474 research outputs found
Bed and Breakfast Homes: A Life of Leisure or a Stressful Encounter
This qualitative study examines stressors and coping mechanisms in bed and breakfast (B&B) homes
Robust interferometer for the routing of light beams carrying orbital angular momentum
We have developed an interferometer requiring only minimal angular alignment for the routing of beams carrying orbital angular momentum. The Mach–Zehnder interferometer contains a Dove prism in each arm where each has a mirror plane around which the transverse phase profile is inverted. One consequence of the inversions is that the interferometer needs no alignment. Instead the interferometer defines a unique axis about which the input beam must be coupled. Experimental results are presented for the fringe contrast, reaching a maximum value of 93±1%
A versatile quantum walk resonator with bright classical light
In a Quantum Walk (QW) the "walker" follows all possible paths at once
through the principle of quantum superposition, differentiating itself from
classical random walks where one random path is taken at a time. This
facilitates the searching of problem solution spaces faster than with classical
random walks, and holds promise for advances in dynamical quantum simulation,
biological process modelling and quantum computation. Current efforts to
implement QWs have been hindered by the complexity of handling single photons
and the inscalability of cascading approaches. Here we employ a versatile and
scalable resonator configuration to realise quantum walks with bright classical
light. We experimentally demonstrate the versatility of our approach by
implementing a variety of QWs, all with the same experimental platform, while
the use of a resonator allows for an arbitrary number of steps without scaling
the number of optics. Our approach paves the way for practical QWs with bright
classical light and explicitly makes clear that quantum walks with a single
walker do not require quantum states of light
Non-song vocalizations of humpback whales in Western Australia
This study presents non-song vocalizations of humpback whales (Megaptera novaeangliae) from two migratory areas off the Western Australian coast: Geographe Bay and Port Hedland. A total of 220 sounds were identified as non-song sounds in 193 h of recordings reviewed. Of those, 68 were measured and qualitatively classified into 17 groups using their spectral features. One group (HW-02) had a high level of variation in terms of spectral slope. However, further classification using statistical classification methods was not possible because of the small sample size. Non-song sound frequencies varied from 9 Hz to 6 kHz, with the majority of sounds under 200 Hz. The duration of non-song sounds varied between 0.09 and 3.59 s. Overall, the use of spectral features allowed general classification of humpback whale sounds in a low sample size scenario that was not conducive to using quantitative methods. However, for highly variable groups, quantitative statistical classification methods (e.g., random forests) are needed to improve classification accuracy. The identification and accurate classification of a species’ acoustic repertoire is key to effectively monitor population status using acoustic techniques and to better understand the vocal behavior of the species. The results of this study improve the monitoring of humpback whales by standardizing the classification of sounds and including them in the species’ repertoire. The inclusion of non-song sounds in passive acoustic monitoring of humpback whales will add females and calves to the detection counts of otherwise only singing males. © Copyright © 2020 Recalde-Salas, Erbe, Salgado Kent and Parsons
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