Optimal length and signal amplification in weakly activated signal transduction cascades

Weakly activated signaling cascades can be modeled as linear systems. The input-to-output transfer function and the internal gain of a linear system, provide natural measures for the propagation of the input signal down the cascade and for the characterization of the final outcome. The most efficient design of a cascade for generating sharp signals, is obtained by choosing all the off rates equal, and a ``universal'' finite optimal length.Comment: 27 pages, 10 figures, LaTeX fil

Clinical Scholarship and the Justice Mission

To many people, the relationship between clinical programs and the justice mission of American law schools is so clear as to be self-evident. These programs may pursue justice on behalf of individual clients or for groups of clients through class-action or other impact litigation. Moreover, clinical teachers frequently discuss with their students the need for the latter to serve justice in their legal careers, whether as the principal focus of their legal work or through pro bono publico activities. Indeed, for many law students, the law clinic may be the only place in which concerns about justice are discussed and, at least sometimes, acted upon. In this brief essay, I want to suggest that clinical scholarship is not an oxymoron. Such scholarship already has contributed to nascent understandings of the different meanings of justice within the academy. If it develops to its full potential, it can broaden still further our understanding of the various visions of justice that exist within both the academy and society at large

Tales from a Supportive Guardianship

F or a number of years now, I have been a committed advocate of supported decision making as an alternative to guardianship for people with intellectual disabilities. In writings, presentations, classes, and meetings,1 I have argued that supported decision making is not only less restrictive than guardianship but more consistent with principles of client-centered counseling and person-centered planning that animate approaches to lawyering and the delivery of services to people with intellectual disabilities. Even the most humane and limited forms of guardianship shift decision-making focus from the individual with a disability to his or her guardian or other surrogate decision maker. In contrast, although the person with an intellectual disability may get significant support from one or more supporters, that person remains the primary decision maker in his or her life

Far-infrared line observations of planetary nebulae. 1: The O 3 spectrum

Observations of the far-infrared fine structure lines of O III have been obtained for six planetary nebulae. The infrared measurements are combined with optical O III line fluxes to probe physical conditions in the gas. From the observed line intensity ratios, a simultaneous solution was obtained for electron temperature and density, as well as means of evaluating the importance of inhomogeneities. Densities determined from the far-infrared O III lines agree well density diagnostics from other ions, indicating a fairly homogeneous density in the emitting gas. Temperatures are determined separately from the O III 4363/5007 A and 5007 A/52 micron intensity ratios and compared. Systematically higher values are derived from the former ratio, which is expected from a nebula which is not isothermal. Allowance for the presence of temperature variations within these nebulae raises their derived oxygen abundances, determinations to be reconciled with the solar value

A far-infrared study of N/O abundance ratio in galactic H 2 regions

Far-infrared lines of N++ and O++ in several galactic H II regions were measured in an effort to probe the abundance ratio N/O. New measurements are presented for W32 (630.8-0.0), Orion A, and G75.84+0.4. The combination of (N III) 57.3 millimicrons and (O III) 88.4 and 51.8 millimicrons yields measurements of N++/O++ that are largely insensitive to electron temperature, density uncertainties, and to clumping of the ionized gas, due to the similarity of the critical densities for these transitions. In the observed nebulae, N++/O++ should be indicative of N/O, a ratio that is of special importance in nucleosynthesis theory. Measurements are compared with previous measurements of M17 and W51. For nebulae in the solar circle, N++/O++ is greater than the N/O values derived from optical studies of N+/O+ in low ionization zones of the same nebulae. We find that N++/O++ in W43 is significantly higher than for the other H II regions in the sample. Since W43 is located at R = 5 kpc, which is the smallest galactocentric distance in our sample, our data appear consistent with the presence of a negative abundance gradient d(N/O)dR