Effects of age, density, and seasonality on molt pattern in the mammal genus (Peromyscus)

Molting, or replacement of pelage (hair) in mammals, occurs during ontogeny as individuals transition from juveniles to adults. Environmental factors can cause variation in molt in many species for thermoregulatory and camouflage purposes. Within and among years molt can vary by time and age or by reproductive status. Past studies have found differences in molt pattern and timing depending upon age, and between captive reared and wild caught individuals. There has been little investigation into the molting characteristics of Peromyscus leucopus and P. maniculatus, specifically in comparison to adults and juveniles. I used molt observed from museum specimens collected at Bartlett Experimental Forest over a three-year period to determine if there are evident molt patterns in both Peromyscus spp. Specifically, I looked for differences in percent molt and number of individuals molting as a result of seasonality and age. Molts were digitized in Photoshop and pattern and symmetry were analyzed in ImageJ. In both species, individuals show a seasonal trend in molt timing and symmetry. This may reflect differences in resource availability and energy expenditure among years

Are homologies in vertebrate sex determination due to shared ancestry or to limited options?

The bewildering array of different sex-determination systems in vertebrates is built on a common set of genes and chromosomes

Case Study of the Science, Engineering, Mathematics, and Aerospace Academy

The science, engineering, mathematics, and aerospace academy (SEMAA) is a federally-funded national out-of-school time (OST) science, technology, engineering, and mathematics (STEM) program that provides K-12 grade participants with hands-on activities and access to an aerospace education laboratory with the goals of increasing participants� engagement and interest in STEM and STEM careers. The SEMAA also provides support, resources, and training for SEMAA participants� parents through the Family Caf�. This multiple-case study investigated participants� and their parents� reasons for enrolling in the SEMAA and characterized the SEMAA in terms of its operations and infrastructure, instructors, learning environment, curriculum and instruction, and parental engagement. This study also assessed the role of the SEMAA in supporting participants� STEM college degree and career interests. Additionally, this study assessed the participants� attitudes towards science and science motivation factors. The findings of this study have implications for SEMAA and other OST STEM program providers related to: (a) recruitment and retention, (b) operations and infrastructure, (c) learning environments, (d) instructors, (e) curriculum and instruction, (f) parental engagement, and (g) OST STEM program outcomes.Education (PhD

Interaction of Oral Bacteria With Gingival Epithelial Cell Multilayers

Primary gingival epithelial cells were cultured in multilayers as a model for the study of interactions with oral bacteria associated with health and periodontal disease. Multilayers maintained at an air-liquid interface in low calcium medium displayed differentiation and cytokeratin properties characteristic of junctional epithelium. Multilayers were infected with fluorescently labeled Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum or Streptococcus gordonii, and bacterial association was determined by confocal microscopy and quantitative image analysis. P. gingivalis invaded intracellularly and spread cell to cell. A. actinomycetemcomitans and F. nucleatum remained extracellular and showed intercellular movement through the multilayer. S. gordonii remained extracellular and predominantly associated with the superficial cell layer. None of the bacterial species disrupted barrier function as measured by transepithelial electrical resistance. P. gingivalis did not elicit secretion of proinflammatory cytokines. However, A. actinomycetemcomitans and S. gordonii induced IL-1β, TNF-α, IL-6 and IL-8 secretion; and F. nucleatum stimulated production of IL-1β and TNF-α. A. actinomycetemcomitans, F. nucleatum and S. gordonii, but not P. gingivalis, increased levels of apoptosis after 24 h infection. The results indicate that the organisms with pathogenic potential were able to traverse the epithelium, while the commensal bacteria did not. In addition, distinct host responses characterized the interaction between the junctional epithelium and oral bacteria

Irreversible transformation of ferromagnetic ordered stripe domains in single-shot IR pump - resonant X-ray scattering probe experiments

The evolution of a magnetic domain structure upon excitation by an intense, femtosecond Infra-Red (IR) laser pulse has been investigated using single-shot based time-resolved resonant X-ray scattering at the X-ray Free Electron laser LCLS. A well-ordered stripe domain pattern as present in a thin CoPd alloy film has been used as prototype magnetic domain structure for this study. The fluence of the IR laser pump pulse was sufficient to lead to an almost complete quenching of the magnetization within the ultrafast demagnetization process taking place within the first few hundreds of femtoseconds following the IR laser pump pulse excitation. On longer time scales this excitation gave rise to subsequent irreversible transformations of the magnetic domain structure. Under our specific experimental conditions, it took about 2 nanoseconds before the magnetization started to recover. After about 5 nanoseconds the previously ordered stripe domain structure had evolved into a disordered labyrinth domain structure. Surprisingly, we observe after about 7 nanoseconds the occurrence of a partially ordered stripe domain structure reoriented into a novel direction. It is this domain structure in which the sample's magnetization stabilizes as revealed by scattering patterns recorded long after the initial pump-probe cycle. Using micro-magnetic simulations we can explain this observation based on changes of the magnetic anisotropy going along with heat dissipation in the film.Comment: 16 pages, 6 figure

Report from the “What is Open?” Workgroup

The scholarly community’s current definition of “open” captures only some of the attributes of openness that exist across different publishing models and content types. Open is not an end in itself, but a means for achieving the most effective dissemination of scholarship and research. We suggest that the different attributes of open exist along a broad spectrum and propose an alternative way of describing and evaluating openness based on four attributes: discoverable, accessible, reusable, and transparent. These four attributes of openness, taken together, form the draft “DART Framework for Open Access.” This framework can be applied to both research artifacts as well as research processes. We welcome input from the broader scholarly community about this framework

PHOSPHATE IONS -DOES EXPOSURE LEAD TO DEGRADATION OF CEMENTITIOUS MATERIALS?

ABSTRACT An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a "bench-scale" laboratory investigatio