Scatter of Journals and Literature Obsolescence Reflected in Document Delivery Requests

In this paper we investigate the scattering of journals and literature obsolescence reflected in more than 137,000 document delivery requests submitted to a national document delivery service. W e first summarize the major findings of the study with regards to the performance of the service.We then identify the “core” journals from which article requests were satisfied and address the following research questions: (a) Does the distribution of core) journals conform to the Bradford’s Law of Scattering? (b) Is there a relationship between usage of journals and impact factors, journals with high impact factors being used more often than the rest? (c) Is there a relationship between usage of journals and total citation counts, journals with high total citation counts being used more often than the rest?(d) What is the median age of use (half-life) of requested articles in general? (e) Do requested articles that appear in core journals get obsolete more slowly? (f) Is there a relationship between obsolescence and journal impact factors, journals with high impact factors being obsolete more slowly? (g) Is there a relationship between obsolescence and total citation counts, journals with high total citation counts being obsolete more slowly? Based on the analysis of findings, we found that the distribution of highly and moderately used journal titles conform to Bradford’s Law.The median age of use was 8 years for all requested articles. Ninety percent of the articles requested were 21 years of age or younger.Articles that appeared in 168 core journal titles seem to get obsolete slightly more slowly than those of all titles.W e observed no statistically significant correlations between the frequency of journal use and ISI journal impact factors, and between the frequency of journal use and ISI-Institute for Scientific Information, Philadelphia, PA) cited half-lives for the most heavily used 168 core journal titles.There was a weak correlation between usage of journals and ISI-reported total citation counts.No statistically significant relationship was found between median age of use and journal impact factors and between median age of use and total citation counts.There was a weak negative correlation between ISI journal impact factors and cited half-lives of 168 core journals, and a weak correlation between ISI citation halflives and use half-lives of core journals.No correlation was found between cited half-lives of 168 core journals and their corresponding total citation counts as reported by ISI.Findings of the current study are discussed along with those of other studies

Revisiting Regional Trading Agreements with Proper Specification of the Gravity Model

This paper uses a gravity model to assess ex-post regional trade agreements. The model includes 130 countries and is estimated in panel over the period 1962-96. The introduction of the correct number of dummy variables allows for identification of Vinerian trade creation and trade diversion effects, while the estimation method takes into account a potential correlation between the explanatory variables and the bilateral specific effects introduced in the model, as well as potential selection bias. In contrast with previous estimates, results show that over the period 1962-1996, regional agreements have generated a significant increase in trade between members, often at the expense of the rest of the world.Gravity equation, Regional trade agreements, Trade creation, Trade diversion, panel data.

Performance interface document for the S-band diplexer for space users of NASA networks

This report discusses the test results and interfacing information of the S-band diplexer development program supported by RTOP 310 funding. The program was implemented to reduce the S-band transponder noise figure by minimizing the receive channel insertion loss and to also provide Space Transportation System (STS) compatibility by providing 70-db rejection up to 16 GHz in the receive channel. This compatibility includes rejection of signals from the Shuttle S-band Data Link, the K-band Data Link, and the K-band Rendezvous Radar. The first of many projects to benefit from this accomplishment was the Earth Radiation Budget Satellite (ERBS)

The Influence of Non-Uniform Cloud Cover on Transit Transmission Spectra

We model the impact of non-uniform cloud cover on transit transmission spectra. Patchy clouds exist in nearly every solar system atmosphere, brown dwarfs, and transiting exoplanets. Our major findings suggest that fractional cloud coverage can exactly mimic high mean molecular weight atmospheres and vice-versa over certain wavelength regions, in particular, over the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) bandpass (1.1-1.7 $\mu$m). We also find that patchy cloud coverage exhibits a signature that is different from uniform global clouds. Furthermore, we explain analytically why the "patchy cloud-high mean molecular weight" degeneracy exists. We also explore the degeneracy of non-uniform cloud coverage in atmospheric retrievals on both synthetic and real planets. We find from retrievals on a synthetic solar composition hot Jupiter with patchy clouds and a cloud free high mean molecular weight warm Neptune, that both cloud free high mean molecular weight atmospheres and partially cloudy atmospheres can explain the data equally well. Another key find is that the HST WFC3 transit transmission spectra of two well observed objects, the hot Jupiter HD189733b and the warm Neptune HAT-P-11b, can be explained well by solar composition atmospheres with patchy clouds without the need to invoke high mean molecular weight or global clouds. The degeneracy between high molecular weight and solar composition partially cloudy atmospheres can be broken by observing the molecular Rayleigh scattering differences between the two. Furthermore, the signature of partially cloudy limbs also appears as a $\sim$100 ppm residual in the ingress and egress of the transit light curves, provided the transit timing is known to seconds.Comment: Accepted to ApJ Feb. 8, 201

Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-Resolution Cross-Correlation Spectroscopy

Hi-resolution spectroscopy (R > 25,000) has recently emerged as one of the leading methods to detect atomic and molecular species in the atmospheres of exoplanets. However, it has so far been lacking in a robust method to extract quantitative constraints on temperature structure and molecular/atomic abundances. In this work we present a novel Bayesian atmospheric retrieval framework applicable to high resolution cross-correlation spectroscopy (HRCCS) that relies upon the cross-correlation between data and models to extract the planetary spectral signal. We successfully test the framework on simulated data and show that it can correctly determine Bayesian credibility intervals on atmospheric temperatures and abundances allowing for a quantitative exploration of the inherent degeneracies. Furthermore, our new framework permits us to trivially combine and explore the synergies between HRCCS and low-resolution spectroscopy (LRS) to provide maximal leverage on the information contained within each. This framework also allows us to quantitatively assess the impact of molecular line opacities at high resolution. We apply the framework to VLT CRIRES K-band spectra of HD 209458 b and HD 189733 b and retrieve abundant carbon monoxide but sub-solar abundances for water, largely invariant under different model assumptions. This confirms previous analysis of these datasets, but is possibly at odds with detections of water at different wavelengths and spectral resolutions. The framework presented here is the first step towards a true synergy between space observatories and ground-based hi-resolution observations.Comment: Accepted Version (01/16/19

Regional Agreements and Welfare in the South:When Scale Economies in Transport Matter

This paper evidences that the accepted pessimistic view, in terms of welfare, of regional trade agreements between developing countries can be challenged by scale economies in transport. This paper focuses on two main issues. First, how is the standard welfare analysis of regional trade agreement affected by the endogeneity of transport costs (i.e. by the joint determination of trade quantities and transport costs)? Second, what are the long-run consequences of endogenous transport costs for welfare if worldwide free trade is achieved through preferential trade agreements? This paper extends the Spilimbergo and Stein (1998)'s model of interindustry trade (generated by relative factors endowment differences) intraindustry trade (generated by scale and product-diversity effects) and iceberg transport costs. In addition of assuming a "hub-and-spoke" transport network structure, we also consider that transport costs depend on the distance between trade partners (three types of costs are defined: regional, continental and across ocean) and on their development level. Most importantly, we allow for an explicit treatment of the transport sector. The main conclusion is that, with scale economies in transport, regional liberalization will have persistent effect on trade flows through irreversible effect on regional transport costs that improve the final welfare, for a developing country, under regional free trade agreement as well as under worldwide free trade.Economies of Scale., Transport Costs, Welfare, regional integration