The Effect of Use and Access on Citations

It has been shown (S. Lawrence, 2001, Nature, 411, 521) that journal articles which have been posted without charge on the internet are more heavily cited than those which have not been. Using data from the NASA Astrophysics Data System (ads.harvard.edu) and from the ArXiv e-print archive at Cornell University (arXiv.org) we examine the causes of this effect.Comment: Accepted for publication in Information Processing & Management, special issue on scientometric

The Scripture of Maps, the Names of Trees

The first six years of life work their subtle power on us throughout our lives. We remember few specifics. But our bedrock emotional security - our trust- comes from this time. We spend our first years striving to develop what psychologists call a sense of competence. This drive for mastery- of grasping, crawling, walking, talking, and play-leads to astonishingly rapid and broad learning. Recent research has surprised us with how emphatically our behavior and personalities are hard-wired by genetics. We start with our general emotional outlook on the world fixed by the magical code of our genes. The bent of personality that makes a girl or boy receptive to natural history may well be something we cannot instill, but rather something with which an individual starts. Nevertheless, genes work in context. No personality or process is independent of environmental and social dimensions

The Scripture of Maps, The Names of Trees

By forging connections with plants, animals, and land, by finding ways to experience some relationship to the Earth, individuals can gain a sense of worth. Herein lies security. Edith Cobb, in analyzing the roots of creativity in great thinkers, found that many had experienced a pivotal childhood discontinuity, an awareness of [one\u27s] own unique separateness and identity, and also a continuity, a renewal of relationship with nature. Cobb marveled at what can grow from this paradox: ... a delighted awareness that knowing and being are in some way coincident and continuous ... and that this kind of knowing is in itself an achievement of psychological balance

A Chandra Search for Coronal X Rays from the Cool White Dwarf GD 356

We report observations with the Chandra X-ray Observatory of the single, cool, magnetic white dwarf GD 356. For consistent comparison with other X-ray observations of single white dwarfs, we also re-analyzed archival ROSAT data for GD 356 (GJ 1205), G 99-47 (GR 290 = V1201 Ori), GD 90, G 195-19 (EG250 = GJ 339.1), and WD 2316+123 and archival Chandra data for LHS 1038 (GJ 1004) and GD 358 (V777 Her). Our Chandra observation detected no X rays from GD 356, setting the most restrictive upper limit to the X-ray luminosity from any cool white dwarf -- L_{X} < 6.0 x 10^{25} ergs/s, at 99.7% confidence, for a 1-keV thermal-bremsstrahlung spectrum. The corresponding limit to the electron density is n_{0} < 4.4 x 10^{11} cm^{-3}. Our re-analysis of the archival data confirmed the non-detections reported by the original investigators. We discuss the implications of our and prior observations on models for coronal emission from white dwarfs. For magnetic white dwarfs, we emphasize the more stringent constraints imposed by cyclotron radiation. In addition, we describe (in an appendix) a statistical methodology for detecting a source and for constraining the strength of a source, which applies even when the number of source or background events is small.Comment: 27 pages, 4 figures, submitted to the Astrophysical Journa

Durability and mode-I fracture of fiber-reinforced plastic (FRP)/wood interface bond

Fiber-reinforced plastic (FRP) composites are being used for reinforcement of wood, concrete, and steel. The objective of this study is to develop a qualification program to evaluate the service performance and fracture of composite/wood bonded interfaces. The proposed method is used for two types of FRP wood interface: FRP strips (plates) bonded to wood (used commercially for glulam timber beams) and wood cores wrapped with FRP by filament winding (being investigated for reinforced railroad wood crossties and utility wood poles). First, the service performance and durability of FRP-wood interface bond is evaluated using a modified ASTM delamination test. Second, the apparent shear strengths of interface bond under both dry and wet conditions are obtained from modified ASTM block shear tests. Finally, a simplified design of an innovative contoured double cantilever beam (CDCB) specimen is developed, and this specimen is used to evaluate Mode-I fracture of interface bonds; interface fracture toughness data are experimentally obtained for dry, wet and 3-cycle aging conditions. (Abstract shortened by UMI.)

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Pneumococcal colonisation is an asymptomatic event in healthy adults using an experimental human colonisation model

Introduction Pneumococcal colonisation is regarded as a pre-requisite for developing pneumococcal disease. In children previous studies have reported pneumococcal colonisation to be a symptomatic event and described a relationship between symptom severity/frequency and colonisation density. The evidence for this in adults is lacking in the literature. This study uses the experimental human pneumococcal challenge (EHPC) model to explore whether pneumococcal colonisation is a symptomatic event in healthy adults. Methods Healthy participants aged 18–50 were recruited and inoculated intra-nasally with either Streptococcus pneumoniae (serotypes 6B, 23F) or saline as a control. Respiratory viral swabs were obtained prior to inoculation. Nasal and non-nasal symptoms were then assessed using a modified Likert score between 1 (no symptoms) to 7 (cannot function). The rate of symptoms reported between the two groups was compared and a correlation analysis performed. Results Data from 54 participants were analysed. 46 were inoculated with S. pneumoniae (29 with serotype 6B, 17 with serotype 23F) and 8 received saline (control). In total, 14 became experimentally colonised (30.4%), all of which were inoculated with serotype 6B. There was no statistically significant difference in nasal (p = 0.45) or non-nasal symptoms (p = 0.28) between the inoculation group and the control group. In those who were colonised there was no direct correlation between colonisation density and symptom severity. In the 22% (12/52) who were co-colonised, with pneumococcus and respiratory viruses, there was no statistical difference in either nasal or non-nasal symptoms (virus positive p = 0.74 and virus negative p = 1.0). Conclusion Pneumococcal colonisation using the EHPC model is asymptomatic in healthy adults, regardless of pneumococcal density or viral co-colonisation