Positional information readout in Ca2+Ca^{2+} signaling

Living cells respond to spatial signals. Signal transmission to the cell interior often involves the release of second messengers like $Ca^{2+}$ . They will eventually trigger a physiological response by activating kinases that in turn activate target proteins through phosphorylation. Here, we investigate theoretically how positional information can be accurately read out by protein phosphorylation in spite of rapid second messenger diffusion. We find that accuracy is increased by binding of the kinases to the cell membrane prior to phosphorylation and by increasing the rate of $Ca^{2+}$ loss from the cell interior. These findings could explain some salient features of conventional protein kinases C

Gravitational Lorentz anomaly from the overlap formula in 2-dimensions

In this letter we show that the overlap formulation of chiral gauge theories correctly reproduces the gravitational Lorentz anomaly in 2-dimensions. This formulation has been recently suggested as a solution to the fermion doubling problem on the lattice. The well known response to general coordinate transformations of the effective action of Weyl fermions coupled to gravity in 2-dimensions can also be recovered.Comment: 7 pages, late

Studies of the dissolved organic compounds in the sea - A preliminary report on the isolation, separation and identification of free amino acids

A method of concentrating and desalting sea water using evaporation and ion exchange techniques is described. Circular paper chromatography has been used to separate and identify free amino acids in desalted concentrates of sea water from three different localities along the Norwegian coast. The following amino acids have so far been identified: cystine, lysine, histidine, arginine, serine, aspartic acid, glycine, hydroxyproline, glutamic acid, threonine, α-alanine, proline, tyrosine, tryptophan, methionine, valine, β-phenylalanine, isoleucine and leucine

World War I and the Idea of Progress in Powers\u27s Three Farmers on Their Way to a Dance

In his article World War I and the Idea of Progress in Powers\u27s Three Farmers on Their Way to a Dance Karsten H. Piep reads Powers\u27s 1985 novel as a critical reexamination of the dynamics and iconography of the early twentieth century that challenges the technological positivism espoused by many U.S. neoconservatives during the 1980s, while insisting on the individual\u27s interpretive powers to discern and release the ever present transformative potentials of history. Situating Three Farmers in the postmodernism debates of the 1980s, Piep argues that the novel succeeds in challenging the idea of history conceived as linear progression, but fails to show how a critical engagement with the past might engender social transformation in the present

Separatist Nationalism in Gilbert Imlay\u27s The Emigrants

Karsten H. Piep, in his paper Separatist Nationalism in Gilbert Imlay\u27s The Emigrants, argues that only recently rediscovered among American scholars and still awaiting much critical work, Gilbert Imlay\u27s The Emigrants offers an intriguing case study in the complex relationship between fictional representation and late eighteenth-century nation formation. Tracing briefly the novel\u27s reception history, Piep locates The Emigrants within the socio-political context of eighteenth-century discourses on revolution, emancipation, and independence. Taking Benedict Anderson\u27s study on the rise of nationalism as a point of reference, Piep argues that Imlay\u27s novel offers an example of a perhaps uniquely American separatist nationalism that proffers, employs, expands, and subverts official or dominant accounts of nationalism by inviting a transatlantic readership to imagine an utopian community in the remote Ohio River Valley. Piep also explores in his study how novelistic representations of Benedict Anderson\u27s notion of homogenous, empty time can be applied with regard to transatlantic imaginings of alternative communities in Imlay\u27s novel

Constraints on the Existence of Chiral Fermions in Interacting Lattice Theories

It is shown that an interacting theory, defined on a regular lattice, must have a vector-like spectrum if the following conditions are satisfied: (a)~locality, (b)~relativistic continuum limit without massless bosons, and (c)~pole-free effective vertex functions for conserved currents. The proof exploits the zero frequency inverse retarded propagator of an appropriate set of interpolating fields as an effective quadratic hamiltonian, to which the Nielsen-Ninomiya theorem is applied.Comment: LaTeX, 9 pages, WIS--93/56--JUNE--P