1,358 research outputs found
Estimating the Economic Viability of a New Crop Alternative for the U.S. Organic Market: Edamame - A Vegetable Soybean
whole farm modeling, edamame, Farm Management, Production Economics,
An Economic Feasibility Assessment of Autonomous Field Machinery in Grain Crop Production
A multi-faceted whole farm planning model is developed to compare conventional and autonomous machinery for grain crop production under various benefit, farm size, suitable field day risk aversion, and grain price scenarios. Results suggest that autonomous machinery can be an economically viable alternative to conventional manned machinery if the establishment of intelligent controls is cost effective. An increase in net returns of 24% over operating with conventional machinery is found when including both input savings and a yield increase due to reduced compaction. This study also identifies the break-even investment price for intelligent controls for the safe and reliable commercialization of autonomous machinery. Results indicate that the break-even investment price is highly variable depending on the financial benefits resulting from the deployment of autonomous machinery, farm size, suitable field day risk aversion, and grain prices. The maximum break-even investment price for intelligent, autonomous controls is nearly US$500 000 for the median days suitable for fieldwork when including both input savings and a yield increase due to reduced compaction
PPARĪ³2 Regulates a Molecular Signature of Marrow Mesenchymal Stem Cells
Bone formation and hematopoiesis are anatomically juxtaposed and share common regulatory mechanisms. Bone marrow mesenchymal stromal/stem cells (MSC) contain a compartment that provides progeny with bone forming osteoblasts and fat laden adipocytes as well as fibroblasts, chondrocytes, and muscle cells. In addition, marrow MSC provide an environment for support of hematopoiesis, including the development of bone resorbing osteoclasts. The PPARĪ³2 nuclear receptor is an adipocyte-specific transcription factor that controls marrow MSC lineage allocation toward adipocytes and osteoblasts. Increased expression of PPARĪ³2 with aging correlates with changes in the MSC status in respect to both their intrinsic differentiation potential and production of signaling molecules that contribute to the formation of a specific marrow micro-environment. Here, we investigated the effect of PPARĪ³2 on MSC molecular signature in respect to the expression of gene markers associated exclusively with stem cell phenotype, as well as genes involved in the formation of a stem cell
supporting marrow environment. We found that PPARĪ³2 is a powerful modulator of stem cell-related gene expression. In general, PPARĪ³2 affects the expression of genes specific for the maintenance of stem cell phenotype, including LIF, LIF receptor, Kit ligand, SDF-1, Rex-1/Zfp42, and Oct-4. Moreover, the antidiabetic PPARĪ³ agonist TZD rosiglitazone specifically affects the expression of āstemnessā genes, including ABCG2, Egfr, and CD44. Our data indicate that aging and anti-diabetic TZD therapy may affect mesenchymal stem cell phenotype through modulation of PPARĪ³2 activity. These observations may have important therapeutic consequences and indicate a need for more detailed studies of PPARĪ³2 role in stem cell biology
Neutron Acceleration in Uniform Electromagnetic Fields
The question as to whether neutron acceleration can occur in uniform
electromagnetic fields is examined. Although such an effect has been predicted
using the canonical equations of motion some doubt has been raised recently as
to whether it is in principle observable for a spin 1/2 particle. To resolve
this issue a gedanken experiment is proposed and analyzed using a wave packet
construction for the neutron beam. By allowing arbitrary orientation for the
neutron spin as well as for the electric and magnetic fields a non vanishing
acceleration of the center of the neutron wave packet is found which confirms
the predictions of the canonical formalism.Comment: 11 page
Thermodynamic basis of the concept of "recombination resistances"
The concept of "recombination resistance" introduced by Shockley and Read
(Phys. Rev. 87, 835 (1952)) is discussed within the framework of the
thermodynamics of irreversible processes ruled by the principle of the minimum
rate of entropy production. It is shown that the affinities of recombination
processes represent "voltages" in a thermodynamic Ohm-like law where the net
rates of recombinations represent the "currents". The quantities thus found
allow for the definition of the "dissipated power" which is to be related to
the rate of entropy production of the recombination processes dealt with.Comment: Submitted to Phys. Rev.
Citation Networks in High Energy Physics
The citation network constituted by the SPIRES data base is investigated
empirically. The probability that a given paper in the SPIRES data base has
citations is well described by simple power laws, ,
with for less than 50 citations and for 50 or more citations. Two models are presented that both represent the
data well, one which generates power laws and one which generates a stretched
exponential. It is not possible to discriminate between these models on the
present empirical basis. A consideration of citation distribution by subfield
shows that the citation patterns of high energy physics form a remarkably
homogeneous network. Further, we utilize the knowledge of the citation
distributions to demonstrate the extreme improbability that the citation
records of selected individuals and institutions have been obtained by a random
draw on the resulting distribution.Comment: 9 pages, 6 figures, 2 table
Chiral Symmetry Versus the Lattice
After mentioning some of the difficulties arising in lattice gauge theory
from chiral symmetry, I discuss one of the recent attempts to resolve these
issues using fermionic surface states in an extra space-time dimension. This
picture can be understood in terms of end states on a simple ladder molecule.Comment: Talk at the meeting "Computer simulations studies in condensed matter
physics XIV" Athens, Georgia, Feb. 19-24, 2001. 14 page
Connectivity of Growing Random Networks
A solution for the time- and age-dependent connectivity distribution of a
growing random network is presented. The network is built by adding sites which
link to earlier sites with a probability A_k which depends on the number of
pre-existing links k to that site. For homogeneous connection kernels, A_k ~
k^gamma, different behaviors arise for gamma1, and gamma=1. For
gamma<1, the number of sites with k links, N_k, varies as stretched
exponential. For gamma>1, a single site connects to nearly all other sites. In
the borderline case A_k ~ k, the power law N_k ~k^{-nu} is found, where the
exponent nu can be tuned to any value in the range 2<nu<infinity.Comment: 4 pages, 2 figures, 2 column revtex format final version to appear in
PRL; contains additional result
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