4,592 research outputs found
An FBAR Circulator
This letter presents the experimental demonstration of a film bulk acoustic
resonator (FBAR) circulator at 2.5 GHz. The circulator is based on
spatio-temporal modulation of the series resonant frequency of FBARs using
varactors and exhibits a large isolation of 76 dB at 2.5 GHz. The FBAR chip
(0.25 mm2) consists of three identical FBARs connected in wye configuration.
The FBAR0s quality factor (Q) of 1250 and piezoelectric coupling coefficient kt
2 of 3% relaxes the modulation requirements, achieving non-reciprocity with
small modulationto- RF frequency ratio bettter than 1:800 (3 MHz:2.5 GHz)
Finding the Center of Mass of a Soft Spring
This article shows how to use calculus to find the center of mass position of
a soft cylindrical helical spring that is suspended vertically. The spring is
non-uniformly stretched by the action of gravity. A general expression for the
vertical position of the center of mass is obtained.Comment: LaTeX, 7 pages, 2 figures. Minor changes to agree with published
versio
STRATEGIC AGRIBUSINESS OPERATION REALIGNMENT IN THE TEXAS PRISON SYSTEM
Mathematical programming-based systems analysis is used to examine the consequences of alternative operation configuration for the agricultural operations within the Texas Department of Criminal Justice. Continuation versus elimination of the total operation as well as individual operating departments are considered. Methodology includes a firm systems operation model combined with capital budgeting and an integer programming based investment model. Results indicate the resources realize a positive return as a whole, but some enterprises are not using resources profitably. The integer investment model is found to be superior for investigating whether to continue multiple interrelated enterprises.agribusiness, enterprise selection, mathematical programming, optimal enterprise organization, Agribusiness,
A report on the nonlinear squeezed states and their non-classical properties of a generalized isotonic oscillator
We construct nonlinear squeezed states of a generalized isotonic oscillator
potential. We demonstrate the non-existence of dual counterpart of nonlinear
squeezed states in this system. We investigate statistical properties exhibited
by the squeezed states, in particular Mandel's parameter, second-order
correlation function, photon number distributions and parameter in
detail. We also examine the quadrature and amplitude-squared squeezing effects.
Finally, we derive expression for the -parameterized quasi-probability
distribution function of these states. All these information about the system
are new to the literature.Comment: Accepted for publication in J. Phys. A: Math. Theo
WormBase 2007
WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences
Methylomic markers of persistent childhood asthma: a longitudinal study of asthma-discordant monozygotic twins.
This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Asthma is the most common chronic inflammatory disorder in children. The aetiology of asthma pathology is complex and highly heterogeneous, involving the interplay between genetic and environmental risk factors that is hypothesized to involve epigenetic processes. Our aim was to explore whether methylomic variation in early childhood is associated with discordance for asthma symptoms within monozygotic (MZ) twin pairs recruited from the Environmental Risk (E-Risk) longitudinal twin study. We also aimed to identify differences in DNA methylation that are associated with asthma that develops in childhood and persists into early adulthood as these may represent useful prognostic biomarkers. RESULTS: We examined genome-wide patterns of DNA methylation in buccal cell samples collected from 37 MZ twin pairs discordant for asthma at age 10. DNA methylation at individual CpG sites demonstrated significant variability within discordant MZ twin pairs with the top-ranked nominally significant differentially methylated position (DMP) located in the HGSNAT gene. We stratified our analysis by assessing DNA methylation differences in a sub-group of MZ twin pairs who remained persistently discordant for asthma at age 18. The top-ranked nominally significant DMP associated with persisting asthma is located in the vicinity of the HLX gene, which has been previously implicated in childhood asthma. CONCLUSIONS: We identified DNA methylation differences associated with childhood asthma in peripheral DNA samples from discordant MZ twin pairs. Our data suggest that differences in DNA methylation associated with childhood asthma which persists into early adulthood are distinct from those associated with asthma which remits.Medical Research Council (MRC)National Institute of Child Health and Development (NICHD)American Asthma FoundationMRC Centenary Awar
High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target
We report on the successful operation of a newly developed cryogenic jet target at high intensity
laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Fa-
cility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton
beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at
1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative
acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able
to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density,
and high-repetition rate capability, this target is promising for future applications
Scenario of Accelerating Universe from the Phenomenological \Lambda- Models
Dark matter, the major component of the matter content of the Universe,
played a significant role at early stages during structure formation. But at
present the Universe is dark energy dominated as well as accelerating. Here,
the presence of dark energy has been established by including a time-dependent
term in the Einstein's field equations. This model is compatible with
the idea of an accelerating Universe so far as the value of the deceleration
parameter is concerned. Possibility of a change in sign of the deceleration
parameter is also discussed. The impact of considering the speed of light as
variable in the field equations has also been investigated by using a well
known time-dependent model.Comment: Latex, 9 pages, Major change
Science and Film-making
The essay reviews the literature, mostly historical, on the relationship between science and film-making, with a focus on the science documentary. It then discusses the circumstances of the emergence of the wildlife making-of documentary genre. The thesis examined here is that since the early days of cinema, film-making has evolved from being subordinate to science, to being an equal partner in the production of knowledge, controlled by non-scientists
Comparative Analysis of Tandem Repeats from Hundreds of Species Reveals Unique Insights into Centromere Evolution
Centromeres are essential for chromosome segregation, yet their DNA sequences
evolve rapidly. In most animals and plants that have been studied, centromeres
contain megabase-scale arrays of tandem repeats. Despite their importance, very
little is known about the degree to which centromere tandem repeats share
common properties between different species across different phyla. We used
bioinformatic methods to identify high-copy tandem repeats from 282 species
using publicly available genomic sequence and our own data. The assumption that
the most abundant tandem repeat is the centromere DNA was true for most species
whose centromeres have been previously characterized, suggesting this is a
general property of genomes. Our methods are compatible with all current
sequencing technologies. Long Pacific Biosciences sequence reads allowed us to
find tandem repeat monomers up to 1,419 bp. High-copy centromere tandem repeats
were found in almost all animal and plant genomes, but repeat monomers were
highly variable in sequence composition and in length. Furthermore,
phylogenetic analysis of sequence homology showed little evidence of sequence
conservation beyond ~50 million years of divergence. We find that despite an
overall lack of sequence conservation, centromere tandem repeats from diverse
species showed similar modes of evolution, including the appearance of higher
order repeat structures in which several polymorphic monomers make up a larger
repeating unit. While centromere position in most eukaryotes is epigenetically
determined, our results indicate that tandem repeats are highly prevalent at
centromeres of both animals and plants. This suggests a functional role for
such repeats, perhaps in promoting concerted evolution of centromere DNA across
chromosomes
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