1,014 research outputs found
Transforming Brazilian agriculture: the experience of the Brazilian-American Commission for the Production of Foodstuffs, 1942-1945
Reponses by the Brazilian and U.S. governments to the pressures of World War II fundamentally altered the course of Brazilâs agricultural development. As fears of a European war arose in the late 1930s, Brazilâs political leadership became convinced that collaboration with the United States was essential to boosting the output of Brazilian agricultural and extractive products. The mutual search for ways to increase the output of agricultural and extractive products created an important incentive for wartime cooperation. Importing technical expertise and equipment from the United States became the primary option for Brazilian economic planners while securing Brazilâs support emerged as a political priority for the Roosevelt administration. While the commission was conceived as an instrument for aiding rubber production in the Amazon, GetĂșlio Vargasâs government transformed it into a massive binational subsidy for the chronically suffering Brazilian Northeast. The joint food production commission also exposed multitudes of farmers to the benefits of increased federal governmental support. Efforts by the Ministry of Agriculture and the commission to introduce even rudimentary agricultural implements led to accelerating the replacement of the digging stick with the hoe and marked the beginnings of more capital-intensive cultivation methods. The linkages between Brazilâs agriculture and the United States also grew, as more Brazilians became aware of the potential benefits to Brazil of the agricultural revolution underway in the United States and U.S. capital related to agriculture would diversify its search for profits offered by Brazil
Landpower and Ambiguous Warfare: The Challenge of Colombia in the 21st Century
On December 10 and 11, 1998, over 100 scholars, civilian government officials, and military officers from the United States, Colombia, Venezuela, Ecuador, Panama and Mexico gathered at the U.S. Army War College to discuss Landpower and Ambiguous Warfare: The Challenge of Colombia in the 21st Century. While the conference adopted no resolutions or conclusions, it provided a valuable forum for expressing widely differing viewpoints on critical components of Colombia\u27s security situation. The meeting highlighted the urgency of the Colombian crisis and the need for a comprehensive response by Colombia, the United States, and the regional community of nations. Much of the dialogue developed the principal subthemes of the conference: the sources of violence; the role of the guerrillas, paramilitaries, and narcotraffickers; the institutional capabilities and responses of the Colombian government and armed forces; and the role of the United States. Here, there was sharp disagreement among the participants, with some arguing in favor of an increased U.S. counternarcotics and/or counterinsurgency role and others emphasizing the priority of the peace process. This report summarizes the issues addressed and the major concerns of the attendees. The Strategic Studies Institute is pleased to offer the monograph as a contribution to the national security debate on Colombia within the United States and abroad.https://press.armywarcollege.edu/monographs/1848/thumbnail.jp
Control of Black Vine Weevil larvae Otiorhynchus sulcatus (Fabricius) (Coleoptera:Curculionidae) in grow bags outdoors with nematodes
1 Outdoor trials were carried out during 2001Ăą02 on strawberries grown in
commercial growing bags naturally infested with black vine weevil larvae
(BVW) Otiorhynchus sulcatus in Co. Wexford, Ireland.
2 The two nematode isolates used in these trials were Heterorhabditis megidis
(UK211) and Heterorhabditis downesi (K122), both laboratory cultured.
Growing bags received nematodes either once (May 2001), twice (May and
October 2001) or three times (May, October 2001 and May 2002). Ten days
after each application date, nine blocks (of the total 27) were randomly
selected, destructively assessed and discarded.
3 The single application (May 2001) resulted in a mortality of black vine weevil
larvae, of 93.4% with H. megidis and 51.3% with H. downesi, compared with
the control treatment at that date. Respective figures after the double application
(May 2001 and October 2001) were 78.9 and 77.6% and after the triple
application (May 2001, October 2001 and May 2002) the figures were 93.7 and
88.1%.
4 Results from these trials clearly indicate that entomopathogenic nematodes are
good alternatives to chemical control of the black vine weevil on strawberries
grown in growing bags in Ireland
Time-Resolved Ultraviolet Observations of the Globular Cluster X-ray Source in NGC 6624: The Shortest Known Period Binary System
Using the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope,
we have obtained the first time-resolved spectra of the King et al.
ultraviolet-bright counterpart to the 11-minute binary X-ray source in the core
of the globular cluster NGC 6624. This object cannot be readily observed in the
visible, even from HST, due to a much brighter star superposed <0.1'' distant.
