Coupling of Nonlocal Potentials to Electromagnetic Fields

Nonlocal Hamiltonians are used widely in first-principles quantum calculations; the nonlocality stems from eliminating undesired degrees of freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to external electromagnetic (EM) fields have been heuristic or limited to weak or long wavelength fields. Using Feynman path integrals, we derive an exact, closed-form coupling of arbitrary EM fields to nonlocal systems. Our results justify and clarify the couplings used to date and are essential for systematic computation of linear and especially nonlinear response.Comment: 1 figure, 1 tabl

The neural connectivity of olfactory bulb regions in ovulated female lampreys (Petromyzon marinus).

This study aims to discover neural pathways stimulated by reproductive pheromones eliciting an attractive locomotor response in sea lampreys. Distinct glomerular territories in the olfactory bulb of ovulated female lampreys were injected with biocytin. Dorsoanterior injections revealed labeling in integrative areas (dorsal, medial, and lateral pallia, habenula, thalamus, hypothalamus) and a locomotor control area (striatum). Medial injections labeled the medial pallium, the thalamus and the striatum. Projections to the hypothalamus and the lateral pallium from the dorsoanterior region of the olfactory bulb, that were absent from medial injections, infer functional difference between these two regions. Lateral injections labeled the striatum, suggesting the lateral olfactory bulb is strongly associated with locomotion. The results demonstrate an anatomical difference in the neural connections of distinct regions of the olfactory bulb.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2006 .C435. Source: Masters Abstracts International, Volume: 45-01, page: 0238. Thesis (M.Sc.)--University of Windsor (Canada), 2006

Mou Zongsan's Translation of Hölderlin's "Withdrawal of God" and His Political Utopia

In the essay Lun Shangdi Yintui [On the Withdrawal of God], Mou Zongsan (1909-1995) recontexulized the concept of “withdrawal of God,” a constant theme repeatedly appearing in Hölderlin’s writing, within a set of Confucian literary and cultural parameters, thus inventing for this concept new readers and challenging the long established Confucian tradition of “tian ren he yi” [the unity of heaven and man]. This transformation has important bearing on Mou’s political philosophy. Though recognized by many scholars as a political utopia, Mou’s political philosophy embodies a utopian impulse that goes beyond the realizable and actualizable in order to bring a fantastic power of transgressing limiting boundaries. In this sense, we find Mou’s political philosophy a plausible one and certainly worthy of our reexamination

Calcium-independent inhibitory G-protein signaling induces persistent presynaptic muting of hippocampal synapses

Adaptive forms of synaptic plasticity that reduce excitatory synaptic transmission in response to prolonged increases in neuronal activity may prevent runaway positive feedback in neuronal circuits. In hippocampal neurons, for example, glutamatergic presynaptic terminals are selectively silenced, creating mute synapses, after periods of increased neuronal activity or sustained depolarization. Previous work suggests that cAMP-dependent and proteasome-dependent mechanisms participate in silencing induction by depolarization, but upstream activators are unknown. We, therefore, tested the role of calcium and G-protein signaling in silencing induction in cultured hippocampal neurons. We found that silencing induction by depolarization was not dependent on rises in intracellular calcium, from either extracellular or intracellular sources. Silencing was, however, pertussis toxin sensitive, which suggests that inhibitory G-proteins are recruited. Surprisingly, blocking four common inhibitory G-protein-coupled receptors (GPCRs) (adenosine A(1) receptors, GABA(B) receptors, metabotropic glutamate receptors, and CB(1) cannabinoid receptors) and one ionotropic receptor with metabotropic properties (kainate receptors) failed to prevent depolarization-induced silencing. Activating a subset of these GPCRs (A(1) and GABA(B)) with agonist application induced silencing, however, which supports the hypothesis that G-protein activation is a critical step in silencing. Overall, our results suggest that depolarization activates silencing through an atypical GPCR or through receptor-independent G-protein activation. GPCR agonist-induced silencing exhibited dependence on the ubiquitin-proteasome system, as was shown previously for depolarization-induced silencing, implicating the degradation of vital synaptic proteins in silencing by GPCR activation. These data suggest that presynaptic muting in hippocampal neurons uses a G-protein-dependent but calcium-independent mechanism to depress presynaptic vesicle release

Customer participation is no panacea for the development of new products

In some contexts, involving the customers can have detrimental effects, argue Woojung Chang and Steven Taylo

Phases of the infinite U Hubbard model

We apply the density matrix renormalization group (DMRG) to study the phase diagram of the infinite U Hubbard model on 2-, 4-, and 6-leg ladders. Where the results are largely insensitive to the ladder width, we consider the results representative of the 2D square lattice model. We find a fully polarized ferromagnetic Fermi liquid phase when n, the density of electrons per site, is in the range 1>n>n_F ~ 4/5. For n=3/4 we find an unexpected commensurate insulating "checkerboard" phase with coexisting bond density order with 4 sites per unit cell and block spin antiferromagnetic order with 8 sites per unit cell. For 3/4 > n, the wider ladders have unpolarized groundstates, which is suggestive that the same is true in 2D