Soviet Transportation

If you think about the role of transportation in the Soviet economy, you have to begin by asking what creates a need for it. I suppose that means you look at the geographic structure, at the resources, arable land, population, and so on which has to be unified in order to produce goods and services

Investigating Experiential Wilderness-Based Professional Development for K-12 Educators

Continuing education programs for teachers have the potential to provide beneficial outcomes for both participants and their students. Experiential wilderness-based programs are a unique form of continuing education because of their use of wilderness-based learning environments, outdoor-recreation activities, and experiential teaching initiatives. Research examining the influence of experiential wilderness programs on a range of outcomes (adjustments in behavioral conduct, pro-environmental behaviors, increased classroom culture) is well documented. However, there is little research focused on the use of these type of programs for professional development for educators. Therefore, this research investigated the North Carolina Outward Bound Educators\u27 Initiative (NCOBEI) program as an experiential wilderness-based professional development opportunity for K-12 educators. First, we explore the range of personal and professional development outcomes educators\u27 associate with participation as well as the influence of specific program elements on each outcome. Second, we investigate if the program assists educators\u27 integration of experiential teaching techniques in their schools and classrooms; and further, if educators\u27 beliefs and confidence regarding using these methods can serve as predictors of their later use. Lastly, we evaluate the NCOBEI program for its\u27 influence on participants\u27 positive character traits, forms of professional development, and post training use of experiential learning methods. Our findings demonstrate the powerful influence of experiential wilderness-based professional development opportunities for educators and should be used to support further opportunities for educators and other stakeholders to participate

A Separable Model for Dynamic Networks

Models of dynamic networks --- networks that evolve over time --- have manifold applications. We develop a discrete-time generative model for social network evolution that inherits the richness and flexibility of the class of exponential-family random graph models. The model --- a Separable Temporal ERGM (STERGM) --- facilitates separable modeling of the tie duration distributions and the structural dynamics of tie formation. We develop likelihood-based inference for the model, and provide computational algorithms for maximum likelihood estimation. We illustrate the interpretability of the model in analyzing a longitudinal network of friendship ties within a school.Comment: 28 pages (including a 4-page appendix); a substantial rewrite, with many corrections, changes in terminology, and a different analysis for the exampl

Testing the DRAMMA Model of Leisure and Subjective Wellbeing on College Students

Background: College students’ declining mental health is a growing concern among institutions of higher education. Although many campuses have provided additional mental health counselors, identifying other mechanisms that facilitate and enhance mental health and wellbeing is also justified. Aim: Using the DRAMMA model as a theoretical framework, this research examined how leisure influences college students’ subjective wellbeing. Methods: An online survey methodology was utilized to measure the psychological outcomes of leisure participation (DRAMMA), leisure satisfaction, and subjective wellbeing of 704 students attending a large 4-year Midwestern residential college. Results: This quantitative study found the five psychological mechanisms of the DRAMMA model (detachment-recovery, autonomy, mastery, meaning, and affiliation) influenced students’ leisure satisfaction and subjective wellbeing. Conclusion: The findings support the need for higher education professionals to create leisure experiences that provide meaning and affiliation to promote subjective wellbeing and improve mental health

Hierarchical Models for Independence Structures of Networks

We introduce a new family of network models, called hierarchical network models, that allow us to represent in an explicit manner the stochastic dependence among the dyads (random ties) of the network. In particular, each member of this family can be associated with a graphical model defining conditional independence clauses among the dyads of the network, called the dependency graph. Every network model with dyadic independence assumption can be generalized to construct members of this new family. Using this new framework, we generalize the Erd\"os-R\'enyi and beta-models to create hierarchical Erd\"os-R\'enyi and beta-models. We describe various methods for parameter estimation as well as simulation studies for models with sparse dependency graphs.Comment: 19 pages, 7 figure

Bayesian Exponential Random Graph Models with Nodal Random Effects

We extend the well-known and widely used Exponential Random Graph Model (ERGM) by including nodal random effects to compensate for heterogeneity in the nodes of a network. The Bayesian framework for ERGMs proposed by Caimo and Friel (2011) yields the basis of our modelling algorithm. A central question in network models is the question of model selection and following the Bayesian paradigm we focus on estimating Bayes factors. To do so we develop an approximate but feasible calculation of the Bayes factor which allows one to pursue model selection. Two data examples and a small simulation study illustrate our mixed model approach and the corresponding model selection.Comment: 23 pages, 9 figures, 3 table

Adjusting for Network Size and Composition Effects in Exponential-Family Random Graph Models

Exponential-family random graph models (ERGMs) provide a principled way to model and simulate features common in human social networks, such as propensities for homophily and friend-of-a-friend triad closure. We show that, without adjustment, ERGMs preserve density as network size increases. Density invariance is often not appropriate for social networks. We suggest a simple modification based on an offset which instead preserves the mean degree and accommodates changes in network composition asymptotically. We demonstrate that this approach allows ERGMs to be applied to the important situation of egocentrically sampled data. We analyze data from the National Health and Social Life Survey (NHSLS).Comment: 37 pages, 2 figures, 5 tables; notation revised and clarified, some sections (particularly 4.3 and 5) made more rigorous, some derivations moved into the appendix, typos fixed, some wording change

Increased genetic marker density reveals high levels of admixture between red deer and introduced Japanese sika in Kintyre, Scotland

Hybridization is a natural process at species range boundaries, but increasing numbers of species are hybridizing due to direct or indirect human activities. In such cases of anthropogenic hybridization, subsequent introgression can threaten the survival of native species. To date, many such systems have been studied with too few genetic markers to assess the level of threat resulting from advanced backcrossing. Here, we use 44,999 single nucleotide polymorphisms (SNPs) and the ADMIXTURE program to study two areas of Scotland where a panel of 22 diagnostic microsatellites previously identified introgression between native red deer (Cervus elaphus) and introduced Japanese sika (Cervus nippon). In Kintyre, we reclassify 26% of deer from the pure species categories to the hybrid category whereas in the NW Highlands we only reclassify 2%. As expected, the reclassified individuals are mostly advanced backcrosses. We also investigate the ability of marker panels selected on different posterior allele frequency criteria to find hybrids assigned by the full marker set and show that in our data, ancestry informative markers (i.e. those that are highly differentiated between the species, but not fixed) are better than diagnostic markers (those markers that are fixed between the species) because they are more evenly distributed in the genome. Diagnostic loci are concentrated on the X chromosome to the detriment of autosomal coverage

Fourier Transform Spectroscopy of the submillimetre continuum emission from hot molecular cores

We have used a Fourier Transform Spectrometer on the James Clerk Maxwell Telescope to study the submillimetre continuum emission from dust in three hot molecular cores (HMC). The spectral index beta of the dust emission for these sources has been determined solely within the 30 GHz wide 350 GHz (850 micron) passband to an accuracy comparable to those determined through multi-wavelength observations. We find an average beta = 1.6, in agreement with spectral indices determined from previous submillimetre observations of these sources and with those determined for HMC in general. The largest single source of uncertainty in these results is the variability of the atmosphere at 350 GHz, and with better sky subtraction techniques we show that the dust spectral index can clearly be determined within one passband to high accuracy with a submillimetre FTS. Using an imaging FTS on SCUBA-2, the next generation wide-field submillimetre camera currently under development to replace SCUBA at the JCMT in 2006, we calculate that at 350 GHz it will be possible to determine beta to +/- 0.1 for sources as faint as 400 mJy/beam and to +/- 0.3 for sources as faint as 140 mJy/beam.Comment: 11 pages, 5 figures, accepted for publication in MNRA