Size-Frequency Distribution of Orbitolina Texana Foraminifera

This study examined size-frequency distributions for an extinct Cretaceous-age benthic foraminifera called Orbitolina Texana in order to determine the health of this foram community during the time of accumulation. Forams were collected from limestone outcrops of the Glen Rose Formation in central Texas. Based on paleontological and sedimentological evidence, Orbitolina Texana are interpreted to be a shallow water (\u3c10 m) benthic organism that was most abundant in back-reef environments. Sizefrequency distributions were generated from the diameters of 4,245 Orbitolina Texana fossils. The results indicate that the Orbitolina Texana population is characterized by a Gaussian (normal) size distribution. Size-frequency distributions of fossilized foraminifera in the stratigraphic record are controlled by two principle variables; environmental controls that affect the biology of the organisms (e.g., environmental stressors, like food availability and ambient conditions) and sedimentological controls that affect how the organisms are distributed (e.g., hydrodynamic parameters, like waves and currents). Based on a sedimentological characterization of the host limestone including lack of high-energy sedimentary structures, high mud content and back-reef position on the depositional profile, hydrodynamic parameters are interpreted to not have exerted a significant effect on the distribution of the forams preserved in the rock record. As such, the biological controls are interpreted to be the dominate control on the foram sizefrequency distribution. Therefore, the Gaussian (normal) size distribution suggests that the mortality rate is independent of size/age, which is classified as Type II survivorship. As this result is consistent with similar taxon, the results indicate that this Orbitolina Texana population was a healthy biologic community, despite the low biologic diversity observed in the Glen Rose Formation

A systems approach to studying online communities

Much early communication research was inspired by systems theory. This approach emphasizes that individuals and groups use communication to interact with and respond to their larger environment and attempts to outline the ways that dif‐ ferent levels interact with each other (e.g., work groups within departments within firms). Many concepts from systems theory—such as emergence and feedback loops—have become integral parts of communication theories. However, until recently, quantitative researchers have struggled to apply a systems approach. Large‐scale, multilevel trace data from online platforms combined with computational advances are enabling a turn back toward systems‐inspired research. I out‐ line four systems‐based approaches that recent research uses to study online communities: community comparisons, indi‐ vidual trajectories, cross‐level mechanisms, and simulating emergent behavior. I end with a discussion of the opportunities and challenges of systems‐based research for quantitative communication scholars

Online Naturalization: Evolving Roles in Online Knowledge Production Communities

Web-based peer production communities, like Wikipedia and open source software, have created digital artifacts of growing cultural, financial, and technological importance. Understanding how and why people choose to join these communities, and why they eventually leave them, is therefore an important topic. We take all of the edit data from six years of activity on the online genealogy wiki WeRelate, and create monthly snapshots of behavior and interaction networks for all 9,570 users who edited the site. We use machine learning to cluster these behavioral snapshots into four behavioral roles . We identify one of these roles as being indicative of a community of practice, and we investigate how users move from role to role. As in many other online, peer production projects, the vast majority of users are only active for a short time, and contribute very little while a small number of users contribute a great deal. Figuring out how to recruit and encourage these users is very important to the success of peer production projects. We use visualizations, regression analysis, and stochastic actor-oriented modeling of four different types of interaction networks to study whether these very active users represent a community of practice that new users can learn from and join. We also study how people leave the community, and whether there are signals that someone is starting to disengage. We do not find much evidence that these users go through a period of legitimate peripheral participation or acculturation. Rather, those who will become core members show behavior that is similar to long-term core members from their first few months on the site. We find that these core members show a clear trend of disengaging from the community over a few months before leaving completely, indicating a period where intervention may be effective. We also find a potentially effective intervention, as those who are actively interacting with others who are core members are less likely to disengage. Our findings provide implications for understanding how online communities function, how interaction networks influence user activity, and how those who are members of these communities might make them more effective. The study also provides a new methodological framework for studying the influence of communicative interactions in online communities

