6,611 research outputs found
Making It to the Major Leagues: Career Movement between Library and Archival Professions and from Small College to Large University Libraries
published or submitted for publicatio
STABILIZATION OF UPLAND RICE PRODUCTION UNDER SHORTENED FALLOW IN WEST AFRICA: RESEARCH PRIORITY SETTING IN A DYNAMIC ENVIRONMENTAL AND ECONOMIC CLIMATE
This paper presents a dynamic model of land resource degradation and shifting rice cultivation in West Africa based upon Boserup and Dvorak. The model indicates the ex ante impact of research strategies to maximize the economic benefits of host plant resistance and land resource management and thereby stabilize yield decline and reduce land degradation.Land Economics/Use, Resource /Energy Economics and Policy,
Glutaraldehyde Fixation Chemistry A Scheme for Rapid Crosslinking and Evidence for Rapid Oxygen Consumption
The chemical literature suggests that pyridine derivatives are the major reaction products of amine-aldehyde reactions. A scheme is proposed for pyridine synthesis which is derived from a classic synthesis of pyridines from one amine molecule and 3 aldehyde molecules. The pyridine polymers are considered as a major class of cross-links in glutaraldehyde fixed cells. This scheme for pyridine synthesis accounts for the following observations of amine-glutaraldehyde react ions: 1) large quantities of acid are rapidly produced, 2) oxygen uptake occurs at a high rate, 3) a variety of products distinguished by molecular size are rapidly and irreversibly synthesized, and 4) the major reaction products share physical and chemical characteristics with highly substituted pyridine compounds. When formaldehyde is added to glutaraldehyde-amine reactions, oxygen uptake is sharply reduced and the product spectrum is changed in a complex manner. Formaldehyde may thus have an entirely different role in the mixed glutaraldehyde-form-aldehyde fixatives than has previously been suggested
Quantitative magnetic resonance image analysis via the EM algorithm with stochastic variation
Quantitative Magnetic Resonance Imaging (qMRI) provides researchers insight
into pathological and physiological alterations of living tissue, with the help
of which researchers hope to predict (local) therapeutic efficacy early and
determine optimal treatment schedule. However, the analysis of qMRI has been
limited to ad-hoc heuristic methods. Our research provides a powerful
statistical framework for image analysis and sheds light on future localized
adaptive treatment regimes tailored to the individual's response. We assume in
an imperfect world we only observe a blurred and noisy version of the
underlying pathological/physiological changes via qMRI, due to measurement
errors or unpredictable influences. We use a hidden Markov random field to
model the spatial dependence in the data and develop a maximum likelihood
approach via the Expectation--Maximization algorithm with stochastic variation.
An important improvement over previous work is the assessment of variability in
parameter estimation, which is the valid basis for statistical inference. More
importantly, we focus on the expected changes rather than image segmentation.
Our research has shown that the approach is powerful in both simulation studies
and on a real dataset, while quite robust in the presence of some model
assumption violations.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS157 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Small-Scale Food Animal Production and Antimicrobial Resistance: Mountain, Molehill, or Something in-between?
SummarySmall-scale food animal production is widely practiced around the globe, yet it is often overlooked in terms of the environmental health risks. Evidence suggests that small-scale food animal producers often employ the use of antimicrobials to improve the survival and growth of their animals, and that this practice leads to the development of antimicrobial resistance (AMR) that can potentially spread to humans. The nature of human-animal interactions in small-scale food animal production systems, generally practiced in and around the home, likely augments spillover events of AMR into the community on a scale that is currently unrecognized and deserves greater attention. https://doi.org/10.1289/EHP2116
Infrasound from Volcanic Rockfalls
Proximal infrasound arrays can robustly track rapidly moving gravity-driven mass wasting, which occurs commonly at erupting volcanoes. This study reports on detection, localization, and quantification of frequent small rockfalls and infrequent pyroclastic density currents descending the southeast flanks of Santiaguito’s active Caliente Dome in January of 2014. Such activities are identified as moving sources, which descend several hundred meters at bulk flow speeds of up to ~10 m/s, which is considerably slower than the descent velocity of individual blocks. Infrasound rockfall signal character is readily distinguishable from explosion infrasound, which is manifested by a relatively fixed location source with lower frequency content. In contrast, the rockfalls of Santiaguito possess higher frequencies dominated by 7.5 to 20Hz energy. During our observation periods typical rockfall signals occurred ~10 times per hour and lasted tens of seconds or more. Array beamforming permitted detection of rockfall transients with amplitudes of only a few tens of millipascals that would be impossible to distinguish from noise using a single sensor. Conjoint time-synchronized video is used to corroborate location and to characterize various gravity-driven events
Employee Age as a Moderator of the Relationship Between Ambition and Work Role Affect
Past research has demonstrated a negative relationship between ambition, or the desire to get ahead, and job satisfaction. In the present paper, age was hypothesized to moderate the relationship between ambition and job satisfaction such that the relationship between ambition and satisfaction is more negative for older employees than for younger employees. Three studies, with three criterion variables (promotion satisfaction, extrinsic job satisfaction, overall job satisfaction), were used to test the hypothesis. Results indicated support for the hypothesized interaction. The discussion focuses on the implications of the results for organizational and individual career management strategies
The Virgin Mary on Screen: Mater Dei or Just a Mother in Guido Chiesa’s Io Sono con Te (I Am with You)
Guido Chiesa’s Io Sono con Te (I Am with You) offers a unique, albeit controversial take on Mary, the mother of Jesus. Filmed in Tunisia, and subject to criticism by Italian Catholic authorities and film critics alike, Io Sono con Te presents a rich anthropological-theological reflection on religion, culture, gender, and sacrifice. Not surprisingly, Chiesa draws on René Girard’s scapegoat theory throughout his film as he fashions Mary as the forceful protagonist in a familiar yet controversial story
Effects of publication bias on conservation planning
Conservation planning needs reliable information on spatial patterns of
biodiversity. However, existing data sets are skewed: some habitats, taxa, and
locations are under-represented. Here, we map geographic publication density at
the sub-national scale of individual 'provinces'. We query the Web of Science
catalogues SCI and SSCI for biodiversity-related publications including country
and province names (for the period 1993-2016). We combine these data with other
provincial-scale factors hypothesised to affect research (i.e. economic
development, human presence, infrastructure and remoteness). We show that sites
that appear to be understudied, compared with the biodiversity expected from
their bioclimatic conditions, are likely to have been inaccessible to
researchers for a diversity of reasons amongst which current or recent armed
conflicts are notable. Finally, we create a priority list of provinces where
geographic publication bias is of most concern, and discuss how our
provincial-scale model can assist in adjusting for publication biases in
conservation planning.Comment: 10 pages; 3 figures; 1 table;R code on
https://github.com/raffael-hickisch; data at
https://zenodo.org/record/998889; interactive at
http://bit.ly/publication_density_ma
Interplay between function and structure in complex networks
We show that abrupt structural transitions can arise in functionally optimal
networks, driven by small changes in the level of transport congestion. Our
results offer an explanation as to why so many diverse species of network
structure arise in Nature (e.g. fungal systems) under essentially the same
environmental conditions. Our findings are based on an exactly solvable model
system which mimics a variety of biological and social networks. We then extend
our analysis by introducing a novel renormalization scheme involving cost
motifs, to describe analytically the average shortest path across
multiple-ring-and-hub networks. As a consequence, we uncover a 'skin effect'
whereby the structure of the inner multi-ring core can cease to play any role
in terms of determining the average shortest path across the network.Comment: Expanded version of physics/0508228 with additional new result
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