305 research outputs found
Ralgro-implanted bulls: Performance, carcass characteristics, longissimus palatability and carcass electrical stimulation
Twenty of 40 Angus bulls were implanted
(I) five times with 36 mg of Ralgro| at average
intervals of 106 d, beginning near birth. All
bulls and their dams were on bluestem pasture
initially and, at an average age of 320 d bulls
were fed a concentrate diet until they were
slaughtered, weighing either 454 or 499 kg. One
side of each carcass was electrically stimulated.
Average daily gain and feed efficiency of I
bulls improved 6.5 to 10.4% and 7.9 to 8.1%,
respectively, depending upon the end point
comparison with nonimplanted (NI) bulls. Implanted
bulls attained their slaughter weights 42
d sooner than did NI bulls. Implantation
decreased (P<.05) penis weight and length,
testicle weight, volume and density, but did not
affect (P>.05) seminal vesicle and pituitary
weights. Carcasses from I bulls had more
(P<.05) skeletal ossification and were fatter
than carcasses from NI bulls. Marbling scores,
quality grades and longissimus cooking losses
and juiciness scores were not affected (P>.05)
by implantation. Taste panel flavor intensity
and detectable connective tissue scores were
higher (P<.05) for steaks from I bulls than
from NI bulls. Longissimus steak tenderness
evaluations were higher (P<.05) for both I
slaughter groups than for the NI light-weight group and were higher (P<.05) for the I lightweight
group than for the NI heavy-weight
group. Longissimus tenderness tended (P = .11)
to be higher for steaks from the I heavy-weight
group than those from the NI heavy-weight
group. Electrical stimulation produced (P<.05)
a softer, coarser textured lean, but it did not
affect lean color, marbling or quality grade.
Steaks from electrically stimulated sides tended
to have higher (P = .09) myofibrillar tenderness
scores and lower (P = .06) flavor scores than
steaks from nonstimulated sides
Mass Flows in Cometary UCHII Regions
High spectral and spatial resolution, mid-infrared fine structure line
observations toward two ultracompact HII (UCHII) regions (G29.96 -0.02 and Mon
R2) allow us to study the structure and kinematics of cometary UCHII regions.
In our earlier study of Mon R2, we showed that highly organized mass motions
accounted for most of the velocity structure in that UCHII region. In this
work, we show that the kinematics in both Mon R2 and G29.96 are consistent with
motion along an approximately paraboloidal shell. We model the velocity
structure seen in our mapping data and test the stellar wind bow shock model
for such paraboloidal like flows. The observations and the simulation indicate
that the ram pressures of the stellar wind and ambient interstellar medium
cause the accumulated mass in the bow shock to flow along the surface of the
shock. A relaxation code reproduces the mass flow's velocity structure as
derived by the analytical solution. It further predicts that the pressure
gradient along the flow can accelerate ionized gas to a speed higher than that
of the moving star. In the original bow shock model, the star speed relative to
the ambient medium was considered to be the exit speed of ionized gas in the
shell.Comment: 34 pages, including 14 figures and 1 table, to be published in ApJ,
September 200
Trends in stream nitrogen concentrations for forested reference catchments across the USA
To examine whether stream nitrogen concentrations in forested reference catchments have changed over time and if patterns were consistent across the USA, we synthesized up to 44 yr of data collected from 22 catchments at seven USDA Forest Service Experimental Forests. Trends in stream nitrogen presented high spatial variability both among catchments at a site and among sites across the USA. We found both increasing and decreasing trends in monthly flow-weighted stream nitrate and ammonium concentrations. At a subset of the catchments, we found that the length and period of analysis influenced whether trends were positive, negative or non-significant. Trends also differed among neighboring catchments within several Experimental Forests, suggesting the importance of catchment-specific factors in determining nutrient exports. Over the longest time periods, trends were more consistent among catchments within sites, although there are fewer long-term records for analysis. These findings highlight the critical value of long-term, uninterrupted stream chemistry monitoring at a network of sites across the USA to elucidate patterns of change in nutrient concentrations at minimally disturbed forested sites
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Language support for immigrant children: a study of state schools in the UK and US
In recent decades, immigrants, refugees and asylum seekers have sought a new way of life in large numbers, often leaving their countries of origin behind in search of places that offer a better way of life. The purpose of this study was to investigate how elementary and middle school students in state schools in Reading, England (primarily speakers of Asian languages), and Richmond, Virginia (primarily speakers of Spanish), were supported academically, when most childrenâs first language was not English. The authors were interested in exploring whether or not there were cultural or structural differences in the way each country helped or hindered these students as they progressed through the school systems. Three UK schools in a district of approximately 100,000 and three US schools in a district of approximately 250,000 were the focus of this exploration from 2000 to 2003. Findings indicated that there were cultural and legislative differences and similarities. Teachers and administrators in both countries attempted to provide services with limited and sometimes diminishing resources. Community support varied based on resources, attitudes toward various ethnic groups, and the coping strategies adopted by these groups in their new environments. Marked differences appeared with regard to the manner in which assessments took place and how the results were made available to the public
Water Vapor on Betelgeuse as Revealed by TEXES High-Resolution 12 Micron Spectra
The outer atmosphere of the M supergiant Betelgeuse is puzzling. Published
observations of different kinds have shed light on different aspects of the
atmosphere, but no unified picture has emerged. They have shown, for example,
evidence of a water envelope (MOLsphere) that in some studies is found to be
