The Democratization of U.S. Research and Development after 1980

Using Compustat data, we document that prior to 1980, large R&D per-forming firms had higher R&D intensity (R&D/Sales) than small firms in the same industries. Over the course of the next two decades, in these same in-dustries, small firms came to rival and even surpass large firms in terms of R&D intensity. During this period, corporate R&D intensity nearly doubled and most of the aggregate increase is due to the substantial increase in R&D intensity among small firms. Little of the change in composition is explained by changes in the industrial distribution of R&D. Why did small firms increase their R&D after 1980 and not before? We argue that, after 1980, small firms were able to compete on better terms in industries already dominated by large firms. We show that the patterns we observe in the data are consistent with a straightforward dynamic model of R&D with falling barriers to entry. But what barriers fell? We argue the shift in R&D intensity by small firms was largely due to the electronics revolution. Prior to the 1980s, a large corporate sales and clerical force was an essential factor for the rapid and widespread distribution of new products. This technology clearly favored large, established firms. But the electronics revolution obviated the need for these factors, making entry easier.R&D, barriers to entry, innovation

Crises and Recoveries in an Empirical Model of Consumption Disasters

We estimate an empirical model of consumption disasters using a new panel data set on personal consumer expenditure for 24 countries and more than 100 years, and study its implications for asset prices. The model allows for permanent and transitory effects of disasters that unfold over multiple years. It also allows the timing of disasters to be correlated across countries. Our estimates imply that the average disaster reaches its trough after 6 years, with a peak-to-trough drop in consumption of about 30%, but that roughly half of this decline is reversed in a subsequent recovery. Uncertainty about consumption growth increases dramatically during disasters. Our estimated model generates a sizable equity premium from disaster risk, but one that is substantially smaller than in models in which disasters are permanent and instantaneous. It yields new predictions for the dynamics of risk-free interest rates, the term structure of interest rates, and the pricing of short-term versus long-term risky assets. The persistence of consumption declines in our model implies that a large value of the intertemporal elasticity of substitution is necessary to explain stock-market crashes at the onset of disasters.

The Biology of the Marquesan Sardine, Sardinella marquesensis

Data and samples obtained in the Marquesas Islands from 1954 to 1960 form the basis of this report. Various morphological traits of the Marquesan sardine, Sardinella marquesensis, are described, and measures of their variation are given . These sardines were found mostly in bays with clear to slightly turbid and clear-green to brownish-green water and with substrate of sand, rock, coral rubble, or a combination of these. The composition of their stomach contents was very similar to that of plankton obtained in sardine habitats. Ten of the 35 species of fish taken with sardines in the seine are probable predators of the latter. Sardine behavior in the field, in captivity, and as tuna bait is noted. Parasites included hemiurid trematodes, camallanid nematodes, and an ergasilid copepod. Attainment of sexual maturity is estimated at a standard length of 84 mm. Spawning is believed to occur throughout the year. Between 1,000 and 8,000 ova are deposited at a single spawning. The sex ratio favored males. The abundance of Marquesan sardines appears to be inadequate to sustain commercial live-bait tuna vessels like those operating from California ports

Evidence for two neutrino mass eigenstates from SN 1987A and the possibility of superluminal neutrinos

This paper reports a new phenomenological analysis of the neutrino burst detected from SN 1987 A, and it reveals the presence of two mass eigenstates. The heavier mass eigenstate has $m_H=21.4 \pm 1.2 eV/c^2$, while the lighter one has $m_L=4.0 \pm0.5 eV/c^2$. It is not the first paper to make such a claim, but it expands on a 1988 conditional analysis by Cowsik, and it attempts to make the evidence more robust through an improved statistical analysis, and through providing reasons why alternative explanations are unlikely. It also shows how the result can be made consistent with existing smaller electron neutrino mass limits with the existence of a third tachyonic (superluminal) mass eigenstate.Comment: 11 pages, 2 figure

Curation and Analysis of Samples from Comet Wild-2 Returned by NASA's Stardust Mission

The NASA Stardust mission returned the first direct samples of a cometary coma from comet 81P/Wild2 in 2006. Intact capture of samples encountered at 6 km/s was enabled by the use of aerogel, an ultralow dense silica polymer. Approximately 1000 particles were captured, with micron and submicron materials distributed along ~mm scale length tracks. This sample collection method and the fine scale of the samples posed new challenges to the curation and cosmochemistry communities. Sample curation involved extensive, detailed photodocumentation and delicate microsurgery to remove particles without loss from the aerogel tracks. This work had to be performed in highly clean facility to minimize the potential of contamination. JSC Curation provided samples ranging from entire tracks to micrometersized particles to external investigators. From the analysis perspective, distinguishing cometary materials from aerogel and identifying the potential alteration from the capture process were essential. Here, transmission electron microscopy (TEM) proved to be the key technique that would make this possible. Based on TEM work by ourselves and others, a variety of surprising findings were reported, such as the observation of high temperature phases resembling those found in meteorites, rarely intact presolar grains and scarce organic grains and submicrometer silicates. An important lesson from this experience is that curation and analysis teams must work closely together to understand the requirements and challenges of each task. The Stardust Mission also has laid important foundation to future sample returns including OSIRISREx and Hayabusa II and future cometary nucleus sample return missions

Exact solution of a model of qubit dephasing due to telegraph noise

We present a general and exact formalism for finding the evolution of a quantum system subject to external telegraph noise. The various qubit decoherence rates are determined by the eigenvalues of a transfer matrix. The formalism can be applied to a qubit subject to an arbitrary combination of dephasing and relaxational telegraph noise, in contrast to existing non-perturbative methods that treat only one or the other of these limits. We present 3 applications: 1) We obtain the full qubit dynamics on time scales short compared with the enviromental correlation times. In the strong coupling cases this reveals unexpected oscillations and induced magnetization components; 2) We find in strong coupling case strong violations of the widely used relation 1/T$_2$ = 1/2T$_1$ + 1/T$_{\phi}$, which is a result of perturbation theory; 3) We discuss the effects of bang-bang and spin-echo controls of the qubit dynamics in general settings of the telegraph noises. %The result shows that these methods are not very effective in %reducing decoherence arising from a single telegraph noise. Finally, we discuss the extension of the method to the cases of many telegraph noise sources and multiple qubits. The method still works when white noise is also present.Comment: 7 pages, 6 figures, revised and extende

Multi-stage high order semi-Lagrangian schemes for incompressible flows in Cartesian geometries

Efficient transport algorithms are essential to the numerical resolution of incompressible fluid flow problems. Semi-Lagrangian methods are widely used in grid based methods to achieve this aim. The accuracy of the interpolation strategy then determines the properties of the scheme. We introduce a simple multi-stage procedure which can easily be used to increase the order of accuracy of a code based on multi-linear interpolations. This approach is an extension of a corrective algorithm introduced by Dupont \& Liu (2003, 2007). This multi-stage procedure can be easily implemented in existing parallel codes using a domain decomposition strategy, as the communications pattern is identical to that of the multi-linear scheme. We show how a combination of a forward and backward error correction can provide a third-order accurate scheme, thus significantly reducing diffusive effects while retaining a non-dispersive leading error term.Comment: 14 pages, 10 figure

Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event.

The structure of the current sheet along the Magnetospheric Multiscale (MMS) orbit is examined during the 11 July 2017 Electron Diffusion Region (EDR) event. The location of MMS relative to the X-line is deduced and used to obtain the spatial changes in the electron parameters. The electron velocity gradient values are used to estimate the reconnection electric field sustained by nongyrotropic pressure. It is shown that the observations are consistent with theoretical expectations for an inner EDR in 2-D reconnection. That is, the magnetic field gradient scale, where the electric field due to electron nongyrotropic pressure dominates, is comparable to the gyroscale of the thermal electrons at the edge of the inner EDR. Our approximation of the MMS observations using a steady state, quasi-2-D, tailward retreating X-line was valid only for about 1.4 s. This suggests that the inner EDR is localized; that is, electron outflow jet braking takes place within an ion inertia scale from the X-line. The existence of multiple events or current sheet processes outside the EDR may play an important role in the geometry of reconnection in the near-Earth magnetotail