From echolocation clicks to animal density--acoustic sampling of harbor porpoises with static dataloggers

Monitoring abundance and population trends of small odontocetes is notoriously difficult and labor intensive. There is a need to develop alternative methods to the traditional visual line transect surveys, especially for low density areas. Here, the prospect of obtaining robust density estimates for porpoises by passive acoustic monitoring (PAM) is demonstrated by combining rigorous application of methods adapted from distance sampling to PAM. Acoustic dataloggers (T-PODs) were deployed in an area where harbor porpoises concurrently were tracked visually. Probability of detection was estimated in a mark-recapture approach, where a visual sighting constituted a "mark" and a simultaneous acoustic detection a "recapture." As a distance could be assigned to each visual observation, a detection function was estimated. Effective detection radius of T-PODs ranged from 22 to 104 m depending on T-POD type, T-POD sensitivity, train classification settings, and snapshot duration. The T-POD density estimates corresponded to the visual densities derived concurrently for the same period. With more dataloggers, located according to a systematic design, density estimates would be obtainable for a larger area. This provides a method suitable for monitoring in areas with densities too low for visual surveys to be practically feasible, e.g., the endangered harbor porpoise population in the Baltic.     

Etude par resonance paramagnetique electronique des verres du systeme B2O3-Na2O-Na3PO4

An EPR study of fast Na⁺ ion vitreous conductors of the system B₂O₃?Na₂O?Na₃PO₄ has been carried out. After X-ray irradiation two types of paramagnetic centers have been observed. The first one is of boron-oxygen hole center (B.O.H.C.) type and similar to that earlier observed for other alkali borate glasses. The second one is of PO₄^2? type. A simulation of its spectrum has been achieved and a defect model discussed.     

Electrochemical behavior of n-and p-type GaxIn1−xP electrodes in sodium iodide liquid ammoniate at room temperature

The electrochemical behavior of p- and n-type Ga_xIn_1-xP electrodes in liquid ammoniate (NaI+3.3 NH₃) in the dark and under illumination has been investigated at room temperature. The flatband potentials of the semiconductors (SC) have been measured either by impedance determinations or by the photoperturbation method. Some specific physical parameters of the polycrystalline material have been deduced, such as E_gap, the electronic transition modes and the carrier densities. The SC behavior in water and in liquid ammoniate has been compared.     

Vinylallenes IX. - preparation de quelques tetraenes-1,2,4,6

The title hydrocarbons have been obtained by the reaction of Grignard reagents with derivatives of 4,6-diene-2-yne-1-ols in the presence of cuprous bromide.     

Formation of a long range ordered polysilsesquioxane O1.5Si-Ph-SiO1.5 by thermal polycondensation of 1,4-bis(trihydroxysilyl)benzene

A study of the polycondensation reaction of 1,4-bis(trihydroxysilyl)benzene 1H by thermal treatment and by a catalytic route is described. The resulting polysilsesquioxane materials O_1.5Si-Ph-SiO_1.5have been compared with those obtained by the classical sol-gel route from 1,4-bis(trimethoxysilyl)benzene 1M. From these results it emerges that the solids obtained by thermal treatment of the solid 1H were drastically different from those obtained in solution, either from 1H or 1M. The thermal polycondensation of 1H led to highly polycondensed non-porous solids having a high density. They were organized at the nanometric scale (X-ray) and at the micrometric scale (TEM images). In contrast, the solids obtained by catalytic polycondensation in solution from 1H or by classical sol-gel route from 1M presented similar properties (moderate level of condensation, high specific surface areas). However, they exhibited different TEM images and chemical reactivity. It has been shown that the long range order observed in the case of the thermal treatment of 1H was not the result of an ordinary thermodynamic rearrangement, since the same treatment applied to the solids obtained by polycondensation in solution of 1H and 1M did not allow such organization.     

A Modified Poincaré Method for the Persistence of Periodic Orbits and Applications

This paper is devoted to the persistence of periodic orbits under perturbations in dynamical systems generated by evolutionary equations, which are not smoothing in finite time, but only asymptotically smoothing. When the periodic orbit of the unperturbed system is non-degenerate, we show the existence and uniqueness of a periodic orbit (with a minimal period near the minimal period of the unperturbed problem) by using “modified” Poincaré methods. Examples of applications, including the perturbed hyperbolic Navier–Stokes equations, systems of damped wave equations and the system of second grade fluids, are given.     

Highly disordered polymer field effect transistors: N-alkyl dithieno[3,2-b:2',3'-d]pyrrole-based copolymers with surprisingly high charge carrier mobilities

A series of novel electroactive and photoactive conjugated copolymers based on N-alkyl dithieno[3,2-b:2',3'-d]pyrroles (DTP) and thiophene (TH) units (DTP-co-THs) were synthesized using a Stille coupling reaction and exhibited molecular weights of 1.6 x 10(4) to 5.0 x 10(4) g/mol. The incorporation of soluble substituted thiophenes and planar DTP units resulted in low band gap, highly conductive polymers. DTP-co-THs exhibited excellent solubility in common organic solvents and formed high-quality films. Optical characterization revealed that the band gaps of DTP-co-THs were between 1.74 and 2.00 eV, lower than regioregular poly(3-alkylthiophenes). Electrochemical characterization showed that the HOMO energy levels of DTP-co-THs are between -4.68 and -4.96 eV. When doped, DTP-co-THs exhibited high conductivities up to 230 S/cm with excellent stability. The different thiophene substituent patterns' effect on the polymers' optical and electronic properties was then examined by density functional theory computations. The microstructure and surface morphologies of poly(2,6-(4-dodecyl-4H-bisthieno[3,2-b:2',3'-d]pyrrole)-random-2,5-(3-dodecylthiophene)) (P4) and poly(2-(4,4'-didodecyl-2,2'-bithiophen-5-yl)-4-octyl-4H-bisthieno[3,2-b:2',3'-d]pyrrole) (P6) thin films were studied by X-ray diffraction and atomic force microscopy. As-cast P4 and P6 thin films exhibited poorly defined, randomly ordered lamellar structure that improved significantly after thermal annealing. Field effect transistor devices fabricated from P4 and P6 showed typical p-channel transistor behavior. Interestingly, the mobilities of as-cast, less ordered samples were much higher than those observed after annealing. The highest values of maximum and average mobilities were observed for the polymer P6 as-cast (0.21 and 0.13 cm(2) V(-1) s(-1), respectively). One of our goals was to test the idea that high mobility and excellent electrical and structural reproducibility could perhaps be achieved by the creation of amorphous pi-conjugated materials that could possess long arrange pi connectivity on the microscopic scale. The results of these studies strongly suggest that the presence of highly ordered microcrystalline structures in thin films of organic semiconductors is not necessary for excellent performance of organic transistors.