A model for the time response of solid-embedded thermocouples

Unlike the transient response of a fluidimmersed thermocouple, and in contrast to common belief, the time response of a solid-embedded thermocouple is far from being similar to that of a first-order process. The current study arises from efforts to characterize the transient response of a solid-embedded thermocouple as a result of a step-like temperature change of the measured domain. Results of this study suggest that the response function of the thermocouple is nearly exponentially dependent on the square root of Fourier number (dimensionless time). It follows that, with respect to fluid temperature measurements, significantly faster time response is expected at the initiation of the process on one hand, and much longer time is required for reaching a steady-state temperature on the other hand. It is shown that the thermal diffusivity of the thermocouple is required to be at least one order of magnitude higher than that of the measured domain in order to obtain meaningful results in transient measurements.     

DNA in nanopores: 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.     

Thermal fluctuations of elastic filaments with spontaneous curvature and torsion

We study the effects of thermal fluctuations on thin elastic filaments with spontaneous curvature and torsion. We derive analytical expressions for the orientational correlation functions and for the persistence length of helices and find that this length varies nonmonotonically with the strength of thermal fluctuations. In the weak fluctuation regime, the persistence length of a spontaneously twisted helix has three resonance peaks as a function of the twist rate. In the limit of strong fluctuations, all memory of the helical shape is lost.     

The effect of temperature-dependent thermal conductivity in heat transfer simulations of frozen biomaterials

The thermal conductivity value of pure water ice is inversely proportional to the temperature and decreases about 5-fold as the temperature increases from the liquid nitrogen boiling temperature (77 K to the freezing point of pure water. The temperature dependency of the thermal conductivity is typically overlooked in bioheat transfer simulations. A closed-form solution of the one-dimensional temperature distribution in frozen water and blood is presented in this study, based on a new thermal conductivity model. Results indicate that temperatures are overestimated up to 38K, and heat fluxes through the frozen region boundaries are underestimated by a factor of 2, when the temperature dependency of the thermal conductivity is neglected.     

Spin-parity analysis of the B meson

We have done a J^P analysis of the low-mass π⁺ω system, using the reaction π⁺p→π⁺ωp at 7.1 GeV/c.     

On Decomposing N=2 Line Bundles as Tensor Products of N=1 Line Bundles

We obtain the existence of a cohomological obstruction to expressing N=2 line bundles as tensor products of N=1 bundles. The motivation behind this paper is an attempt at understanding the N=2 super KP equation via Baker functions, which are special sections of line bundles on supercurves.     

Ag8 fluorescence in argon

The fluorescence of Ag8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs.