129 research outputs found
Land Use Influence on the Characteristics of Groundwater Inputs to the Great Bay Estuary, New Hampshire
This research examines the sources and factors affecting nutrient-laden groundwater discharge to the Great Bay Estuary. To further understand this relationship, examination of groundwater residence time, a review of historic land uses, and nitrate source tracking strategies were used. Seven submarine groundwater discharge (SGD) sites were selected, and groundwater monitoring networks were installed to examine the relationship between land use and groundwater quality at the discharge zones. Field activities were performed in the summer and fall of 2003 and 2004. Estuarine water intrusion in groundwater discharge samples confounded the analyses for major ion chemistry and boron isotopes. CFC-derived and modeled groundwater ages in the study area averaged 23.2 years (±15.0 years). CFC analysis enabled correlation of nitrate concentrations at the SGD sites with the historic land use coverage for the years 1974 (for most of the sites) or 1962 (SGD 58.4). Two types of correlation were made: 1) between the agricultural and residential land use for all observed nitrate concentrations in the recharge areas, and 2) correlation with the nitrate concentrations between developed and undeveloped land uses. Both statistical correlations (Kendallâs Tau and Spearmanâs Rho) indicated a connection between the increase of residential land use of the last three decades with the high nitrate-bearing groundwater discharging to the Great Bay (NH). The geochemical composition of the SGD water was also investigated by using simple mixing models that attempted to explain the water chemistry characteristics of the targeted SGD sites. Based on these models it was concluded that overburden groundwater comprises 75% to 95% of the groundwater discharging at the SGD sites. A significant correlation (Tauâs, p=0.021) between nitrate-bearing groundwater and CFCderived groundwater ages was detected supporting the hypothesis that high nitrate bearing groundwater will be discharged to the Great Bay in the near future accounting for the increase of residential land use of 1990âs. Continuous monitoring of SGD sites was suggested to be included as part of the periodic environmental quality monitoring activities of the Great Bay. Long-term step-wise sampling for groundwater dating is required to develop a stronger chronological evolution of groundwater nitrate inputs. Further research should concentrate on detailing the overburden water chemistry, flow paths, and nitrogen loading characteristics
Comprehensive theory of the Lamb shift in light muonic atoms
We present a comprehensive theory of the Lamb shift in light muonic atoms,
such as H, D, He, and He, with all quantum
electrodynamic corrections included at the precision level constrained by the
uncertainty of nuclear structure effects. This analysis can be used in the
global adjustment of fundamental constants and in the determination of nuclear
charge radii. Further improvements in the understanding of electromagnetic
interactions of light nuclei will allow for a promising test of fundamental
interactions by comparison with "normal" atomic spectroscopy, in particular,
with H-D and He-He isotope shifts.Comment: 21 pages, 4 figures, expanded introductio
First direct mass-measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He
The first direct mass-measurement of He has been performed with the
TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the
mass of He was determined with improved precision over our previous
measurement. The obtained masses are (He) = 6.018 885 883(57) u and
(He) = 8.033 934 44(11) u. The He value shows a deviation from
the literature of 4. With these new mass values and the previously
measured atomic isotope shifts we obtain charge radii of 2.060(8) fm and
1.959(16) fm for He and He respectively. We present a detailed
comparison to nuclear theory for He, including new hyperspherical harmonics
results. A correlation plot of the point-proton radius with the two-neutron
separation energy demonstrates clearly the importance of three-nucleon forces.Comment: 4 pages, 2 figure
Electric dipole polarizability of Ca
The electric dipole strength distribution in Ca between 5 and 25 MeV
has been determined at RCNP, Osaka, from proton inelastic scattering
experiments at very forward angles. Combined with total photoabsorption data at
higher excitation energy, this enables an extraction of the electric dipole
polarizability (Ca) = 1.92(17) fm. Together with
the measured in Ca, it provides a stringent test of
modern theoretical approaches, including coupled cluster calculations with
chiral effective field theory interactions and state-of-the art energy density
functionals. The emerging picture is that for this medium-mass region dipole
polarizabilities are well described theoretically, with important constraints
for the neutron skin in Ca and related equation of state quantities.Comment: 6 pages, 3 figure
Machine learning in predicting respiratory failure in patients with COVID-19 pneumonia - challenges, strengths, and opportunities in a global health emergency.
Aims- The aim of this study was to estimate a 48 hour prediction of moderate to severe respiratory failure, requiring mechanical ventilation, in hospitalized patients with COVID-19 pneumonia.
Methods- This was an observational study that comprised consecutive patients with COVID-19 pneumonia admitted to hospital from 21 February to 6 April 2020. The patients\u2019 medical history, demographic, epidemiologic and clinical data were collected in an electronic patient chart. The dataset was used to train predictive models using an established machine learning framework leveraging a hybrid approach where clinical expertise is applied alongside a data-driven analysis. The study outcome was the onset of moderate to severe respiratory failure defined as PaO 2 /FiO 2 ratio <150 mmHg in at least one of two consecutive arterial blood gas analyses in the following 48 hours. Shapley Additive exPlanations values were used to quantify the positive or negative impact of each variable included in each model on the predicted outcome.
