Symbolic computation of exact solutions expressible in hyperbolic and elliptic functions for nonlinear PDEs

Algorithms are presented for the tanh- and sech-methods, which lead to closed-form solutions of nonlinear ordinary and partial differential equations (ODEs and PDEs). New algorithms are given to find exact polynomial solutions of ODEs and PDEs in terms of Jacobi's elliptic functions. For systems with parameters, the algorithms determine the conditions on the parameters so that the differential equations admit polynomial solutions in tanh, sech, combinations thereof, Jacobi's sn or cn functions. Examples illustrate key steps of the algorithms. The new algorithms are implemented in Mathematica. The package DDESpecialSolutions.m can be used to automatically compute new special solutions of nonlinear PDEs. Use of the package, implementation issues, scope, limitations, and future extensions of the software are addressed. A survey is given of related algorithms and symbolic software to compute exact solutions of nonlinear differential equations.Comment: 39 pages. Software available from Willy Hereman's home page at http://www.mines.edu/fs_home/whereman

Breeding Forage Grasses for Increased Heat Tolerance to Combat Climate Change

The onset of climate change brings many challenges for forage production in the southeastern United States, where it is projected to become hotter and dryer in the next century. To combat this climatic challenge, recurrent phenotypic selection was conducted in growth chambers on annual ryegrass (Lolium multiflorum Lam.) and orchardgrass (Dactylis glomerata L.) to select seedlings that can germinate and survive at temperatures of 40°C. Following three cycles of selection, germination was increased from \u3c 5% to 45% in annual ryegrass, and from 20% to 80% in orchardgrass. The rate of germination also increased, in both species by a factor of 8x that of the base germplasm. Realized heritability also increased by 40 – 45% for each species by the end of the project. This work successfully improved a quantitative trait using recurrent phenotypic selection using growth chambers as a stable environment and provided the basis for combatting climate change in other outcrossing forage species

Anisotropic composite fermions and fractional quantum Hall effect

We study the role of anisotropy on the transport properties of composite fermions near Landau level filling factor $\nu=1/2$ in two-dimensional holes confined to a GaAs quantum well. By applying a parallel magnetic field, we tune the composite fermion Fermi sea anisotropy and monitor the relative change of the transport scattering time at $\nu=1/2$ along the principal directions. Interpreted in a simple Drude model, our results suggest that the scattering time is longer along the longitudinal direction of the composite fermion Fermi sea. Furthermore, the measured energy gap for the fractional quantum Hall state at $\nu=2/3$ decreases when anisotropy becomes significant. The decrease, however, might partly stem from the charge distribution becoming bilayer-like at very large parallel magnetic fields

Low frequency m=1 normal mode oscillations of a self-gravitating disc

A continuous system such as a galactic disc is shown to be well approximated by an N-ring differentially rotating self-gravitating system. Lowest order (m=1) non-axisymmetric features such as lopsidedness and warps are global in nature and quite common in the discs of spiral galaxies. Apparently these two features of the galactic discs have been treated like two completely disjoint phenomena. The present analysis based on an eigenvalue approach brings out clearly that these two features are fundamentally similar in nature and they are shown to be very Low frequency Normal Mode (LNM) oscillations manifested in different symmetry planes of the galactic disc. Our analysis also show that these features are actually long-lived oscillating pattern of the N-ring self-gravitating system.Comment: 5 figures. Accepted for publication in MNRAS Letter

Origins of Chevron Rollovers in Non-Two-State Protein Folding Kinetics

Chevron rollovers of some proteins imply that their logarithmic folding rates are nonlinear in native stability. This is predicted by lattice and continuum G\=o models to arise from diminished accessibilities of the ground state from transiently populated compact conformations under strongly native conditions. Despite these models' native-centric interactions, the slowdown is due partly to kinetic trapping caused by some of the folding intermediates' nonnative topologies. Notably, simple two-state folding kinetics of small single-domain proteins are not reproduced by common G\=o-like schemes.Comment: 10 pages, 4 Postscript figures (will appear on PRL

Mental health and wellbeing during the transition to fatherhood: A systematic review of first time fathers’ experiences

