567 research outputs found
A filter synthesis technique applied to the design of multistage broad-band microwave amplifiers
A method for designing multistage broad-band
amplifiers based upon well-known filter synthesis techniques is presented. Common all-pole low-pass approximations are used to synthesize prototype amplifier circuits that may be scaled in frequency and impedance. All-pass filters introduced at the first stage are shown to improve input match while maintaining circuit
performance less 6 dB gain. A theoretical comparison is made with the distributed amplifier and the cascaded single-stage distributed amplifier. Theoretically, a larger gain-bandwidth product is achieved using the synthesis technique. A proof-of-concept Butterworth
low-pass two-stage amplifier was designed, simulated,
and measured and achieved a flat gain performance of 1–4 GHz with a power gain of 14.5±1 dB close to the predicted 1–4.2 GHz, 15±1 dB
Using a mixture of cottonseed hulls and cottonseed meal to replace alfalfa hay in diets for stressed feeder calves
One 28-day receiving experiment was
conducted using 625 exotic × British cross
heifers to evaluate growth performance and
morbidity on receiving diets that contained
either alfalfa hay or a pellet composed of
65% cottonseed hulls and 35% cottonseed
meal as the roughage source. Heifers fed the
cotton byproduct pellet consumed more feed
(P<0.01) but tended to be less efficient than
those fed alfalfa hay. Daily gain was comparable
between diets (P>0.05), and the percentages
of heifers diagnosed, treated, or
retreated for respiratory disease were similar
Effects of supplementation of limit-fed growing diets with either soybean meal or nonenzymatically browned soybean meal on steer performance
Seventy two individually fed Angus × Hereford
steers (642 lb) were used to evaluate the
effects of supplementing limit-fed, growing diets
with either soybean meal (SBM) or nonenzymatically
browned soybean meal (NSBM).
Eight steers were allotted to a control diet
composed of 39.1% high-moisture corn, 42%
cottonseed hulls, 10.4% ground corn, 5% cane
molasses 2.25% urea, and 1.5% vitamins and
minerals (dry basis). The remaining steers were
allotted to diets that derived 100, 80, 60, or
40% of their supplemental protein from SBM or
60, 45, 30, or 15% of their supplemental protein
from NSBN. The balance of supplemental
protein came from urea. All diets were formulated
to contain 13.0% crude protein (dry
basis). Steers were fed once daily for 80 days
at 2.25% of BW. Average daily gain and
efficiency did not differ (P>.05) between
sources (ADG=1.932 + .103 × (% CP from
SBM) + .097 × (% CP from NSBM);
gain:feed=.140 + .0058 × (% CP from SBM) +
.0051 × (% CP from NSBM)). The lack of
response to NBSBM supplementation above
that for SBM suggests that either degradable
intake protein was limiting in the basal diet or a
large proportion of the amino acids in the
NSBM were unavailable due to overprocessing
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Application of the risk-based strategy to the Hanford tank waste organic-nitrate safety issue
This report describes the results from application of the Risk-Based Decision Management Approach for Justifying Characterization of Hanford Tank Waste to the organic-nitrate safety issue in Hanford single-shell tanks (SSTs). Existing chemical and physical models were used, taking advantage of the most current (mid-1997) sampling and analysis data. The purpose of this study is to make specific recommendations for planning characterization to help ensure the safety of each SST as it relates to the organic-nitrate safety issue. An additional objective is to demonstrate the viability of the Risk-Based Strategy for addressing Hanford tank waste safety issues
Betaine as a dietary supplement for finishing cattle
One hundred seventy five steers (902 lb
initial body weight) were used in a finishing
study to determine the effect of betaine,
provided either as feed-grade betaine
(Betafin-S6, Finnsugar Bioproducts) or as
concentrated separator by-product (CSB; desugared
beet molasses), on animal performance and carcass characteristics. Steers were fed a finishing diet based on steam-flaked and dry-rolled corn. Treatments included 10.5 or 21 g/steer daily supplemental feed-grade betaine or 250 g (15.5 betaine) or 500 g (31 g betaine) of CSB per steer
daily. Dry matter intakes increased (linear,
P<0.1) for steers supplemented with feed-
grade betaine. Average daily gains and feed
efficiencies were not affected by treatments.
