3,406 research outputs found
THE BUTCHER THE BAKER THE PHARMACEUTICAL MAKER: WHY THE AGRICULTURAL BIOTECH INDUSTRY MAY DIFFER FROM THE GENERAL BIOTECH INDUSTRY
This paper explores the apparent anomaly in the patenting strategies found in the agricultural biotechnology industry, when it is compared to the literature's view of the patenting strategies in the general biotechnology industry and in the pharmaceutical industry in particular. By extending an extensive game model of the agriculture biotechnology industry, we show that, like the rest of the biotechnology industry, the integration of the agriculture biotechnology industry into several large private research firms with accompanying government laboratories can be transactions-costs limiting and thus efficient, given the existing institutional structure. A review of the literature respecting the general biotechnology industry reveals an apparent anomaly between the general industry and our findings with respect to the Canadian agricultural biotechnology industry. The literature seems to suggest, as one might expect, that the choice of patenting strategy in the general industry is dependent upon a positive probability of litigation over opportunistic patenting strategies, with the probability of facing litigation being dependent on the type of patenting strategy adopted. In contrast, we found general opportunistic patenting strategies in the Canadian agricultural biotechnology industry, independent of potential litigation. A comparison of the income elasticities of demand for food compared to other biotechnological products, particularly pharmaceuticals, can account for the apparent differences. We briefly assess the policy implications of these observations, particularly examining why the manner in which publicly funded research programs compensate the inventors of the intellectual property that they control may limit the incentives for these programs to control the apparent opportunistic behavior we perceive in the agricultural biotechnology research sector.Research and Development/Tech Change/Emerging Technologies,
Using EFT to analyze low-energy Compton scattering from protons and light nuclei
We discuss the application of an effective field theory (EFT) which
incorporates the chiral symmetry of QCD to Compton scattering from the proton
and deuteron. We describe the chiral EFT analysis of the proton Compton
scattering database presented in our recent review (arXiv:1203.6834), which
gives: alpha^{(p)}=10.5 +/- 0.5(stat) +/- 0.8(theory); beta^{(p)}= 2.7 +/-
0.5(stat) +/- 0.8(theory), for the electric and magnetic dipole polarizability
of the proton. We also summarize the chiral EFT analysis of the world data on
coherent Compton scattering from deuterium presented in arXiv:1203.6834. That
yields: alpha^{(s)}=10.5 +/- 2.0(stat) +/- 0.8(theory); beta^{(s)}=3.6 +/-
1.0(stat) +/- 0.8(theory).Comment: 5 pages. Invited talk, presented by Phillips at the 11th Conference
on the Intersections of Nuclear and Particle Physics (CIPANP 2012), St.
Petersburg, FL, May 201
Nucleon Polarisabilities at and Beyond Physical Pion Masses
We examine the results of Chiral Effective Field Theory (EFT) for the
scalar- and spin-dipole polarisabilities of the proton and neutron, both for
the physical pion mass and as a function of . This provides chiral
extrapolations for lattice-QCD polarisability computations. We include both the
leading and sub-leading effects of the nucleon's pion cloud, as well as the
leading ones of the resonance and its pion cloud. The analytic
results are complete at NLO in the -counting for pion masses close
to the physical value, and at leading order for pion masses similar to the
Delta-nucleon mass splitting. In order to quantify the truncation error of our
predictions and fits as \% degree-of-belief intervals, we use a Bayesian
procedure recently adapted to EFT expansions. At the physical point, our
predictions for the spin polarisabilities are, within respective errors, in
good agreement with alternative extractions using experiments and
dispersion-relation theory. At larger pion masses we find that the chiral
expansion of all polarisabilities becomes intrinsically unreliable as
approaches about MeV---as has already been seen in other observables.