COPYRIGHT 2018 THE AUTHORS PUBLISHED BY WOLTERS KLUWER HEALTH, INC. ON BEHALF OF THE JOANNA BRIGGS INSTITUTE. Objective: The aim of this systematic review was to identify and synthesize the best available evidence on first time fathers’ experiences and needs in relation to their mental health and wellbeing during their transition to fatherhood. Introduction: Men’s mental health and wellbeing during their transition to fatherhood is an important public health issue that is currently under-researched from a qualitative perspective and poorly understood. Inclusion criteria: Resident first time fathers (biological and non-biological) of healthy babies born with no identified terminal or long-term conditions were included. The phenomena of interest were their experiences and needs in relation to mental health and wellbeing during their transition to fatherhood, from commencement of pregnancy until one year after birth. Studies based on qualitative data, including, but not limited to, designs within phenomenology, grounded theory, ethnography and action research were included. Methods: A three-step search strategy was used. The search strategy explored published and unpublished qualitative studies from 1960 to September 2017. All included studies were assessed by two independent reviewers and any disagreements were resolved by consensus or with a third reviewer. The recommended Joanna Briggs Institute (JBI) approach to critical appraisal, study selection, data extraction and data synthesis was used. Results: Twenty-two studies met the eligibility criteria and were included in the review, which were then assessed to be of moderate to high quality (scores 5-10) based on the JBI Critical Appraisal Checklist for Qualitative Research. The studies were published between 1990 and 2017, and all used qualitative methodologies to accomplish the overall aim of investigating the experiences of expectant or new fathers. Nine studies were from the UK, three from Sweden, three from Australia, two from Canada, two from the USA, one from Japan, one from Taiwan and one from Singapore. The total number of first time fathers included in the studies was 351. One hundred and forty-four findings were extracted from the included studies. Of these, 142 supported findings were aggregated into 23 categories and seven synthesized findings: 1) New fatherhood identity, 2) Competing challenges of new fatherhood, 3) Negative feelings and fears, 4) Stress and coping, 5) Lack of support, 6) What new fathers want, and 7) Positive aspects of fatherhood. Conclusions: Based on the synthesized findings, three main factors that affect first time fathers’ mental health and wellbeing during their transition to fatherhood were identified: the formation of the fatherhood identity, competing challenges of the new fatherhood role and negative feelings and fears relating to it. The role restrictions and changes in lifestyle often resulted in feelings of stress, for which fathers used denial or escape activities, such as smoking, working longer hours or listening to music, as coping techniques. Fathers wanted more guidance and support around the preparation for fatherhood, and partner relationship changes. Barriers to accessing support included lack of tailored information resources and acknowledgment from health professionals. Better preparation for fatherhood, and support for couple relationships during the transition to parenthood could facilitate better experiences for new fathers, and contribute to better adjustments and mental wellbeing in new fathers

Impact of disorder on the 5/2 fractional quantum Hall state

We compare the energy gap of the \nu=5/2 fractional quantum Hall effect state obtained in conventional high mobility modulation doped quantum well samples with those obtained in high quality GaAs transistors (heterojunction insulated gate field-effect transistors). We are able to identify the different roles that long range and short range disorders play in the 5/2 state and observe that the long range potential fluctuations are more detrimental to the strength of the 5/2 state than short-range potential disorder.Comment: PRL 106, 206806 (2011

A more representative chamber: representation and the House of Lords

Since 1997 there has been substantive reform of the House of Lords in an effort to make the chamber ‘more democratic and more representative’. Whilst the Labour government failed to press ahead with any of the proposed plans for further reform following the removal of the bulk of the hereditary peers in 1999, it remained committed to the notion that such reform must make the second chamber ‘more representative’. The coalition government's programme advocates a long-term aspiration for a House wholly or mainly elected on the basis of proportional representation, and a short-term approach based on additional appointments to ensure a balance of the parties. What is clear in all of these proposals for reform is a desire for the House of Lords to become more representative than it is at present. However, what is less clear is what is meant by ‘representative’ – who the House of Lords is supposed to represent, and what form representation will take. Moreover, in proposing to make the chamber more representative, either through appointment or election, little attention has been paid to how the current House of Lords provides representation. This article examines these questions in the context of Pitkin's classic conceptions of representation and peers' attitudes towards their own representative rol