398 research outputs found
Sensitivity of the Quarantine Pest Rough Sweetpotato Weevil, Blosyrus asellus to Postharvest Irradiation Treatment
Rough sweetpotato weevil, Blosyrus asellus (Olivier), is a new quar- antine pest of Hawaii sweetpotatoes. Currently, sweetpotatoes can be exported from Hawaii to the U.S. mainland using a postharvest irradiation treatment of 150 Gy to control three other regulated insect pests. Studies were conducted to deter- mine whether this current radiation dose will also control any rough sweetpotato weevils in export shipments. Adult weevils were treated at various levels between 25 to 125 Gy and egg laying and egg hatch were measured. Rough sweetpotato weevil was found to be highly susceptible to irradiation, with no egg hatch at any radiation dose, even 25 Gy, the lowest dose tested. Results suggest that the 150 Gy irradiation treatment should be sufficient for control of rough sweetpotato weevil in Hawaii sweetpotatoes
Status of the Resource Room Model in Local Education Agencies: A Descriptive Study
Although resource room programs are widely used, only limited information is available on implementation of this model. The purpose of the present investigation was to survey a nationwide sample of local education agencies (LEAs) to determine the status of this model at the local level and to identify the characteristics of resource programs as they are currently implemented. A questionnaire was sent to a 5% stratified random sample of LEAs with a 53.4% response rate. Results indicated that most local education agencies use resource room programs, and have done so for at least three years. Most programs are multicategorical. The majority of respondents indicated that they believed the programs were effective, and that they would continue to be used. A major conclusion from this study relates to the need for descriptions of model resource room programs and practices.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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The Propagation of Coherent Waves Across Multiple Solar Magnetic Pores
Solar pores are efficient magnetic conduits for propagating magnetohydrodynamic wave energy into the outer regions of the solar atmosphere. Pore observations often contain isolated and/or unconnected structures, preventing the statistical examination of wave activity as a function of the atmospheric height. Here, using high-resolution observations acquired by the Dunn Solar Telescope, we examine photospheric and chromospheric wave signatures from a unique collection of magnetic pores originating from the same decaying sunspot. Wavelet analysis of high-cadence photospheric imaging reveals the ubiquitous presence of slow sausage-mode oscillations, coherent across all photospheric pores through comparisons of intensity and area fluctuations, producing statistically significant in-phase relationships. The universal nature of these waves allowed an investigation of whether the wave activity remained coherent as they propagate. Utilizing bisector Doppler velocity analysis of the Ca ii 8542 Ă
line, alongside comparisons of the modeled spectral response function, we find fine-scale 5 mHz power amplification as the waves propagate into the chromosphere. Phase angles approaching zero degrees between co-spatial line depths spanning different line depths indicate standing sausage modes following reflection against the transition region boundary. Fourier analysis of chromospheric velocities between neighboring pores reveals the annihilation of the wave coherency observed in the photosphere, with examination of the intensity and velocity signals from individual pores indicating they behave as fractured waveguides, rather than monolithic structures. Importantly, this work highlights that wave morphology with atmospheric height is highly complex, with vast differences observed at chromospheric layers, despite equivalent wave modes being introduced into similar pores in the photosphere
Collisions of particles in locally AdS spacetimes I. Local description and global examples
We investigate 3-dimensional globally hyperbolic AdS manifolds containing
"particles", i.e., cone singularities along a graph . We impose
physically relevant conditions on the cone singularities, e.g. positivity of
mass (angle less than on time-like singular segments). We construct
examples of such manifolds, describe the cone singularities that can arise and
the way they can interact (the local geometry near the vertices of ).
We then adapt to this setting some notions like global hyperbolicity which are
natural for Lorentz manifolds, and construct some examples of globally
hyperbolic AdS manifolds with interacting particles.Comment: This is a rewritten version of the first part of arxiv:0905.1823.
