15,968 research outputs found
POLICY IMPLICATIONS ON THE REDUCTION OF NITROGEN FERTILIZER USE ON NON-IRRIGATED CORN-WINTER WHEAT PRODUCTION IN NORTH ALABAMA
Environmental and economic effects of nitrogen fertilizer reduction on North Alabama small farms are evaluated using GPFARM. GPFARM incorporates climate, soil data and management practices to simulate science and economic analysis for a farm/ranch management unit. Nitrate leaching, crop yield and profitability are evaluated and presented under different policy scenarios. Key words: nitrate leaching, profitability, management unit, GPFARMnitrate leaching, profitability, management unit, GPFARM, Crop Production/Industries,
Synthesis and Structures of Co Bis-Trifluoromethylpyrazolate Complexes
Reactions of Co(PMe3)(3)Cl or CoCl2 with 3,5-(CF3)(2)-PzNa in hexane give Co(PMe3)(3)(3,5-(CF3)(2)-Pz) (1) and Co(PMe3)(3)(3,5-(CF3)(2)-Pz)(2) (2) respectively (3,5-(CF3)(2)-PzNa = sodium bis-trifluoromethylpyrazolate). Reaction of (3,5-(CF3)(2)-PzH) with Co(PMe3)(4) produces the unusual complex [cis-Co(PMe3)(4)H-2][Co(PMe3)(3,5-( CF3)(2)-Pz)(3)] (3) which formally contains a [Co(III)](+)[Co(II)](-) complex ion pair. Reaction of 3,5-(CF3)(2)-PzLi with an oxygenated suspension of CoCl2 and 3 equivalents of PMe3 gives (3,5-(CF3)(2)-Pz)(2)Co(mu-3,5-(CF3)(2)Pz)(mu-OPMe3)Li(OPMe3)(2) (4), while 2 reacts with LiOH to give [(PMe3)Co(mu-3,5-(CF3)(2)-Pz)(2)(mu(3)-OH)Li](2) (5). Both 2 and 3 react with O-2 in toluene solution to give Co(OPMe3)(2)(3,5-(CF3)(2)-Pz)(2) (6). All compounds have been characterized spectroscopically and by single crystal X-ray diffraction studies.Welch Foundation F-816Petroleum Research Fund 47014-ACSNSF 0741973Chemistr
Return to wine: A comparison of the hedonic, repeat sales, and hybrid approaches
Comparisons between the return to wine and standard financial assets are complicated in that the return to wine must be estimated from infrequent sales of heterogeneous wine brands. Wine returns can be estimated using several different approaches, and here the performance of the hedonic approach, repeat sales approach, and hybrid approach are compared using 14,102 auction sale observations for Australian wine over the period 1988 to 2000. For the data set considered the results show that the hybrid approach provides the most efficient estimates, and that the repeat sales approach provides significantly higher total return estimates than the other two approaches. The portfolio diversification benefit attributed to holding wine is then shown to vary with estimation method.Return to wine, Price index, Research Methods/ Statistical Methods, C33, G12,
Narrow-band noise due to the moving vortex lattice in superconducting niobium
We report measurements of voltage noise due to vortex motion in Niobium, a
conventional low-Tc superconductor. A coherent oscillation leading to narrow
band noise (NBN) is evidenced. Its characteristic frequency is a linear
function of the overcritical transport current in the flux-flow regime, and
hence scales as the main velocity of the vortex flow. The associated length
scale is not the intervortex distance but the width of the sample, indicating
temporal coherence at a large scale. NBN is also observed in the non linear
part of the V(I) at the onset of depinning, in apparent disagreement with a
stochastic creep motion of flux bundles. NBN exists in the peak effect region,
showing that long range temporal correlations are preserved in this regime.Comment: accepted for publication in Phys Rev
Image-Optimized Coronal Magnetic Field Models
We have reported previously on a new method we are developing for using
image-based information to improve global coronal magnetic field models. In
that work we presented early tests of the method which proved its capability to
improve global models based on flawed synoptic magnetograms, given excellent
constraints on the field in the model volume. In this follow-up paper we
present the results of similar tests given field constraints of a nature that
could realistically be obtained from quality white-light coronagraph images of
the lower corona. We pay particular attention to difficulties associated with
the line-of-sight projection of features outside of the assumed coronagraph
image plane, and the effect on the outcome of the optimization of errors in
localization of constraints. We find that substantial improvement in the model
field can be achieved with this type of constraints, even when magnetic
features in the images are located outside of the image plane
Cure or Bandage? New York City's 80/20 Program
http://deepblue.lib.umich.edu/bitstream/2027.42/120390/1/Jones_CureOrBandage.pd
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The Political Ecology of Early Childhood Lead Exposure at the New York African Burial Ground
Nearly 25 years ago federal officials unearthed over 400 skeletal remains in Lower Manhattan. The site of the excavation was the New York African Burial Ground (NYABG), a 17th- and 18th-century cemetery for the city’s mostly enslaved African population. Today, the burial ground serves as a reminder of New York’s 200-year experiment with slavery. It is the first National Monument to honor enslaved African New Yorkers. This recognition is a testament to the resolve of African American descendants and their allies who, through political activism, would see these ancestors afforded in death some of the respect denied them in life.
