Parity Violating Electron Scattering Measurements of Neutron Densities

Parity violating electron scattering allows model independent measurements of neutron densities that are free from most strong interaction uncertainties. In this paper we present statistical error estimates for a variety of experiments. The neutron radius $R_n$ can be measured in several nuclei, as long as the nuclear excited states are not too low in energy. We present error estimates for $R_n$ measurements in $^{40}$Ca, $^{48}$Ca, $^{112}$Sn, $^{120}$Sn, $^{124}$Sn, and $^{208}$Pb. In general, we find that the smaller the nucleus, the easier the measurement. This is because smaller nuclei can be measured at higher momentum transfers where the parity violating asymmetry $A_{pv}$ is larger. Also in general, the more neutron rich the isotope, the easier the measurement, because neutron rich isotopes have larger weak charges and larger $A_{pv}$. Measuring $R_n$ in $^{48}$Ca appears very promising because it has a higher figure of merit than $^{208}$Pb. In addition, $R_n(^{48}$Ca) may be more easily related to two nucleon and three nucleon interactions, including very interesting three neutron forces, than $R_n(^{208}$Pb). After measuring $R_n$, one can constrain the surface thickness of the neutron density $a_n$ with a second measurement at somewhat higher momentum transfers. We present statistical error estimates for measuring $a_n$ in $^{48}$Ca, $^{120}$Sn, and $^{208}$Pb. Again, we find that $a_n$ is easier to measure in smaller nuclei.Comment: 10 pages, 7 fig., minor changes, J. Phys. G in pres

Electroweak Measurements of Neutron Densities in CREX and PREX at JLab, USA

Measurement of the parity-violating electron scattering asymmetry is an established technique at Jefferson Lab and provides a new opportunity to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively; these are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter ${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces.Comment: A contribution to the upcoming EPJA Special Volume on Nuclear Symmetry Energ

Spatial control of irreversible protein aggregation

Liquid cellular compartments spatially segregate from the cytoplasm and can regulate aberrant protein aggregation, a process linked to several medical conditions, including Alzheimer's and Parkinson's diseases. Yet the mechanisms by which these droplet-like compartments affect protein aggregation remain unknown. Here, we combine kinetic theory of protein aggregation and liquid-liquid phase separation to study the spatial control of irreversible protein aggregation in the presence of liquid compartments. We find that, even for weak interactions between the compartment constituents and the aggregating monomers, aggregates are strongly enriched inside the liquid compartment relative to the surrounding cytoplasm. We show that this enrichment is caused by a positive feedback mechanism of aggregate nucleation and growth which is mediated by a flux maintaining the phase equilibrium between the compartment and the cytoplasm. Our model predicts that the compartment volume that maximizes aggregate enrichment in the compartment is determined by the reaction orders of aggregate nucleation. The underlying mechanism of aggregate enrichment could be used to confine cytotoxic protein aggregates inside droplet-like compartments suggesting potential new avenues against aberrant protein aggregation. Our findings could also represent a common mechanism for the spatial control of irreversible chemical reactions in general

Editorial.

Welcome to the third issue of our journal . We are delighted to feature in this issue two peer-reviewed papers looking in detail at some of the outcomes of the ring-fenced money used for researcher development in the UK under the guise of Roberts funding. In her paper looking at impact of the training provided by this funding on late stage doctoral student researchers, Walsh and colleagues draw our attention to detailed analysis of impact via a variety of evaluation approaches. She also alerts us to the question of whether such development programmes should run alongside the traditional apprenticeship style training of such students. The second paper by Heading and colleagues provides a detailed example of a development programme event in information management and provides further evidence for impact of such training. Bai and Hudson move the focus to the research –teaching nexus and highlight the difficulty for TEFL staff in Chinese HEIs to develop a research strand in their careers. The importance in developing research capacity, providing support and mentoring to such staff is shown to be pivotal in their development. Finally conceptions of research from a variety of viewpoints are analyzed by Pitcher. Pitcher considers how the PhD itself, alongwith how the knowledge and outcomes of PhD research are perceived. In a preliminary survey of students on these matters, Pitcher highlights the importance of alignment with these concepts between student and supervisor thus avoiding difficulties between apprentice and supervisor as the research progresses which might inhibit development

Low Vision in Older Adults

Educational Objectives 1. Understand the epidemiology of visual impairments of older adults. 2. Understand the symptoms of functional loss secondary to visual impairments. 3. Understand the rehabilitative options available for those with vision loss. 4. Understand the multi-disciplinary approach in low vision rehabilitation. 5. Understand the impact of low vision rehabilitation services