Life history parameters in acellular extrinsic fiber cementum microstructure

Life-history parameters such as pregnancies, skeletal trauma, and renal disease have previously been identified from hypomineralized growth layers (incremental lines) of acellular extrinsic fiber cementum (AEFC). The precise periodicity of these growth layers remains vaguely approximated, so causal life-history explanations using tooth cementum cannot yet be rigorously calculated or tested. On the other hand, we show how life history parameters in AEFC can be identified by two contrasting elemental detection methods. Based on our results we reject the possibility of accurate estimation of pregnancies and other life history parameters from cementum using scanning electron microscopy alone. Here, we propose a new methodological approach for cementum research, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), to measure degree and distribution of mineralization of cementum growth layers. Our results show that Tof-SIMS can significantly increase our knowledge of cementum composition and is therefore a powerful new tool for life history researchers

Covalent Post-assembly Modification Triggers Multiple Structural Transformations of a Tetrazine-Edged Fe4L6 Tetrahedron

Covalent post-assembly modification (PAM) reactions are useful synthetic tools for functionalizing and stabilizing self-assembled metal-organic complexes. Recently, PAM reactions have also been explored as stimuli for triggering supramolecular structural transformations. Herein we demonstrate the use of inverse electron-demand Diels-Alder (IEDDA) PAM reactions to induce supramolecular structural transformations starting from a tetrazine-edged FeII4L6 tetrahedral precursor. Following PAM, this tetrahedron rearranged to form three different architectures depending on the addition of other stimuli: an electron-rich aniline or a templating anion. By tracing the stimulus-response relationships within the system, we deciphered a network of transformations that mapped different combinations of stimuli onto specific transformation products. Given the many functions being developed for self-assembled three-dimensional architectures, this newly established ability to control the interconversion between structures using combinations of different stimulus types may serve as the basis for switching the functions expressed within a system.D.A.R. acknowledges the Gates Cambridge Trust. B.S.P. acknowledges the Royal Commission for the Exhibition of 1851 Fellowship and Corpus Christi College, Cambridge. This work was supported by the UK Engineering and Physical Sciences Research Council (EP/M01083X/1)

Something’s Fishy: A Genetic Investigations Of Sculpin Species In Western Montana

Sculpin (Cottus spp.) are small, cryptic, bottom-dwelling fish native to cool and coldwater systems throughout North America. Although three species of primarily streamdwelling sculpin are thought to occur in Montana (one of which is a species of concern), their taxonomy, distribution, and origin are not well understood. In western Montana, the present distribution of sculpin species may have been shaped by both historical events, e.g., the Columbian Ice Sheet, and contemporary landscape changes (passage barriers, climate change, pollution, etc.). To evaluate sculpin presence, and species diversity, we analyzed sculpins from river drainages throughout western Montana—the Clark Fork, Blackfoot, Flathead, Bitterroot, Kootenai, Gallatin, Madison, and Missouri—east and west of the Continental Divide. We analyzed 135 samples at the mitochondrial DNA COXI gene and at 11 microsatellite DNA loci. Preliminary results of genetic analysis suggest the presence of four distinct species with hybridization among three of the species in some locations. Hybridization led to uncertainty in species designations based on morphology, but even genetically pure fish were occasionally misidentified. One species may represent an undescribed taxon that is limited in its distribution to the St. Regis drainage, although its relation to sculpin in Idaho is unknown. A second species, previously thought to be Cottus bairdii, is distinct from that taxon and is distributed on both sides of the Continental Divide

Genetic Sampling of Palmer\u27s Chipmunks in the Spring Mountains, Nevada

Palmer\u27s chipmunk (Neotamias palmeri) is a medium-sized chipmunk whose range is limited to the higherelevation areas of the Spring Mountain Range, Nevada. A second chipmunk species, the Panamint chipmunk (Neotamias panamintinus), is more broadly distributed and lives in lower-elevation, primarily pinyon-juniper (Pinus monophylla-Juniperus osteosperma) habitat types. Panamint chipmunks are not closely related to Palmer\u27s, but field identification of the 2 species is unreliable. Palmer\u27s chipmunk is a species of concern in the state of Nevada and is listed by the International Union for Conservation of Nature (IUCN) as endangered. As such, conservation of Palmer\u27s chipmunks is a priority in the Spring Mountains National Recreation Area. We sampled putative Palmer\u27s chipmunks from 13 sites distributed across the Spring Mountains during 2010–2011. We removed Panamint chipmunks by using DNA-based identifications and then analyzed the genetic population structure of Palmer\u27s chipmunks by using a panel of 9 microsatellites. Of the 228 samples that were genotyped, 186 were Palmer\u27s; there was no evidence of hybridization between species. Four sites had exclusively Panamint chipmunks, 5 had exclusively Palmer\u27s chipmunks, and 3 had a mixture of the 2 species. In this study, Palmer\u27s chipmunks were exclusively captured at sites above 2400 m elevation, and Panamint chipmunks were exclusively captured at sites below 2200 m. Panamint chipmunks were trapped in areas typed as pinyon-juniper, but they were also trapped at sites typed as ponderosa pine (Pinus ponderosa) and mixed conifer. Both species were trapped at 3 sites; at all 3 sites, the lowerelevation traps contained Panamint chipmunks and the higher ones Palmer\u27s chipmunks. Population structure within Palmer\u27s chipmunks was minimal: heterozygosity was relatively high, and the populations displayed no signs of recent bottlenecks. Indications are that the distribution of Palmer\u27s chipmunk is limited to higher-elevation areas in the Spring Mountains, but within this area, Palmer\u27s chipmunk occurs as a single, large, well-connected, and stable population

Post-assembly Modification of Tetrazine-Edged Fe(II)4L6 Tetrahedra.

