Sunspot rotation. I. A consequence of flux emergence

Context. Solar eruptions and high flare activity often accompany the rapid rotation of sunspots. The study of sunspot rotation and the mechanisms driving this motion are therefore key to our understanding of how the solar atmosphere attains the conditions necessary for large energy release. Aims. We aim to demonstrate and investigate the rotation of sunspots in a 3D numerical experiment of the emergence of a magnetic flux tube as it rises through the solar interior and emerges into the atmosphere. Furthermore, we seek to show that the sub-photospheric twist stored in the interior is injected into the solar atmosphere by means of a definitive rotation of the sunspots. Methods. A numerical experiment is performed to solve the 3D resistive magnetohydrodynamic (MHD) equations using a Lagrangian-Remap code. We track the emergence of a toroidal flux tube as it rises through the solar interior and emerges into the atmosphere investigating various quantities related to both the magnetic field and plasma. Results. Through detailed analysis of the numerical experiment, we find clear evidence that the photospheric footprints or sunspots of the flux tube undergo a rotation. Significant vertical vortical motions are found to develop within the two polarity sources after the field emerges. These rotational motions are found to leave the interior portion of the field untwisted and twist up the atmospheric portion of the field. This is shown by our analysis of the relative magnetic helicity as a significant portion of the interior helicity is transported to the atmosphere. In addition, there is a substantial transport of magnetic energy to the atmosphere. Rotation angles are also calculated by tracing selected fieldlines; the fieldlines threading through the sunspot are found to rotate through angles of up to 353 degrees over the course of the experiment

Probation, credibility and justice

This paper explores the difficulties that arise for probation agencies or those that deliver community sanctions in developing and maintaining their credibility in prevailing ‘late-modern’ social conditions. It begins by questioning the limits of the pursuit and promise of ‘public protection’ as a source of credibility, and then proceeds to examine the emergence of an alternative strategy – based principally on reparation and ‘payback’ – in Scotland, arguing that these Scottish developments have much to say to the emerging debates in England and Wales (and elsewhere) about the ‘rehabilitation revolution’ and the proper use of imprisonment. The paper provides a critical account of the development and meaning of the Scottish version of ‘payback’, linking it to some important philosophical and empirical studies that may help to steer the development of payback away from a ‘merely punitive’ drift. In the conclusion, I argue that probation agencies and services need to engage much more deeply and urgently with their roles as justice services, rather than as ‘mere’ crime reduction agencies

Systematic Review on the Associations between Objectively Measured Breaks in Sitting Time and Cardiovascular Health in Youth

The aim of this systematic review was to summarize the literature on the associations between breaks in sitting time and cardiovascular health, in children and adolescents. The search was conducted using five databases (MEDLINE, SCOPUS, WEB OF SCIENCE, PSYCINFO and CINAHL) through to 01 October 2019. Due to heterogeneity of the data, meta-analyses were not possible. We screened 2577 studies, and 15 studies were included, representing 9116 participants, from six different countries. Five observational studies and four experimental studies showed associations between breaks in sitting time and cardiovascular health, i.e. an increased number of breaks in sitting time was negatively associated with a cardiovascular health outcome. No associations between number of breaks in sitting time and cardiovascular health outcomes were found in the six remaining studies. Studies examining associations between breaks in sitting time and cardiovascular health in children have shown some favorable associations. More epidemiological evidence is required, to inform lifestyle interventions and public health policies, which could translate into long-term implications on population health

England SimSmoke: the impact of nicotine vaping on smoking prevalence and smoking‐attributable deaths in England

BACKGROUND AND AIMS: While the use of nicotine vaping products (NVPs) is widespread, their impact on smoking prevalence is controversial. This study considered the potential impact of NVPs on smoking prevalence in England. DESIGN: Indirect simulation model. The England SimSmoke model is validated through 2012, before NVP use became more widely used by smokers. Because information on NVP-related transitions is limited, an indirect method is used; the difference in observed smoking prevalence (reflecting NVPs) is compared with a 2012-2019 counterfactual No-NVP scenario (without NVPs) to estimate the impact of NVPs on smoking and smoking-attributable deaths. SETTING: England, 2000-2019. PARTICIPANTS: Nationally representative sample of population. MEASUREMENTS: England's population, mortality rates, and smoking prevalence estimates from three national surveys and tobacco control policies. FINDINGS: Between 2000 and 2012, SimSmoke projected a decline in age 18+ smoking prevalence of 23.5% in men and 27.0% in women. These projections, as well as those by specific age groups, were generally consistent with findings from the three national surveys. Comparing 2012-2019 relative reduction in age 18+ prevalence from the Annual Population Survey (males 27.5%) with the model-predicted No-NVP reduction (males 7.3%), the implied NVP-attributable relative reduction in adult smoking prevalence was 20.2% (95% CI, 18.8%-22.0%) for males and 20.4% (18.7%-22.2%) for females. The NVP-attributable reduction was 27.2% (22.8%-31.6%) for males and 31.7% (27.4%-36.5%) for females ages 18-24 and 18.6% (15.2%-21.8%) for males and 15.0% (11.1%-18.8%) for females ages 25-34, with similar reductions for ages 35 and above. The implied reduction in smoking prevalence between 2012 and 2019 equates to 165,660 (132,453-199,501) averted deaths by 2052. Other surveys yielded smaller, but relatively consistent results. CONCLUSIONS: An indirect method of simulation modeling indicates that substantial reductions in smoking prevalence occurred in England from 2012 to 2019 coinciding with the growth in nicotine vaping product use

