Upper Energy Limit of Heavy Baryon Chiral Perturbation Theory in Neutral Pion Photoproduction

With the availability of the new neutral pion photoproduction from the proton data from the A2 and CB-TAPS Collaborations at Mainz it is mandatory to revisit Heavy Baryon Chiral Perturbation Theory (HBChPT) and address the extraction of the partial waves as well as other issues such as the value of the low-energy constants, the energy range where the calculation provides a good agreement with the data and the impact of unitarity. We find that, within the current experimental status, HBChPT with the fitted LECs gives a good agreement with the existing neutral pion photoproduction data up to $\sim$170 MeV and that imposing unitarity does not improve this picture. Above this energy the data call for further improvement in the theory such as the explicit inclusion of the \Delta (1232). We also find that data and multipoles can be well described up to $\sim$185 MeV with Taylor expansions in the partial waves up to first order in pion energy.Comment: 6 pages, 5 figures, version to be published in Physics Letters

Multiple output production with undesirable outputs : an application to nitrogen surplus in agriculture

Many production processes yield both good outputs and undesirable ones (e.g., pollutants). In this article we develop a generalization of a stochastic frontier model that is appropriate for such technologies. We discuss efficiency analysis and, in particular, define technical and environmental efficiency in the context of our model. We develop methods for carrying out Bayesian inference and apply them to a panel data set of Dutch dairy farms, where excess nitrogen production constitutes an important environmental problem

Broadband suppression of backscattering at optical frequencies using low permittivity dielectric spheres

The exact suppression of backscattering from rotationally symmetric objects requires dual symmetric materials where ${\epsilon_r} = {\mu_r}$. This prevents their design at many frequency bands, including the optical one, because magnetic materials are not available. Electromagnetically small non-magnetic spheres of large permittivity offer an alternative. They can be tailored to exhibit balanced electric and magnetic dipole polarizabilities, which result in approximate zero backscattering. In this case, the effect is inherently narrowband. Here, we put forward a different alternative that allows broadband functionality: Electromagnetically large spheres made from low permittivity materials. The effect occurs in a parameter regime that approaches the trivial ${\epsilon_r} \to {\mu_r} =1$ case, where approximate duality is met in a weakly wavelength dependence fashion. Despite the low permittivity, the overall scattering response of the spheres is still significant. Radiation patterns from these spheres are shown to be highly directive across an octave spanning band. The effect is analytically and numerically shown using the Mie coefficients.Comment: 6 Figure

Results on a pedagogic approach for tailoring public health interventions to minimise opportunistic infections.

We are performing curriculum modifications on the first year BSc (Hons) Biomedical Science module “Basic Microbiology” (De Montfort University, UK) to increase students’ knowledge of basic medical parasitology and infectious diseases, so these students can acquire the necessary skills to tackle their final degree module “Medical Microbiology”. Following student feedback on a novel short intervention in 2017/18 to promote awareness about human immunodeficiency virus (HIV), we have created an engaging workshop session to cover not only HIV but also the opportunistic infections that can affect HIV patients that have developed acquired immune deficiency syndrome (AIDS) and how to prevent them. The objective of this work was to evaluate the effectiveness of the improved workshop developed and to collect students’ impressions to perform further modifications if needed. Briefly, students were required to develop public health measures for HIV positive patients with two different degrees of immunosuppression (i.e. with CD4+ T cells in peripheral blood above and below 200 cells/μl) to prevent exposure and infection from opportunistic pathogens such as Cryptosporidium spp., Toxoplasma gondii or Pneumocystis jirovecii from: a) sexual exposures; b) intravenous drug use; b) environment and work; c) food and water; d) foreign travel. Students, following evidence-based public health methodology, tailored their measures or interventions using the most up-to-date information reported in the literature regarding HIV chemoprophylaxis and recent guidelines published by US Department of Health and Human Services on HIV/AIDS treatment and prevention. Interventions were critically analysed with all students in the last 20 min. of the workshop, which was repeated several times due to the number of students (n=203). The objectives of this workshop were evaluated by careful analysis of a specific feedback questionnaire (n=46 out of 203) voluntarily completed by students at the end of the workshop. The questionnaire showed the following feedback: 80.4% (65.2% agreed; 15.2% strongly agreed) indicated that they learnt how to identify public health interventions; and 95.7% (56.5% agreed; 39.1% strongly agreed) indicated that they would be able to establish measures to reduce HIV transmission and prevent opportunistic infections. Additionally, 95.7% (39.1% agreed; 56.5% strongly agreed) indicated that the workshop helped them to understand the relevance of local and global interventions. Finally, 97.8% of responders considered that the content (52.2% agreed; 45.7% strongly agreed) and duration (60.9% agreed; 37% strongly agreed) of the workshop was appropriate; and 89.1% (58.7% agreed; 30.4% strongly agreed) and 73.9% (41.3% agreed; 32.6% strongly agreed) enjoyed and were satisfied with the workshop provided, respectively. In conclusion, the improved workshop developed would seem to be effective for promoting sexual and public health education to minimise opportunistic pathogen infections in relevant patients when delivered to students with a basic knowledge of microbiology and parasitology