A two-step biopolymer nucleation model shows a nonequilibrium critical point

Biopolymer self-assembly pathways are complicated by the ability of their monomeric subunits to adopt different conformational states. This means nucleation often involves a two-step mechanism where the monomers first condense to form a metastable intermediate, which then converts to a stable polymer by conformational rearrangement of constituent monomers. Nucleation intermediates play a causative role in amyloid diseases such as Alzheimer’s and Parkinson’s. While existing mathematical models neglect the conversion dynamics, experiments show that conversion events frequently occur on comparable timescales to the condensation of intermediates and growth of mature polymers and thus cannot be ignored. We present a model that explicitly accounts for simultaneous assembly and conversion. To describe conversion, we propose an experimentally motivated initiation-propagation mechanism in which the stable phase arises locally within the intermediate and then spreads by nearest-neighbor interactions, in a manner analogous to one-dimensional Glauber dynamics. Our analysis shows that the competing timescales of assembly and conversion result in a nonequilibrium critical point, separating a regime where intermediates are kinetically unstable from one where conformationally mixed intermediates accumulate. This strongly affects the accumulation rate of the stable biopolymer phase. Our model is uniquely able to explain experimental phenomena such as the formation of mixed intermediates and abrupt changes in the scaling exponent γ, which relates the total monomer concentration to the accumulation rate of the stable phase. This provides a first step toward a general model of two-step biopolymer nucleation, which can quantitatively predict the concentration and composition of biologically crucial intermediates

The late stages of evolution of helium star-neutron star binaries and the formation of double neutron star systems

With a view to understanding the formation of double neutron-stars (DNS), we investigate the late stages of evolution of helium stars with masses of 2.8 - 6.4 Msun in binary systems with a 1.4 Msun neutron-star companion. We found that mass transfer from 2.8 - 3.3 Msun helium stars and from 3.3 - 3.8 Msun in very close orbits (P_orb > 0.25d) will end up in a common-envelope (CE) and spiral-in phase due to the development of a convective helium envelope. If the neutron star has sufficient time to complete the spiraling-in process before the core collapses, the system will produce very tight DNSs (P_orb ~ 0.01d) with a merger timescale of the order of 1 Myr or less. These systems would have important consequences for the detection rate of GWR and for the understanding of GRB progenitors. On the other hand, if the time left until the explosion is shorter than the orbital-decay timescale, the system will undergo a SN explosion during the CE phase. Helium stars with masses 3.3 - 3.8 Msun in wider orbits (P_orb > 0.25d) and those more massive than 3.8 Msun do not go through CE evolution. The remnants of these massive helium stars are DNSs with periods in the range of 0.1 - 1 d. This suggests that this range of mass includes the progenitors of the galactic DNSs with close orbits (B1913+16 and B1534+12). A minimum kick velocity of 70 km/s and 0 km/s (for B1913+16 and B1534+12, respectively) must have been imparted at the birth of the pulsar's companion. The DNSs with wider orbits (J1518+4904 and probably J1811-1736) are produced from helium star-neutron star binaries which avoid RLOF, with the helium star more massive than 2.5 Msun. For these systems the minimum kick velocities are 50 km/s and 10 km/s (for J1518+4904 and J1811-1736, respectively).Comment: 16 pages, latex, 12 figures, accepted for publication in MNRA

The transfer of fibres in the carding machine

The problem of understanding the transfer of fibres between carding-machine surfaces is addressed by considering the movement of a single fibre in an airflow. The structure of the aerodynamic flow field predicts how and when fibres migrate between the different process surfaces. In the case of a revolving-flats carding machine the theory predicts a “strong” aerodynamic mechanism between taker-in and cylinder and a “weak” mechanism between cylinder and removal cylinder resulting in effective transfer in the first case and a more limited transfer in the second

Data Set for the Reporting of Malignant Odontogenic Tumors Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

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Schwinger Terms and Cohomology of Pseudodifferential Operators

We study the cohomology of the Schwinger term arising in second quantization of the class of observables belonging to the restricted general linear algebra. We prove that, for all pseudodifferential operators in 3+1 dimensions of this type, the Schwinger term is equivalent to the ``twisted'' Radul cocycle, a modified version of the Radul cocycle arising in non-commutative differential geometry. In the process we also show how the ordinary Radul cocycle for any pair of pseudodifferential operators in any dimension can be written as the phase space integral of the star commutator of their symbols projected to the appropriate asymptotic component.Comment: 19 pages, plain te

Pair excitations and parameters of state of imbalanced Fermi gases at finite temperatures

The spectra of low-lying pair excitations for an imbalanced two-component superfluid Fermi gas are analytically derived within the path-integral formalism taking into account Gaussian fluctuations about the saddle point. The spectra are obtained for nonzero temperatures, both with and without imbalance, and for arbitrary interaction strength. On the basis of the pair excitation spectrum, we have calculated the thermodynamic parameters of state of cold fermions and the first and second sound velocities. The parameters of pair excitations show a remarkable agreement with the Monte Carlo data and with experiment.Comment: 14 pages, 5 figure

