Soluble organic and inorganic nutrient fluxes in clearcut and mature deciduous forests

ABSTRACT The mechanisms by which forest ecosystems retain or lose soluble inorganic nutrients after disturbance are well known, but substantial amounts of soluble organic nutrients may also be released from cut vegetation. Our objective was to compare the leaching of dissolved organic and inorganic nutrients in cut and mature forest stands and to develop hypotheses about factors controlling the retention of soluble organic nutrients after disturbance. Solution chemistry was measured for 2 yr after clearcutting a small area in the surrounding undisturbed deciduous forest on a reference watershed at the Coweeta Hydrologic Laboratory in the Appalachian Mountains. Concentrations of dissolved organic C (DOC) and N (DON) in slash leachate were 2.6 to 3.2 times the concentrations in throughfall from undisturbed forest Concentrations in forest floor, A horizon, and B horizon solutions from cut plots were 1.2 to 3.8 times those from undisturbed forest. Dissolved organic P (DOP) concentrations in cut plots were 3.1 and 3.6 times those of uncut plots in solutions from slash and forest floor, respectively, but did not differ in mineral soil. Fluxes of DOC, DON, and DOP in all strata were greater in cut plots than uncut plots. Fluxes of DON were greater than those of ammonium plus nitrate N in all strata of both cut and uncut plots. We hypothesize that the wellrecognized retention mechanisms for inorganic nutrients combine with equilibrium adsorption of dissolved organic matter to efficiently buffer against leaching of both soluble inorganic and organic nutrients after clearcutting

Measurement of F 17 (d,n) Ne 18 and the impact on the F 17 (p,γ) Ne 18 reaction rate for astrophysics

Background: The F17(p,γ)Ne18 reaction is part of the astrophysical hot CNO cycles that are important in astrophysical environments like novas. Its thermal reaction rate is low owing to the relatively high energy of the resonances and therefore is dominated by direct, nonresonant capture in stellar environments at temperatures below 0.4 GK. Purpose: An experimental method is established to extract the proton strength to bound and unbound states in experiments with radioactive ion beams and to determine the parameters of direct and resonant capture in the F17(p,γ)Ne18 reaction. Method: The F17(d,n)Ne18 reaction is measured in inverse kinematics using a beam of the short-lived isotope F17 and a compact setup of neutron, proton, γ-ray, and heavy-ion detectors called resoneut. Results: The spectroscopic factors for the lowest l=0 proton resonances at Ec.m.=0.60 and 1.17 MeV are determined, yielding results consistent within 1.4σ of previous proton elastic-scattering measurements. The asymptotic normalization coefficients of the bound 21+ and 22+ states in Ne18 are determined and the resulting direct-capture reaction rates are extracted. Conclusions: The direct-capture component of the F17(p,γ)Ne18 reaction is determined for the first time from experimental data on Ne18

Experimental Investigation of the Ne 19 (p,γ)20Na Reaction Rate and Implications for Breakout from the Hot CNO Cycle

The Ne19(p,γ)Na20 reaction is the second step of a reaction chain which breaks out from the hot CNO cycle, following the O15(α,γ)Ne19 reaction at the onset of x-ray burst events. We investigate the spectrum of the lowest proton-unbound states in Na20 in an effort to resolve contradictions in spin-parity assignments and extract reliable information about the thermal reaction rate. The proton-transfer reaction Ne19(d,n)Na20 is measured with a beam of the radioactive isotope Ne19 at an energy around the Coulomb barrier and in inverse kinematics. We observe three proton resonances with the Ne19 ground state, at 0.44, 0.66, and 0.82 MeV c.m. energies, which are assigned 3+, 1+, and (0+), respectively. In addition, we identify two resonances with the first excited state in Ne19, one at 0.20 MeV and one, tentatively, at 0.54 MeV. These observations allow us for the first time to experimentally quantify the astrophysical reaction rate on an excited nuclear state. Our experiment shows an efficient path for thermal proton capture in Ne19(p,γ)Na20, which proceeds through ground state and excited-state capture in almost equal parts and eliminates the possibility for this reaction to create a bottleneck in the breakout from the hot CNO cycle

The Impact of Child Characteristics on Mothers' Sleep Patterns

The sleep patterns of 45 mothers of children with moderate to severe multiple disabilities, 45 mothers of children with Down syndrome, and 45 mothers of typically developing children were compared by means of a 7-day diary. The children ranged in age from 6 months to 5 years. The Caregiver's Activity and Recording of Events (CARE) Inventory was completed by each subject to record mothers' activities in half-hour segments throughout a 24-hour day. Activities were coded into nine categories including rest/sleep. The three groups of mothers were compared on total hours of rest/sleep per day, number of sleep interruptions, reason for sleep interruptions, influences of siblings of target children, and number of times the father attended to the target child during the night as perceived by the mother. Surprisingly, the results indicated that mothers of children with multiple disabilities reported more sleep than did mothers in the other two groups. There were no significant differences found among the groups in the following: amount of weekly daytime sleep; frequency and duration of child-related interruptions per week; number of nights of uninterrupted sleep per week; maximum number of sleep interruptions in one night; and mothers' perception of fathers' nighttime assistance. The data indicated that many mothers in all three groups experienced numerous weekly sleep interruptions, particularly mothers of infants 6 to 12 months of age. Professionals working with mothers of young children must consider the effects of shortened and interrupted sleep patterns on the day time functioning and health of mothers and the effect on the well-being of the entire family.</jats:p

Egyptian LNG - The Value of Standardisation

This reference is for an abstract only. A full paper was not submitted for this conference. Abstract Key decisions at the beginning of any grassroots LNG project critically impact the ultimate success of the project. The variables to consider are numerous but from a high-level perspective, commercial variables such as available gas reserves, finance ability, corporate objectives and market penetration must be considered in combination with project related variables such as schedule, capital expenditures, and life cycle costs. The ultimate objective is to develop a strategy providing the highest rate of return to the owners whilst taking full account of the risks that can be managed by the owners. Shipping logistics, pre-investment for expansion trains, safety and environmental impact, technology selection and EPC contracting strategy all come into consideration early on in the process. One of the factors that most shape a LNG project is train capacity. Given the importance of economies of scale, the LNG train size that is chosen, along with the associated refrigeration turbine/compressor configuration, is a key decision that impacts almost all other variables. However, since the train capacity impacts so many project factors, the correct choice for one project is not necessarily the correct choice for another. The unique challenges that each project faces must be considered in order to arrive at the best decision for a given project. This paper draws on the experience of the Egyptian LNG project which is one of several grassroots projects started in the 2000's that remained with the nominal train size of 3.6 MTPA that became standard in the last half of the1990's. It should be noted that 3.6 MTPA is an annualized FOB rate - the actual PFD rate or design rate of the facility is over 4 MTPA. Some other contemporary projects have designed at 5 MTPA and one recent project has announced a 7.5MTPA train. Is it possible for smaller trains to compete in today's LNG business? The overall strategy for the Egyptian LNG project has been to standardize on the design developed for Atlantic LNG Trains 1–3. In this paper, we will provide an evaluation of the key considerations leading to this strategy and show that highly competitive capital costs can be achieved with smaller trains whilst also significantly reducing project schedule and minimizing owner risk. </jats:sec