A Toll for lupus

Toll-like receptor (TLR)-9 recognizes CpG motifs in microbial DNA. TLR9 signalling stimulates innate antimicrobial immunity and modulates adaptive immune responses including autoimmunity against chromatin, e.g., in systemic lupus erythematosus (SLE). This review summarizes the available data for a role of TLR9 signalling in lupus and discusses the following questions that arise from these observations: 1) Is CpG-DNA/TLR9 interaction involved in infection-induced disease activity of lupus? 2) What are the risks of CpG motifs in vaccine adjuvants for lupus patients? 3) Is TLR9 signalling involved in the pathogenesis of lupus by recognizing self DNA

Measurement-dependent corrections to work distributions arising from quantum coherences

For a quantum system undergoing a unitary process work is commonly defined based on the Two Projective Measurement (TPM) protocol which measures the energies of the system before and after the process. However, it is well known that projective measurements disregard quantum coherences of the system with respect to the energy basis, thus removing potential quantum signatures in the work distribution. Here we consider weak measurements of the system's energy difference and establish corrections to work averages arising from initial system coherences. We discuss two weak measurement protocols that couple the system to a detector, prepared and measured either in the momentum or the position eigenstates. Work averages are derived for when the system starts in the proper thermal state versus when the initial system state is a pure state with thermal diagonal elements and coherences characterised by a set of phases. We show that by controlling only the phase differences between the energy eigenstate contributions in the system's initial pure state, the average work done during the same unitary process can be controlled. By changing the phases alone one can toggle from regimes where the systems absorbs energy, i.e. a work cost, to the ones where it emits energy, i.e. work can be drawn. This suggests that the coherences are additional resources that can be used to manipulate or store energy in a quantum system.Comment: 9 pages, 3 figure

Nonequilibrium dynamics in the O(N) model to next-to-next-to-leading order in the 1/N expansion

Nonequilibrium dynamics in quantum field theory has been studied extensively using truncations of the 2PI effective action. Both 1/N and loop expansions beyond leading order show remarkable improvement when compared to mean-field approximations. However, in truncations used so far, only the leading-order parts of the self energy responsible for memory loss, damping and equilibration are included, which makes it difficult to discuss convergence systematically. For that reason we derive the real and causal evolution equations for an O(N) model to next-to-next-to-leading order in the 2PI-1/N expansion. Due to the appearance of internal vertices the resulting equations appear intractable for a full-fledged 3+1 dimensional field theory. Instead, we solve the closely related three-loop approximation in the auxiliary-field formalism numerically in 0+1 dimensions (quantum mechanics) and compare to previous approximations and the exact numerical solution of the Schroedinger equation.Comment: 29 pages, minor changes, references added; to appear in PR

Renormalization Group Approach to Spectral Properties of the Two-Channel Anderson Impurity Model

The impurity Green function and dynamical susceptibilties for the two-channel Anderson impurity model are calculated. An exact expression for the self-energy of the impurity Green function is derived. The imaginary part of the self-energy scales as \sqrt{|\w/T_K|} for $T\to 0$ serving as a hallmark for non-Fermi behavior. The many-body resonance is pinned to a universal value $1/(2\pi\Delta)$ at \w=0. Its shape becomes increasingly more symmetric for the Kondo-regimes of the model. The dynamical susceptibilities are governed by two energy scales $T_K$ and $T_h$ and approach a constant value for \w\to 0, whereas relation \chi''(\w)\propto \w holds for the single channel model.Comment: 4 pages, 4 figure, revte

Meteoritic material on the moon

Three types of meteoritic material are found on the moon: micrometeorites, ancient planetesimal debris from the "early intense bombardment," and debris of recent, craterforming projectiles. Their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distributed over the entire lunar surface, but is seen most clearly in mare soils. It has a primitive, C1-chondrite-like composition, and comprises 1 to 1.5 percent of mature soils. Apparently it represents cometary debris. The ancient component is seen in highland breccias and soils. Six varieties have been recognized, differing in their proportions of refractories (Ir, Re), volatiles (Ge, Sb), and Au. All have a fractionated composition, with volatiles depleted relative to siderophiles. The abundance patterns do not match those of the known meteorite classes. These ancient meteoritic components seem to represent the debris of an extinct population of bodies (planetisimals, moonlets) that produced the mare basins during the first 700 Myr of the moon's history. On the basis of their stratigraphy and geographic distribution, five of the six groups are tentatively assigned to specific mare basins: Imbrium, Serenitatis, Crisium, Nectaris, and Humorum or Nubium