Flamingo Vol. I N 3

Voo-Doo. Untitled. Prose. 1. Widow. Untitled. Prose. 1. Tiger. Untitled. Prose. 1. Purple Cow. Untitled. Prose. 1. Anonymous. Untitled. Prose. 1. Life. Untitled. Prose. 2. Yale Record. Untitled. Prose. 2. Voo-Doo. Untitled. Prose. 2. Sour Owl. Untitled. Prose. 2. Puppet. Untitled. Prose. 2. Sun Dial. Untitled. Prose. 2. Anonymous. Untitled. Prose. 2. Nottingham, Ruth. Teddy . Prose. 5. Grogan. Untitled. Picture. 7. Anonymous. Untitled. Prose. 7. Anonymous. An Easy One . Prose. 7. Anonymous. How Terrible! Prose. 7. Anonymous. Untitled. Prose. 7. Anonymous. Untitled. Poem. 7. F.H.G. Untitled. Picture. 7. Wood, J.E.F. When mother Went to College . Prose. 8. E.D.T. Chicago Corn Exchange . Poem. 8. Anonymous. Untitled. Prose. 8. Anonymous. Untitled. Poem. 8. Anonymous. All But . Prose. 8. R.D.B. Roscoe to The Rescue . Prose. 9. Leet, L.D. On The Efficacy of Dreams . Prose. 10. Orange Ade. The Fable of the Coffin Nailer . Prose. 11. Orange Ade. Time Wasted . Prose. 11. Orange Ade. The Americanized Boy . Prose. 11. Orange Ade. Anything to Oblige . Prose. 11. Orange Ade. Tit For Tat . Prose. 11. Orange Ade. Good Alibi . Prose. 11. Orange Ade. Untitled. Prose. 11. Grogan. Untitled. Picture. 11. Lusk, R.G. On The Absurdity of Catching Fish When A-Fishing . Prose. 12. Anonymous. Co-eds and Plain Eds in 1950 . Picture. 13. Potter, W.M. Letters of A Japanese Sandman . Prose. 13. Anonymous. Ex Facultate . Prose. 13. Anonymous. Untitled. Prose. 13. R.J.S. An Uplifting Influence . Picture. 13. Anonymous. Consider the Luxite Girl . Poem. 14. Anonymous. Shades of Orpheus . Poem. 14. Anonymous. With The Gospel Team . Poem. 14. Anonymous. Untitled. Prose. 14. Anonymous. Untitled. Poem. 14. Anonymous. A Dirty Trick . Prose. 14. Taylor, Elsie D. Vestigial Customs . Prose. 15. Anonymous. Untitled. Prose. 16. Anonymous. A New version of Anthropology . Prose. 18. Anonymous. A New version of Anthropology . Picture. 18. Anonymous. Untitled. Prose. 18. Funk, Dorothy K. Untitled. Picture. 18. Anonymous. A Deep one . Prose. 18. Anonymous. Take His Name . Prose. 18. Olney, Clarke. The Evolution of An Intellectual . Prose. 19. Anonymous. Untitled. Prose. 19. Anonymous. Untitled. Prose. 20. W.A.W. On Getting Up For Breakfast . Prose. 20. McCann. Untitled. Picture. 21. Anonymous. Untitled. Prose. 21. Anonymous. S.S.S. . Prose. 21. Anonymous. The Judge Disagreed . Prose. 21. Anonymous. The Modern Woman . Prose. 21. Anonymous. Denison Slang in Japan . Prose. 22. Anonymous. Being Specific . Prose. 22. Anonymous. Then The Fun Began . Prose. 22. Anonymous. Then The Fun Began . Prose. 22. Anonymous. Chess Nuts . Poem. 22. Anonymous. Chess Nuts . Picture. 22. Funk, Dorothy K. Untitled. Picture. 22. Anonymous. Untitled. Prose. 22. Reel, Virginia. Untitled. Prose. 22. Anonymous. Untitled. Prose. 23. Anonymous. Take This to Heart . Prose. 23. Anonymous. Stepping Out . Picture. 23. Olney, Clarke. Untitled. Picture. 23. Anonymous. To Lalage . Prose. 23. Anonymous. Untitled. Poem. 24. Anonymous. Description of the Day . Prose. 25. Anonymous. Untitled. Prose. 25. Voo-Doo. Good Bizziness . Prose. 26. Anonymous. Fore! . Prose. 26. Anonymous. Untitled. Prose. 26. Brelsford, Ernest C. Souveniring . Prose. 27. Anonymous. Untitled. Prose. 30. Burr. Sweet Dreams . Prose. 30. Jester. Untitled. Prose. 30. Judge. Untitled. Prose. 30. Goblin. Untitled. Prose. 30. Cracker. Sanitation . Poem. 32. Anonymous. Untitled. Prose. 32. Jester. Untitled. Prose. 32. Goblin. Untitled. Prose. 32. Record. Untitled. Prose. 32. Linotype. Untitled. Prose. 32. Holt, Kilburn. The Schemer\u27s Lament . Poem. 7. Owen, Ernest t. Mother . Poem. 3. Owen, Ernest T. To--- . Poem. 24

Pion-Muon Asymmetry Revisited

Long ago an unexpected and unexplainable phenomena was observed. The distribution of muons from positive pion decay at rest was anisotropic with an excess in the backward direction relative to the direction of the proton beam from which the pions were created. Although this effect was observed by several different groups with pions produced by different means, the result was not accepted by the physics community, because it is in direct conflict with a large set of other experiments indicating that the pion is a pseudoscalar particle. It is possible to satisfy both sets of experiments if helicity-zero vector particles exist and the pion is such a particle. Helicity-zero vector particles have direction but no net spin. For the neutral pion to be a vector particle requires an additional modification to conventional theory as discussed herein. An experiment is proposed which can prove that the asymmetry in the distribution of muons from pion decay is a genuine physical effect because the asymmetry can be modified in a controllable manner. A positive result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure