The "True" Column Density Distribution in Star-Forming Molecular Clouds

We use the COMPLETE Survey's observations of the Perseus star-forming region to assess and intercompare three methods for measuring column density in molecular clouds: extinction mapping (NIR); thermal emission mapping (FIR); and mapping the intensity of CO isotopologues. The structures shown by all three tracers are morphologically similar, but important differences exist. Dust-based measures give similar, log-normal, distributions for the full Perseus region, once careful calibration corrections are made. We also compare dust- and gas-based column density distributions for physically-meaningful sub-regions of Perseus, and we find significant variations in the distributions for those regions. Even though we have used 12CO data to estimate excitation temperatures, and we have corrected for opacity, the 13CO maps seem unable to give column distributions that consistently resemble those from dust measures. We have edited out the effects of the shell around the B-star HD 278942. In that shell's interior and in the parts where it overlaps the molecular cloud, there appears to be a dearth of 13CO, likely due either to 13CO not yet having had time to form in this young structure, and/or destruction of 13CO in the molecular cloud. We conclude that the use of either dust or gas measures of column density without extreme attention to calibration and artifacts is more perilous than even experts might normally admit. And, the use of 13CO to trace total column density in detail, even after proper calibration, is unavoidably limited in utility due to threshold, depletion, and opacity effects. If one's main aim is to map column density, then dust extinction seems the best probe. Linear fits amongst column density tracers are given, quantifying the inherent uncertainties in using one tracer (when compared with others). [abridged]Comment: Accepted in ApJ. 13 pages, 6 color figures. It includes small changes to improve clarity. For a version with high-resolution figures see http://www.cfa.harvard.edu/COMPLETE/papers/Goodman_ColumnDensity.pd

Genetic sampling for estimating density of common species.

Understanding population dynamics requires reliable estimates of population density, yet this basic information is often surprisingly difficult to obtain. With rare or difficult-to-capture species, genetic surveys from noninvasive collection of hair or scat has proved cost-efficient for estimating densities. Here, we explored whether noninvasive genetic sampling (NGS) also offers promise for sampling a relatively common species, the snowshoe hare (Lepus americanus Erxleben, 1777), in comparison with traditional live trapping. We optimized a protocol for single-session NGS sampling of hares. We compared spatial capture-recapture population estimates from live trapping to estimates derived from NGS, and assessed NGS costs. NGS provided population estimates similar to those derived from live trapping, but a higher density of sampling plots was required for NGS. The optimal NGS protocol for our study entailed deploying 160 sampling plots for 4 days and genotyping one pellet per plot. NGS laboratory costs ranged from approximately $670 to$3000 USD per field site. While live trapping does not incur laboratory costs, its field costs can be considerably higher than for NGS, especially when study sites are difficult to access. We conclude that NGS can work for common species, but that it will require field and laboratory pilot testing to develop cost-effective sampling protocols

The Determinants of National Innovative Capacity

Motivated by differences in R&D productivity across advanced economies, this paper presents an empirical examination of the determinants of country-level production of international patents. We introduce a novel framework based on the concept of national innovative capacity. National innovative capacity is the ability of a country to produce and commercialize a flow of innovative technology over the long term. National innovative capacity depends on the strength of a nation's common innovation infrastructure (cross-cutting factors which contribute broadly to innovativeness throughout the economy), the environment for innovation in its leading industrial clusters, and the strength of linkages between these two areas. We use this framework to guide our empirical exploration into the determinants of country-level R&D productivity, specifically examining the relationship between international patenting (patenting by foreign countries in the United States) and variables associated with the national innovative capacity framework. While acknowledging important measurement issues arising from the use of patent data, we provide evidence for several findings. First, the production function for international patents is surprisingly well-characterized by a small but relatively nuanced set of observable factors, including R&D manpower and spending, aggregate policy choices such as the extent of IP protection and openness to international trade, and the share of research performed by the academic sector and funded by the private sector. As well, international patenting productivity depends on each individual country's knowledge stock.' Further, the predicted level of national innovative capacity has an important impact on more downstream commercialization and diffusion activities (such as achieving a high market share of high-technology export markets). Finally, there has been convergence among OECD countries in terms of the estimated level of innovative capacity over the past quarter century.

Generalizations of the Abstract Boundary singularity theorem

The Abstract Boundary singularity theorem was first proven by Ashley and Scott. It links the existence of incomplete causal geodesics in strongly causal, maximally extended spacetimes to the existence of Abstract Boundary essential singularities, i.e., non-removable singular boundary points. We give two generalizations of this theorem: the first to continuous causal curves and the distinguishing condition, the second to locally Lipschitz curves in manifolds such that no inextendible locally Lipschitz curve is totally imprisoned. To do this we extend generalized affine parameters from $C^1$ curves to locally Lipschitz curves.Comment: 24 page

1997 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1997 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1997. The average net advisory price across all 23 corn programs is $2.32 per bushel. The net advisory prices for corn range from a minimum of$2.00 per bushel to a maximum of $2.74 per bushel. The average net advisory price across all 21 soybean programs is$6.40 per bushel. The net advisory prices for soybeans range from a minimum of $6.08 per bushel to a maximum of$6.99 per bushel.evaluation of advisory services, pricing performance, soybeans, C8, D4, D8, L1, M3, Q0, Z0, Marketing,

1995 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1995 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1995. The average net advisory price across all 25 corn programs is $3.04 per bushel. The range of net advisory prices for corn is quite large, with a minimum of$2.34 per bushel and a maximum of $3.81 per bushel. The average net advisory price across all 25 soybean programs is$6.61 per bushel. As with corn, the range of net advisory prices for soybeans is substantial, with a minimum of $5.75 per bushel and a maximum of$7.92 per bushel.Agricultural Market Advisory Service (AgMAS) Project, D4, D7, D8, G1, G2, H4, H8, Q1, Z1, Marketing,

DEVELOPMENT OF A MARKET BENCHMARK PRICE FOR AGMAS PERFORMANCE EVALUATIONS

The purpose of this research report is to identify the appropriate market benchmark price to use to evaluate the pricing performance of market advisory services that are included in the annual AgMAS pricing performance evaluations. Five desirable properties of market benchmark prices are identified. Three potential specifications of the market benchmark price are considered: the average price received by Illinois farmers, the harvest cash price, and the average cash price over a two-year crop marketing window. The average cash price meets all of the desired properties, except that it would not be easily implementable by producers. It can be shown, though, that the price realized via a more manageable strategy of "spreading" sales during the marketing window very closely approximates the average cash price. Therefore, it is determined that the average cash price meets all five selection criteria, and is the most appropriate market benchmark to be used in evaluating the pricing performance of market advisory services.advisory services, evaluating the pricing performance, market benchmark price, C8, C0, D4, D8, L1, M3, Q0, Z0, Marketing,

1996 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1996 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1996. The average net advisory price across all 26 corn programs is $2.63 per bushel. The range of net advisory prices for corn is quite large, with a minimum of$2.08 per bushel and a maximum of $3.12 per bushel. The average net advisory price across all 24 soybean programs is$7.27 per bushel. As with corn, the range of net advisory prices for soybeans is substantial, with a minimum of $6.80 per bushel and a maximum of$7.80 per bushel.Agricultural Market Advisory Services, G1, D8, D7, D4, G2, H4, H8, Q1, Z1, Marketing,

DO AGRICULTURAL MARKET ADVISORY SERVICES BEAT THE MARKET? EVIDENCE FROM THE CORN AND SOYBEAN MARKETS OVER 1995-1997

The purpose of this paper is to address two basic performance questions for market advisory services: 1) Do market advisory services, on average, outperform an appropriate market benchmark? and 2) Do market advisory services exhibit persistence in their performance from year-to-year? Data on corn and soybean net price received for advisory services, as reported by the AgMAS Project, are available for the 1995, 1996 and 1997 marketing years. Performance test results suggest that, on average, market advisory services exhibit a small ability to "beat the market" for the 1995 through 1997 corn and soybean crops. This conclusion is somewhat sensitive to the type of performance test and market benchmark considered. The predictability results provide little evidence that future advisory service pricing performance can be predicted from past performance. When services are grouped by performance quantile, some evidence of predictability is found for the poorest performing services, but not for top performing services.Marketing,