18,939 research outputs found
Farm-nonfarm linkages in rural sub-Saharan Africa
This paper is an accumulation, over the past 25 years, of a body of detailed work examining the structure of Africa's rural, nonfarm economy. First, it systematically reviews empirical evidence on the nature and magnitude of the African rural, nonfarm economy. It then explores differences across locality and size, across countries and over time, in an effort to assess likely patterns of growth. A subsequent review of key production and consumption parameters allows an estimate of the magnitude of the agricultural growth multipliers in Africa. The paper concludes with a brief discussion of policies and programs that will be necessary if farm-nonfarm growth linkages are to achieve their full potential.Banks&Banking Reform,Agricultural Knowledge&Information Systems,Municipal Financial Management,Environmental Economics&Policies,Economic Theory&Research
Fiducial Stellar Population Sequences for the u'g'r'i'z' System
We describe an extensive observational project that has obtained high-quality
and homogeneous photometry for a number of different Galactic star clusters
(including M 92, M 13, M 3, M 71, and NGC 6791) spanning a wide range in
metallicity (-2.3<[Fe/H]<+0.4), as observed in the u'g'r'i'z' passbands with
the MegaCam wide-field imager on the Canada-France-Hawaii Telescope. By
employing these purest of stellar populations, fiducial sequences have been
defined from color-magnitude diagrams that extend from the tip of the red-giant
branch down to approximately 4 magnitudes below the turnoff: these sequences
have been accurately calibrated to the standard u'g'r'i'z' system via a set of
secondary photometric standards located within these same clusters.
Consequently, they can serve as a valuable set of empirical fiducials for the
interpretation of stellar populations data in the u'g'r'i'z' system.Comment: 16 pages, 7 tables, 13 figures; accepted for publication in A
Testing isomorphism of graded algebras
We present a new algorithm to decide isomorphism between finite graded
algebras. For a broad class of nilpotent Lie algebras, we demonstrate that it
runs in time polynomial in the order of the input algebras. We introduce
heuristics that often dramatically improve the performance of the algorithm and
report on an implementation in Magma
Measuring reproducibility of high-throughput experiments
Reproducibility is essential to reliable scientific discovery in
high-throughput experiments. In this work we propose a unified approach to
measure the reproducibility of findings identified from replicate experiments
and identify putative discoveries using reproducibility. Unlike the usual
scalar measures of reproducibility, our approach creates a curve, which
quantitatively assesses when the findings are no longer consistent across
replicates. Our curve is fitted by a copula mixture model, from which we derive
a quantitative reproducibility score, which we call the "irreproducible
discovery rate" (IDR) analogous to the FDR. This score can be computed at each
set of paired replicate ranks and permits the principled setting of thresholds
both for assessing reproducibility and combining replicates. Since our approach
permits an arbitrary scale for each replicate, it provides useful descriptive
measures in a wide variety of situations to be explored. We study the
performance of the algorithm using simulations and give a heuristic analysis of
its theoretical properties. We demonstrate the effectiveness of our method in a
ChIP-seq experiment.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS466 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
CHANGES IN THE STRUCTURE OF WAGES IN THE U.S. PORK INDUSTRY
Consolidation in the U.S. pork industry continues to reduce the number of operations, while increasing the demand for hired labor. This paper explores how wages have evolved over time by decomposing the increase in wages into a change in the level of wages, human capital, and returns to human capital.Labor and Human Capital, Livestock Production/Industries,
Regulatory taxes, investment, and financing decision for insured banks
An investigation of the effects of interest rate and credit risk on optimal capital structure and investment decisions. The authors show that with no uncertainty in interest rates, capital regulation will reduce the risk of the bank's assets, but that under interest rate uncertainty, the impact of regulation may be detrimental and raise the risk of the deposits as well as government subsidies to the bank's shareholders.Bank capital ; Deposit insurance
On credit spread slopes and predicting bank risk
The authors examine whether credit-spread curves, engendered by a mandatory subordinated-debt requirement for banks, would help predict bank risk. They extract the credit-spread curves each quarter for each bank in our sample, and analyze the information content of credit-spread slopes. They find that credit-spread slopes are significant predictors of future credit spreads. However, credit-spread slopes do not provide significant additional information on future bank-risk variables, over and above other bank-specific and market-wide information.Bank capital ; Risk
Guided ion beam studies of the reactions of Crn+ (n=1-18) with CO2: chromium cluster oxide bond energies
Journal ArticleThe kinetic energy dependence of the reactions of Crn+ (n=1-18) with CO2 are studied in a guided ion beam mass spectrometer. The primary product ions are CrnO+, which then decompose by sequential loss of chromium atoms as the kinetic energy is increased. Simple collision-induced dissociation to form the Crn+-1 product ions is also observed. Large cluster ions, n≥9, form the CrnCO2+ adduct at low kinetic energies
Guided ion beam studies of the reactions of Crn + (n=2-18) with O2: chromium cluster oxide and dioxide bond energies
Journal ArticleThe kinetic energy dependence of the reactions of Crn+ (n=2-18) with O2 are studied in a guided ion beam mass spectrometer. A variety of CrmO2+, CrmO+, and Crm+ product ions, where m≤n, are observed, with the dioxide cluster ions dominating the products for all larger reactant cluster ions. Reaction efficiencies are near unity for all but the smallest clusters. The energy dependence of the product cross sections is analyzed in several different ways to determine thermochemistry for both the first and second oxygen atom binding to chromium cluster ions. These values show little dependence on cluster size for clusters larger than three atoms. The trends in this thermochemistry are discussed and compared to bulk phase oxidation values
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