Our FOS data show a highly statistically significant UV flux modulation with a
period of 11.46+-0.04 min, very similar to the 685 sec period of the known
X-ray modulation, definitively confirming the association between the King et
al. UV counterpart and the intense X-ray source. The UV amplitude is very large
compared with the observed X-ray oscillations: X-ray variations are generally
reported as 2-3% peak-to-peak, whereas our data show an amplitude of about 16%
in the 126-251 nm range. A model for the system by Arons & King predicts
periodic UV fluctuations in this shortest-known period binary system, due to
the cyclically changing aspect of the X-ray heated face of the secondary star
(perhaps a very low mass helium degenerate). However, prior to our
observations, this predicted modulation has not been detected. Employing the
Arons & King formalism, which invokes a number of different physical
assumptions, we infer a system orbital inclination 35deg<i<50 deg. Amongst the
three best-studied UV/optical counterparts to the intense globular cluster
X-ray sources, two are now thought to consist of exotic double-degenerate
ultrashort period binary systems.Comment: 10 pages including 2 figures in Latex (AASTeX 4.0). Accepted for
publication in vol. 482 (1997 June 10 issue) of The Astrophysical Journal
(Letters
Galactic S Stars: Investigations of Color, Motion, and Spectral Features
Known bright S stars, recognized as such by their enhanced s-process
abundances and C/O ratio, are typically members of the asymptotic giant branch
(AGB) or the red giant branch (RGB). Few modern digital spectra for these
objects have been published, from which intermediate resolution spectral
indices and classifications could be derived. For published S stars we find
accurate positions using the Two-Micron All Sky Survey (2MASS), and use the
FAST spectrograph of the Tillinghast reflector on Mt. Hopkins to obtain the
spectra of 57 objects. We make available a digital S star spectral atlas
consisting of 14 spectra of S stars with diverse spectral features. We define
and derive basic spectral indices that can help distinguish S stars from
late-type (M) giants and carbon stars. We convolve all our spectra with the
SDSS bandpasses, and employ the resulting gri magnitudes together with 2MASS
JHK mags to investigate S star colors. S stars have colors similar to carbon
and M stars, and are therefore difficult to distinguish by color alone. Using
near and mid-infrared colors from IRAS and AKARI, we identify some of the stars
as intrinsic (AGB) or extrinsic (with abundances enhanced by past
mass-transfer). We also use V band and 2MASS magnitudes to calculate a
temperature index for stars in the sample. We analyze the proper motions and
parallaxes of our sample stars to determine upper and lower limit absolute
magnitudes and distances, and confirm that most are probably giants.Comment: 11 pages. Accepted for publication in ApJS July 19, 2011. Spectra
available as http://hea-www.harvard.edu/~pgreen/SStarAtlas.ta
Characterization of the Mutagenic Spectrum of 4-Nitroquinoline 1-Oxide (4-NQO) in Aspergillus nidulans by Whole Genome Sequencing
4-Nitroquinoline 1-oxide (4-NQO) is a highly carcinogenic chemical that induces mutations in bacteria, fungi, and animals through the formation of bulky purine adducts. 4-NQO has been used as a mutagen for genetic screens and in both the study of DNA damage and DNA repair. In the model eukaryote Aspergillus nidulans, 4-NQOâbased genetic screens have been used to study diverse processes, including gene regulation, mitosis, metabolism, organelle transport, and septation. Early work during the 1970s using bacterial and yeast mutation tester strains concluded that 4-NQO was a guanine-specific mutagen. However, these strains were limited in their ability to determine full mutagenic potential, as they could not identify mutations at multiple sites, unlinked suppressor mutations, or G:C to C:G transversions. We have now used a whole genome resequencing approach with mutant strains generated from two independent genetic screens to determine the full mutagenic spectrum of 4-NQO in A. nidulans. Analysis of 3994 mutations from 38 mutant strains reveals that 4-NQO induces substitutions in both guanine and adenine residues, although with a 19-fold preference for guanine. We found no association between mutation load and mutagen dose and observed no sequence bias in the residues flanking the mutated purine base. The mutations were distributed randomly throughout most of the genome. Our data provide new evidence that 4-NQO can potentially target all base pairs. Furthermore, we predict that current practices for 4-NQOâinduced mutagenesis are sufficient to reach gene saturation for genetic screens with feasible identification of causative mutations via whole genome resequencing
Molecular gas and dust around a radio-quiet quasar at redshift 4.69.
Galaxies are believed to have formed a large proportion of their stars in giant bursts of star formation early in their lives, but when and how this took place are still very uncertain. The presence of large amounts of dust in quasars and radio galaxies at redshifts z > 4 shows that some synthesis of heavy elements had already occurred at this time. This implies that molecular gas--the building material of stars--should also be present, as it is in galaxies at lower redshifts (z approximately = 2.5, refs 7-10). Here we report the detection of emission from dust and carbon monoxide in the radio-quiet quasar BR1202 - 0725, at redshift z = 4.69. Maps of these emissions reveal two objects, separated by a few arc seconds, which could indicated either the presence of a companion to the quasar or gravitational lensing of the quasar itself. Regardless of the precise interpretation of the maps, the detection of carbon monoxide confirms the presence of a large mass of molecular gas in one of the most distant galaxies known, and shows that conditions conducive to huge bursts of star formation existed in the very early Universe
The Circumnuclear Molecular Gas in the Seyfert Galaxy NGC4945
We have mapped the central region of NGC 4945 in the transition of
CO, CO, and CO, as well as the continuum at 1.3 mm, at an
angular resolution of 5\farc \times 3\farc with the Submillimeter Array. The
relative proximity of NGC 4945 (distance of only 3.8 Mpc) permits a detailed
study of the circumnuclear molecular gas and dust in a galaxy exhibiting both
an AGN (classified as a Seyfert 2) and a circumnuclear starburst in an inclined
ring with radius 2\farcs5 (50 pc). We find that all three molecular
lines trace an inclined rotating disk with major axis aligned with that of the
starburst ring and large-scale galactic disk, and which exhibits solid-body
rotation within a radius of 5\farc (95 pc). We infer an inclination
for the nuclear disk of , somewhat smaller than the
inclination of the large-scale galactic disk of . The
continuum emission at 1.3 mm also extends beyond the starburst ring, and is
dominated by thermal emission from dust. If it traces the same dust emitting in
the far-infrared, then the bulk of this dust must be heated by star-formation
activity rather than the AGN. We discover a kinematically-decoupled component
at the center of the disk with a radius smaller than 1\farcs4 (27 pc), but
which spans approximately the same range of velocities as the surrounding disk.
This component has a higher density than its surroundings, and is a promising
candidate for the circumnuclear molecular torus invoked by AGN unification
models.Comment: 13 pages, 10 figures,accepted by Ap
Catalog of 93 Nova Light Curves: Classification and Properties
We present a catalog of 93 very-well-observed nova light curves. The light
curves were constructed from 229,796 individual measured magnitudes, with the
median coverage extending to 8.0 mag below peak and 26% of the light curves
following the eruption all the way to quiescence. Our time-binned light curves
are presented in figures and as complete tabulations. We also calculate and
tabulate many properties about the light curves, including peak magnitudes and
dates, times to decline by 2, 3, 6, and 9 magnitudes from maximum, the time
until the brightness returns to quiescence, the quiescent magnitude, power law
indices of the decline rates throughout the eruption, the break times in this
decline, plus many more properties specific to each nova class. We present a
classification system for nova light curves based on the shape and the time to
decline by 3 magnitudes from peak (t3). The designations are S for smooth light
curves (38% of the novae), P for plateaus (21%), D for dust dips (18%), C for
cusp-shaped secondary maxima (1%), O for quasi-sinusoidal oscillations
superposed on an otherwise smooth decline (4%), F for flat-topped light curves
(2%), and J for jitters or flares superposed on the decline (16%). Our
classification consists of this single letter followed by the t3 value in
parentheses; so for example V1500 Cyg is S(4), GK Per is O(13), DQ Her is
D(100), and U Sco is P(3).Comment: Astronomical Journal, in press, 19 figures, 73 page
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