Facebook Twitter Google+LinkedInPinterestWhatsAppTerrece Bootle Bethel, Family Island Administrator for Long Island wishes to advise residents from Petty’s to Salt Pond – affected by Hurricane Joaquin – to meet at the NGM Major High School in Buckley’s at 9am on Tuesday, October 6, 2015. Members of the Disaster Preparedness Committee are also asked to attend.Also, residents from Gordon’s to Hamilton are to meet at Clarence Town’s Community Centre at 9am on Tuesday, October 6, 2015. On hand would also be personnel from the Department of Social Services to assist ALL in need.Residents in New Providence who wish to provide assistance to their relatives and othes impacted by the hurricane on Long Island are asked to call: (242) 337-3031. Recommended for you Related Items:announcement, Clarence Town’s Community Centre, hurricane joaquin, Long Island, NGM Major hogh School Long Island fire extinguished Facebook Twitter Google+LinkedInPinterestWhatsApp Louis Bacon’s Moore Bahamas Foundation Announces Donation To Rotary Club Of The Bahamas For Relief Efforts In The Bahamas North to Middle Caicos Causeway behind schedule; residents concerned over Joaquin flooding
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Image: Wikipedia This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Simple technique results in surprising repellency results Explore further (PhysOrg.com) — Anyone who has ever swum around near the bottom of a swimming pool, or flippered along an ocean floor for any length of time without benefit of an air supply knows that there is a decision making process going on from the moment the dive begins: when to surface? In people, the process clearly involves some calculating. The deeper a person dives, the more time must be allotted to reach the surface. A miscalculation can result in panic, or worse tragedy. But then, people aren’t exactly at home in the deep water; but penguins are. So, how do they figure out when it’s time to surface? Surely they’re not thinking it over the whole time, that would take away from focusing on the reason for the dive. Finding and eating fish. That’s what Dr Kozue Shiomi and his colleagues from the University of Tokyo wanted to know, so they set about studying emperor penguins to find out. As it turns out, as they explain in their paper published in The Journal of Experimental Biology, it’s not so much about timing as it is about energy used in flapping their wings underwater to chase after prey.Dr. Shiomi and his team studied the penguins in their two major diving environments: in open water, and when diving from and returning to a hole in the ice. In both cases, the birds were timed to see how long their foraging expeditions under the water lasted.When fishing in open water, the ten free-rangers studied, over the course of 15,978 dives stayed under for an average of 5.7 minutes. When fishing from a hole in the ice however, the three birds under study dived 495 times but stayed under much longer, which led the researchers to believe that the penguins’ decision to end their time under water wasn’t about how long they’d been under at all. This led them to consider the possibility that it was based on energy expended instead, which is how they came to start counting how many times the penguins flapped their wings to propel themselves while chasing after fish.Turns out regardless of whether the penguins are fishing in open water, or through a hole in the ice, they flap on average 237 times before surfacing. Thus, it seems rather clear that they are basing their time spent under water on energy spent flapping, rather than on some predetermined time span; though, how they count and keep track, is still anyone’s guess. © 2011 PhysOrg.com More information: Point of no return in diving emperor penguins: is the timing of the decision to return limited by the number of strokes? J Exp Biol 215, 135-140. January 1, 2012. doi: 10.1242/jeb.064568AbstractAt some point in a dive, breath-hold divers must decide to return to the surface to breathe. The issue of when to end a dive has been discussed intensively in terms of foraging ecology and behavioral physiology, using dive duration as a temporal parameter. Inevitably, however, a time lag exists between the decision of animals to start returning to the surface and the end of the dive, especially in deep dives. In the present study, we examined the decision time in emperor penguins under two different conditions: during foraging trips at sea and during dives at an artificial isolated dive hole. It was found that there was an upper limit for the decision-to-return time irrespective of dive depth in birds diving at sea. However, in a large proportion of dives at the isolated dive hole, the decision-to-return time exceeded the upper limit at sea. This difference between the decision times in dives at sea versus the isolated dive hole was accounted for by a difference in stroke rate. The stroke rates were much lower in dives at the isolated hole and were inversely correlated with the upper limit of decision times in individual birds. Unlike the decision time to start returning, the cumulative number of strokes at the decision time fell within a similar range in the two experiments. This finding suggests that the number of strokes, but not elapsed time, constrained the decision of emperor penguins to return to the surface. While the decision to return and to end a dive may be determined by a variety of ecological, behavioral and physiological factors, the upper limit to that decision time may be related to cumulative muscle workload. Citation: Researchers find clue to explain how penguins know when to surface (2011, December 9) retrieved 18 August 2019 from https://phys.org/news/2011-12-clue-penguins-surface.html
Journal information: Nature Nanotechnology (Phys.org)—A team of researchers with members from the Netherlands, Australia, and the U.K. has developed a new way to build an extremely sensitive magnetic sensor. As they describe in their paper published in the journal Nature Nanotechnology, their sensors are based on sensing with a single electron spin using real-time adaptive measurements. The work by the team marks the development of the first quantum sensor to be based on the spin of a single electron, which in this case, was trapped in a diamond nitrogen-vacancy center. It is so sensitive that it is able to measure the strength of a magnetic field to the very limits of that described by quantum physics.The problem with attempting to use the spin of an electron as a sensor, of course, is that it must be measured, which causes the quantum state to be affected. To get around this problem the researchers used an atomic sized defect in diamond kept in an extremely cold environment—the spin in its defect (nitrogen-vacancy) is not very sensitive to environmental noise because it has no net nuclear spin. The sensor works by taking multiple measurements as the electron is exposed to the magnetic field, on the spin defect, using optimal settings based on prior measurements and then adjusting those that come after using Bayesian statistics—it is based on Zeeman interactions, the researches explain—which is what happens when an electron moves into an magnetic field. The actual measurements are taken by subjecting the spin to microwave radiation, then exciting it with a laser and then measuring the fluorescent signals that are produced. The data is then processed (on an off-the-shelf microprocessor they programmed for their purposes) and the results are used to set the settings for the next measurement, and so on.The result is a sensor that is 100 times more precise than previous sensors, though the team acknowledges that to make it useful, they will have to find a way to make it usable at room temperature. If they can do that, the sensor could conceivably be used to image the makeup of individual molecules, or perhaps as a method for storing qubits in a quantum computer. Explore further More information: C. Bonato et al. Optimized quantum sensing with a single electron spin using real-time adaptive measurements, Nature Nanotechnology (2015). DOI: 10.1038/nnano.2015.261AbstractQuantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz−1/2 over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance. Spin lifetime of electrons in graphene increased by magnetic fields © 2015 Phys.org Experiment apparatus. Credit: (c) 2015 Nature Nanotechnology (2015) doi:10.1038/nnano.2015.261 Citation: Researchers build quantum sensors based on single solid-state spins (2015, December 2) retrieved 18 August 2019 from https://phys.org/news/2015-12-quantum-sensors-based-solid-state.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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