Low-loss flake-graphene saturable absorber mirror for laser mode-locking at sub-200-fs pulse duration

Saturable absorbers are a key component for mode-locking femtosecond lasers. Polymer films containing graphene flakes have recently been used in transmission as laser mode-lockers, but suffer from high nonsaturable loss, limiting their application in low-gain lasers. Here we present a saturable absorber mirror based on a film of pure graphene flakes. The device is used to mode lock an erbium-doped fiber laser, generating pulses with state-of-the-art, sub-200-fs duration. The laser characteristic indicate that the film exhibits low nonsaturable loss (13% per pass) and large absorption modulation depth (45% of low-power absorption)

Climate change promotes parasitism in a coral symbiosis.

Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals' sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodinium phylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change

PREY AVAILABILITY AND SELECTION BY MOUNTAIN LIONS IN ARAVAIPA-KLONDYKE AREA OF ARIZONA

Prey selection by mountain lions (Felis concolor) in the Aravaipa-Klondyke area (2,000 km) in southeastern Arizona was studied from February 1991 through September 1993. Overall diet from frequency of occurrence as determined from 370 scats was: 48% deer (white-tailed and mule deer combined), 34% cattle, 17% javelinas, 6% rabbit (cottontail and jackrabbit), 4% rodent, and 2% desert bighorn. Using a correction factor developed by Ackerman et al. (1984), we also estimated percent biomass and proportion of individuals killed. With respect to biomass consumed, cattle was 44%, deer 40%, javelinas 10.9%, rabbits 2.9%, and rodents 0.02%. Based on weights of prey consumed, proportion of individuals eaten changed to rabbits 52.7%, deer 16.3%, rodents 12%, javelinas 10% cattle 8%, and desert bighorn 0.5% Comparisons with availability as determined from four separate four-day double-count helicopter surveys found that lions selected calves (ate more than expected based on availability alone), killed and ate less deer than expected, and javelinas as would be expected

PREY AVAILABILITY AND SELECTION BY MOUNTAIN LIONS IN ARAVAIPA-KLONDYKE AREA OF ARIZONA

Prey selection by mountain lions (Felis concolor) in the Aravaipa-Klondyke area (2,000 km) in southeastern Arizona was studied from February 1991 through September 1993. Overall diet from frequency of occurrence as determined from 370 scats was: 48% deer (white-tailed and mule deer combined), 34% cattle, 17% javelinas, 6% rabbit (cottontail and jackrabbit), 4% rodent, and 2% desert bighorn. Using a correction factor developed by Ackerman et al. (1984), we also estimated percent biomass and proportion of individuals killed. With respect to biomass consumed, cattle was 44%, deer 40%, javelinas 10.9%, rabbits 2.9%, and rodents 0.02%. Based on weights of prey consumed, proportion of individuals eaten changed to rabbits 52.7%, deer 16.3%, rodents 12%, javelinas 10% cattle 8%, and desert bighorn 0.5% Comparisons with availability as determined from four separate four-day double-count helicopter surveys found that lions selected calves (ate more than expected based on availability alone), killed and ate less deer than expected, and javelinas as would be expected