The hbar Expansion in Quantum Field Theory

We show how expansions in powers of Planck's constant hbar = h/2\pi can give new insights into perturbative and nonperturbative properties of quantum field theories. Since hbar is a fundamental parameter, exact Lorentz invariance and gauge invariance are maintained at each order of the expansion. The physics of the hbar expansion depends on the scheme; i.e., different expansions are obtained depending on which quantities (momenta, couplings and masses) are assumed to be independent of hbar. We show that if the coupling and mass parameters appearing in the Lagrangian density are taken to be independent of hbar, then each loop in perturbation theory brings a factor of hbar. In the case of quantum electrodynamics, this scheme implies that the classical charge e, as well as the fine structure constant are linear in hbar. The connection between the number of loops and factors of hbar is more subtle for bound states since the binding energies and bound-state momenta themselves scale with hbar. The hbar expansion allows one to identify equal-time relativistic bound states in QED and QCD which are of lowest order in hbar and transform dynamically under Lorentz boosts. The possibility to use retarded propagators at the Born level gives valence-like wave-functions which implicitly describe the sea constituents of the bound states normally present in its Fock state representation.Comment: 8 pages, 1 figure. Version to be published in Phys. Rev.

Application of ERTS-1 Imagery to Flood Inundation Mapping

Application of ERTS-1 imagery to flood inundation mapping in East and West Nishnabotna basins of southwestern Iow

Many-Body Dynamics and Exciton Formation Studied by Time-Resolved Photoluminescence

The dynamics of exciton and electron-hole plasma populations is studied via time-resolved photoluminescence after nonresonant excitation. By comparing the peak emission at the exciton resonance with the emission of the continuum, it is possible to experimentally identify regimes where the emission originates predominantly from exciton and/or plasma populations. The results are supported by a microscopic theory which allows one to extract the fraction of bright excitons as a function of time.Comment: 11 pages, 5 figure

Spatial propagation of excitonic coherence enables ratcheted energy transfer

Experimental evidence shows that a variety of photosynthetic systems can preserve quantum beats in the process of electronic energy transfer, even at room temperature. However, whether this quantum coherence arises in vivo and whether it has any biological function have remained unclear. Here we present a theoretical model that suggests that the creation and recreation of coherence under natural conditions is ubiquitous. Our model allows us to theoretically demonstrate a mechanism for a ratchet effect enabled by quantum coherence, in a design inspired by an energy transfer pathway in the Fenna-Matthews-Olson complex of the green sulfur bacteria. This suggests a possible biological role for coherent oscillations in spatially directing energy transfer. Our results emphasize the importance of analyzing long-range energy transfer in terms of transfer between inter-complex coupling (ICC) states rather than between site or exciton states.Comment: Accepted version for Phys. Rev. E. 14 pages, 7 figure

Formation and clearance of tubulointerstitial immune complexes in kidneys of rats immunized with heterologous antisera to Tamm-Horsfall protein

Formation and clearance of tubulointerstitial immune complexes in kidneys of rats immunized with heterologous antisera to Tamm-Horsfall protein. Tubulointerstitial immune complex nephritis was produced by passive immunization of rats with antisera to rat Tamm-Horsfall protein (TH), a surface membrane glycoprotein of the cells of the thick ascending limb of Henle's loop. Circulating anti-TH antibodies were deposited in the kidney after an intravenous injection of rabbit antisera to TH. These anti-TH antibodies combined with TH at the base of tubular cells in the thick ascending limb of Henle's loop and formed granular immune complexes in situ in the space between basal cell surface membranes and tubular basement membranes. Immune complexes were also selectively formed in this site during perfusion of isolated kidneys with antisera to TH. Tubular immune complexes containing immunoglobulin, complement, and TH were maximal during the first week after an intravenous injection while high circulating anti-TH antibody titers were present. As the antibody titers subsequently fell to undetectable levels, tubular immune complexes were rapidly cleared and were virtually absent 4 weeks after the injection. During this clearance phase, rabbit IgG and rat TH were detected in the renal interstitium and in renal hilar lymph nodes. The rapid clearance of subepithelial TH immune complexes contrasts with the prolonged persistance of both glomerular subepithelial immune complexes and basement membrane deposits formed after injection of heterologous antisera to other renal components. The process of rapid clearance of tubulointerstitial immune complexes may allow rapid reversibility of immune injury in tubulointerstitial nephritis.Formation et disparition d'immuns-complexes tubulo-interstitiels dans les reins de rats immunises avec des anti-serums heterologues contre la proteine de Tamm-Horsfall. Une néphrite tubulo-interstitielle à immuns complexes était produit chez des rats par immunisation passive avec un anti-sérum anti-protéine de Tamm-Horsfall de rat (TH), une glycoprotéine de la surface membranaire des cellules de la partie ascendante large de l'anse de Henle. Des anticorps anti-TH circulants se déposaient dans le rein après injection intraveineuse d'antisérum anti-TH de lapin. Ces anticorps anti-TH se combinaient avec la protéine de TH à la base des cellules tubulaires de la partie large ascendante de l'anse de Henlé et formaient in situ des immuns-complexes granuleux dans l'espace entre les membranes basales cellulaires et la basale tubulaire. De même, des immuns complexes se formaient sélectivement dans cette zone lors de la perfusion de reins isolés avec un antisérum anti-TH. La quantité d'immuns complexes tubulaires contenant des immunoglobulines, du complément et de la protéine de TH était maximale pendant la première semaine après l'injection i.v. au moment ou on trouvait des titres élevés d'anticorps anti-TH. Lorsque les anticorps retombaient à un taux indétectable, les immuns complexes tubulaires disparaissaient rapidement, et on n'en trouvait pratiquement plus 4 semaines après l'injection. Pendant cette période d'élimination on détectait des IgG de lapin et de la protéine de TH de rat dans l'interstitium et les ganglions hilaires rénaux. La disparition rapide des immuns complexes à TH sous épithéliaux contrastait avec la persistance prolongée des immuns complexes sous épithéliaux et des dépôts dans la membrane basale glomérulaire formés après injection d'anti-sérums hétérologues contre d'autres constituants du rein. La disparition rapide des immuns complexes tubulo-interstitiels pourrait permettre une régression rapide des lésions immunes au cours des néphrites tubulo-interstitielles

Homiletics

Homiletics: Preaching Dialogicall