EFT also predicts a substantial isospin splitting above the physical
point for both the electric and magnetic scalar polarisabilities; and we
speculate on the impact this has on the stability of nucleons. Our results
agree very well with emerging lattice computations in the realm where EFT
converges. Curiously, for the central values of some of our predictions, this
agreement persists to much higher pion masses. We speculate on whether this
might be more than a fortuitous coincidence.Comment: 39 pages LaTeX2e (pdflatex) including 12 figures as 16 .pdf files
using includegraphics. Version approved for publication in EPJA includes
modifications, clarifications and removal of typographical errors in
refereeing and publication proces
Compton scattering from the proton in an effective field theory with explicit Delta degrees of freedom
We analyse the proton Compton-scattering differential cross section for
photon energies up to 325 MeV using Chiral Effective Field Theory and extract
new values for the electric and magnetic polarisabilities of the proton. Our
EFT treatment builds in the key physics in two different regimes: photon
energies around the pion mass ("low energy") and the higher energies where the
Delta(1232) resonance plays a key role. The Compton amplitude is complete at
N4L0, O(e^2 delta^4), in the low-energy region, and at NLO, O(e^2 delta^0), in
the resonance region. Throughout, the Delta-pole graphs are dressed with pi-N
loops and gamma-N-Delta vertex corrections. A statistically consistent database
of proton Compton experiments is used to constrain the free parameters in our
amplitude: the M1 gamma-N-Delta transition strength b_1 (which is fixed in the
resonance region) and the polarisabilities alpha and beta (which are fixed from
data below 170 MeV). In order to obtain a reasonable fit we find it necessary
to add the spin polarisability gammaM1 as a free parameter, even though it is,
strictly speaking, predicted in chiral EFT at the order to which we work. We
show that the fit is consistent with the Baldin sum rule, and then use that sum
rule to constrain alpha+beta. In this way we obtain
alpha=[10.65+/-0.35(stat})+/-0.2(Baldin)+/-0.3(theory)]10^{-4} fm^3, and beta
=[3.15-/+0.35(stat)-/+0.2(Baldin)-/+0.3(theory)]10^{-4} fm^3, with chi^2 =
113.2 for 135 degrees of freedom. A detailed rationale for the theoretical
uncertainties assigned to this result is provided.Comment: 36 pages, 15 figures Version 2 is shortened for publication; version
1 is more self-contained. Results section unchange
Comprehensive Study of Observables in Compton Scattering on the Nucleon
We present an analysis of observables in Compton scattering on the
proton. Cross sections, asymmetries with polarised beam and/or targets, and
polarisation-transfer observables are investigated for energies up to the
resonance to determine their sensitivity to the proton's dipole
scalar and spin polarisabilities. The Chiral Effective Field Theory Compton
amplitude we use is complete at NLO, , for photon
energies , and so has an accuracy of a few per cent there. At
photon energies in the resonance region it is complete at NLO,
, and so its accuracy there is about \%. We find
that for energies from pion-production threshold to about ,
multiple asymmetries have significant sensitivity to presently ill-determined
combinations of proton spin polarisabilities. We also argue that the broad
outcomes of this analysis will be replicated in complementary theoretical
approaches, e.g., dispersion relations. Finally, we show that below the
pion-production threshold, observables suffice to reconstruct the Compton
amplitude, and above it are required. Although not necessary for
polarisability extractions, this opens the possibility to perform "complete"
Compton-scattering experiments. An interactive Mathematica notebook, including
results for the neutron, is available from [email protected] .Comment: 75 pages LaTeX2e (pdflatex) including 37 figures as .pdf files using
includegraphics; minor corrections. Text-identical to published version but
including the Online Supplement. Higher-resolution figures are available at
http://home.gwu.edu/~hgrie/Compton/one-N-comprehensive-observables-delta4.v2.0.high-resolution-figures.tg
Compton Scattering and Nucleon Polarisabilities in Chiral EFT: Update and Future
We review theoretical progress and prospects for determining the nucleon's
static dipole polarisabilities from Compton scattering on few-nucleon targets,
including new values; see Refs. [1-5] for details and a more thorough
bibliography.Comment: 6 pages LaTeX2e (pdflatex) including 11 figures as .pdf files. First
presented by Griesshammer at the 12th Conference on the Intersections of
Nuclear and Particle Physics CIPANP2015, 19-24 May 2015, Vail (CO), USA;
updated for 22nd International Spin Symposium (SPIN 2016), University of
Illinois, Urbana (USA), 26-30 September 2016. Corrected 2 figures, added
clarifying tex
What different variants of chiral EFT predict for the proton Compton differential cross section - and why
We compare the predictions of different variants of chiral effective field
theory for the gamma-p elastic scattering differential cross section. We pay
particular attention to the role of pion loops, and the impact that a
heavy-baryon expansion has on the behavior of those loops. We also correct
erroneous results for these loops that were published in Phys. Rev. C 67,
055202 (2003) [ arXiv:nucl-th/0212024 ].Comment: 4 pages, 2 figure
Using effective field theory to analyse low-energy Compton scattering data from protons and light nuclei
Compton scattering provides important insight into the structure of the
nucleon. For photons up to about 300 MeV, it is parameterised by six dynamical
dipole polarisabilities which characterise the response of the nucleon to a
monochromatic photon of fixed frequency and multipolarity. Their zero-energy
limit yields the well-known static electric and magnetic dipole
polarisabilities \alpha and \beta, and the four dipole spin polarisabilities.
