Exact spinor-scalar bound states in a QFT with scalar interactions

We study two-particle systems in a model quantum field theory, in which scalar particles and spinor particles interact via a mediating scalar field. The Lagrangian of the model is reformulated by using covariant Green's functions to solve for the mediating field in terms of the particle fields. This results in a Hamiltonian in which the mediating-field propagator appears directly in the interaction term. It is shown that exact two-particle eigenstates of the Hamiltonian can be determined. The resulting relativistic fermion-boson equation is shown to have Dirac and Klein-Gordon one-particle limits. Analytic solutions for the bound state energy spectrum are obtained for the case of massless mediating fields.Comment: 12 pages, RevTeX, 1 figur

Hole-mediated photoredox catalysis: Tris(: P-substituted)biarylaminium radical cations as tunable, precomplexing and potent photooxidants

As a combination of visible light photoredox catalysis and synthetic organic electrochemistry, electrochemically-mediated photoredox catalysis emerged as a powerful synthetic technique in recent years, overcoming fundamental limitations of electrochemistry and photoredox catalysis in the single electron transfer activation of small organic molecules. Herein we report a tunable class of electroactivated photoredox catalyst, tri(para-substituted)biarylamines, that become superoxidants in their photoexcited states even able to oxidize molecules beyond the solvent window limits of cyclic voltammetry (such as polyfluorobenzene and trifluorotoluene). Furthermore, we demonstrate that precomplexation not only permits the excited state photochemistry of tris(para-substituted)biarylaminium cations to overcome picosecond lifetime, but enables and rationalizes the surprising photochemistry of their higher-order doublet (Dn) excited states, unlocking extremely high oxidative potentials (up to a record-breaking ∼+4.4 V vs. SCE). This journal i

KOtBu : a privileged reagent for electron transfer reactions?

Many recent studies have used KOtBu in organic reactions that involve single electron transfer; in the literature, the electron transfer is proposed to occur either directly from the metal alkoxide or indirectly, following reaction of the alkoxide with a solvent or additive. These reaction classes include coupling reactions of halobenzenes and arenes, reductive cleavages of dithianes and SRN1 reactions. Direct electron transfer would imply that alkali metal alkoxides are willing partners in these electron transfer reactions, but the literature reports provide little or no experimental evidence for this. This paper examines each of these classes of reaction in turn, and contests the roles proposed for KOtBu; instead, it provides new mechanistic information that in each case supports the in situ formation of organic electron donors. We go on to show that direct electron transfer from KOtBu can however occur in appropriate cases, where the electron acceptor has a reduction potential near the oxidation potential of KOtBu, and the example that we use is CBr4. In this case, computational results support electrochemical data in backing a direct electron transfer reaction

The effect of multiple host species on a keystone parasitic plant and its aphid herbivores

1. The exploitation of shared resources by diverse organisms underpins the structure of ecological communities. Hemiparasitic plants and the insect herbivores feeding on them both rely, directly and indirectly, on the resources supplied by the parasite's host plant. Therefore, the identity and number of host plant species providing these resources is likely to be critical for parasite and herbivore performance. 2. We tested the effect of single and multiple host species on the biomass of the generalist parasitic plant Rhinanthus minor and the abundance of its aphid (Aphis gossypii) herbivores. 3. Parasite biomass was proportional to the number of haustorial connections to host roots and was determined by host species identity rather than host functional group. Host species identity was also an important influence on aphid population size, and parasites attached to Lotus corniculatus experienced a considerable reduction in aphid herbivory. 4. The effects on the parasite attaching to multiple hosts depended on the combination of species present. However, host mixtures generally benefitted aphids by diluting the negative effects of particular host species. 5. Our findings suggest that the specificity of host attachment alters the impact of this keystone parasitic plant on its own herbivores and, potentially, on the wider plant and herbivore community

Inventory of ATT system requirements for elderly and disabled drivers and travellers

This Inventory of ATT System Requirements for Elderly and Disabled Drivers and Travellers is the product of the TELSCAN project’s Workpackage 3: Identification and Updating of User Requirements of Elderly and Disabled Travellers. It describes the methods and tools used to identify the needs of elderly and disabled (E&D) travellers. The result of this investigation is a summary of the requirements of elderly and disabled travellers using different modes of transport, including private cars, buses/trams, metros/trains, ships and airplanes. It provides a generic user requirements specification which can guide the design of all transport telematics systems. However, it is important to stress that projects should also capture a more detailed definition of user requirements for their specific application area or system

Mutual aid groups in psychiatry and substance misuse

Background: Mutuality is a feature of many ‘self-help groups’ for people with mental health and/or substance misuse needs. These groups are diverse in terms of membership, aims, organisation and resources. Collectively, in terms of the pathways for seeking help, support, social capital or simply validation as people, mutual aid groups figure at some time in the life story of many psychiatric and/or substance misuse patients. From the viewpoint of clinical services, relations with such groups range from formal collaboration, through incidental shared care, via indifference, to incomprehension, suspicion, or even hostility. How should mental health and substance misuse clinicians relate to this informal care sector, in practice? Aims: To synthesise knowledge about three aspects of the relationship between psychiatric/substance misuse services and mutual aid groups: profile groups' engagement of people with mental health and/or substance misuse needs at all stages of vulnerability, illness or recovery; characterise patterns of health benefit or harm to patients, where such outcome evidence exists; identify features of mutual aid groups that distinguish them from clinical services. Method: A search of both published and unpublished literature with a focus on reports of psychiatric and substance misuse referral routes and outcomes, compiled for meta-synthesis. Results: Negative outcomes were found occasionally, but in general mutual aid group membership was repeatedly associated with positive benefits. Conclusions: Greater awareness of this resource for mental health and substance misuse fields could enhance practice

EUS-derived criteria for distinguishing benign from malignant metastatic solid hepatic masses

Background Detection of hepatic metastases during EUS is an important component of tumor staging. Objective To describe our experience with EUS-guided FNA (EUS-FNA) of solid hepatic masses and derive and validate criteria to help distinguish between benign and malignant hepatic masses. Design Retrospective study, survey. Setting Single, tertiary-care referral center. Patients Medical records were reviewed for all patients undergoing EUS-FNA of solid hepatic masses over a 12-year period. Interventions EUS-FNA of solid hepatic masses. Main Outcome Measurements Masses were deemed benign or malignant according to predetermined criteria. EUS images from 200 patients were used to create derivation and validation cohorts of 100 cases each, matched by cytopathologic diagnosis. Ten expert endosonographers blindly rated 15 initial endosonographic features of each of the 100 images in the derivation cohort. These data were used to derive an EUS scoring system that was then validated by using the validation cohort by the expert endosonographer with the highest diagnostic accuracy. Results A total of 332 patients underwent EUS-FNA of a hepatic mass. Interobserver agreement regarding the initial endosonographic features among the expert endosonographers was fair to moderate, with a mean diagnostic accuracy of 73% (standard deviation 5.6). A scoring system incorporating 7 EUS features was developed to distinguish benign from malignant hepatic masses by using the derivation cohort with an area under the receiver operating curve (AUC) of 0.92; when applied to the validation cohort, performance was similar (AUC 0.86). The combined positive predictive value of both cohorts was 88%. Limitations Single center, retrospective, only one expert endosonographer deriving and validating the EUS criteria. Conclusion An EUS scoring system was developed that helps distinguish benign from malignant hepatic masses. Further study is required to determine the impact of these EUS criteria among endosonographers of all experience