Stochastic Development Regression on Non-Linear Manifolds

We introduce a regression model for data on non-linear manifolds. The model describes the relation between a set of manifold valued observations, such as shapes of anatomical objects, and Euclidean explanatory variables. The approach is based on stochastic development of Euclidean diffusion processes to the manifold. Defining the data distribution as the transition distribution of the mapped stochastic process, parameters of the model, the non-linear analogue of design matrix and intercept, are found via maximum likelihood. The model is intrinsically related to the geometry encoded in the connection of the manifold. We propose an estimation procedure which applies the Laplace approximation of the likelihood function. A simulation study of the performance of the model is performed and the model is applied to a real dataset of Corpus Callosum shapes

Ceased grazing management changes the ecosystem services of semi-natural grasslands

Understanding how drivers of change affect ecosystem services (ES) is of great importance. Indicators of ES can be developed based on biophysical measures and be used to investigate the service flow from ecosystems to socio-ecological systems. However, the ES concept is multivariate and the use of normalized composite indicators reduces complexity and facilitates communication between science and policy. The aim of this study is to analyze how land use change affects ES and species richness and how the effects are modified by environmental factors by using composite indicators based on biophysical indicators. Using multivariate and regression analyses, we analyze the effect of grazing management abandonment in semi-natural grasslands in Norway on six ES: nutrient cycling, pollination, forage quality, aesthetics and global and regional climate regulation in addition to species richness along soil and climate gradients. Nutrient cycling, forage quality, regional climate regulation, aesthetics and species richness are larger in managed compared to abandoned grasslands. There are trade-offs among ES as different management strategies provide various ES and these trade-offs vary along environmental gradients. Management policies that aim to conserve ES need to have conservation goals that are context dependent, should recognize ES trade-offs and be adapted to local conditions

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

The Bibliometric Properties of Article Readership Information

The NASA Astrophysics Data System (ADS), along with astronomy's journals and data centers (a collaboration dubbed URANIA), has developed a distributed on-line digital library which has become the dominant means by which astronomers search, access and read their technical literature. Digital libraries such as the NASA Astrophysics Data System permit the easy accumulation of a new type of bibliometric measure, the number of electronic accesses (``reads'') of individual articles. We explore various aspects of this new measure. We examine the obsolescence function as measured by actual reads, and show that it can be well fit by the sum of four exponentials with very different time constants. We compare the obsolescence function as measured by readership with the obsolescence function as measured by citations. We find that the citation function is proportional to the sum of two of the components of the readership function. This proves that the normative theory of citation is true in the mean. We further examine in detail the similarities and differences between the citation rate, the readership rate and the total citations for individual articles, and discuss some of the causes. Using the number of reads as a bibliometric measure for individuals, we introduce the read-cite diagram to provide a two-dimensional view of an individual's scientific productivity. We develop a simple model to account for an individual's reads and cites and use it to show that the position of a person in the read-cite diagram is a function of age, innate productivity, and work history. We show the age biases of both reads and cites, and develop two new bibliometric measures which have substantially less age bias than citationsComment: ADS bibcode: 2005JASIS..56..111K This is the second paper (the first is Worldwide Use and Impact of the NASA Astrophysics Data System Digital Library) from the original article The NASA Astrophysics Data System: Sociology, Bibliometrics, and Impact, which went on-line in the summer of 200

Macaque models of human infectious disease.

Macaques have served as models for more than 70 human infectious diseases of diverse etiologies, including a multitude of agents-bacteria, viruses, fungi, parasites, prions. The remarkable diversity of human infectious diseases that have been modeled in the macaque includes global, childhood, and tropical diseases as well as newly emergent, sexually transmitted, oncogenic, degenerative neurologic, potential bioterrorism, and miscellaneous other diseases. Historically, macaques played a major role in establishing the etiology of yellow fever, polio, and prion diseases. With rare exceptions (Chagas disease, bartonellosis), all of the infectious diseases in this review are of Old World origin. Perhaps most surprising is the large number of tropical (16), newly emergent (7), and bioterrorism diseases (9) that have been modeled in macaques. Many of these human diseases (e.g., AIDS, hepatitis E, bartonellosis) are a consequence of zoonotic infection. However, infectious agents of certain diseases, including measles and tuberculosis, can sometimes go both ways, and thus several human pathogens are threats to nonhuman primates including macaques. Through experimental studies in macaques, researchers have gained insight into pathogenic mechanisms and novel treatment and vaccine approaches for many human infectious diseases, most notably acquired immunodeficiency syndrome (AIDS), which is caused by infection with human immunodeficiency virus (HIV). Other infectious agents for which macaques have been a uniquely valuable resource for biomedical research, and particularly vaccinology, include influenza virus, paramyxoviruses, flaviviruses, arenaviruses, hepatitis E virus, papillomavirus, smallpox virus, Mycobacteria, Bacillus anthracis, Helicobacter pylori, Yersinia pestis, and Plasmodium species. This review summarizes the extensive past and present research on macaque models of human infectious disease

Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We report the discovery of an esdL3 subdwarf, ULAS J020858.62+020657.0 and a usdL4.5 subdwarf, ULAS J230711.01+014447.1. They were identified as L subdwarfs by optical spectra obtained with the Gran Telescopio Canarias, and followed up by optical to near infrared spectroscopy with the Very Large Telescope. We also obtained an optical to near infrared spectrum of a previously known L subdwarf, ULAS J135058.85+081506.8, and re-classified it as a usdL3 subdwarf. These three objects all have typical halo kinematics. They have $T_{\rm eff}$ around 2050-2250 K, $-$1.8 $\leq$ [Fe/H] $\leq -$1.5, and mass around 0.0822-0.0833 M$_{\odot}$, according to model spectral fitting and evolutionary models. These sources are likely halo transitional brown dwarfs with unsteady hydrogen fusions, as their masses are just below the hydrogen-burning minimum mass, which is $\sim$ 0.0845 M$_{\odot}$ at [Fe/H] = $-$1.6 and $\sim$ 0.0855 M$_{\odot}$ at [Fe/H] = $-$1.8. Including these, there are now nine objects in the `halo brown dwarf transition zone', which is a `substellar subdwarf gap' spans a wide temperature range within a narrow mass range of the substellar population.Peer reviewedFinal Accepted Versio