A Search for Fine Structure of the Knee in EAS Size Spectra

28 size spectra of extensive air showers from 7 different experiments are analysed consistently. They are fitted by adjusting either 4 or 5 parameters: knee position, power law exponents above and below the knee, overall intensity and, in addition, a parameter describing the smoothness of the bend. The residuals are then normalized to the same knee position and averaged. When 5 parameters are employed no systematic deviation from a single smooth knee is apparent at the 1% level up to a factor of 4 above the knee. At larger shower sizes a moderately significant deviation can be seen whose shape and position are compatible with a second knee caused by iron group nuclei.Comment: 17 pages, 5 figs.; Astroparticle Physics, in pres

A Marxian Analysis of Inter-Industry Linkages and the Time Structure of Production

In this paper we analyze and model the flows of capital in an interlinked economy exhibiting complete simple reproduction. Drawing heavily on Marx\u27s description of circulation in volume 2 of Capital, we graphically and symbolically model the transfer of value between money, productive, and commodity capital. In addition, we allow for the creation of surplus value through production. Combining this with Marx\u27s discussion of simple reproduction and the MELT (Monetary Expression of Labor Time), our model illustrates a capitalist economy in a state of general equilibrium. As a powerful descriptive tool, this mathematical and Maple-coded model combines the insights of volumes 1 and 2 of Capital to enable a more complete understanding of Marxian theory. This model will be usable both as a descriptive and teaching tool, as well as potentially being used to analyze the equalization of profit rates, and the related transformation problem

Optimization of a satellite project

Improvement in technological performance by project optimizatio

The importance of nuclear masses in the astrophysical rp-process

The importance of mass measurements for astrophysical capture processes in general, and for the rp-process in X-ray bursts in particular is discussed. A review of the current uncertainties in the effective lifetimes of the major waiting points 64Ge, 68Se, and 72Kr demonstrates that despite of recent measurements uncertainties are still significant. It is found that mass measurements with an accuracy of the order of 10 keV or better are desirable, and that reaction rate uncertainties play a critical role as well.Comment: 14 pages, 4 figures, to appear in International Journal of Mass Spectroscop

How proteins are transported into mitochondria

Most mitochondrial polypeptides are synthesized outside the organelle as precursors which are usually larger than the ‘mature’ polypeptides found within mitochondria. The precursors are imported into the mitochondria by a process which is independent of protein synthesis but dependent on high-energy phosphate bonds inside the mitochondria. This mechanism is basically different from that which governs the movement of secretory polypeptides across the membrane of the endoplasmic reticulum

Quantum mechanical reactive scattering for three-dimensional atom plus diatom systems. II. Accurate cross sections for H+H_2

Accurate three‐dimensional reactive and nonreactive quantum mechanical cross sections for the H+H_2 exchange reaction on the Porter–Karplus potential energy surface are presented. Tests of convergence in the calculations indicate an accuracy of better than 5% for most of the results in the energy range considered (0.3 to 0.7 eV total energy). The reactive differential cross sections are exclusively backward peaked, with peak widths increasing monotonically from about 32° at 0.4 eV to 51° at 0.7 eV. Nonreactive inelastic differential cross sections show backwards to sidewards peaking, while elastic ones are strongly forward peaked with a nearly monotonic decrease with increasing scattering angle. Some oscillations due to interferences between the direct and exchange amplitudes are obtained in the para‐to‐para and ortho‐to‐ortho antisymmetrized cross sections above the effective threshold for reaction. Nonreactive collisions do not show a tendency to satisfy a "j_z‐conserving" selection rule. The reactive cross sections show significant rotational angular momentum polarization with the m_j=m′_j=0 transition dominating for low reagent rotational quantum number j. In constrast, the degeneracy averaged rotational distributions can be fitted to statistical temperaturelike expressions to a high degree of accuracy. The integral cross sections have an effective threshold total energy of about 0.55 eV, and differences between this quantity and the corresponding 1D and 2D results can largely be interpreted as resulting from bending motions in the transition state. In comparing these results with those of previous approximate dynamical calculations, we find best overall agreement between our reactive integral and differential cross sections and the quasiclassical ones of Karplus, Porter, and Sharma [J. Chem. Phys. 43, 3259 (1965)], at energies above the quasiclassical effective thresholds. This results in the near equality of the quantum and quasiclassical thermal rate constants at 600 K. At lower temperatures, however, the effects of tunneling become very important with the quantum rate constant achieving a value larger than the quasiclassical one by a factor of 3.2 at 300 K and 18 at 200 K

Role of direct and resonant (compound state) processes and of their interferences in the quantum dynamics of the collinear H + H2 exchange reaction

The question of the relative importance of compound state (i.e., activated complex) and direct reaction mechanisms has been of central importance for the dynamical foundations of chemical kinetics [1,2]. The studies here reported indicate that in the quantum dynamics of the historically important H + H2 exchange reaction not only do both such mechanisms contribute but also that their interference plays a central role in determining the pronounced quantum oscillations of the reaction probability as a function of energy [3]. This accounts not only for the absence of such oscillations in quasiclassical calculations [4], but also for the inability of the present semiclassical formalism [5] to produce them [6]