Infinitesimally Nonlocal Lorentz Violation

We introduce a new Lorentz-violating modification to a scalar quantum field theory. This interaction, while super-renormalizable by power counting, is fundamentally different from the interactions previously considered within the Lorentz-violating standard model extension. The Lagrange density is nonlocal, because of the presence of a Hilbert transform term; however, this nonlocality is also very weak. The theory has reasonable stability and causality properties and, although the Lorentz-violating interaction possesses a single vector index, the theory is nonetheless CPT even. As an application, we analyze the possible effects of this new form of Lorentz violation on neutral meson oscillations. We find that under certain circumstances, the interaction may lead to quite peculiar sidereal modulations in the oscillation frequency.Comment: 10 page

Sticky Wages. Evidence from Quarterly Microeconomic Data.

This paper documents nominal wage stickiness using an original quarterly firm-level dataset. We use the ACEMO survey, which reports the base wage for up to 12 employee categories in French firms over the period 1998 to 2005, and obtain the following main results. First, the quarterly frequency of wage change is around 35 percent. Second, there is some downward rigidity in the base wage. Third, wage changes are mainly synchronized within firms but to a large extent staggered across .firms. Fourth, standard Calvo or Taylor schemes fail to match micro wage adjustment patterns, but fixed duration "Taylor-like" wage contracts are observed for a minority of firms. Based on a two-thresholds sample selection model, we perform an econometric analysis of wage changes. Our results suggest that the timing of wage adjustments is not state-dependent, and are consistent with existence of predetermined of wage changes. They also suggest that both backward- and forward-looking behavior is relevant in wage setting.Wage stickiness ; Wage predetermination.

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

New CP-violation and preferred-frame tests with polarized electrons

We used a torsion pendulum containing $\sim 9 \times 10^{22}$ polarized electrons to search for CP-violating interactions between the pendulum's electrons and unpolarized matter in the laboratory's surroundings or the sun, and to test for preferred-frame effects that would precess the electrons about a direction fixed in inertial space. We find $|g_{\rm P}^e g_{\rm S}^N|/(\hbar c)< 1.7 \times 10^{-36}$ and $|g_{\rm A}^e g_{\rm V}^N|/(\hbar c) < 4.8 \times 10^{-56}$ for $\lambda > 1$AU. Our preferred-frame constraints, interpreted in the Kosteleck\'y framework, set an upper limit on the parameter $|\bm{\tilde {b}}^e| \leq 5.0 \times 10^{-21}$ eV that should be compared to the benchmark value $m_e^2/M_{\rm Planck}= 2 \times 10^{-17}$ eV.Comment: 4 figures, accepted for publication in Physical Review Letter

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

Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale

We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 micrometers, probing distances less than the dark-energy length scale $\lambda_{\rm d}=\sqrt[4]{\hbar c/\rho_{\rm d}}\approx 85 \mu$m. We find with 95% confidence that the inverse-square law holds ($|\alpha| \leq 1$) down to a length scale $\lambda = 56 \mu$m and that an extra dimension must have a size $R \leq 44 \mu$m.Comment: 4 pages, 6 figure

Diversity and regulatory impact of copy number variation in the primate Macaca fascicularis.

Copy number variations (CNVs) are a significant source of genetic diversity and commonly found in mammalian genomes. We have generated a genome-wide CNV map for Cynomolgus monkeys (Macaca fascicularis). This crab-eating macaque is the closest animal model to humans that is used in biomedical research. We show that Cynomolgus monkey CNVs are in general much smaller in size than gene loci and are specific to the population of origin. Genome-wide expression data from five vitally important organs demonstrates that CNVs in close proximity to transcription start sites associate strongly with expression changes. Among these eQTL genes we find an overrepresentation of genes involved in metabolism, receptor activity, and transcription. These results provide evidence that CNVs shape tissue transcriptomes in monkey populations, potentially offering an adaptive advantage. We suggest that this genetic diversity should be taken into account when using Cynomolgus macaques as models

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

Timing strains of the marine insect Clunio marinus diverged and persist with gene flow

Genetic divergence of populations in the presence of gene flow is a central theme in speciation research. Theory predicts that divergence can happen with full range overlap – in sympatry – driven by ecological factors, but there are few empirical examples of how ecologically divergent selection can overcome gene flow and lead to reproductive isolation. In the marine midge Clunio marinus (Diptera: Chironomidae) reproduction is ecologically restricted to the time of the lowest tides, which is ensured through accurate control of development and adult emergence by circalunar and circadian clocks. As tidal regimes differ along the coastline, locally adapted timing strains of C. marinus are found in different sites across Europe. At the same time, ecologically suitable low tides occur at both full and new moon and twice a day, providing C. marinus with four non-overlapping temporal niches at every geographic location. Along the coast of Brittany, which is characterized by a steep gradient in timing of the tides, we found an unusually large number of differentially adapted timing strains, and the first known instances of sympatric C. marinus strains occupying divergent temporal niches. Analysis of mitochondrial genotypes suggests that these timing strains originated from a single recent colonization event. Nuclear genotypes show strong gene flow, sympatric timing strains being the least differentiated. Even when sympatric strains exist in non-overlapping temporal niches, timing adaptations do not result in genome-wide genetic divergence, suggesting timing adaptations are maintained by permanent ecological selection. This constitutes a model case for incipient ecological divergence with gene flow