The QCD rotator in the chiral limit

The low lying spectrum of QCD in the delta-regime is calculated here in chiral perturbation theory up to NNL order. The spectrum has a simple form in terms of the pion decay constant F and a combination of the low energy constants Lambda1 and Lambda2. Since measuring low lying stable masses is among the easiest numerical tasks, the results should help fixing these parameters to good precision.Comment: 17 pages; typos are corrected and a paragraph added for better understanding; the present version is identical with the published paper in N.Phys.B. except a typo in eq(35) which is also corrected her

Quenched chiral perturbation theory to one loop

We calculate the divergences of the generating functional of quenched chiral perturbation theory at one loop, and renormalize the theory by an appropriate definition of the counterterms. We show that the quenched chiral logarithms can be accounted for by defining a renormalized B0 parameter which, at lowest order, is proportional to the vacuum expectation value of the scalar quark density. Finally, we calculate several quantities at one loop to better analyze the modifications induced by quenching in the ultraviolet finite part of the one-loop corrections. We point out that some of the finite loop corrections may diverge in the chiral limit.

Transfer in a Connectionist Model of the Acquisition of Morphology

The morphological systems of natural languages are replete with examples of the same devices used for multiple purposes: (1) the same type of morphological process (for example, suffixation for both noun case and verb tense) and (2) identical morphemes (for example, the same suffix for English noun plural and possessive). These sorts of similarity would be expected to convey advantages on language learners in the form of transfer from one morphological category to another. Connectionist models of morphology acquisition have been faulted for their supposed inability to represent phonological similarity across morphological categories and hence to facilitate transfer. This paper describes a connectionist model of the acquisition of morphology which is shown to exhibit transfer of this type. The model treats the morphology acquisition problem as one of learning to map forms onto meanings and vice versa. As the network learns these mappings, it makes phonological generalizations which are embedded in connection weights. Since these weights are shared by different morphological categories, transfer is enabled. In a set of experiments with artificial stimuli, networks were trained first on one morphological task (e.g., tense) and then on a second (e.g., number). It is shown that in the context of suffixation, prefixation, and template rules, the second task is facilitated when the second category either makes use of the same forms or the same general process type (e.g., prefixation) as the first.Comment: 21 pages, uuencoded compressed Postscrip

Lattice calculation of the strangeness and electromagnetic nucleon form factors

We report on recent lattice QCD calculations of the strangeness magnetic moment of the nucleon and the nucleon electromagnetic form factors, when we allow the electromagnetic current to connect to quark loops as well as to the valence quarks. Our result for the strangeness magnetic moment is G_M^s(0)=-0.36+/-0.20. The sea contributions from the u and d quarks are about 80% larger. However, they cancel to a large extent due to their electric charges, resulting in a smaller net sea contribution of -0.097+/-0.037 mu_N to the nucleon magnetic moment. As far as the neutron to proton magnetic moment ratio is concerned, this sea contribution tends to cancel out the cloud-quark effect from the Z-graphs and results in a ratio of -0.68+/-0.04 which is close to the SU(6) relation and the experiment. The strangeness Sachs electric mean-square radius _E is found to be small and negative and the total sea contributes substantially to the neutron electric form factor.Comment: LATTICE98(matrixelement); 3 pages, no figures, to appear in Lattice '98 proceeding

On the large-NcN_c behavior of the L7L_7 coupling in χ\chiPT

It is shown that the usual large-$N_c$ counting of the coupling constant $L_{7}$ of the ${\cal O}(p^4)$ low-energy chiral $SU(3)$ Lagrangian \cite{GL85} is in conflict with general properties of QCD in the large-$N_c$ limit. The solution of this conflict within the framework of a chiral $U(3)$ Lagrangian is explained.Comment: 6 pages, latex(includes macro at the beginning of file), no figure

Roles for the Uptake\u3csub\u3e2\u3c/sub\u3e Transporter OCT3 in Regulation of Dopaminergic Neurotransmission and Behavior

Transporter-mediated uptake determines the peak concentration, duration, and physical spread of released monoamines. Most studies of monoamine clearance focus on the presynaptic uptake1 transporters SERT, NET and DAT. However, recent studies have demonstrated the expression of the uptake2 transporter OCT3 (organic cation transporter 3), throughout the rodent brain. In contrast to NET, DAT and SERT, OCT3 has higher capacity and lower affinity for substrates, is sodium-independent, and is multi-specific, with the capacity to transport norepinephrine, dopamine, serotonin and histamine. OCT3is insensitive to inhibition by cocaine and antidepressant drugs but is inhibited directly by the glucocorticoid hormone corticosterone. Thus, OCT3 represents a novel, stress hormone-sensitive, monoamine transport mechanism. Incorporating this transporter into current models of monoaminergic neurotransmission requires information on: A) the cellular and subcellular localization of the transporter; B) the effects of OCT3 inhibitors on monoamine clearance; and C) the consequences of decreased OCT3-mediated transport on physiology and/or behavior. This review summarizes studies describing the anatomical distribution of OCT3, its cellular and subcellular localization, its contribution to the regulation of dopaminergicsignaling, and its roles in the regulation of behavior. Together, these and other studies suggest that both Uptake1 and Uptake2 transporters play key roles in regulating monoaminergic neurotransmission and the effects of monoamines on behavior

Aristotle on Self-Sufficiency, External Goods, and Contemplation

Aristotle tells us that contemplation is the most self-sufficient form of virtuous activity: we can contemplate alone, and with minimal resources, while moral virtues like courage require other individuals to be courageous towards, or courageous with. This is hard to square with the rest of his discussion of self-sufficiency in the Ethics: Aristotle doesn't generally seek to minimize the number of resources necessary for a flourishing human life, and seems happy to grant that such a life will be self-sufficient despite requiring a lot of external goods. In this paper I develop an interpretation of self-sufficiency as a form of independence from external contributors to our activity, and argue that this interpretation accounts both for Aristotle's views on contemplation and for the role self-sufficiency plays in his broader account of human happiness