Mental health professionals' perceptions, judgements and decision-making practices regarding the use of electronic cigarettes as a tobacco harm reduction intervention in mental healthcare: A qualitative focus group study

Background: Smoking prevalence remains significantly higher among individuals with mental health conditions compared with the general population. Tobacco harm reduction (THR) in the form of replacing cigarettes for electronic cigarettes (ECs) is an alternative approach which may prove useful for these smokers who find it difficult to quit. Exploring how mental health professionals' (MHPs) perceive ECs, and how these influence decision making regarding their use in clinical settings is essential to determine the feasibility of incorporating ECs into the treatment pathway. Methods: We conducted six focus groups between March and August 2017. A total of 39 MHPs were recruited from mental healthcare services in England. Discussions were guided by a semi-structured guide, and responses were recorded, transcribed and coded using thematic framework analysis. Results: MHPs generally adopt a risk-averse approach when judging the safety and suitability of ECs. Risk-aversion was influenced by perceived obscurity surrounding ECs and THR, as well as high exposure to adverse and unreliable information regarding ECs, and perceived analogies between ECs and conventional cigarettes. Some MHPs adopt a pragmatic approach when making decisions based on THR and EC use in daily practice by considering the context of treatment and patient circumstances. However, this is often accompanied by a high degree of caution and misconceptions which limits the potential benefit this intervention could have in mental healthcare settings. Conclusion: Improved dissemination of national guidance and scientific literature regarding THR and ECs is essential in mental healthcare to eliminate misconceptions and better inform MHPs evidence-based decision-making practices

Different energetics at donor:acceptor interfaces in bilayer and bulk-heterojunction polymer:non-fullerene organic solar cells

To understand the limitations placed on the open-circuit voltage of bulk heterojunction (BHJ) organic solar cells, the energy levels of neat donor and acceptor samples are often characterized and applied to study BHJ blends. However, energy levels derived from neat samples may not necessarily reflect those at the donor:acceptor interface in blends. The properties of organic semiconductors are sensitive to microstructural changes, with non-fullerene acceptors (NFAs) in particular known to exhibit different thin-film polymorphs. To investigate the influence of differences in molecular packing in neat and blend films, temperature-dependent current–voltage characteristics are measured for bilayer (BL) and BHJ devices. Herein, the fullerene acceptor PC71BM is compared—whose energy levels are expected to be less sensitive to molecular packing—with the NFA ITIC, paired with the same donor polymer PTB7-Th. It is found that the interfacial energy levels differ for BL and BHJ devices for the PTB7-Th:ITIC system but remain the same for the PTB7-Th:PC71BM system. Furthermore, X-ray scattering measurements identify that ITIC exhibits a different packing mode in neat films and in BHJ blends. Such microstructure-dependent differences between neat and blend samples need to be considered when studying energy losses in NFA BHJ solar cells

An alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses

A new synthetic route, to prepare an alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor (C8-ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new acceptor C8-ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB-T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB-T. The resulting blend with C8-ITIC shows an impressive PCE up to 13.2% as a result of the higher open-circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB-T/C8-ITIC-based cells exhibiting a small energy loss of 0.6 eV combined with a high JSCof 19.6 mA cm-2

Diversifying crop rotations with temporary grasslands : potentials for weed management and farmland biodiversity