Chiral Effective Field Theory (ChiEFT) describes nucleon, deuteron and 3-He
Compton scattering, using consistent nuclear currents, rescattering and wave
functions. It can thus also be used to extract useful information on the
neutron amplitude from Compton scattering on light nuclei. We summarise past
work in ChiEFT on all of these reactions and compare with other theoretical
approaches. We also discuss all proton experiments up to about 400 MeV, as well
as the three modern elastic deuteron data sets, paying particular attention to
precision and accuracy of each set. Constraining the Delta(1232) parameters
from the resonance region, we then perform new fits to the proton data up to
omega(lab)=170 MeV, and a new fit to the deuteron data. After checking in each
case that a two-parameter fit is compatible with the respective Baldin sum
rules, we obtain, using the sum-rule constraints in a one-parameter fit,
\alpha=10.7\pm0.3(stat)\pm0.2(Baldin)\pm0.8(theory),
\beta=3.1\mp0.3(stat)\pm0.2(Baldin)\pm0.8(theory), for the proton
polarisabilities, and \alpha =10.9\pm 0.9(stat)\pm0.2(Baldin)\pm0.8(theory),
\beta =3.6\mp 0.9(stat)\pm0.2(Baldin)\pm0.8(theory), for the isoscalar
polarisabilities, each in units of 10^(-4) fm^3. We discuss plans for polarised
Compton scattering, their promise as tools to access spin polarisabilities, and
other future avenues for theoretical and experimental investigation.Comment: 82 pages LaTeX2e including 24 figures as .eps file embedded with
includegraphicx; review for Prog. Part Nucl Phys. Final version identical to
published areticle; spelling and grammar correcte
Compton scattering from the proton: An analysis using the delta expansion up to N3LO
We report on a chiral effective field theory calculation of Compton
scattering from the proton. Our calculation includes pions, nucleons, and the
Delta(1232) as explicit degrees of freedom. It uses the "delta expansion", and
so implements the hierarchy of scales m_pi < M_Delta-M_N < Lambda_chi. In this
expansion the power counting in the vicinity of the Delta peak changes, and
resummation of the loop graphs associated with the Delta width is indicated.
We have computed the nucleon Compton amplitude in the delta expansion up to
N3LO for photon energies of the order of m_pi. This is the first order at which
the proton Compton scattering amplitudes receive contributions from contact
operators which encode contributions to the spin-independent polarisabilities
from states with energies of the order of Lambda_chi. We fit the coefficients
of these two operators to the experimental proton Compton data that has been
taken in the relevant photon-energy domain, and are in a position to extract
new results for the proton polarisabilities alpha and beta.Comment: 6 pages. Proceeding of Sixth International Workshop on Chiral
Dynamics, Bern (Switzerland), 6th -- 10th July 2009. To be published in Po
Predictions for Polarized-Beam/Vector-Polarized-Target Observables in Elastic Compton Scattering on the Deuteron
Motivated by developments at HIGS at TUNL that include increased photon flux
and the ability to circularly polarize photons, we calculate several
beam-polarization/target-spin dependent observables for elastic Compton
scattering on the deuteron. This is done at energies of the order of the pion
mass within the framework of Heavy Baryon Chiral Perturbation Theory. Our
calculation is complete to O(Q^3) and at this order there are no free
parameters. Consequently, the results reported here are predictions of the
theory. We discuss paths that may lead to the extraction of neutron
polarizabilities. We find that the photon/beam polarization asymmetry is not a
good observable for the purpose of extracting \alpha_n and \beta_n. However,
one of the double polarization asymmetries, \Sigma_x, shows appreciable
sensitivity to \gamma_{1n} and could be instrumental in pinning down the
neutron spin polarizabilities.Comment: 26 pages, 13 figures, revised version to be published in PR
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