2,029 research outputs found
Discovery of a Novel Bat Gammaherpesvirus
Zoonosis is the leading cause of emerging infectious diseases. In a recent article, R. S. Shabman et al. (mSphere 1[1]:e00070-15, 2016, http://dx.doi.org/10.1128/mSphere.00070-15) report the identification of a novel gammaherpesvirus in a cell line derived from the microbat Myotis velifer incautus. This is the first report on a replicating, infectious gammaherpesvirus from bats. The new virus is named bat gammaherpesvirus 8 (BGHV8), also known as Myotis gammaherpesvirus 8, and is able to infect multiple cell lines, including those of human origin. Using next-generation sequencing technology, the authors constructed a full-length annotated genomic map of BGHV8. Phylogenetic analysis of several genes from BGHV8 revealed similarity to several mammalian gammaherpesviruses, including Kaposiâs sarcoma-associated herpesvirus (KSHV)
An empirical initial-final mass relation from hot, massive white dwarfs in NGC 2168 (M35)
The relation between the zero-age main sequence mass of a star and its
white-dwarf remnant (the initial-final mass relation) is a powerful tool for
exploration of mass loss processes during stellar evolution. We present an
empirical derivation of the initial-final mass relation based on spectroscopic
analysis of seven massive white dwarfs in NGC 2168 (M35). Using an internally
consistent data set, we show that the resultant white dwarf mass increases
monotonically with progenitor mass for masses greater than 4 solar masses, one
of the first open clusters to show this trend. We also find two massive white
dwarfs foreground to the cluster that are otherwise consistent with cluster
membership. These white dwarfs can be explained as former cluster members
moving steadily away from the cluster at speeds of <~0.5 km/s since their
formation and may provide the first direct evidence of the loss of white dwarfs
from open clusters. Based on these data alone, we constrain the upper mass
limit of WD progenitors to be >=5.8 solar masses at the 90% confidence level
for a cluster age of 150 Myr.Comment: 14 pages, 3 figures. Accepted for publication in the Astrophysical
Journal Letters. Contains some acknowledgements not in accepted version (for
space reasons), otherwise identical to accepted versio
SDSS J142625.71+575218.3: A Prototype for A New Class of Variable White Dwarf
We present the results of a search for pulsations in six of the recently discovered carbon-atmosphere white dwarf ("hot DQ") stars. On the basis of our theoretical calculations, the star SDSS J142625.71 + 575218.3 is the only object expected to pulsate. We observe this star to be variable, with significant power at 417.7 s and 208.8 s ( first harmonic), making it a strong candidate as the first member of a new class of pulsating white dwarf stars, the DQVs. Its folded pulse shape, however, is quite different from that of other white dwarf variables and shows similarities with that of the cataclysmic variable AM CVn, raising the possibility that this star may be a carbon-transferring analog of AM CVn stars. In either case, these observations represent the discovery of a new and exciting class of object.NSF AST-0507639, AST-0602288, AST-0607480, AST-0307321Astronom
Logic Gates and Ring Oscillators Based on Ambipolar Nanocrystalline-Silicon TFTs
Nanocrystalline silicon (nc-Si) thin film transistors (TFTs) are well suited for circuit applications that require moderate device performance and low-temperature CMOS-compatible processing below 250°C. Basic logic gate circuits fabricated using ambipolar nc-Si TFTs alone are presented and shown to operate with correct outputs at frequencies of up to 100âkHz. Ring oscillators consisting of nc-Si TFT-based inverters are also shown to operate at above 20âkHz with a supply voltage of 5âV, corresponding to a propagation delay of 5âV for several hours
Examining the Inclusive Summer Camp Environment as an Opportunity for Developing Social and Self-Determination Skills of Youth with Disabilities
