How do firms respond to cheaper computers? Microeconometric evidence for France based on a production function approach

The continuous innovation process experienced by the information technology industries over the last decades has caused the price of computer power to decrease dramatically. This has led many firms to invest massively in increasingly efficient computers. This paper is an attempt to assess the impact of the fall of the cost of this particular input, on the performances of firms in terms of marginal cost, aggregate labor demand and employment by skill. Unlike most studies dealing with the technological bias issue, most of which rely on the estimation of factor demand equations, our evaluation of the complementarities between computers, skilled and unskilled labor rests on the sole estimation of a production function. We define a set of parameters of interest, depending on the observations and on the structural parameters of the production function, enabling us to examine the impact of the computer price decrease on marginal cost, labor demand and the relative demand for skills. Using a panel of more than 5000 continuing French firms followed between 1994 and 1997, we estimate a translog production function and find that the effects of the decrease in the price of computers have been large, both in terms of marginal cost reduction and in terms of skill structure. A 15% fall of the computer price should lead to a decrease of around 0.7% in the marginal cost of production and to a rise of about 3.5% of the skilled to unskilled ratio, other input prices being held fixed.Computers, production function, marginal cost, factor demands, technological bias

Spin-Dependent Macroscopic Forces from New Particle Exchange

Long-range forces between macroscopic objects are mediated by light particles that interact with the electrons or nucleons, and include spin-dependent static components as well as spin- and velocity-dependent components. We parametrize the long-range potential between two fermions assuming rotational invariance, and find 16 different components. Applying this result to electrically neutral objects, we show that the macroscopic potential depends on 72 measurable parameters. We then derive the potential induced by the exchange of a new gauge boson or spinless particle, and compare the limits set by measurements of macroscopic forces to the astrophysical limits on the couplings of these particles.Comment: 37 page

The Riemann-Cartan space in the O-theory

Nonrelativistic equation of particle with a spin for the Lagrangian on a nonassociative algebra is obtained. It is shown that in this model arises Riemann-Cartan space. In the case of central symmetry in addition to the pseudo-curvature appears torsion as pseudovector that interacts with the spin of the particle. An estimation of the influence of torsion on the strength of gravitational attraction in the central gravitational field is given.Comment: 12 page

Measurement of Linear Stark Interference in 199Hg

We present measurements of Stark interference in the 6$^1S_0$ $\rightarrow$ 6$^3P_1$ transition in $^{199}$Hg, a process whereby a static electric field $E$ mixes magnetic dipole and electric quadrupole couplings into an electric dipole transition, leading to $E$-linear energy shifts similar to those produced by a permanent atomic electric dipole moment (EDM). The measured interference amplitude, $a_{SI}$ = $(a_{M1} + a_{E2})$ = (5.8 $\pm$ 1.5)$\times 10^{-9}$ (kV/cm)$^{-1}$, agrees with relativistic, many-body predictions and confirms that earlier central-field estimates are a factor of 10 too large. More importantly, this study validates the capability of the $^{199}$Hg EDM search apparatus to resolve non-trivial, controlled, and sub-nHz Larmor frequency shifts with EDM-like characteristics.Comment: 4 pages, 4 figures, 1 table; revised in response to reviewer comment

Improved limit on the permanent electric dipole moment of 199Hg

We report the results of a new experimental search for a permanent electric dipole moment of 199Hg utilizing a stack of four vapor cells. We find d(199Hg) = (0.49 \pm 1.29_stat \pm 0.76_syst) x 10^{-29} e cm, and interpret this as a new upper bound, |d(199Hg)| < 3.1 x 10^{-29} e cm (95% C.L.). This result improves our previous 199Hg limit by a factor of 7, and can be used to set new constraints on CP violation in physics beyond the standard model.Comment: 4 pages, 4 figures. additional reference, minor edits in response to reviewer comment

Approaches to land snail shell bead manufacture in the Early Holocene of Malawi

Shell disc beads are important archeological indicators of social communication and exchange networks. There has been substantial research on ostrich eggshell (OES) beads, but little is known about the manufacture or chronology of similar beads from land snail shells (LSS). LSS beads are associated with Holocene hunter-gatherers in Africa, though direct dates are limited to the Iron Age, and there are no images or descriptions of the manufacturing sequence. Here, we combine experimental and archeological data to resolve the chronology, operational chains, and material properties of LSS bead manufacture. We then recommend and apply a modified OES production sequence to three Later Stone Age assemblages from the Kasitu Valley of northern Malawi (Hora 1, Mazinga 1, and Kadawonda 1). At these sites, LSS shows an unexpectedly high proportion of Pathway 2 manufacture (disc shaping prior to perforation), in direct contrast with known OES bead manufacture. Application of red color occurred at all stages of manufacture, albeit inconsistently. Production of finished beads involved substantial removal of material from preforms to create the final product. Finally, we report the earliest evidence for LSS bead manufacture with two directly dated preforms (~ 9500 cal BP), showing that the origins of LSS beadmaking do precede the Iron Age.Introduction Background and previous research - The problem of land snail disc beads - Land snail shell versus ostrich eggshell Materials and methods - Experimental methods -- Breakage -- Shaping -- Drilling -- Pigments - Archeological samples -- Site descriptions -- Recovery protocols -- Sorting, data collection, and analysis -- Dating Results - Experimental results -- Breakage -- Shaping -- Drilling -- Production stages specific to LSS -- Application of pigments - Archeological results -- Assemblage description -- Manufacturing chains -- Dating Discussion Conclusion

Movers and shakers: Granular damping in microgravity

The response of an oscillating granular damper to an initial perturbation is studied using experiments performed in microgravity and granular dynamics mulations. High-speed video and image processing techniques are used to extract experimental data. An inelastic hard sphere model is developed to perform simulations and the results are in excellent agreement with the experiments. The granular damper behaves like a frictional damper and a linear decay of the amplitude is bserved. This is true even for the simulation model, where friction forces are absent. A simple expression is developed which predicts the optimal damping conditions for a given amplitude and is independent of the oscillation frequency and particle inelasticities.Comment: 9 pages, 9 figure

Differential regulation of local mRNA dynamics and translation following long-term potentiation and depression

Decades of work have demonstrated that messenger RNAs (mRNAs) are localized and translated within neuronal dendrites and axons to provide proteins for remodeling and maintaining growth cones or synapses. It remains unknown, however, whether specific forms of plasticity differentially regulate the dynamics and translation of individual mRNA species. To address this, we targeted three individual synaptically localized mRNAs, CamkIIa, β-actin, Psd95, and used molecular beacons to track endogenous mRNA movements. We used reporters and CRISPR/Cas9 gene editing to track mRNA translation in cultured neurons. We found alterations in mRNA dynamic properties occurred during two forms of synaptic plasticity, long-term potentiation (cLTP) and depression (mGluR-LTD). Changes in mRNA dynamics following either form of plasticity resulted in an enrichment of mRNA in the vicinity of dendritic spines. Both the reporters and tagging of endogenous proteins revealed the transcript-specific stimulation of protein synthesis following cLTP or mGluR-LTD. As such, the plasticity-induced enrichment of mRNA near synapses could be uncoupled from its translational status. The enrichment of mRNA in the proximity of spines allows for localized signaling pathways to decode plasticity milieus and stimulate a specific translational profile, resulting in a customized remodeling of the synaptic proteome