354 research outputs found
The Possibilist Transactional Interpretation and Relativity
A recent ontological variant of Cramer's Transactional Interpretation, called
"Possibilist Transactional Interpretation" or PTI, is extended to the
relativistic domain. The present interpretation clarifies the concept of
'absorption,' which plays a crucial role in TI (and in PTI). In particular, in
the relativistic domain, coupling amplitudes between fields are interpreted as
amplitudes for the generation of confirmation waves (CW) by a potential
absorber in response to offer waves (OW), whereas in the nonrelativistic
context CW are taken as generated with certainty. It is pointed out that
solving the measurement problem requires venturing into the relativistic domain
in which emissions and absorptions take place; nonrelativistic quantum
mechanics only applies to quanta considered as 'already in existence' (i.e.,
'free quanta'), and therefore cannot fully account for the phenomenon of
measurement, in which quanta are tied to sources and sinks.Comment: Final version with some minor corrections as published in Foundations
of Physics. This paper has significant overlap with Chapter 6 of my book on
the Transactional Interpretation, forthcoming from Cambridge University
Press:
http://www.cambridge.org/us/knowledge/isbn/item6860644/?site_locale=en_US
(Additional preview material is available at rekastner.wordpress.com)
Comments welcom
The Glauber model and the heavy ion reaction cross section
We reexamine the Glauber model and calculate the total reaction cross section
as a function of energy in the low and intermediate energy range, where many of
the corrections in the model, are effective.
The most significant effect in this energy range is by the modification of
the trajectory due to the Coulomb field. The modification in the trajectory due
to nuclear field is also taken into account in a self consistent way.
The energy ranges in which particular corrections are effective, are
quantified and it is found that when the center of mass energy of the system
becomes 30 times the Coulomb barrier, none of the trajectory modification to
the Glauber model is really required.
The reaction cross sections for light and heavy systems, right from near
coulomb barrier to intermediate energies have been calculated. The exact
nuclear densities and free nucleon-nucleon (NN) cross sections have been used
in the calculations. The center of mass correction which is important for light
systems, has also been taken into account.
There is an excellent agreement between the calculations with the modified
Glauber model and the experimental data. This suggests that the heavy ion
reactions in this energy range can be explained by the Glauber model in terms
of free NN cross sections without incorporating any medium modification.Comment: RevTeX, 21 pages including 9 Postscript figures, submitted to Phys.
Rev.
Neutron charge form factor at large
The neutron charge form factor is determined from an analysis of
the deuteron quadrupole form factor data. Recent calculations, based
on a variety of different model interactions and currents, indicate that the
contributions associated with the uncertain two-body operators of shorter range
are relatively small for , even at large momentum transfer . Hence,
can be extracted from at large without undue
systematic uncertainties from theory.Comment: 8 pages, 3 figure
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High temperature corrosion research at the Albany Research Center
The Severe Environment Corrosion and Erosion Research Facility (SECERF) at the Albany Research Center is operational. SECERF consists of 6 modules that share the availability of up to 10 different gases to produce environments for high temperature corrosion and erosion research. Projects to be conducted in the modules include: corrosion sensors for fossil energy systems, thermal gradient effects on high temperature corrosion, the development of sulfidation resistant alloys, determination of the effects of ash on the corrosion of metals and alloys in coal and waste combustion and coal gasification environments, high temperature erosion-corrosion of metals, and molten slag effects on refractories. Results from two areas, the effect of ash deposits on alloy corrosion and thermal gradient effects on the corrosion of metals, will be highlighted. Ash produced in coal gasifiers, coal combustors, and waste combustors, when deposited on metal surfaces, provides sites for corrosion attack and contributes chemical species that participate in the corrosion reaction. Results are presented for the corrosion of 304L stainless steel, that was either uncoated or coated with ash or with ash containing NaCl or Na2SO4, in air-water vapor mixtures at 600 C. The presence of high heat fluxes and temperature gradients in many fossil energy systems creates the need for an understanding of their effects on corrosion and oxidation. Such information would