Post-assembly modification (PAM) is a powerful tool for the modular functionalization of self-assembled structures. We report a new family of tetrazine-edged Fe(II)4L6 tetrahedral cages, prepared using different aniline subcomponents, which undergo rapid and efficient PAM by inverse electron-demand Diels-Alder (IEDDA) reactions. Remarkably, the electron-donating or -withdrawing ability of the para-substituent on the aniline moiety influences the IEDDA reactivity of the tetrazine ring 11 bonds away. This effect manifests as a linear free energy relationship, quantified using the Hammett equation, between σ(para) and the rate of the IEDDA reaction. The rate of PAM can thus be adjusted by varying the aniline subcomponent.This work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC). The au-thors thank Diamond Light Source (UK) for synchro-tron beamtime on I19 (MT8464), the Department of Chemistry NMR facility, University of Cambridge, and the EPSRC UK National Mass Spectrometry Facility at Swansea University. D.A.R. acknowledges the Gates Cambridge Trust for Ph.D. funding. B.S.P. acknowledges the Herchel Smith Research Fellowship from the University of Cambridge and the Fellowship from Corpus Christi College, Cambridge.This is the final version of the article. It first appeared from the American Chemical Society via http://dx.doi.org/10.1021/jacs.5b0508

Assessing temporal genetic variation in a cougar population: influence of harvest and neighboring populations

The geography of the Black Hills region of South Dakota and Wyoming may limit connectivity for many species. For species with large energetic demands and large home ranges or species at low densities this can create viability concerns. Carnivores in this region, such as cougars (Puma concolor), have the additive effect of natural and human-induced mortality; this may act to decrease long-term viability. In this study we set out to explore genetic diversity among cougar populations in the Black Hills and surrounding areas. Specifically, our objectives were to first compare genetic variation and effective number of breeders of cougars in the Black Hills during three harvest regimes: pre (2003–2006), moderate (2007–2010), and heavy (2011–2013), to determine if harvest impacted genetic variation. Second, we compared genetic structure of the Black Hills cougar population with cougar populations in neighboring eastern Wyoming and North Dakota. Using 20 microsatellite loci, we conducted genetic analysis on DNA samples from cougars in the Black Hills (n = 675), North Dakota (n = 113), and eastern Wyoming (n = 62) collected from 2001–2013. Here we report that the Black Hills cougar population maintained genetic variation over the three time periods. Our substructure analysis suggests that the maintenance of genetic variation was due to immigration from eastern Wyoming and possibly North Dakota

Probing the Sensitivity of Electron Wave Interference to Disorder-Induced Scattering in Solid-State Devices

The study of electron motion in semiconductor billiards has elucidated our understanding of quantum interference and quantum chaos. The central assumption is that ionized donors generate only minor perturbations to the electron trajectories, which are determined by scattering from billiard walls. We use magnetoconductance fluctuations as a probe of the quantum interference and show that these fluctuations change radically when the scattering landscape is modified by thermally-induced charge displacement between donor sites. Our results challenge the accepted understanding of quantum interference effects in nanostructures.Comment: 8 pages, 5 figures, Submitted to Physical Review

The impact of smart grid technology on dielectrics and electrical insulation

Delivery of the Smart Grid is a topic of considerable interest within the power industry in general, and the IEEE specifically. This paper presents the smart grid landscape as seen by the IEEE Dielectrics and Electrical Insulation Society (DEIS) Technical Committee on Smart Grids. We define the various facets of smart grid technology, and present an examination of the impacts on dielectrics within power assets. Based on the trajectory of current research in the field, we identify the implications for asset owners and operators at both the device level and the systems level. The paper concludes by identifying areas of dielectrics and insulation research required to fully realize the smart grid concept. The work of the DEIS is fundamental to achieving the goals of a more active, self-managing grid

The ethos of physical activity delivery in mental health: a narrative study of service user experiences.

Our research into the physical activity experiences of people with severe mental illness has led us to take seriously the social and cultural environment in which physical activity is delivered. In this study, through narrative methodology, we examine service user accounts of physical activity to illuminate the characteristics of physical activity groups that are experienced as positive, helpful, or beneficial. We present several qualities and show how effective leadership and coaching is central to these qualities being present. We conclude that it is not so much what activity is delivered, but how it is delivered that is critical for sustained participation and positive outcomes