Characterisation of tropospheric turbulent layers from radiosondedata

Thin cloudy turbulent layers, responsible for tropospheric scintillation on earth-space paths, are proved to be efficiently detected and characterised from radiosonde ascents. Based on one complete year of radiosonde data, statistical distributions of turbulent layer height, thickness and intensity are analysed, as is their seasonal variability     

Heat transfer in solar-bioclimatic houses

A study is presented on the ventilation mechanism of patio dwellings. The combined heat transfer by natural and forced convections, conduction is studied by solving the governing equations for mixed convection and conduction. The flow is assumed to be laminar and two dimensional. The density variation is taken into account by the Boussinesq approximation. The control-volume approach is used for solving the governing equations of conjugate heat transfer involving conduction in the walls. The study covers the Rayleigh number from 10³ to 10⁶, the Reynolds number from 10 to 10³ and k_r = k_mat/k_air from 0 to 100 for Pr = 0.72 (air) and cavity aspect ratio B from 0.8 to 1.3. produced and the results are presented in terms of the Nusselt number as function of other parameters. The mechanism of ventilation in patio systems is discussed.     

Superconductivity of Organic Materials: Beyond the Fullerenes

We first briefly review the application of the BCS mechanism with electron-phonon interaction to the superconductivity of the A₃C₆₀ compounds. We then explore an extension of this family of compounds by using aromatic cryptands that we consider as “pseudo fullerene molecules”. Preliminary measurements of low field microwave absorption are consistent with superconducting behavior and a Tc ∼ 50K.     

Tracking the dynamics of translation and absolute orientation of a sphere in a turbulent flow

We study the six-dimensional dynamics--position and orientation--of a large sphere advected by a turbulent flow. The movement of the sphere is recorded with two high-speed cameras. Its orientation is tracked using a novel, efficient algorithm; it is based on the identification of possible orientation "candidates" at each time step, with the dynamics later obtained from maximization of a likelihood function. Analysis of the resulting linear and angular velocities and accelerations reveal a surprising intermittency for an object whose size lies in the inertial range, close to the integral scale of the underlying turbulent flow.     

Erbium-activated silica-zirconia planar waveguides prepared by sol-gel route

Er³⁺ doped (100 − x)SiO₂ − xZrO₂ planar waveguides were prepared by the sol-gel route, with x ranging from 10 up to 30 mol%. Multilayer films doped with 0.3 mol% Er³⁺ ions were deposited on fused quartz substrates by the dip-coating technique. The thickness and refractive index were measured by m-line spectroscopy at different wavelengths. The fabrication protocol was optimized in order to confine one propagating mode at 1.5 μm. Photoluminescence in the near and visible region indicated a crystalline local environment for the Er³⁺ ion.     

Sr-hexaferrite/maghemite composite nanoparticles-possible new mediators for magnetic hyperthermia

Composite nanoparticles with variable ratios of M-type Sr-hexaferrite and maghemite phases were prepared via the sol-gel method employing polyvinylalcohol as the stabilizing agent, followed by thermal treatment at 600?°C for 32-190?min. The measurements in static magnetic field revealed considerable variation of the coercivity and remanence depending on the relative content of the highly magnetically anisotropic Sr-hexaferrite phase. Calorimetric heating experiments were carried out on aqueous gel suspensions under an alternating magnetic field of maximum amplitude H(max) = 15.1-68.4?kA?m(-1) and frequency ν = 108?kHz. They showed a strong dependence of the heating efficiency on the coercivity and remanence of the composites, with a specific absorption rate (SAR) value ranging from units to tens of W/g(Fe(ferrimagnetic)).     

Making tiestalls more comfortable: III. Providing additional lateral space to improve the resting capacity and comfort of dairy cows

Dairy cows housed in tiestalls are restricted to one space; therefore, this space should be designed to accommodate all the activities cows need to perform. Lying is a very important behavior for dairy cows as well as a critical measure in the assessment of stall designs, to ensure that the cows' needs for resting space are met. The objective of this study was to determine if increasing tiestall width alters the lying behavior of lactating dairy cows. Two treatments were compared: the current recommendation (139 cm) and a double stall (284 cm). Sixteen cows were blocked by parity and lactation stage, then randomly allocated to a treatment and a stall within 1 of 2 rows in the research barn, for 6 wk. The average stall length was 188 cm. Leg-mounted accelerometers were used to record lying behaviors. Cows were video-recorded 24 h/wk using surveillance cameras positioned above the stalls. Video data from wk 1, 3, and 6 were extracted at a rate of 1 image/min and analyzed by a trained observer to assess the position and the location of the cow's body, head, and limbs during the lying hours. Lying behaviors and frequency of each position and location were analyzed in SAS (SAS Institute Inc., Cary, NC) using a mixed model in which treatment, block, and week were included as fixed factors, and cow and row as random factors. Multiple comparisons were adjusted using the Scheffé method. Results indicate that cows in double stalls fully extended their hindlimbs more often than single stall cows (21.7 vs. 7.6% of lying time). Cows in double stalls also intruded in the neighboring stalls with their hindlimbs less often (1.3 vs. 14.7% of lying time), instead positioning them inside their own stall more often (92.7 vs. 84.6% of lying time). Use of the second stall in the double stall group totaled 11.6, 5.1, 33.8, and 18.0% of lying time, respectively, for the head, front legs, hind legs, and body. Total lying time was not statistically different between double (716 min/d) and single stall (671 min/d) groups. Contacts with stall hardware during lying-down movements were also less frequent in double stalls (43.1 vs. 77.1% of lying events) compared with single stalls. These results suggest that dairy cows housed in double stalls modified their resting habits and used the extra space made available to them. Increasing stall width beyond the current recommendation is likely to benefit the cows by improving their ability to rest.