Crop rotation may be used to prevent the continuous selection of particular weed species adapted to one crop type. This might be useful for weed management, economy in herbicide applications and promoting biodiversity. Common simple crop sequences might be diversified by introducing perennial forage crops. Impacts of such perennial crops on weeds were studied with four approaches: 1) Large-scale weed surveys in 632 fields in western France showed that weed species composition differed most strongly between perennial alfalfa crops and annual crops. Comparisons of fields before, during and after perennial alfalfa suggested that community composition varies in a cyclic way during such crop rotations. Several weed species problematic in annual crops were suppressed during and after perennial crops, but the appearance of other species led to equal or even higher plant diversities. 2) A 3-year field experiment with contrasting crop management options allowed an investigation of the underlying mechanisms for this: The absence of soil tillage reduced weed emergence but increased the survival of established plants. The permanent vegetation cover and frequent hay cuttings reduced weed growth, plant survival and seed production. 3) Greenhouse experiments testing the regrowth ability of individual plants after cutting showed strong differences between species and functional groups. An two-factorial experiment suggested that the negative impacts of cutting and competition on weed growth were mainly additive. 4) Special measurements of weed seed predation in the field experiment showed positive correlations with vegetation cover, indicating that this ecosystem service may be particularly fostered by perennial crops. Consistent preferences of seed predators for certain weed species indicates that seed predation may be another cause of the observed weed community shifts.Fruchtfolgen können dazu dienen, die kontinuierliche Selektion von Unkrautarten zu verhindern, die an eine bestimmte Kultur angepasst sind. Dies könnte dem Unkrautmanagement, der Einsparung von Herbiziden, und der Biodiversität dienen. Heutige, sehr einfache Furchtfolgen könnten durch mehrjährige Futterkulturen diversifiziert werden. Die Einflüsse solcher mehrjähriger Kulturen auf Unkräuter wurden in vier Ansätzen untersucht: 1) Vegetationsaufnahmen auf 632 Feldern in Westfrankreich zeigten, dass die Unkrautzusammensetzung zwischen mehrjährigen Futterkulturen und einjährigen Kulturen stark variiert. Der Vergleich von Feldern vor, während und nach mehrjährigen Futterkulturen legte nahe, dass die Pflanzengemeinschaft während solcher Fruchtfolgen zyklisch variiert. Mehrere problematische Unkrautarten wurden während und nach den mehrjährigen Kulturen zurückgedrängt. Das Auftauchen anderer Arten führte jedoch zu einer gleichbleibenden oder leicht erhöhten Pflanzenvielfalt. 2) Ein dreijähriger Feldversuch mit verschiedenen Bearbeitungsoptionen ermöglichte es, die zugrunde liegenden Mechanismen zu untersuchen: Die fehlende Bodenbearbeitung hat das Auflaufen der Unkräuter reduziert und das Überleben der adulten Pflanzen erhöht. Die permanente Vegetationsbedeckung und die häufigen Heuschnitte haben das Wachstum, das Überleben und die Samenproduktion vermindert. 3) Gewächshausexperimente zum Nachwachsen von Unkrautpflanzen nach Heuschnitten zeigten große Unterschiede zwischen verschiedenen Arten und funktionellen Gruppen. Ein Experiment mit zwei Faktoren lässt vermuten, dass die negativen Effekte der Schnitte und der Konkurrenz auf das Unkrautwachstum sich addieren. 4) Spezielle Messungen der Prädation von Unkrautsamen auf den untersuchten Feldern zeigten positive Korrelationen mit der Vegetationsbedeckung, was auf eine besondere Wichtigkeit dieser Ökosystemdienstleistung in ausdauernden Kulturen hindeutet. Die Präferenz von bestimmten Samenarten deutet darauf hin, dass Samenprädation ein weiterer Grund für die beobachteten Änderungen der Unkrautgemeinschaften sein kann

Comparison of phase-leg circuits for cryogenic operation in the all-electric aircraft

Commercial all-electric aircraft are projected to be flying as early as 2035, where hydrogen is selected to supply fuel and coolant. The cryogenic aircraft's powertrain includes the turbines, generators, power electronics and fan motors. As most of the powertrain is located at cryogenic temperature, it is preferable to co-locate the power electronics in the same region to reduce the engineering system's complexity. Silicon super-junction MOSFETs are known for their high efficiency, thus lower cooling requirements at cryogenic temperature. However, in phase-leg circuits, the behaviour of the MOSFET's intrinsic diode, and its output capacitance are challenging. These issues can be addressed by using the MOSFET with ancillary power devices to realise diode deactivation. This paper compares different permutations of intrinsic diode deactivation devices at room temperature and cryogenic temperature. The paper presents a demonstrator phase-leg built with different ancillary power devices. It is operated from a DC voltage of 270 V, and supplies a phase current of up to 10 A