That preprint was too long and contained two types of results, so we sliced
it in two. This is the first part. Some sections have been completely
rewritten so as to be more readable, at the cost of slightly less general
statements. Others parts have been notably improved to increase readabilit
Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study
This study explores the potential to enhance the reflectance of solar
insolation by the human settlement and grassland components of the Earth's
terrestrial surface as a climate change mitigation measure. Preliminary
estimates derived using a static radiative transfer model indicate that such
efforts could amplify the planetary albedo enough to offset the current global
annual average level of radiative forcing caused by anthropogenic greenhouse
gases by as much as 30 percent or 0.76 W/m2. Terrestrial albedo amplification
may thus extend, by about 25 years, the time available to advance the
development and use of low-emission energy conversion technologies which
ultimately remain essential to mitigate long-term climate change. However,
additional study is needed to confirm the estimates reported here and to assess
the economic and environmental impacts of active land-surface albedo
amplification as a climate change mitigation measure.Comment: 21 pages, 3 figures. In press with Mitigation and Adaptation
Strategies for Global Change, Springer, N
Diverse Durham collection phages demonstrate complex BREX defence responses
Bacteriophages (phages) outnumber bacteria ten-to-one and cause infections at a rate of 1025 per second. The ability of phages to reduce bacterial populations makes them attractive alternative antibacterials for use in combating the rise in antimicrobial resistance. This effort may be hindered due to bacterial defenses such as Bacteriophage Exclusion (BREX) that have arisen from the constant evolutionary battle between bacteria and phages. For phages to be widely accepted as therapeutics in Western medicine, more must be understood about bacteriaâphage interactions and the outcomes of bacterial phage defense. Here, we present the annotated genomes of 12 novel bacteriophage species isolated from water sources in Durham, UK, during undergraduate practical classes. The collection includes diverse species from across known phylogenetic groups. Comparative analyses of two novel phages from the collection suggest they may be founding members of a new genus. Using this Durham phage collection, we determined that particular BREX defense systems were likely to confer a varied degree of resistance against an invading phage. We concluded that the number of BREX target motifs encoded in the phage genome was not proportional to the degree of susceptibility
Functional genomics analysis identifies T and NK cell activation as a driver of epigenetic clock progression
Background Epigenetic clocks use DNA methylation (DNAm) levels of specific sets of CpG dinucleotides to accurately predict individual chronological age. A popular application of these clocks is to explore whether the deviation of predicted age from chronological age is associated with disease phenotypes, where this deviation is interpreted as a potential biomarker of biological age. This wide application, however, contrasts with the limited insight in the processes that may drive the running of epigenetic clocks. Results We perform a functional genomics analysis on four epigenetic clocks, including Hannum's blood predictor and Horvath's multi-tissue predictor, using blood DNA methylome and transcriptome data from 3132 individuals. The four clocks result in similar predictions of individual chronological age, and their constituting CpGs are correlated in DNAm level and are enriched for similar histone modifications and chromatin states. Interestingly, DNAm levels of CpGs from the clocks are commonly associated with gene expression in trans. The gene sets involved are highly overlapping and enriched for T cell processes. Further analysis of the transcriptome and methylome of sorted blood cell types identifies differences in DNAm between naive and activated T and NK cells as a probable contributor to the clocks. Indeed, within the same donor, the four epigenetic clocks predict naive cells to be up to 40 years younger than activated cells. Conclusions The ability of epigenetic clocks to predict chronological age involves their ability to detect changes in proportions of naive and activated immune blood cells, an established feature of immuno-senescence. This finding may contribute to the interpretation of associations between clock-derived measures and age-related health outcomes.Molecular Epidemiolog
Experimental Tests of Factorization in Charmless Non-Leptonic Two-Body B Decays
Using a theoretical framework based on the next-to-leading order QCD-improved
effective Hamiltonian and a factorization Ansatz for the hadronic matrix
elements of the four-quark operators, we reassess branching fractions in
two-body non-leptonic decays , involving the lowest lying
light pseudoscalar and vector mesons in the standard model. Using
the sensitivity of the decay rates on the effective number of colors, , as
a criterion of theoretical predictivity, we classify all the current-current
(tree) and penguin transitions in five different classes. The recently measured
charmless two-body decays and charge conjugates) are
dominated by the -stable QCD penguins (class-IV transitions) and their
estimates are consistent with data. The measured charmless and transition ,
on the other hand, belong to the penguin (class-V) and tree (class-III)
transitions. The class-V penguin transitions are in general more difficult to
predict. We propose a number of tests of the factorization framework in terms
of the ratios of branching ratios for some selected decays
involving light hadrons and , which depend only moderately on the
form factors. We also propose a set of measurements to determine the effective
coefficients of the current-current and QCD penguin operators. The potential
impact of decays on the CKM phenomenology is emphasized by
analyzing a number of decay rates in the factorization framework.Comment: 64 pages (LaTex) including 13 figures, requires epsfig.sty; submitted
to Phys. Rev.
B^0-\bar{B}^0 mixing and B \to X_s \gamma decay in the third type 2HDM: effects of NLO QCD contributions
In this paper, we calculated the next-to-leading order (NLO) new physics
contributions to the mass splitting \dmd and the branching ratio \brbxsga
induced by the charged Higgs loop diagrams in the third type of
two-Higgs-doublet models (model III) and draw the constraints on the free
parameters of model III. For the model III under consideration, we found that
(a) an upper limit |\ltt|\leq 1.7 is obtained from the precision data of
\dmd=0.502 \pm 0.007 ps^{-1}, while |\ltt| \approx 0.5 is favored
phenomenologicaly; (b) for decay, the NLO QCD contributions
tend to cancel the LO new physics contributions; (c) a light charged Higgs
boson with a mass around or even less than 200 GeV is still allowed at NLO
level by the measured branching ratio \brbxsga: numerically, 188 \leq \mh
\leq 215 GeV for (|\ltt|,|\lbb|)=(0.5,18); (d) the NLO QCD contributions
tend to cancel the LO contributions effectively, the lower limit on \mh is
consequently decreased by about 200 GeV; (e) the allowed region of \mh will
be shifted toward heavy mass end for a non-zero relative phase between
the Yukawa couplings \ltt and \lbb. The numerical results for the
conventional model II are also presented for the sake of a comparison.Comment: 42 pages, 18 eps figures, Revtex, new references adde
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