2,774 research outputs found
MILK PRICING IN THE UNITED STATES
This report provides a primer on the complex pricing system that has evolved in the United States to deal with milk production, its assembly (collection), and its distribution to alternative users. All the various government and private institutions making up the system are expected to work together to ensure that the public gets the milk it wants, while dairy farmers get the economic returns needed to provide the milk. The major institutions are the Federal milk price support program and milk marketing orders, the Northeast Interstate Dairy Compact, State regulations, dairy cooperatives, and milk and dairy product futures and options markets. Our goal is to provide a primer on milk pricing that can serve as a steppingstone to other, more detailed works for those so inclined.Dairy, milk pricing, Demand and Price Analysis, Livestock Production/Industries,
Structure of Dairy Markets: Past, Present, Future
The U.S. dairy industry, many segments of which supported dairy policy changes in the 1996 Federal Agriculture Improvement and Reform Act, is much different than it was 20 or even 10 years ago. This report provides a historical overview of the industry, more detailed examinations of the fluid milk market and selected manufactured dairy product markets, a discussion of future prospects and trends in the industry, and some thoughts on the implications of those prospects and trends for dairy farmers and their organizations, processors, dairy product manufacturers, and retailers.dairy, butter, cheese, nonfat dry milk, market structure, pricing, competition, Livestock Production/Industries, Marketing,
Simulation of Flux Emergence from the Convection Zone to the Corona
Here, we present numerical simulations of magnetic flux buoyantly rising from
a granular convection zone into the low corona. We study the complex
interaction of the magnetic field with the turbulent plasma. The model includes
the radiative loss terms, non-ideal equations of state, and empirical corona
heating. We find that the convection plays a crucial role in shaping the
morphology and evolution of the emerging structure. The emergence of magnetic
fields can disrupt the convection pattern as the field strength increases, and
form an ephemeral region-like structure, while weak magnetic flux emerges and
quickly becomes concentrated in the intergranular lanes, i.e. downflow regions.
As the flux rises, a coherent shear pattern in the low corona is observed in
the simulation. In the photosphere, both magnetic shearing and velocity
shearing occur at a very sharp polarity inversion line (PIL). In a case of
U-loop magnetic field structure, the field above the surface is highly sheared
while below it is relaxed
Anatomical and biomechanical traits of broiler chickens across ontogeny. Part II. Body segment inertial properties and muscle architecture of the pelvic limb
In broiler chickens, genetic success for desired production traits is often shadowed by welfare concerns related to musculoskeletal health. Whilst these concerns are clear, a viable solution is still elusive. Part of the solution lies in knowing how anatomical changes in afflicted body systems that occur across ontogeny influence standing and moving. Here, to demonstrate these changes we quantify the segment inertial properties of the whole body, trunk (legs removed) and the right pelvic limb segments of five broilers at three different age groups across development. We also consider how muscle architecture (mass, fascicle length and other properties related to mechanics) changes for selected muscles of the pelvic limb. All broilers used had no observed lameness, but we document the limb pathologies identified post mortem, since these two factors do not always correlate, as shown here. The most common leg disorders, including bacterial chondronecrosis with osteomyelitis and rotational and angular deformities of the lower limb, were observed in chickens at all developmental stages. Whole limb morphology is not uniform relative to body size, with broilers obtaining large thighs and feet between four and six weeks of age. This implies that the energetic cost of swinging the limbs is markedly increased across this growth period, perhaps contributing to reduced activity levels. Hindlimb bone length does not change during this period, which may be advantageous for increased stability despite the increased energetic costs. Increased pectoral muscle growth appears to move the centre of mass cranio-dorsally in the last two weeks of growth. This has direct consequences for locomotion (potentially greater limb muscle stresses during standing and moving). Our study is the first to measure these changes in the musculoskeletal system across growth in chickens, and reveals how artificially selected changes of the morphology of the pectoral apparatus may cause deficits in locomotion
Buildup of Magnetic Shear and Free Energy During Flux Emergence and Cancellation
We examine a simulation of flux emergence and cancellation, which shows a
