BICCO-Net II. Final report to the Biological Impacts of Climate Change Observation Network (BICCO-Net) Steering Group

• BICCO-Net Phase II presents the most comprehensive single assessment of climate change impacts on UK biodiversity to date. • The results provide a valuable resource for the CCRA 2018, future LWEC report cards, the National Adaptation Programme and other policy-relevant initiatives linked to climate change impacts on biodiversity

Molecular simulation of chevrons in confined smectic liquid crystals

Chevron structures adopted by confined smectic liquid crystals are investigated via molecular dynamics simulations of the Gay-Berne model. The chevrons are formed by quenching nematic films confined between aligning planar substrates whose easy axes have opposing azimuthal components. When the substrates are perfectly smooth, the chevron formed migrates rapidly towards one of the confining walls to yield a tilted layer structure. However, when substrate roughness is included, by introducing a small-amplitude modulation to the particle- substrate interaction well-depth, a symmetric chevron is formed which remains stable over sufficiently long runtimes for detailed structural information, such as the relevant order parameters and director orien- tation, to be determined. For both smooth and rough boundaries, the smectic order parameter remains non-zero across the entire chevron, implying that layer identity is maintained across the chevron tip. Also, when the surface-stabilised chevron does eventually revert to a tilted layer structure, it does so via surface slippage, such that layer integrity is maintained throughout the chevron to tilted layer relaxation process. </p

Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

A bilayer model of the double hysteresis loop in antiferroelectric liquid crystals

We investigate, both analytically and numerically, a simple model of the field induced double hysteresis loop in AFLC materials. This bilayer model of the bulk of an AFLC describes the free energy in terms of polar and non-polar interactions due to surface alignment, the electric field/dipole interaction in each layer and the dipole/dipole interaction between the layers. The static hysteresis loop is found analytically and the stability of each analytic solution is investigated. The dynamic switching characteristics are found numerically and then investigated as the system parameters and electric field characteristics are changed

Preliminary communication: thresholdless switching induced by polar anchoring in antiferroelectric liquid crystals

We present a novel thresholdless switching mode in an antiferroelectric liquid crystal cell which is stabilized by the presence of polar anchoring at the cell surfaces and the antiferroelectric nature of the material. We also suggest other possible configurations which are induced by strong polar anchoring and possess quite different director structures and optical characteristics

Register bypassing in an asynchronous superscalar processor

Register bypassing, universally provided in synchronous processors, is more difficult to implement in an asynchronous design. Asynchronous bypassing requires synchronization between the forwarding and receiving units, with the danger that the advantages of synchronization operation may be nullified by reintroducing the lock-step operation of synchronous processors. We present a novel implementation of register bypassing in an asynchronous processor architecture. Our technique of Decoupled Operand Forwarding provides centralized control over the bypassing operation, yet allows multiple execution units to function asynchronously. Our ideas are presented within the context of the development of Hades, a generic asynchronous processor architecture. We employ single-issue and dual-issue simulations of Hades to quantify the benefits of Decoupled Operand Forwarding and conclude that Decoupled Operand Forwarding yields significant speedups because of its success in removing register files from the critical timing path

Biaxial modeling of the structure of the chevron interface in smectic liquid crystals

We have included the inherent molecular biaxiality of the smectic C phase in a model of the chevron structure. This molecular biaxiality is related to a hindered rotation about the molecular long axis which for chiral, polar molecules induces a spontaneous polarization. Through the coupling between biaxiality and the smectic cone angle, continuity of the molecular distribution at the chevron interface leads to changes in the cone angle. Under certain approximations we are able to find analytic expressions for the chevron structure and consequently estimate the width of the chevron interface. There are in fact two correlation lengths which govern variations in the cone angle and the biaxiality

Observations of diffraction and self diffraction effects during two wave mixing in a nematic liquid crystal

We report observations of the diffraction pattern resulting when a nematic liquid crystal is illuminated with two equal power, high intensity beams of light from an Ar+ laser. The time evolution of the pattern is followed from the initial production of higher diffraction orders to a final striking display arising as a result of the self-diffraction of the two incident beams. The experimental results are described with good approximation by a model assuming a phase distribution at the output plane of the liquid crystal in the form of the sum of a gaussian and a sinusoid

Stability of the formation of the chevron structure

A simple model of the formation of the chevron structure and tilted layer structure in the smectic C liquid crystal phase from the bookshelf structure in the smectic A phase is considered. Energetic considerations of this system indicate that in the absence of layer pinning forces at the surface, a transition to the tilted structure is expected. However, combining the model with 'weak' surface positional anchoring effects allows the chevron structure to form