Metastable tight knots in a worm-like polymer

Based on an estimate of the knot entropy of a worm-like chain we predict that the interplay of bending energy and confinement entropy will result in a compact metastable configuration of the knot that will diffuse, without spreading, along the contour of the semi-flexible polymer until it reaches one of the chain ends. Our estimate of the size of the knot as a function of its topological invariant (ideal aspect ratio) agrees with recent experimental results of knotted dsDNA. Further experimental tests of our ideas are proposed.Comment: 4 pages, 3 figure

Fear of terror and increased job burnout over time: Examining the mediating role of insomnia and the moderating role of work support

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110573/1/job1980.pd

On the stability of quark solitons in QCD

We critically re-examine our earlier derivation of the effective low energy action for QCD in 4 dimensions with chiral fields transforming non-trivially under both color and flavor, using the method of anomaly integration. We find several changes with respect to our previous results, leading to much more compact expressions, and making it easier to compare with results of other approaches to the same problem. With the amended effective action, we find that there are no stable soliton solutions. In the context of the quark soliton program, we interpret this as an indication that the full low-energy effective action must include additional terms, reflecting possible modifications at short distances and/or the non-trivial structure of the gauge fields in the vacuum, such as \neq 0. Such terms are absent in the formalism based on anomaly integration

Stretching Instability of Helical Spring

We show that when a gradually increasing tensile force is applied to the ends of a helical spring with sufficiently large ratios of radius to pitch and twist to bending rigidity, the end-to-end distance undergoes a sequence of discontinuous stretching transitions. Subsequent decrease of the force leads to step-like contraction and hysteresis is observed. For finite helices, the number of these transitions increases with the number of helical turns but only one stretching and one contraction instability survive in the limit of an infinite helix. We calculate the critical line that separates the region of parameters in which the deformation is continuous from that in which stretching instabilities occur, and propose experimental tests of our predictions.Comment: 5 pages, 4 figure

Velocity fluctuations of population fronts propagating into metastable states

The position of propagating population fronts fluctuates because of the discreteness of the individuals and stochastic character of processes of birth, death and migration. Here we consider a Markov model of a population front propagating into a metastable state, and focus on the weak noise limit. For typical, small fluctuations the front motion is diffusive, and we calculate the front diffusion coefficient. We also determine the probability distribution of rare, large fluctuations of the front position and, for a given average front velocity, find the most likely population density profile of the front. Implications of the theory for population extinction risk are briefly considered.Comment: 8 pages, 3 figure

Pengaruh Citra Merek, Fitur dan Harga terhadap Keputusan Pembelian Handphone Samsung (Studi pada Mahasiswa Feb Unsrat Manado)

Alat komunikasi dalam perkembangan dunia modern dan globalisasi sangat penting bagi kalangan masyarakat. Kebutuhan tersebut berdampak pada meningkatnya permintaan akan berbagai jenis alat komunikasi yang mengakibatkan semakin meningkatnya persaingan dalam dunia bisnis dibidang telekomunikasi. Membanjirnya produk handphone dipasaran mempengaruhi sikap seseorang terhadap pembelian dan pemakaian handphone. Tujuan penelitian ini untuk melihat apakah Citra Merek, Fitur dan Harga mempengaruhi Keputusan Pembelian handphone. Metode Penelitian dalam penelitian ini adalah Asosiatif, dengan teknik Analisis Regresi Berganda dan yang menjadi sampel penelitian adalah Mahasiswa Fakultas Ekonomi dan Bisnis Universitas Sam Ratulangi Manado. Hasil penelitian menunjukkan Citra Merek, Fitur dan Harga memiliki pengaruh yang signifikan secara bersama terhadap Keputusan Pembelian handphone Samsung. Sebaiknya manajemen Perusahaan Samsung fokus terhadap loyalitas konsumen dalam penelitian ini yaitu, perlunya penerapan atau fokus pada Fitur handphone Samsung serta menjaga harga agar tetap bersaing. Kata kunci: citra merek, fitur, harga,keputusan pembelian

DNA in nanopore-counterion condensation and coion depletion

Molecular dynamics simulations are used to study the equilibrium distribution of monovalent ions in a nanopore connecting two water reservoirs separated by a membrane, both for the empty pore and that with a single stranded DNA molecule inside. In the presence of DNA, the counterions condense on the stretched macromolecule effectively neutralizing it, and nearly complete depletion of coions from the pore is observed. The implications of our results for experiments on DNA translocation through alpha-hemolysin nanopores are discussed.Comment: 8 pages, 2 figure

Nature of the Ferroelectric Phase Transition in PbTiO₃

We have measured quantitatively the temperature dependence of the local distortions of PbTiO3 crystals below and above the structural ferroelectric phase transition, using x-ray absorption fine-structure (XAFS) measurements. Two probe atoms, Pb and Ti, were used. The results were analyzed by fitting parametrized theoretical XAFS spectra to the experimental results. These measurements provide quantitative distortion parameters defined as the difference between the distance of the probe to its nearest neighbor measured in the actual structure and that in a centrosymmetric structure with the same unit cell dimensions. At low temperatures the Pb-edge spectra were fit using four shells and included single, double, and triple scattering configurations. The high-temperature fits included only two shells. The Ti-edge spectra were fitted with the first shell only. The Pb and Ti distortions vary relatively little with temperature below the transition and decrease faster near the transition temperature. Above the transition temperature, the Pb and Ti distortions at the peaks of their distortion distribution function (DDFs) are both more than 70% of the corresponding low-temperature values. These results show that an essential element of order-disorder is present even in this nominally pure ferroelectric crystal which displays a soft mode and a dielectric constant typical of displacive-type ferroelectrics. The presence of the local distortions suggests that the displacements should have at least two correlation length scales, one associated with the local distortions, the other with the order parameter