Results- A total of 198 patients contributed to generate 1068 usable observations which allowed to build 3 predictive models based respectively on 31-variables signs and symptoms, 39-variables laboratory biomarkers and 91-variables as a composition of the two. A fourth \u201cboosted mixed model\u201d included 20 variables was selected from the model 3, achieved the best predictive performance (AUC=0.84) without worsening the FN rate. Its clinical performance was applied in a narrative case report as an example.
Conclusion- This study developed a machine model with 84% prediction accuracy, which is able to assist clinicians in decision making process and contribute to develop new analytics to improve care at high technology readiness levels
Neutrino-driven wind simulations and nucleosynthesis of heavy elements
Neutrino-driven winds, which follow core-collapse supernova explosions,
present a fascinating nuclear astrophysics problem that requires understanding
advanced astrophysics simulations, the properties of matter and neutrino
interactions under extreme conditions, the structure and reactions of exotic
nuclei, and comparisons against forefront astronomical observations. The
neutrino-driven wind has attracted vast attention over the last 20 years as it
was suggested to be a candidate for the astrophysics site where half of the
heavy elements are produced via the r-process. In this review, we summarize our
present understanding of neutrino-driven winds from the dynamical and
nucleosynthesis perspectives. Rapid progress has been made during recent years
in understanding the wind with improved simulations and better micro physics.
The current status of the fields is that hydrodynamical simulations do not
reach the extreme conditions necessary for the r-process and the proton or
neutron richness of the wind remains to be investigated in more detail.
However, nucleosynthesis studies and observations point already to
neutrino-driven winds to explain the origin of lighter heavy elements, such as
Sr, Y, Zr.Comment: Submitted to: J. Phys. G: Nucl. Phy
Uncertainty in land-use adaptation persists despite crop model projections showing lower impacts under high warming
Climate change is expected to impact crop yields and alter resource availability. However, the understanding of the potential of agricultural land-use adaptation and its costs under climate warming is limited. Here, we use a global land system model to assess land-use-based adaptation and its cost under a set of crop model projections, including CO2 fertilization, based on climate model outputs. In our simulations of a low-emissions scenario, the land system responds through slight changes in cropland area in 2100, with costs close to zero. For a high emissions scenario and impacts uncertainty, the response tends toward cropland area changes and investments in technology, with average adaptation costs between â1.5 and +19 US$05 per ton of dry matter per year. Land-use adaptation can reduce adverse climate effects and use favorable changes, like local gains in crop yields. However, variance among high-emissions impact projections creates challenges for effective adaptation planning
Controle massal da brocaâdoâcafĂ© com armadilhas de garrafa Pet vermelha em cafeeiro
The objective of this work was to evaluate the efficacy of red PETâbottle traps, containing attractive alcoholic volatile compounds, in the mass control of coffee berry borer (Hypothenemus hampei). The evaluations were carried out in four coffee crops, during two years. Nine hundred PETâbottle traps, painted red, were distributed in three of the four coffee crops; one crop without traps was used as a control. Holes drilled into berries (%) were determined in these crops. There was a reduction in drilled berries in crops with traps, from the 2007/2008 harvest to the 2008/2009 harvest. The highest coffee berry borer densities in traps was observed in the flowering and smallâgreen berries stages. The red PETâbottle trap is efficient in the mass control of the coffee berry borer population, since it reduces the percentage of drilled berries in 57%; however, this reduction is not enough to keep borer densities below the control level.O objetivo deste trabalho foi avaliar a eficĂĄcia de armadilha de garrafa Pet vermelha contendo compostos volĂĄteis alcoĂłlicos atrativos, no controle massal da brocaâdoâcafĂ© (Hypothenemus hampei). As avaliaçÔes foram realizadas em quatro lavouras de cafĂ©, durante dois anos. Foram distribuĂdas 900 armadilhas de garrafa Pet, pintadas de vermelho, em trĂȘs das quatro lavouras; uma lavoura sem armadilhas foi usada como controle. O broqueamento dos frutos (%) foi determinado nessas lavouras. Houve redução do broqueamento de frutos nas lavouras com armadilhas, da safra 2007/2008 para a safra 2008/2009. As maiores densidades da brocaâdoâcafĂ© nas armadilhas foram observadas nos estĂĄdios de floração e de frutos chumbinho. A armadilha de garrafa Pet vermelha Ă© eficaz no controle massal da população da brocaâdoâcafĂ©, por reduzir a percentagem de frutos broqueados em 57%; entretanto, essa redução nĂŁo Ă© suficiente para manter as densidades da broca abaixo do nĂvel de controle
- âŠ