Cetacean population density estimation from single fixed sensors using passive acoustics

Passive acoustic methods are increasingly being used to estimate animal population density. Most density estimation methods are based on estimates of the probability of detecting calls as functions of distance. Typically these are obtained using receivers capable of localizing calls or from studies of tagged animals. However, both approaches are expensive to implement. The approach described here uses a MonteCarlo model to estimate the probability of detecting calls from single sensors. The passive sonar equation is used to predict signal-to-noise ratios (SNRs) of received clicks, which are then combined with a detector characterization that predicts probability of detection as a function of SNR. Input distributions for source level, beam pattern, and whale depth are obtained from the literature. Acoustic propagation modeling is used to estimate transmission loss. Other inputs for density estimation are call rate, obtained from the literature, and false positive rate, obtained from manual analysis of a data sample. The method is applied to estimate density of Blainville's beaked whales over a 6-day period around a single hydrophone located in the Tongue of the Ocean, Bahamas. Results are consistent with those from previous analyses, which use additional tag data.     

Nanohybrids investigation by waveguide SNOM illumination mode

We demonstrate how optical waveguides can serve as a high resolution illumination source to image hybrid nano-objects in near field optical microscopy. Nanohybrid particles deposited on the surface of glass waveguides are imaged in terms of topography, scattering and fluorescence.     

High‐Nitrogen‐Based Pyrotechnics: Perchlorate‐Free Red‐ and Green‐Light Illuminants Based on 5‐Aminotetrazole

Prototype testing of perchlorate‐free hand‐held signal illuminants for the US Army’s M126 A1 red‐star and M195 green‐star parachute illuminants are described. Although previous perchlorate‐free variants for these items have been developed based on high‐nitrogen compounds that are not readily available, the new formulations consist of anhydrous 5‐aminotetrazole as the suitable perchlorate replacement. Compared to the perchlorate‐containing control, the disclosed illuminants exhibited excellent stabilities toward various ignition stimuli and had excellent pyrotechnic performance. The illuminants are important from both military and civil fireworks perspectives, as the perchlorate‐free nature of the illuminants adequately address environmental concerns associated with perchlorate‐containing red‐ and green‐light‐emitting illuminants.     

Quantum Out-States Holographically Induced by Asymptotic Flatness: Invariance under Spacetime Symmetries, Energy Positivity and Hadamard Property

This paper continues the analysis of the quantum states introduced in previous works and determined by the universal asymptotic structure of four-dimensional asymptotically flat vacuum spacetimes at null infinity M. It is now focused on the quantum state λ _M , of a massless conformally coupled scalar field propagating in M. λ _M is “holographically” induced in the bulk by the universal BMS-invariant state λ defined on the future null infinity of M. It is done by means of the correspondence between observables in the bulk and those on the boundary at future null infinity discussed in previous papers. This induction is possible when some requirements are fulfilled, in particular whenever the spacetime M and the associated unphysical one, M͂, are globally hyperbolic and M admits future time infinity i ⁺. λ _M coincides with Minkowski vacuum if M is Minkowski spacetime. It is now proved that, in the general case of a curved spacetime M, the state λ _M enjoys the following further remarkable properties:

Application of FDTD Method to the Analysis and Design of Leaky-Wave Antennas at Microwaves and Millimeter Waves

The Finite-Difference Time-Domain (FDTD) method, though rather heavy from the computational point of view, allows a complete characterization of a radiating structure, permitting also the accuracy evaluation of the other available solutions. Numerical results have been derived for a broad class of leaky-wave antennas proposed in the literature, always revealing a very good agreement with the methods previously employed. By the FDTD technique it is possible to easily determine the propagation and radiation characteristics of such structures, to obtain the radiation pattern in the far field, and to simulate the longitudinal tapering, necessary to satisfy the design requirements usually imposed to reduce sidelobes in the radiation diagram.     

IR and FIR Spectroscopy of 13CH3I

We have investigated the ¹³CH₃I isotopomer of methyl iodide as a source of Far Infrared (FIR) laser radiation using the optical pumping technique. The molecule is pumped by using a pulsed waveguided CO₂ laser, driven by a novel all solid state power supply that lases on the 10HP band as well as the regular bands. We discovered and assigned two new FIR laser emissions and we give further spectroscopic information about polarization and pump frequency offset for five already known lines.     

A high‐energy‐resolution resonant inelastic X‐ray scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end‐station for resonant inelastic X‐ray scattering and (resonant) X‐ray emission spectroscopy at beamline ID20 of ESRF – The European Synchrotron is presented. The spectrometer hosts five crystal analysers in Rowland geometry for large solid angle collection and is mounted on a rotatable arm for scattering in both the horizontal and vertical planes. The spectrometer is optimized for high‐energy‐resolution applications, including partial fluorescence yield or high‐energy‐resolution fluorescence detected X‐ray absorption spectroscopy and the study of elementary electronic excitations in solids. In addition, it can be used for non‐resonant inelastic X‐ray scattering measurements of valence electron excitations.