be useful for both improved alloy design and for better translation of isothermal laboratory results to field use. Temperature gradients in a solid oxide result in two changes that modify diffusion within the oxide. The first is when a gradient in point defect concentration is created within the oxide, for example, where more vacancies are expected at a higher temperature. The second change is when the presence of a temperature gradient biases the diffusion jump of an atom. Results of tests are presented for cobalt with metal surface temperatures of approximately 920-950 C in N2 plus 1-10 vol% O2 environments with a heat flux of about 40 kW/m2. Non-equilibrium thermodynamics were used to develop oxidation rate equations in temperature gradients that were combined with point defect information of CoO to predict oxidation rates
Optimal Flying Wings: A Numerical Optimization Study
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97067/1/AIAA2012-1758.pd
Maternal distress and perceptions of infant development following extracorporeal membrane oxygenation and conventional ventilation for persistent pulmonary hypertension
Neurodevelopmental outcome and concurrent maternal distress were examined for infants who suffered persistent pulmonary hypertension at birth and were treated with either extracorporeal membrane oxygenation (ECMO) ( n = 19) or conventional ventilation (CV) ( n = 15). Mothers were asked to complete inventories assessing their infant's (mean age 8.74 months) developmental growth as well as their own psychological health. Relevant sociodemographic and treatment parameters were also entered into the analysis. The results indicated that ECMO and CV infants did not differ on developmental indices and impairment rates were 15–23% respectively, similar to previous reports, in addition, ECMO and CV mothers did not differ in their reports of psychological distress. Correlational analyses revealed that length of treatment for ECMO but not CV infants significantly predicted developmental delay and maternal distress. For CV mothers, maternal distress was associated with the perception of delayed language. The results are discussed in terms of the limited morbidity associated with ECMO and CV interventions and the possible role of a ‘vulnerable child syndrome’ in understanding the maternal-infant relationship following ECMO therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73367/1/j.1365-2214.1995.tb00410.x.pd
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at GeV
Identified mid-rapidity particle spectra of , , and
from 200 GeV p+p and d+Au collisions are reported. A
time-of-flight detector based on multi-gap resistive plate chamber technology
is used for particle identification. The particle-species dependence of the
Cronin effect is observed to be significantly smaller than that at lower
energies. The ratio of the nuclear modification factor () between
protons and charged hadrons () in the transverse momentum
range GeV/c is measured to be
(stat)(syst) in minimum-bias collisions and shows little
centrality dependence. The yield ratio of in minimum-bias d+Au
collisions is found to be a factor of 2 lower than that in Au+Au collisions,
indicating that the Cronin effect alone is not enough to account for the
relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from
transverse momentum 1.8 GeV/c to 3. GeV/
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Single Spin Asymmetry in Polarized Proton-Proton Elastic Scattering at GeV
We report a high precision measurement of the transverse single spin
asymmetry at the center of mass energy GeV in elastic
proton-proton scattering by the STAR experiment at RHIC. The was measured
in the four-momentum transfer squared range \GeVcSq, the region of a significant interference between the
electromagnetic and hadronic scattering amplitudes. The measured values of
and its -dependence are consistent with a vanishing hadronic spin-flip
amplitude, thus providing strong constraints on the ratio of the single
spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated
by the Pomeron amplitude at this , we conclude that this measurement
addresses the question about the presence of a hadronic spin flip due to the
Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
We report a measurement of the longitudinal double-spin asymmetry A_LL and
the differential cross section for inclusive Pi0 production at midrapidity in
polarized proton collisions at sqrt(s) = 200 GeV. The cross section was
measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be
in good agreement with a next-to-leading order perturbative QCD calculation.
The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T <
11 GeV/c and excludes a maximal positive gluon polarization in the proton. The
mean transverse momentum fraction of Pi0's in their parent jets was found to be
around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC
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