3,368 research outputs found
The Influence of Single, Two, and Three Stage Bleaching on the Opacity of Deinked Stock
Bleaching may be defined as the alteration of coloring matter in such fashion as to cause it to reflect more true white, or the solubilizing of such coloring matter to make it possible to wash out the color substance, or both. (2) The most common method of bleaching is the oxidation of the coloring substance although reduction with ZnS2O is sometimes used with ground-wood. This discussion will be limited to bleaching by means of oxidizing agents namely: chlorine and calcium hypochlorite
Estimating productivity of water at different spatial scales using simulation modeling
Water resources / Productivity / Simulation models / Water scarcity / Water supply / Water balance / Performance indexes / Indicators / River basins / Cropping systems / Crop yield / Cotton / Hydrology / Economic analysis
Comparing estimates of actual evapotranspiration from satellites, hydrological models, and field data: a case study from Western Turkey
Evapotranspiration / Estimation / Remote sensing / Satellite surveys / Field tests / Measurement / Productivity / Crops / Water requirements / Water balance / Irrigation management / River basins / Hydrology / Models / Turkey / Gediz River
Integrated basin modeling
Simulation models / Irrigation management / Water balance / Groundwater / River basins / Hydrology / Flow / Evapotranspiration / Precipitation / Soils / Turkey / Gediz Basin
Sustained eruptions on Enceladus explained by turbulent dissipation in tiger stripes
Spacecraft observations suggest that the plumes of Saturn's moon Enceladus
draw water from a subsurface ocean, but the sustainability of conduits linking
ocean and surface is not understood. Observations show sustained (though
tidally modulated) fissure eruptions throughout each orbit, and since the 2005
discovery of the plumes. Peak plume flux lags peak tidal extension by 1
radian, suggestive of resonance. Here we show that a model of the tiger stripes
as tidally-flexed slots that puncture the ice shell can simultaneously explain
the persistence of the eruptions through the tidal cycle, the phase lag, and
the total power output of the tiger stripe terrain, while suggesting that the
eruptions are maintained over geological timescales. The delay associated with
flushing and refilling of \emph{O}(1) m-wide slots with ocean water causes
erupted flux to lag tidal forcing and helps to buttress slots against closure,
while tidally pumped in-slot flow leads to heating and mechanical disruption
that staves off slot freeze-out. Much narrower and much wider slots cannot be
sustained. In the presence of long-lived slots, the 10-yr average power
output of the tiger stripes is buffered by a feedback between ice melt-back and
subsidence to \emph{O}(10) W, which is similar to the observed power
output, suggesting long-term stability. Turbulent dissipation makes testable
predictions for the final flybys of Enceladus by the \emph{Cassini} spacecraft.
Our model shows how open connections to an ocean can be reconciled with, and
sustain, long-lived eruptions. Turbulent dissipation in long-lived slots helps
maintain the ocean against freezing, maintains access by future Enceladus
missions to ocean materials, and is plausibly the major energy source for tiger
stripe activity
Valuing life detection missions
Recent discoveries imply that Early Mars was habitable for
life-as-we-know-it; that Enceladus might be habitable; and that many stars have
Earth-sized exoplanets whose insolation favors surface liquid water. These
exciting discoveries make it more likely that spacecraft now under construction
- Mars 2020, ExoMars rover, JWST, Europa Clipper - will find habitable, or
formerly habitable, environments. Did these environments see life? Given finite
resources (\$10bn/decade for the US ), how could we best test the hypothesis of
a second origin of life? Here, we first state the case for and against flying
life detection missions soon. Next, we assume that life detection missions will
happen soon, and propose a framework for comparing the value of different life
detection missions:
Scientific value = (Reach x grasp x certainty x payoff) / \$
After discussing each term in this framework, we conclude that scientific
value is maximized if life detection missions are flown as hypothesis tests.
With hypothesis testing, even a nondetection is scientifically valuable.Comment: Accepted by "Astrobiology.
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