Low noise all-fiber amplification of a coherent supercontinuum at 2 \mu m and its limits imposed by polarization noise

We report the amplification of an all-normal dispersion supercontinuum pulse in a Thulium / Holmium co-doped all-fiber chirped pulse amplification system. With a -20 dB bandwidth of more than 300 nm in the range 1800-2100 nm the system delivers high quality 66 fs pulses with more than 70 kW peak power directly from the output fiber. The coherent seeding of the entire emission bandwidth of the doped fiber and the stability of the supercontinuum generation dynamics in the silicate glass all-normal dispersion photonic crystal fiber result in excellent noise characteristics of the amplified ultrashort pulses

Ultrathin epitaxial Fe films in vicinal GaAs(001): A study by spin-resolved photoelectron spectroscopy

Thin epitaxial Fe films have been grown on vicinal GaAs(001) substrates and their remanent magnetic properties and the degree of substrate atom diffusion investigated using synchrotron-based photoelectron spectroscopy. The vicinal Fe films, though exhibiting greater As diffusion than their singular homologues, displayed better film quality both from the structural and the magnetic points of view. The spin-resolved valence spectra of the vicinal films resemble those for crystalline bulk Fe at lower film thicknesses than for singular films

Construction of an Accessible Ocean-Acidification Simulator to Investigate Physiological Responses of the Green Crab, Carcinus Maenas, to Acidified Conditions

The European green crab Carcinus maenas L, is a major invasive species in North America as well as many other regions around the world, including South Africa, Australia, South America, and Asia. The species poses a significant threat to the diverse ecosystems and the aquaculture industries on the East coast of the United States, with the state of Maine particularly at risk. The shellfish industry is a significant part of Maine’s economy, and is threatened by the foraging behavior of green crabs toward small bivalves (Beal 2015). Climate change likely plays a large role in the rapid population growth of C. maenas over the last 5-10 years by opening up marginal habitats for the crabs to occupy (Beal 2015). Steroid activity is highly dependent on environmental conditions, and changes in temperature have been linked to the ecological success of C. maenas. This project will focus on developing an accessible low-cost ocean-acidification simulator at the University of Maine Aquaculture Research Center to be used to explore physiological responses of C. maenas to acidified conditions and quantify estradiol levels in the animals using an Enzyme-Linked Immunosorbent Assay (ELISA). Animal trials conducted with the system will provide information on parameters related to the effect of acidic stress on the endocrine system of green crabs. Additionally, the outlines for the construction of the simulator can be used as a model for students for an inexpensive holding facility to test effects of acidification. Data obtained from the Accessible Low-Cost Ocean Acidification Simulation Tool (ALCOAST) can also be used by policy makers to evaluate whether climate change can provide information on physiological interactions between C. maenas and its environment. This study stands to fill a significant gap in knowledge that is relevant not only to Maine’s economy and management of invasive species, but also to studies of how invasive species react to climate change

Maximum illumination control system for photovoltaic panels orientation

The article describes the solar tracker for photovoltaic panels and energy systems based on such devices. The authors introduce the results of calculations of the solar tracker application effectiveness for solar energy systems and the results of the field testing in Tomsk

Information environment of project training accommodation

The article considers the issues of information support for project teaching of students. The configuration and composition of the information environment based on the areas of knowledge of project management

Highly dynamic cellular-level response of symbiotic coral to a sudden increase in environmental nitrogen

Metabolic interactions with endosymbiotic photosynthetic dinoflagellate Symbiodinium spp. are fundamental to reefbuilding corals (Scleractinia) thriving in nutrient-poor tropical seas. Yet, detailed understanding at the single-cell level of nutrient assimilation, translocation, and utilization within this fundamental symbiosis is lacking. Using pulse-chase 15N labeling and quantitative ion microprobe isotopic imaging (NanoSIMS; nanoscale secondary-ion mass spectrometry), we visualized these dynamic processes in tissues of the symbiotic coral Pocillopora damicornis at the subcellular level. Assimilation of ammonium, nitrate, and aspartic acid resulted in rapid incorporation of nitrogen into uric acid crystals (after ~45 min), forming temporary N storage sites within the dinoflagellate endosymbionts. Subsequent intracellular remobilization of this metabolite was accompanied by translocation of nitrogenous compounds to the coral host, starting at ~6 h. Within the coral tissue, nitrogen is utilized in specific cellular compartments in all four epithelia, including mucus chambers, Golgi bodies, and vesicles in calicoblastic cells. Our study shows how nitrogen-limited symbiotic corals take advantage of sudden changes in nitrogen availability; this opens new perspectives for functional studies of nutrient storage and remobilization in microbial symbioses in changing reef environments. IMPORTANCE The methodology applied, combining transmission electron microscopy with nanoscale secondary-ion mass spectrometry (NanoSIMS) imaging of coral tissue labeled with stable isotope tracers, allows quantification and submicrometric localization of metabolic fluxes in an intact symbiosis. This study opens the way for investigations of physiological adaptations of symbiotic systems to nutrient availability and for increasing knowledge of global nitrogen and carbon biogeochemical cycling. © 2013 Kopp et al