Selective harvest focused on sexual signal traits can lead to extinction under directional environmental change

Humans commonly harvest animals based on their expression of secondary sexual traits such as horns or antlers. This selective harvest is thought to have little effect on harvested populations because offtake rates are low and usually only the males are targeted. These arguments do not, however, take the relationship between secondary sexual trait expression and animal condition into account: there is increasing evidence that in many cases the degree of expression of such traits is correlated with an animal's overall well-being, which is partly determined by their genetic match to the environment. Using an individual-based model, we find that when there is directional environmental change, selective harvest of males with the largest secondary sexual traits can lead to extinction in otherwise resilient populations. When harvest is not selective, the males best suited to a new environment gain the majority of matings and beneficial alleles spread rapidly. When these best-adapted males are removed, however, their beneficial alleles are lost, leading to extinction. Given the current changes happening globally, these results suggest that trophy hunting and other cases of selective harvest (such as certain types of insect collection) should be managed with extreme care whenever populations are faced with changing conditions.</jats:p

A proposal for a comprehensive grading of Parkinson's disease severity combining motor and non-motor assessments: meeting an unmet need.

Non-motor symptoms are present in Parkinson's disease (PD) and a key determinant of quality of life. The Non-motor Symptoms Scale (NMSS) is a validated scale that allows quantifying frequency and severity (burden) of NMS. We report a proposal for using NMSS scores to determine levels of NMS burden (NMSB) and to complete PD patient classification

Using Accounting and Financing to Recover the Value of Natural Capital

The value of natural capital in countries around the world, including the UK, has been continuously decreasing due to the degradation of natural resources. The lack of accounting and nancial mechanisms dedicated to measure and recover the value of natural capital, combined with low investment allocations from private investors, have been a determinant factor contributing to this decline. Given this consideration, the present work de nes three objectives in relation to natural capi- tal accounting and nance. First, to investigate the use of natural capital accounts to study changes in natural capital value and identify the major factors impacting the risk of declining natural capital and wealth using the case study of the UK. Second, to analyse the performance of investments in natural capital assets. Fi- nally, to examine the use of Sovereign Wealth Funds as a nancial mechanism to dedicate major investments in natural capital. In relation to the rst objective, a stochastic model for risk analysis is developed to estimate changes in UKs wealth using data on produced, human, and natural capital asset values reported by UK authorities between 1992 and 2012. Results show that natural capital losses in the UK have been mainly driven by a decrease in value of non-renewable natural capital, together with variations in the value of ecosystem services. Nevertheless, as non-renewable natural capital reach depletion, focus shall be given over coming years to recover renewable natural capital. As part of the second objective, the present work evaluates the performance of investments in real and non-real natu- ral assets and compare it with those of traditional asset classes using time series analysis of historical returns. The obtained results indicate that, when investing in natural capital, investors should focus on real natural assets as their nan- cial bene ts are higher than those from equities, bonds, real estate or even some infrastructure assets. Regarding the nal objective, this work models the invest- ment portfolio of an oil-based SWF using Norways Pension Fund Global as a case study and employs out-of-sample simulation technique to estimate global e cient portfolios while considering their relationship with oil prices. In this regard, the nal results demonstrate that SWFs are able to challenge their current allocation range in natural assets (2-5%) to a higher range (15-20%) while still bene ting from those investments. The overall conclusion from this research suggests that combining the importance of e ective natural capital accounts, the nancial ben- e ts of natural capital investments, and the role of nancial mechanisms such as SWFs is essential to increase the value of natural capital

Persistence and Eventual Demise of Oxygen Molecules at Terapascal Pressures

Computational searches for structures of solid oxygen under high pressures in the multi-TPa range are carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into a semiconducting square-spiral-like polymeric structure (I41/acd) with a band gap of ∼3.0  eV. Solid oxygen forms a metallic zigzag chainlike structure (Cmcm) at about 3.0 TPa, but the chains in each layer gradually merge as the pressure is increased and a structure of Fmmm symmetry forms at about 9.3 TPa in which each atom has four nearest neighbors. The superconducting properties of molecular oxygen do not vary much with compression, although the structure becomes more symmetric. The electronic properties of oxygen have a complex evolution with pressure, swapping between insulating, semiconducting, and metallic

Comparison of Interactions Between Control and Mutant Macrophages

This paper presents a preliminary study on macrophages migration in Drosophila embryos, comparing two types of cells. The study is carried out by a framework called macrosight which analyses the movement and interaction of migrating macrophages. The framework incorporates a segmentation and tracking algorithm into analysing motion characteristics of cells after contact. In this particular study, the interactions between cells is characterised in the case of control embryos and Shot3 mutants, where the cells have been altered to suppress a specific protein, looking to understand what drives the movement. Statistical significance between control and mutant cells was found when comparing the direction of motion after contact in specific conditions. Such discoveries provide insights for future developments in combining biological experiments to computational analysis

Decomposition and Terapascal Phases of Water Ice

Computational searches for stable and metastable structures of water ice and other H:O compositions at TPa pressures have led us to predict that H2O decomposes into H2O2 and a hydrogen-rich phase at pressures of a little over 5 TPa. The hydrogen-rich phase is stable over a wide range of hydrogen contents, and it might play a role in the erosion of the icy component of the cores of gas giants as H2O comes into contact with hydrogen. Metallization of H2O is predicted at a higher pressure of just over 6 TPa, and therefore H2O does not have a thermodynamically stable low-temperature metallic form. We have also found a new and rich mineralogy of complicated water ice phases that are more stable in the pressure range 0.8–2 TPa than any predicted previously

Spin and Statistics and First Principles

It was shown in the early Seventies that, in Local Quantum Theory (that is the most general formulation of Quantum Field Theory, if we leave out only the unknown scenario of Quantum Gravity) the notion of Statistics can be grounded solely on the local observable quantities (without assuming neither the commutation relations nor even the existence of unobservable charged field operators); one finds that only the well known (para)statistics of Bose/Fermi type are allowed by the key principle of local commutativity of observables. In this frame it was possible to formulate and prove the Spin and Statistics Theorem purely on the basis of First Principles. In a subsequent stage it has been possible to prove the existence of a unique, canonical algebra of local field operators obeying ordinary Bose/Fermi commutation relations at spacelike separations. In this general guise the Spin - Statistics Theorem applies to Theories (on the four dimensional Minkowski space) where only massive particles with finite mass degeneracy can occur. Here we describe the underlying simple basic ideas, and briefly mention the subsequent generalisations; eventually we comment on the possible validity of the Spin - Statistics Theorem in presence of massless particles, or of violations of locality as expected in Quantum Gravity.Comment: Survey based on a talk given at the Meeting on "Theoretical and experimental aspects of the spin - statistics connection and related symmetries", Trieste, Italy - October 21-25, 200

On the molecular origins of the ferroelectric splay nematic phase

Nematic liquid crystals have been known for more than a century, but it was not until the 60s–70s that, with the development of room temperature nematics, they became widely used in applications. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. Synthesis of materials with nematic polar ordering at room temperature is certainly challenging and requires a deep understanding of its formation mechanisms, presently lacking. Here, we compare two materials of similar chemical structure and demonstrate that just a subtle change in the molecular structure enables denser packing of the molecules when they exhibit polar order, which shows that reduction of excluded volume is in the origin of the polar nematic phase. Additionally, we propose that molecular dynamics simulations are potent tools for molecular design in order to predict, identify and design materials showing the polar nematic phase and its precursor nematic phases