Dressing percent and twelfth rib back fat
increased (P<0.1) for steers that received
feed-grade betaine. Rib-eye area decreased
(P<0.1) when steers were supplemented with
either feed-grade betaine or CSB. Yield
grades were significantly higher (linear,
P<0.1) for cattle receiving supplemental CSB
or feed-grade betaine (quadratic, P<.05). Hot carcass weights, KPH, marbling scores, and percentage of carcasses grading USDA
Choice were not affected by supplemental
betaine. In this study, betaine supplementation did not markedly alter growth performance, but carcass fatness tended to increase
for both supplements
Vertical distribution and migration of fish larvae in the NW Iberian upwelling system during the winter mixing period: implications for cross-shelf distribution
The vertical distribution and vertical migrations of fish
larvae and implications for their cross-shelf distribution
were investigated in the northern limit of the NE
Atlantic upwelling region during the late winter mixing
period of 2012. The average positive values of the
upwelling index for February and March of this year
were far from normal, although the average hydrographic
conditions during the period of study were of
downwelling and the water column was completely
mixed. Fish larvae, most in the preflexion stage, were
concentrated in the upper layers of the water column
and their distribution was depth stratified, both day
and night. However, the larval fish community was
not structured in the vertical plane and fish larvae did
not show significant diel vertical migration (DVM),
although five species showed ontogenetic vertical
migration. In regions of coastal upwelling and in the
absence of DVM, the location of fish larvae in the
water column is crucial for their cross-shelf distribution.
Thus, the cross-shelf distribution of the six most
abundant species collected in this study can be
explained by the surface onshore flow associated with coastal downwelling, retaining larvae of the coastal
spawning species with a relatively shallow distribution
in the shelf region and transporting larvae of slope
spawning species onto the shelf. The wide vertical distribution
shown by larvae of the offshore spawning
species could be an adaptation of these species to
ensure that some larvae reach the inshore nursery
areasPlan Nacional de I+D+i (CRAMERCTM2010- 21856-CO3-02), Junta de Galicia (ECOPREGA-10MMA602021PR), Principado de Asturias (GRUPIN14-144)Postprint2,044
Modeling DNA Structure, Elasticity and Deformations at the Base-pair Level
We present a generic model for DNA at the base-pair level. We use a variant
of the Gay-Berne potential to represent the stacking energy between neighboring
base-pairs. The sugar-phosphate backbones are taken into account by semi-rigid
harmonic springs with a non-zero spring length. The competition of these two
interactions and the introduction of a simple geometrical constraint leads to a
stacked right-handed B-DNA-like conformation. The mapping of the presented
model to the Marko-Siggia and the Stack-of-Plates model enables us to optimize
the free model parameters so as to reproduce the experimentally known
observables such as persistence lengths, mean and mean squared base-pair step
parameters. For the optimized model parameters we measured the critical force
where the transition from B- to S-DNA occurs to be approximately . We
observe an overstretched S-DNA conformation with highly inclined bases that
partially preserves the stacking of successive base-pairs.Comment: 15 pages, 25 figures. submitted to PR
Low-mass pre--main-sequence stars in the Magellanic Clouds
[Abridged] The stellar Initial Mass Function (IMF) suggests that sub-solar
stars form in very large numbers. Most attractive places for catching low-mass
star formation in the act are young stellar clusters and associations, still
(half-)embedded in star-forming regions. The low-mass stars in such regions are
still in their pre--main-sequence (PMS) evolutionary phase. The peculiar nature
of these objects and the contamination of their samples by the evolved
populations of the Galactic disk impose demanding observational techniques for
the detection of complete numbers of PMS stars in the Milky Way. The Magellanic
Clouds, the companion galaxies to our own, demonstrate an exceptional star
formation activity. The low extinction and stellar field contamination in
star-forming regions of these galaxies imply a more efficient detection of
low-mass PMS stars than in the Milky Way, but their distance from us make the
application of special detection techniques unfeasible. Nonetheless, imaging
with the Hubble Space Telescope yield the discovery of solar and sub-solar PMS
stars in the Magellanic Clouds from photometry alone. Unprecedented numbers of
such objects are identified as the low-mass stellar content of their
star-forming regions, changing completely our picture of young stellar systems
outside the Milky Way, and extending the extragalactic stellar IMF below the
persisting threshold of a few solar masses. This review presents the recent
developments in the investigation of PMS stars in the Magellanic Clouds, with
special focus on the limitations by single-epoch photometry that can only be
circumvented by the detailed study of the observable behavior of these stars in
the color-magnitude diagram. The achieved characterization of the low-mass PMS
stars in the Magellanic Clouds allowed thus a more comprehensive understanding
of the star formation process in our neighboring galaxies.Comment: Review paper, 26 pages (in LaTeX style for Springer journals), 4
figures. Accepted for publication in Space Science Review
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