Faculty advisor: David R. JohnsonImportant developmental aspects in adolescence include the ability to acquire and cultivate friendships, proficiencies, healthy lifestyle habits, and an overall purpose and meaning in life. Inclusion provides each child an equal opportunity to develop in a normal and integrated environment. Participation in stimulating and intrinsically motivating recreation and leisure activities offers a central means for the growth of this development in children with and without disabilities. The social and self-determination skills of youth with disabilities were hypothesized to develop and improve as the youth became more actively involved and engaged with other children, daily activities, and the experiences of an inclusive summer day camp program. The sample was composed of 29 youth participants with various disabilities, aged 6-14. The frequency of participation and level of engagement for the above measures was recorded weekly over the participantsâ involvement in inclusive summer camp programs. The average length of enrollment in the summer camp programs was 4.31 ± 1.47 weeks. The frequency of participation and level of engagement for each study measure of the Youth Participation and Engagement Scale was positively correlated with the involvement of youth with disabilities in an inclusive summer camp program. While the correlations did not showed significant regression values, each measure indicated a positive growth of each skill. The results of this study show the benefits of the inclusive and recreational setting for the development of all youth, but especially for those with disabilities.This research was supported by the Undergraduate Research Opportunities Program (UROP)
Selectivity of CâH vs. CâF Bond Oxygenation by Homo- and Heterometallic Fe_4, Fe_3Mn, and Mn_4 Clusters
A series of tetranuclear [LM_3(HFArPz)_3OM'][OTf]_2 (M, M' = Fe or Mn) clusters that displays 3-(2-fluorophenyl)pyrazolate (HFArPz) as bridging ligand is reported. With these complexes manganese is demonstrated to facilitate C(sp^2)âF bond oxygenation via a putative terminal metal-oxo species. Moreover, the presence of both ortho C(sp^2)âH and C(sp^2)âF bonds in proximity provides an opportunity to investigate the selectivity of intramolecular C(sp^2)âX bond oxygenation (X = H or F) in these isostructural compounds. With iron as the apical metal center (M' = Fe) C(sp^2)âF bond oxygenation occurs almost exclusively, whereas with manganese (M' = Mn) the opposite reactivity is preferred
Responsive and In situ-forming chitosan scaffolds for bone tissue engineering applications : an overview of the last decade
The use of bioabsorbable polymeric scaffolds is being investigated for use in bone tissue engineering applications, as their properties can be tailored to allow them to degrade and integrate at optimal rates as bone remodelling is completed. The main goal of this review is to highlight the âintelligentâ properties exhibited by chitosan scaffolds and their use in the bone tissue engineering field. To complement the fast evolution of the bone tissue engineering field, it is important to propose the use of responsive scaffolds and take advantage of bioinspired materials and their properties as emerging technologies. There is a growing interest and need for new biomaterials, such as âsmartâ/responsive materials with the capability to respond to changes in the in vivo environment. This review will provide an overview of strategies that can modulate bone tissue regeneration by using in situ-forming scaffolds
Spatio-Temporal Pattern Recognition in Neural Circuits with Memory-Transistor-Driven Memristive Synapses
Spiking neural circuits have been designed in which the memristive synapses exhibit spike timing-dependent plasticity (STDP). STDP is a learning mechanism where synaptic weight (the strength of the connection between two neurons) depends on the timing of pre-and post-synaptic action potentials. A known capability of networks with STDP is detection of simultaneously recurring patterns within the population of afferent neurons. This work uses SPICE (simulation program with integrated circuit emphasis) to demonstrate the spatio-temporal pattern recognition (STPR) effect in networks with 25 afferent neurons. The neuron circuits are the leaky integrate-and-fire (I&F) type and implemented using extensively validated ambipolar nano-crystalline silicon (nc-Si) thin-film transistors (TFT) models. Ideal memristor synapses are driven by a nanoparticle memory thin-film transistor (np-TFT) with a short retention time attached to each neuron circuit output. This device serves to temporally modulate the conductance path from post-synaptic neurons, providing rate-based and timing-dependent learning. With this configuration, the use of a crossbar structures would also be possible, providing dense synaptic connections and potentially reduced energy consumption
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