disease holistically at the household level. We sought to test the ability of this model, which is based on the Brazilian Family Health Strategy, to increase prevention uptake in the UK. Methods Analysis of primary care patient records for 662 households that were allocated to five CHWWs from July 2021. Primary outcome was the Composite Referral Completion Indicator (CRCI), a measure of how many health promotion activities were received by members of a household relative to the ones that they were eligible for during the period July 2021-April 2022. The CRCI was compared between the intervention group (those who had received at least one visit) and the control group (allocated households that were yet to receive a visit). A secondary outcome was the number of GP visits in the intervention and control groups during the study period and compared to a year prior. Results Intervention and control groups were largely comparable in terms of household occupancy and service eligibilities. A total of 2251 patients in 662 corresponding households were allocated to 5 CHWs and 160 households had received at least one visit during the intervention period. The remaining households were included in the control group. Overall service uptake was 40% higher in the intervention group compared to control group (CRCI: 0.21 ± 0.15 and 0.15 ± 0.19 respectively). Likelihood of immunisation uptake specifically was 47% higher and cancer screening and NHS Health Checks was 82% higher. The average number of GP consultations per household decreased by 7.4% in the intervention group over the first 10 months of the pilot compared to the 10 months preceding its start, compared with a 0.6% decrease in the control group. Conclusions Despite the short study period these are promising findings in this deprived, traditionally hard to reach community and demonstrates potential for the Brazilian community health worker model to be impactful in the UK. Further analysis is needed to examine if this approach can reduce health inequalities and increase cost effectiveness of health promotion approaches