Meteoritic material on the moon

Micrometeorites, ancient planetesimal debris from the early intense bombardment, and debris of recent, crater-forming projectiles are discussed and their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distrubuted over the entire lunar surface, but is seen most clearly in mare soils whereas, the ancient component is seen in highland breccias and soils. A few properties of the basin-forming objects are inferred from the trace element data. An attempt is made to reconstruct the bombardment history of the moon from the observation that only basin-forming objects fell on the moon after crustal differentiation. The apparent half-life of basin-forming bodies is close to the calculated value for earth-crossing planetesimals. It is shown that a gap in radiometric ages is expected between the Imbrium and Nectaris impacts, because all 7 basins formed in this interval lie on the farside or east limb

Canonical density matrix perturbation theory

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical density matrix perturbation theory can be used to calculate temperature dependent response properties from the coupled perturbed self-consistent field equations as in density functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large non-metallic materials and metals at high temperatures.Comment: 21 pages, 3 figure

Energy-temperature uncertainty relation in quantum thermodynamics

This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this record.Much like Heisenberg’s uncertainty principle in quantum mechanics, there exists a thermodynamic uncertainty relation in classical statistical mechanics that limits the simultaneous estimation of energy and temperature for a system in equilibrium. However, for nanoscale systems deviations from standard thermodynamics arise due to non-negligible interactions with the environment. Here we include interactions and, using quantum estimation theory, derive a generalised thermodynamic uncertainty relation valid for classical and quantum systems at all coupling strengths. We show that the non-commutativity between the system’s state and its effective energy operator gives rise to additional quantum fluctuations that increase the uncertainty in temperature and modify the heat capacity. Surprisingly, these quantum fluctuations are described by the average Wigner-Yanase-Dyson skew information, a quantity intimately connected to measures of coherence. For temperature estimation we demonstrate that the optimal signal-to-noise ratio is constrained not only by the heat capacity, but an additional dissipative term arising from the non-negligible interactions. Practically this will inform the design of optimal nanoscale thermometers. On the fundamental side the results shed light on the interplay between classical and non-classical fluctuations in quantum thermodynamics.HM is supported by EPSRC through a Doctoral Training Grant. J.A. acknowledges support from EPSRC, grant EP/M009165/1, and the Royal Society. This research was supported by the COST network MP1209 “Thermodynamics in the quantum regime”

Neutrino fluence after r-process freeze-out and abundances of Te isotopes in presolar diamonds

Using the data of Richter et al. (1998) on Te isotopes in diamond grains from a meteorite, we derive bounds on the neutrino fluence and the decay timescale of the neutrino flux relevant for the supernova r-process. Our new bound on the neutrino fluence F after freeze-out of the r-process peak at mass number A = 130 is more stringent than the previous bound F < 0.045 (in units of 10**37 erg/cm**2) of Qian et al. (1997) and Haxton et al. (1997) if the neutrino flux decays on a timescale tau > 0.65 s. In particular, it requires that a fluence of F = 0.031 be provided by a neutrino flux with tau < 0.84 s. Such a fluence may be responsible for the production of the solar r-process abundances at A = 124-126 (Qian et al. 1997; Haxton et al. 1997). Our results are based on the assumption that only the stable nuclei implanted into the diamonds are retained while the radioactive ones are lost from the diamonds upon decay after implantation (Ott 1996). We consider that the nanodiamonds are condensed in an environment with C/O > 1 in the expanding supernova debris or from the exterior H envelope. The implantation of nuclei would have occurred 10**4-10**6 s after r-process freeze-out. This time interval may be marginally sufficient to permit adequate cooling upon expansion for the formation of diamond grains. The mechanisms of preferential retention/loss of the implanted nuclei are not well understood.Comment: AASTeX, 11 pages, 3 Postscript figure

Half-Filled Lowest Landau Level on a Thin Torus

We solve a model that describes an interacting electron gas in the half-filled lowest Landau level on a thin torus, with radius of the order of the magnetic length. The low energy sector consists of non-interacting, one-dimensional, neutral fermions. The ground state, which is homogeneous, is the Fermi sea obtained by filling the negative energy states and the excited states are gapless neutral excitations out of this one-dimensional sea. Although the limit considered is extreme, the solution has a striking resemblance to the composite fermion description of the bulk $\nu=1/2$ state--the ground state is homogeneous and the excitations are neutral and gapless. This suggests a one-dimensional Luttinger liquid description, with possible observable effects in transport experiments, of the bulk state where it develops continuously from the state on a thin torus as the radius increases.Comment: 4 pages, 1 figur