complex sequence of processes that accumulate free magnetic energy in the solar
corona essential for the eruptive events such as coronal mass ejections (CMEs),
filament eruptions and flares. The flow velocity at the surface and in the
corona shows a consistent shearing pattern along the polarity inversion line
(PIL), which together with the rotation of the magnetic polarities, builds up
the magnetic shear. Tether-cutting reconnection above the PIL then produces
longer sheared magnetic field lines that extend higher into the corona, where a
sigmoidal structure forms. Most significantly, reconnection and upward
energy-flux transfer are found to occur even as magnetic flux is submerging and
appears to cancel at the photosphere. A comparison of the simulated coronal
field with the corresponding coronal potential field graphically shows the
development of nonpotential fields during the emergence of the magnetic flux
and formation of sunspots
Dynamic Coupling of Convective Flows and Magnetic Field during Flux Emergence
We simulate the buoyant rise of a magnetic flux rope from the solar
convection zone into the corona to better understand the energetic coupling of
the solar interior to the corona. The magnetohydrodynamic model addresses the
physics of radiative cooling, coronal heating and ionization, which allow us to
produce a more realistic model of the solar atmosphere. The simulation
illustrates the process by which magnetic flux emerges at the photosphere and
coalesces to form two large concentrations of opposite polarities. We find that
the large-scale convective motion in the convection zone is critical to form
and maintain sunspots, while the horizontal converging flows in the near
surface layer prevent the concentrated polarities from separating. The foot
points of the sunspots in the convection zone exhibit a coherent rotation
motion, resulting in the increasing helicity of the coronal field. Here, the
local configuration of the convection causes the convergence of opposite
polarities of magnetic flux with a shearing flow along the polarity inversion
line. During the rising of the flux rope, the magnetic energy is first injected
through the photosphere by the emergence, followed by energy transport by
horizontal flows, after which the energy is subducted back to the convection
zone by the submerging flows
The Evolution of PSR J0737-3039B and a Model for Relativistic Spin Precession
We present the evolution of the radio emission from the 2.8-s pulsar of the
double pulsar system PSR J0737-3039A/B. We provide an update on the Burgay et
al. (2005) analysis by describing the changes in the pulse profile and flux
density over five years of observations, culminating in the B pulsar's radio
disappearance in 2008 March. Over this time, the flux density decreases by
0.177 mJy/yr at the brightest orbital phases and the pulse profile evolves from
a single to a double peak, with a separation rate of 2.6 deg/yr. The pulse
profile changes are most likely caused by relativistic spin precession, but can
not be easily explained with a circular hollow-cone beam as in the model of
Clifton & Weisberg (2008). Relativistic spin precession, coupled with an
elliptical beam, can model the pulse profile evolution well. This particular
beam shape predicts geometrical parameters for the two bright orbital phases
which are consistent and similar to those derived by Breton et al. (2008).
However, the observed decrease in flux over time and B's eventual disappearance
cannot be easily explained by the model and may be due to the changing
influence of A on B.Comment: 20 pages, 18 figures, Accepted by ApJ on 2 August 201
Chandra observations of the old pulsar PSR B1451-68
We present 35 ks Chandra ACIS observations of the 42 Myr old radio pulsar PSR
B1451-68. A point source is detected 0.32" +/- 0.73" from the expected radio
pulsar position. It has ~200 counts in the 0.3-8 keV energy range. We identify
this point source as the X-ray counterpart of the radio pulsar. PSR B1451-68 is
located close to a 2MASS point source, for which we derive 7% as the upper
limit on the flux contribution to the measured pulsar X-ray flux. The pulsar
spectrum can be described by either a power-law model with photon index
Gamma=2.4 (+0.4/-0.3) and a unrealistically high absorbing column density N(H)=
(2.5 (+1.2/-1.3)) * 10^(21) cm^-2, or by a combination of a kT=0.35
(+0.12/-0.07) keV blackbody and a Gamma = 1.4 +/- 0.5 power-law component for
N(H)[DM]= 2.6 * 10^(20) cm^-2, estimated from the pulsar dispersion measure. At
the parallactic, Lutz-Kelker bias corrected distance of 480 pc, the non-thermal
X-ray luminosities in the 0.3-8 keV energy band are either Lx(nonth)= (11.3 +/-
1.7) * 10^(29) erg/s or Lx(nonth)= (5.9 (+4.9/-5.0)) * 10^(29) erg/s,
respectively. This corresponds to non-thermal X-ray efficiencies of either
eta(nonth)= Lx(nonth) / (dE/dt) ~ 0.005 or 0.003, respectively.Comment: 19 pages, 9 figures, 2 tables, accepted by Ap
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