Descendant community activism also paved the way for the site’s interdisciplinary investigation, the NYABG Project. Recovering complex diasporic biohistories from the NYABG was a major scientific undertaking made more challenging and rewarding by the project’s high standards of public inclusion and accountability. Co-developed by community members and scholars, the NYABG Project now stands as a model of critically engaged biocultural anthropology.
This dissertation study draws upon and continues the work of NYABG researchers. It is a reconstruction of early life lead exposure via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of dental enamel. With its high inorganic content, enamel provides a stable chemical record of an individual’s diet, nutrition and pollution events, which in turn reflect political, economic and cultural factors. For this population, relatively high levels of skeletal lead suggest time spent in the Americas while low levels more likely indicate birth in Africa prior to forced migration. Here, lead concentrations in enamel that forms during the first several years of life are measured, mapped microspatially, and rendered as chronological age profiles. Mean differences and distribution/age profiles are compared for 44 NYABG children and adults in order to determine their African or American birthplaces and related health and cultural experiences (e.g., lead poisoning and dental modification). For some individuals, comparative analysis of later forming teeth was undertaken to explore the possibility of migration during childhood.
Enamel-lead concentrations range from 0.39 μg g-1 (i.e., the instrument limit of detection or LOD) to 14.7 μg g-1, suggesting a range of exposures in which some individuals spent their childhoods in high-lead environments. The most striking finding is that mean enamel-lead concentration for young children (5.88 μg g-1) is over five times that of adults (1.11 μg g-1), a significant difference reflecting these groups’ mostly American versus African geographic origins, respectively. Other findings raise questions at the intersections of natality, health and culture. For example, contra most reports, do relatively high lead concentrations for some individuals indicate that cultural dental modification persisted in the Americas?
This study is the first quantitative LA-ICP-MS analysis of human lead exposure in early America. LA-ICP-MS has proven critical for assessing overall lead burden as well as age-related changes in the sources and nature of exposure. The methodology developed for this study has enabled a rich assessment of African diasporic environmental biohistory, health and culture during slavery. As with the “rediscovery” of the NYABG, this is a moment and a tool for discovering new history and new dimensions of the human experience, then and now
Quantum Information Processing with Delocalized Qubits under Global Control
Any technology for quantum information processing (QIP) must embody within it
quantum bits (qubits) and maintain control of their key quantum properties of
superposition and entanglement. Typical QIP schemes envisage an array of
physical systems, such as electrons or nuclei, with each system representing a
given qubit. For adequate control, systems must be distinguishable either by
physical separation or unique frequencies, and their mutual interactions must
be individually manipulable. These difficult requirements exclude many
nanoscale technologies where systems are densely packed and continuously
interacting. Here we demonstrate a new paradigm: restricting ourselves to
global control pulses we permit systems to interact freely and continuously,
with the consequence that qubits can become delocalized over the entire device.
We realize this using NMR studies of three carbon-13 nuclei in alanine,
demonstrating all the key aspects including a quantum mirror, one- and
two-qubit gates, permutation of densely packed qubits and Deutsch algorithms.Comment: 4 pages, 5 figure
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