84,445 research outputs found

    A Cold-Strontium Laser in the Superradiant Crossover Regime

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    Recent proposals suggest that lasers based on narrow dipole-forbidden transitions in cold alkaline earth atoms could achieve linewidths that are orders of magnitude smaller than linewidths of any existing lasers. Here, we demonstrate a laser based on the 7.5 kHz linewidth dipole forbidden 3^3 P1_1 to 1^1 S0_0 transition in laser-cooled and tightly confined 88^{88}Sr. We can operate this laser in the bad-cavity regime, where coherence is primarily stored in the atoms, or continuously tune to the more conventional good-cavity regime, where coherence is primarily stored in the light field. We show that the cold-atom gain medium can be repumped to achieve quasi steady-state lasing, and demonstrate up to an order of magnitude suppression in the sensitivity of laser frequency to changes in cavity length, the primary limitation for the most frequency stable lasers today.Comment: 5 pages, 4 figure

    A New \u3ci\u3eFlexamia\u3c/i\u3e (Homoptera: Cicadellidae: Deltocephalinae) From Southern Michigan

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    A new species, Flexamia huroni, is described from a prairie fen in south- eastern Michigan. This leafhopper is closely related to the western F. serrata B & T, a specialist on mat muhly (Muhlenbergia richardsonis). Like its sister species, F. huroni was found only in close association with mat muhly, a grass listed as a threatened species in Michigan and Wisconsin. The regional rarity of mat muhly, its association with a globally imperiled plant commnity (prairie fen) and the absence of F. huroni from several fens known to contain this grass, make this new Flexamia a strong candidate for listing as endangered in Michigan

    Environment for the People

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    Environment for the People, a joint publication of PERI and the Centre for Science and the Environment (CSE) in India, documents innovative strategies used by environmental activists around the world to build natural assets. In diverse landscapes, from Bangladesh's riverine delta to Somalia's arid uplands, ommunities are investing in ecological restoration. In 'extractive reserves' in the Amazon rainforest, the defense of sustainable livelihoods goes hand-in-hand with defense of bio-diversity. In the Peruvian Andes, indigenous communities are fighting to protect their lands and water from the ravages of the mining industry. And in cities around the world, from Los Angeles to New Delhi, communities are mobilizing to defend the right to clean air. These and other inspiring cases profiled in Environment for the People illustrate that humankind does not face an inexorable 'tradeoff' between protecting the natural environment and improving economic well-being. On the contrary, struggles for environmental protection and sustainable livelihoods are bound together

    Determinants of household choice of breakfast cereals: healthy or unhealthy?

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    We studied consumer demand for more and less healthy breakfast cereals. Using ACNielsen Homescan database and USDA food nutrition data, we developed three cereal nutrition indexes for each household in the data. In addition to the standard demographic characteristics of households and prices, we included variables representing differences between private labels and national brands. We found that the structure of the industry, through its effect on the product mix produced, affects consumer choice of nutritious foods. Some households buy fewer healthy cereals simply through reluctance to trust private labels. Among all factors expected to influence consumer purchases, the prices appear to have the strongest effect on the healthiness of the choice of breakfast cereals, which is a relatively inexpensive product. Households with children and teens buy less healthy cereals, while older and more educated households make healthier choices.consumer demand, healthy and unhealthy food, breakfast cereals, Consumer/Household Economics,
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