There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

We describe Hi-C, a method that probes the three-dimensional architecture of whole genomes by coupling proximity-based ligation with massively parallel sequencing. We constructed spatial proximity maps of the human genome with Hi-C at a resolution of 1 megabase. These maps confirm the presence of chromosome territories and the spatial proximity of small, gene-rich chromosomes. We identified an additional level of genome organization that is characterized by the spatial segregation of open and closed chromatin to form two genome-wide compartments. At the megabase scale, the chromatin conformation is consistent with a fractal globule, a knot-free, polymer conformation that enables maximally dense packing while preserving the ability to easily fold and unfold any genomic locus. The fractal globule is distinct from the more commonly used globular equilibrium model. Our results demonstrate the power of Hi-C to map the dynamic conformations of whole genomes.

/pdf/comprehensive-mapping-of-long-range-interactions-reveals-15wp5ww9ic.pdf

Comprehensive mapping of long-range interactions reveals folding principles of the human genome.

Polyampholytes (PAs) are heteropolymers with long range Coulomb interactions. Unlike polymers with short range forces, PA energy levels have non-vanishing correlations and are thus very different from the Random Energy Model (REM). Nevertheless, if charges in the PA globule are screened as in a regular plasma, PAs freeze in REM fashion. Our results shed light on the potential role of Coulomb interactions in folding and evolution of {\it proteins}, which are weakly charged PAs, in particular making connection with the finding that sequences of charged amino acids in proteins are not random.

Freezing Transition of Compact Polyampholytes.

Nonequilibrium systems with conserved quantities like density or momentum are known to exhibit long-ranged correlations. This, in turn, leads to long-ranged fluctuation-induced (Casimir) forces, predicted to arise in a variety of nonequilibrium settings. Here, we study such forces, which arise transiently between parallel plates or compact inclusions in a gas of particles, following a change (``quench'') in temperature or activity of the medium. Analytical calculations, as well as numerical simulations of passive or active Brownian particles, indicate two distinct forces: (i) The immediate effect of the quench is adsorption or desorption of particles of the medium to the immersed objects, which in turn initiates a front of relaxing (mean) density. This leads to time-dependent density-induced forces. (ii) A long-term effect of the quench is that density fluctuations are modified, manifested as transient (long-ranged) (pair-)correlations that relax diffusively to their (short-ranged) steady-state limit. As a result, transient fluctuation-induced forces emerge. We discuss the properties of fluctuation-induced and density-induced forces as regards universality, relaxation as a function of time, and scaling with distance between objects. Their distinct signatures allow us to distinguish the two types of forces in simulation data. Our simulations also show that a quench of the effective temperature of an active medium gives rise to qualitatively similar effects to a temperature quench in a passive medium. Based on this insight, we propose several scenarios for the experimental observation of the forces described here.

Nonequilibrium forces following quenches in active and thermal matter

The crumpling transition of D-dimensional elastic membranes is studied for large dimensions of embedding space d. The magnetic and thermal critical exponents ${y}_{m}$ and ${y}_{t}$ for isotropic membranes are obtained in a 1/d expansion. Both exponents vanish simultaneously at a lower critical dimension ${D}_{\mathrm{LC}=2\mathrm{\ensuremath{-}}2/\mathrm{d}+\mathrm{O}(1/{d}^{2}}$). We also consider the role of self-avoidance and of elastic anisotropies.

Renormalization-group analysis of the crumpling transition in large d.

Passive scalar advection: Dust particles or dye or a hot fluid element entrained by a flow, but having no effect on the flow.

/pdf/passive-sliders-on-growing-surface-and-anti-advection-in-es034vdqu0.pdf

Passive Sliders on Growing Surface and (Anti-)Advection in Burger’s Flows

Elastic Ising antiferromagnets are studied on a triangular lattice. Magnetic 'frustration' is removed at low temperatures by a lattice distortion, and the resulting ground state has alternating rows of up and down spins. The authors discuss the onset of this magnetoelastic instability, and the symmetry breakings involved. The effective Poisson's ratio approaches a universal value sigma =+1 close to the transition. The behaviour of XY spins (relevant to the study of oxygen layers) is compared and contrasted to Ising spins.

http://iopscience.iop.org/article/10.1088/0022-3719/19/34/019/pdf

Mehran Kardar

Papers

Freezing Transition of Compact Polyampholytes.

Nonequilibrium forces following quenches in active and thermal matter

Renormalization-group analysis of the crumpling transition in large d.

Passive Sliders on Growing Surface and (Anti-)Advection in Burger’s Flows

Elastic antiferromagnets on a triangular lattice