Mass Effects in Hard Exclusive Photoproduction of J/ΨJ/\Psi Mesons

We report on an attempt to describe hard exclusive photoproduction of $J/\Psi$ mesons, i.e. the reaction $\gamma p \to J/\Psi p$, by means of a modified version of the hard-scattering approach, in which the proton is treated as a quark-diquark rather than a three-quark system. In order to improve the applicability of the model at momentum transfers of only a few GeV we take into account constituent-mass effects in the calculation of the perturbative scattering amplitude. With a standard $J/\Psi$-meson distribution amplitude and diquark-model parameters adopted from preceding investigations of other photon-induced reactions our predictions for differential cross sections overestimate the naive extrapolation of the low-momentum transfer ZEUS data. Our results, however, reveal the importance of taking into account the charm-quark mass.Comment: 4 pages, 4 eps-figures, uses espcrc1.st

Charge transport and vector meson dissociation across the thermal phase transition in lattice QCD with two light quark flavors

We compute and analyze correlation functions in the isovector vector channel at vanishing spatial momentum across the deconfinement phase transition in lattice QCD. The simulations are carried out at temperatures $T/T_c=0.156, 0.8, 1.0, 1.25$ and $1.67$ with $T_c\simeq203$MeV for two flavors of Wilson-Clover fermions with a zero-temperature pion mass of $\simeq270$MeV. Exploiting exact sum rules and applying a phenomenologically motivated ansatz allows us to determine the spectral function $\rho(\omega,T)$ via a fit to the lattice correlation function data. From these results we estimate the electrical conductivity across the deconfinement phase transition via a Kubo formula and find evidence for the dissociation of the $\rho$ meson by resolving its spectral weight at the available temperatures. We also apply the Backus-Gilbert method as a model-independent approach to this problem. At any given frequency, it yields a local weighted average of the true spectral function. We use this method to compare kinetic theory predictions and previously published phenomenological spectral functions to our lattice study.Comment: 28 pages, 6 figure

A new representation of the Adler function for lattice QCD

We address several aspects of lattice QCD calculations of the hadronic vacuum polarization and the associated Adler function. We implement a representation derived previously which allows one to access these phenomenologically important functions for a continuous set of virtualities, irrespective of the flavor structure of the current. Secondly we present a theoretical analysis of the finite-size effects on our particular representation of the Adler function, based on the operator product expansion at large momenta and on the spectral representation of the Euclidean correlator at small momenta. Finally, an analysis of the flavor structure of the electromagnetic current correlator is performed, where a recent theoretical estimate of the Wick-disconnected diagram contributions is rederived independently and confirmed.Comment: 9 pages, 5 figure

INITIAL CHARACTERIZATION OF MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) CLASS IIB EXON 2 IN AN ENDANGERED RATTLESNAKE, THE EASTERN MASSASAUGA (SISTRURUS CATENATUS)

Genes of the major histocompatibility complex (MHC) play an important role in the vertebrate immune system and exhibit remarkably high levels of polymorphism, maintained by strong balancing selection. While the conservation implications of MHC variation have been explored in a variety of vertebrates, non-avian reptiles (most notably snakes) have received less attention. To address this gap and take the first steps toward more extensive population-level analyses, we cloned and sequenced MHC IIB exon 2 in an endangered rattlesnake, the Eastern Massasauga (Sistrurus catenatus). Based on three individuals, we found evidence of at least four putatively functional loci. These sequences exhibited relatively high levels of variation and significantly higher rates of nonsynonymous to synonymous substitutions, especially within the antigen-binding sites, indicating strong positive selection. Phylogenetic analysis revealed a pattern of trans-species polymorphism, also suggesting positive selection. These results contribute to our understanding of MHC variation in non-avian reptiles and form a basis for more studies of MHC variation in snakes of conservation concern

Isolation of Enteric Ganglia from the Myenteric Plexus of Adult Rats

Enteric neurons and glia cells were isolated from adult Sprague Dawley rats. A procedure is described using a combination of microdissection and mechanical dissociation after enzyme treatment which yields large numbers of cell clusters suitable for tissue culture and grafting into the injured spinal cord. Differentiated enteric ganglia remained viable for at least 5 days in vitro Cultured neurons expressed histochemical reactivity for acetylcholinesterase and nicotinamide adenine dinucleotide phosphate diaphorase. Nestin positive glia, which represented a population of non-myelinating enteric Schwann cells, could also be identified in cultures maintained 5 days or longer in vitro. The myenteric plexus of adult rats can provide a readily available source of neurons and Schwann cells for grafting to the central nervous system

Does That Sound Familiar? : Creators\u27 Liability for Unconscious Copyright Infringement

In 1953, a twenty-seven year old man underwent brain surgery to treat the severe epilepsy that had plagued him during his youth. The surgeon, Dr. William Scoville, removed portions of the young man\u27s brain that were involved in memory processing. Most notably, Dr. Scoville removed most of his patient\u27s hippocampus. The surgery left the young man, now known to psychologists as H.M., with anterograde amnesia: he still had a short-term memory, but he was unable to convert any of his short-term memories into new long-term memories. Although H.M. could not form new long-term memories, psychologists found that he still could learn some new skills. For instance, researchers had H.M. complete repeated trials of the Tower of Hanoi puzzle, which challenges participants to rearrange three to five blocks of increasing size on vertical pegs according to certain rules. H.M. had no conscious recollection of completing the Tower of Hanoi puzzle in earlier trials, but his performance nevertheless improved with practice. H.M.\u27s mystifying improvement can be explained by the influence of implicit memory, and a wealth of subsequent research with nonamnesiac participants demonstrates that implicit memory influences the actions of everyday people. Implicit memories are memories that influence an individual\u27s behavior even though the individual is not aware of their influence. For example, imagine that you attend a summer camp as a child and develop a secret handshake with your roommate at the camp. The next summer, you return to the camp. When you see your roommate from the previous summer, he extends his hand. At this point, you may consciously recognize that he wants to do the secret handshake, recall when and how you developed the handshake, and then perform the handshake step by step with reference to your memory. This is an example of explicit memory: you are aware that you are reconstructing the handshake with reference to an episodic memory from the previous summer. However, you may reach out and perform the handshake without thinking about the previous summer at all. This is an example of implicit memory: you are able to perform the handshake correctly, but you do not consciously refer to any memory of the previous summer. Implicit memory is relevant to copyright law because, just as an implicit memory of a handshake might influence future handshakes, implicit memories of songs, pictures, and phrases might influence a creator as she produces her own music, painting, or story. Implicit memory is likely involved in instances of unintentional plagiarism, or unconscious copying. Unconscious copying occurs when a creator is familiar with an original, copyrighted work, and this familiarity leads the creator to produce a work similar to the original without ever recognizing the influence or its source. Presently, copyright law treats unconscious copying no differently than conscious copying-both deliberate and inadvertent copiers are liable for copyright infringement. This Note argues that, in light of the empirical research establishing that implicit memory influences human behavior, the present approach to unconscious copying is at odds with psychological realities and is inconsistent with the fundamental purposes of copyright law