Interaction between coherent structures and surface temperature and its effect on ground heat flux in an unstably stratified boundary layer

Surface layer plumes, thermals, downdrafts and roll vortices are the most prominent coherent structures in an unstably stratified boundary layer. They contribute most of the temperature and vertical velocity variance, and their time scales increase with height. The effects of these multi-scale structures (surface layer plumes scale with surface layer depth, thermals scale with boundary layer height and the resulting roll vortices scale with convective time scale) on the surface temperature and ground heat flux were studied using turbulence measurements throughout the atmospheric boundary layer and the surface temperature measurements from an infrared camera. Plumes and thermals imprint on the surface temperature as warm structures and downdrafts imprint as cold structures. The air temperature trace shows a ramp-like pattern, with small ramps overlaid on a large ramp very close to the surface; on the other hand, surface temperature gradually increases and decreases. Turbulent heat flux and ground heat flux show similar patterns, with the former lagging the latter. The maximum values of turbulent heat flux and ground heat flux are 4 and 1.2 times the respective mean values during the ejection event. Surface temperature fluctuations follow a similar power-law exponent relationship with stability as suggested by surface layer similarity theory. © 2013 Copyright Taylor and Francis Group, LLC

Search for a circum-planetary material and orbital period variations of short-period Kepler exoplanet candidates

A unique short-period Mercury-size Kepler exoplanet candidate KIC012557548b has been discovered recently by Rappaport et al. (2012). This object is a transiting disintegrating exoplanet with a circum-planetary material - comet-like tail. Close-in exoplanets, like KIC012557548b, are subjected to the greatest planet-star interactions. This interaction may have various forms. In certain cases it may cause formation of the comet-like tail. Strong interaction with the host star, and/or presence of an additional planet may lead to variations in the orbital period of the planet. Our main aim is to search for comet-like tails similar to KIC012557548b and for long-term orbital period variations. We are curious about frequency of comet-like tail formation among short-period Kepler exoplanet candidates. We concentrate on a sample of 20 close-in candidates with a period similar to KIC012557548b from the Kepler mission.Comment: 19 pages, 75 figures, AN accepte

Broadband potential optimisation of a full scale acoustic metawindow performance

Noise control and airflow in duct-like systems are among some of the most interesting applications to conjugate AMMs innovation and sustainability. Specifically applied to the built environment, they opened up a new field of research supporting indoor wellbeing, sanitised environments, and public activities. Previous research conducted by the authors has proved AMM based window to be a resourceful way to address both natural ventilation and reduce the incoming noise propagation; however, the effective spectral range did not cover lower frequencies (50-350 Hz). For this reason, in the presented paper, implementation in the AMM unit geometry was performed over a full-scale acoustic metawindow (AMW). The resonating volume has been enhanced (by 200% of the original one) and coupled with a set of lateral flanks. Numerical analysis through FEM proved that on a range of opening ratio from 3 to 33%, the TL related to the window is improved overall of the 70% on the frequency range from 50 to 350 Hz. Such results encourage the use of new AMMs ergonomic windows in place of standard ones to achieve both natural ventilation and noise attenuation from 50 to 5k Hz, being resourceful for domestic, sanitary, and public applications

Hydraulic failure by heave and piping

It is generally agreed the same criterion for hydraulic heave and for piping can be used. In vertical upward flow the theory is well established. The weight of the soil must be greater than the seepage force of the water. Despite this well established theory piping and sand boiling occurs at much lower hydraulic gradient than the theoretical value. It is concluded that this discrepancy resulting from a conceptual error by not making distinction between the local and the global equilibrium. In the case of hydraulic heave the equilibrium of the entire soil prism (global equilibrium), while for the initiation of piping on the surface of the soil the equilibrium of one grain (local equilibrium) should be investigated. Investigating the local equilibrium of a single grain physical model for the initiation of piping is proposed. Criterion for piping on the top of a horizontal surface in granular soil subject to an upward flow deduced from first principles. It is concluded that hydraulic gradient alone does not sufficiently describe the hydraulic stability of the soil. The particle size and its distribution also have effect on the hydraulic stability of the soil. Critical grain diameter corresponding to the critical hydraulic gradient is introduced. If the diameters of the grains in a soil matrix are bigger than the critical diameter then the Terzaghi criterion is valid. Grains with smaller diameters lose their stability at lower hydraulic gradient than the critical one. The removals of grains from the soil matrix increase both the hydraulic gradient and the permeability of the soil. Thus the initial grain removal from the surface of the soil can progressively lead to sand boiling; therefore, the stronger criterion of piping should also be required for hydraulic heave

A two-state model for helicase translocation and unwinding of nucleic acids

Helicases are molecular motors that unwind double-stranded nucleic acids (dsNA), such as DNA and RNA). Typically a helicase translocates along one of the NA single strands while unwinding and uses adenosine triphosphate (ATP) hydrolysis as an energy source. Here we model of a helicase motor that can switch between two states, which could represent two different points in the ATP hydrolysis cycle. Our model is an extension of the earlier Betterton-J\"ulicher model of helicases to incorporate switching between two states. The main predictions of the model are the speed of unwinding of the dsNA and fluctuations around the average unwinding velocity. Motivated by a recent claim that the NS3 helicase of Hepatitis C virus follows a flashing ratchet mechanism, we have compared the experimental results for the NS3 helicase with a special limit of our model which corresponds to the flashing ratchet scenario. Our model accounts for one key feature of the experimental data on NS3 helicase. However, contradictory observations in experiments carried out under different conditions limit the ability to compare the model to experiments.Comment: minor modification

The temperature dependence of the isothermal bulk modulus at 1 bar pressure

It is well established that the product of the volume coefficient of thermal expansion and the bulk modulus is nearly constant at temperatures higher than the Debye temperature. Using this approximation allows predicting the values of the bulk modulus. The derived analytical solution for the temperature dependence of the isothermal bulk modulus has been applied to ten substances. The good correlations to the experiments indicate that the expression may be useful for substances for which bulk modulus data are lacking

Epaiketa eta Endogamia Nafarroako Margaritaren Le Miroir de l'âme pécheresse-n [Arima Bekatariaren Mirailan]

To Jane Donawerth and Jeanne Fahnestock, thanks. 1. Sarrera 1.1. Artikuluaren alderdi zabalak Gurako nioke nire lanari abia eman berez duen itzala baino esparru zabalagoan kokatuz eta holan iradokiz inoizkorako asko interesatzen zaizkidan zenbait ikerlerro ; hots ikerlerrook ez dira artikuluan bertan landuko baina esparrua definitzen langa lanak egingo dituzte. Ikerlerro horiek hurrengo kontzeptuen arteko hartu emana dute lan-hazitzat : ahozkotasunaren eta ida-tzizkotasunaren arteko harremana..