An Examination of the Hydrological Environment in Choctaw County Mississippi since 1995, with a Focus on an Area Surrounding an Industrial Complex established in 1998

The population and industrial complexes of Choctaw County obtains much of its water from an aquifer system in the Tertiary age Wilcox unit of the Mississippi Embayment. Utilizing 20 years of physical chemistry (P-Chem) analysis, potentiometric groundwater records of Choctaw County public water wells as well as industrial P-Chem analysis and surface and ground water level records from an industrial complex, this study examined the changes to the hydrosphere that has taken place since 1995. Analysis of the hydrosphere shows that over the last 20 years, there has been a drop in the potentiometric surface of the Wilcox aquifer system. The analysis also shows changes in the P-Chem of the hydrosphere, changes such as a decrease in the concentration of free CO2 and chloride, and fluctuations of Alkalinity. Comparisons between groundwater records taken from the industrial complex and other locations around Choctaw County, show little variation in the physical chemistry

edge2vec: Representation learning using edge semantics for biomedical knowledge discovery

Representation learning provides new and powerful graph analytical approaches and tools for the highly valued data science challenge of mining knowledge graphs. Since previous graph analytical methods have mostly focused on homogeneous graphs, an important current challenge is extending this methodology for richly heterogeneous graphs and knowledge domains. The biomedical sciences are such a domain, reflecting the complexity of biology, with entities such as genes, proteins, drugs, diseases, and phenotypes, and relationships such as gene co-expression, biochemical regulation, and biomolecular inhibition or activation. Therefore, the semantics of edges and nodes are critical for representation learning and knowledge discovery in real world biomedical problems. In this paper, we propose the edge2vec model, which represents graphs considering edge semantics. An edge-type transition matrix is trained by an Expectation-Maximization approach, and a stochastic gradient descent model is employed to learn node embedding on a heterogeneous graph via the trained transition matrix. edge2vec is validated on three biomedical domain tasks: biomedical entity classification, compound-gene bioactivity prediction, and biomedical information retrieval. Results show that by considering edge-types into node embedding learning in heterogeneous graphs, \textbf{edge2vec}\ significantly outperforms state-of-the-art models on all three tasks. We propose this method for its added value relative to existing graph analytical methodology, and in the real world context of biomedical knowledge discovery applicability.Comment: 10 page

Reduction of Injection-Related Risk Behaviors After Emergency Implementation of a Syringe Services Program During an HIV Outbreak

Objective: To describe injection-related HIV risk behaviors preimplementation and postimplementation of an emergency syringe services program (SSP) in Scott County, Indiana, after an HIV outbreak among persons who inject drugs (PWID). Design: Mixed methods retrospective pre–post intervention analysis. Methods: We analyzed routine SSP program data collected at first and most recent visit among clients with ≥2 visits, ≥7 days apart from April 4 to August 30, 2015, to quantify changes in injection-related risk behaviors. We also analyzed qualitative data collected from 56 PWID recruited in Scott County to understand factors contributing to these behaviors. Results: SSP clients included in our analysis (n = 148, 62% of all SSP clients) reported significant (P < 0.001) reductions over a median 10 weeks (range 1–23) in syringe sharing to inject (18%–2%) and divide drugs (19%–4%), sharing other injection equipment (eg, cookers) (24%–5%), and number of uses of the same syringe [2 (interquartile range: 1–4) to 1 (interquartile range: 1–1)]. Qualitative study participants described access to sterile syringes and safer injection education through the SSP, as explanatory factors for these reductions. Injection frequency findings were mixed, but overall suggested no change. The number of syringes returned by SSP clients increased from 0 at first visit to median 57. All qualitative study participants reported using sharps containers provided by the SSP. Conclusions: Analyses of an SSP program and in-depth qualitative interview data showed rapid reduction of injection-related HIV risk behaviors among PWID post-SSP implementation. Sterile syringe access as part of comprehensive HIV prevention is an important tool to control and prevent HIV outbreaks