optically thick in the mid-infrared. In this paper, we present high-resolution,
mid-infrared spectra of Betelgeuse recorded with the TEXES spectrograph. The
spectra clearly show absorption features of water vapor and OH. We show that a
spectrum based on a spherical, hydrostatic model photosphere with T_eff = 3600
K, an effective temperature often assumed for Betelgeuse, fails to model the
observed lines. Furthermore, we show that published MOLspheres scenarios are
unable to explain our data. However, we are able to model the observed spectrum
reasonably well by adopting a cooler outer photospheric structure corresponding
to T_mod = 3250 K. The success of this model may indicate the observed
mid-infrared lines are formed in cool photospheric surface regions. Given the
uncertainties of the temperature structure and the likely presence of
inhomogeneities, we cannot rule out the possibility that our spectrum could be
mostly photospheric, albeit non-classical. Our data put new, strong constraints
on atmospheric models of Betelgeuse and we conclude that continued
investigation requires consideration of non-classical model photospheres as
well as possible effects of a MOLsphere. We show that the mid-infrared
water-vapor features have great diagnostic value for the environments of K and
M (super-) giant star atmospheres.Comment: Accepted by Ap
High-Fat Diet with Acyl-Ghrelin Treatment Leads to Weight Gain with Low Inflammation, High Oxidative Capacity and Normal Triglycerides in Rat Muscle
Obesity is associated with muscle lipid accumulation. Experimental models suggest that inflammatory cytokines, low mitochondrial oxidative capacity and paradoxically high insulin signaling activation favor this alteration. The gastric orexigenic hormone acylated ghrelin (A-Ghr) has antiinflammatory effects in vitro and it lowers muscle triglycerides while modulating mitochondrial oxidative capacity in lean rodents. We tested the hypothesis that A-Ghr treatment in high-fat feeding results in a model of weight gain characterized by low muscle inflammation and triglycerides with high muscle mitochondrial oxidative capacity. A-Ghr at a non-orexigenic dose (HFG: twice-daily 200-Âľg s.c.) or saline (HF) were administered for 4 days to rats fed a high-fat diet for one month. Compared to lean control (C) HF had higher body weight and plasma free fatty acids (FFA), and HFG partially prevented FFA elevation (P<0.05). HFG also had the lowest muscle inflammation (nuclear NFkB, tissue TNF-alpha) with mitochondrial enzyme activities higher than C (P<0.05 vs C, Pâ=âNS vs HF). Under these conditions HFG prevented the HF-associated muscle triglyceride accumulation (P<0.05). The above effects were independent of changes in redox state (total-oxidized glutathione, glutathione peroxidase activity) and were not associated with changes in phosphorylation of AKT and selected AKT targets. Ghrelin administration following high-fat feeding results in a novel model of weight gain with low inflammation, high mitochondrial enzyme activities and normalized triglycerides in skeletal muscle. These effects are independent of changes in tissue redox state and insulin signaling, and they suggest a potential positive metabolic impact of ghrelin in fat-induced obesity
The TEXES Survey For H2 Emission From Protoplanetary Disks
We report the results of a search for pure rotational molecular hydrogen
emission from the circumstellar environments of young stellar objects with
disks using the Texas Echelon Cross Echelle Spectrograph (TEXES) on the NASA
Infrared Telescope Facility and the Gemini North Observatory. We searched for
mid-infrared H2 emission in the S(1), S(2), and S(4) transitions. Keck/NIRSPEC
observations of the H2 S(9) transition were included for some sources as an
additional constraint on the gas temperature. We detected H2 emission from 6 of
29 sources observed: AB Aur, DoAr 21, Elias 29, GSS 30 IRS 1, GV Tau N, and HL
Tau. Four of the six targets with detected emission are class I sources that
show evidence for surrounding material in an envelope in addition to a
circumstellar disk. In these cases, we show that accretion shock heating is a
plausible excitation mechanism. The detected emission lines are narrow (~10
km/s), centered at the stellar velocity, and spatially unresolved at scales of
0.4 arcsec, which is consistent with origin from a disk at radii 10-50 AU from
the star. In cases where we detect multiple emission lines, we derive
temperatures > 500 K from ~1 M_earth of gas. Our upper limits for the
non-detections place upper limits on the amount of H2 gas with T > 500 K of
less than a few Earth masses. Such warm gas temperatures are significantly
higher than the equilibrium dust temperatures at these radii, suggesting that
the gas is decoupled from the dust in the regions we are studying and that
processes such as UV, X-ray, and accretion heating may be important.Comment: 24 pages, 16 figures, 5 tables, ApJ accepte
Upper atmospheres and ionospheres of planets and satellites
The upper atmospheres of the planets and their satellites are more directly
exposed to sunlight and solar wind particles than the surface or the deeper
atmospheric layers. At the altitudes where the associated energy is deposited,
the atmospheres may become ionized and are referred to as ionospheres. The
details of the photon and particle interactions with the upper atmosphere
depend strongly on whether the object has anintrinsic magnetic field that may
channel the precipitating particles into the atmosphere or drive the
atmospheric gas out to space. Important implications of these interactions
include atmospheric loss over diverse timescales, photochemistry and the
formation of aerosols, which affect the evolution, composition and remote
sensing of the planets (satellites). The upper atmosphere connects the planet
(satellite) bulk composition to the near-planet (-satellite) environment.
Understanding the relevant physics and chemistry provides insight to the past
and future conditions of these objects, which is critical for understanding
their evolution. This chapter introduces the basic concepts of upper
atmospheres and ionospheres in our solar system, and discusses aspects of their
neutral and ion composition, wind dynamics and energy budget. This knowledge is
key to putting in context the observations of upper atmospheres and haze on
exoplanets, and to devise a theory that explains exoplanet demographics.Comment: Invited Revie
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