568 research outputs found
Induction of Estrus and Fertility in Anestrous Ewes
Mites are a major concern to the national agricultural economy and as such share with insects a position of pest importance to the economy of South Dakota. This bulletin includes: (1) species of plant feeding mites collected in past years in so0uth Dakota and reported I the state insect survey reports, and (2) systematic phytophagous mite collections since 1964 as part of south Dakota Experiemtn Station project No. 433
An Overshoot Approach to Recurrence and Transience of Markov Processes
We develop criteria for recurrence and transience of one-dimensional Markov
processes which have jumps and oscillate between and . The
conditions are based on a Markov chain which only consists of jumps
(overshoots) of the process into complementary parts of the state space. In
particular we show that a stable-like process with generator
such that for and
for for some and is
transient if and only if , otherwise it is recurrent. As a
special case this yields a new proof for the recurrence, point recurrence and
transience of symmetric -stable processes
The climate emergency in Africa
© 2023 ROAPE Publications Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Peer reviewe
Standing and travelling waves in the shallow-water circular hydraulic jump
A wave equation for a time-dependent perturbation about the steady
shallow-water solution emulates the metric an acoustic white hole, even upon
the incorporation of nonlinearity in the lowest order. A standing wave in the
sub-critical region of the flow is stabilised by viscosity, and the resulting
time scale for the amplitude decay helps in providing a scaling argument for
the formation of the hydraulic jump. A standing wave in the super-critical
region, on the other hand, displays an unstable character, which, although
somewhat mitigated by viscosity, needs nonlinear effects to be saturated. A
travelling wave moving upstream from the sub-critical region, destabilises the
flow in the vicinity of the jump, for which experimental support has been
given.Comment: 9 pages, REVTeX, Additional treatment on travelling waves.
Extensively revised in the publised version. Contains a full new section on
the role of nonlinearit
Methods for meta‐analysis of multiple traits using GWAS summary statistics
Genome‐wide association studies (GWAS) for complex diseases have focused primarily on single‐trait analyses for disease status and disease‐related quantitative traits. For example, GWAS on risk factors for coronary artery disease analyze genetic associations of plasma lipids such as total cholesterol, LDL‐cholesterol, HDL‐cholesterol, and triglycerides (TGs) separately. However, traits are often correlated and a joint analysis may yield increased statistical power for association over multiple univariate analyses. Recently several multivariate methods have been proposed that require individual‐level data. Here, we develop metaUSAT (where USAT is unified score‐based association test), a novel unified association test of a single genetic variant with multiple traits that uses only summary statistics from existing GWAS. Although the existing methods either perform well when most correlated traits are affected by the genetic variant in the same direction or are powerful when only a few of the correlated traits are associated, metaUSAT is designed to be robust to the association structure of correlated traits. metaUSAT does not require individual‐level data and can test genetic associations of categorical and/or continuous traits. One can also use metaUSAT to analyze a single trait over multiple studies, appropriately accounting for overlapping samples, if any. metaUSAT provides an approximate asymptotic P‐value for association and is computationally efficient for implementation at a genome‐wide level. Simulation experiments show that metaUSAT maintains proper type‐I error at low error levels. It has similar and sometimes greater power to detect association across a wide array of scenarios compared to existing methods, which are usually powerful for some specific association scenarios only. When applied to plasma lipids summary data from the METSIM and the T2D‐GENES studies, metaUSAT detected genome‐wide significant loci beyond the ones identified by univariate analyses. Evidence from larger studies suggest that the variants additionally detected by our test are, indeed, associated with lipid levels in humans. In summary, metaUSAT can provide novel insights into the genetic architecture of a common disease or traits.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142462/1/gepi22105_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142462/2/gepi22105.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142462/3/gepi22105-sup-0001-SuppMat.pd
A Petal of the Sunflower: Photometry of the Stellar Tidal Stream in the Halo of Messier 63 (NGC 5055)
We present surface photometry of a very faint, giant arc feature in the halo
of the nearby spiral galaxy NGC 5055 (M63) that is consistent with being a part
of a stellar stream resulting from the disruption of a dwarf satellite galaxy.
This faint feature was first detected in early photographic studies by van der
Kruit (1979); more recently by Mart\'inez-Delgado et al. (2010) and as
presented in this work, the loop has been realized to be the result of a recent
minor merger through evidence obtained by deep images taken with a telescope of
only 0.16 m aperture. The stellar stream is confirmed in additional images
taken with the 0.5 m of the BlackBird Remote Observatory and the 0.8 m of the
McDonald Observatory. This low surface brightness structure around the disk of
the galaxy extends ~29 kpc from its center, with a projected width of 3.3 kpc.
The stream's morphology is consistent with that of the visible part of a
"great-circle" stellar stream originating from the accretion of a ~10^8 M_sun
dwarf satellite in the last few Gyr. The progenitor satellite's current
position and fate are not conclusive from our data. The color of the stream's
stars is consistent with Local Group dwarfs and is similar to the outer regions
of M63's disk and stellar halo. We detect other low surface brightness
"plumes"; some of these may be extended spiral features related to the galaxy's
complex spiral structure and others may be tidal debris associated with the
disruption of the galaxy's outer stellar disk as a result of the accretion
event. We differentiate between features related to the tidal stream and faint,
blue features in the outskirts of the galaxy's disk previously detected by the
GALEX satellite. With its highly warped HI gaseous disk (~20 deg), M63
represents one of several examples of an isolated spiral galaxy with a warped
disk showing strong evidence of an ongoing minor merger.Comment: 16 pages, 10 figures, 3 tables, Accepted for publication in The
Astronomical Journa
Microscopic Studies on Two-Phonon Giant Resonances
A new class of giant resonances in nuclei, namely double giant resonances, is
discussed. They are giant resonances built on top of other giant resonances.
Investigation on their properties, together with similar studies on low-lying
two-phonon states, should give an answer on how far the harmonic picture of
boson-type excitations holds in the finite fermion systems like atomic nuclei.
The main attention in this review is paid to double giant dipole resonances
(DGDR) which are observed in relativistic heavy ion collisions with very large
cross sections. A great experimental and theoretical effort is underway to
understand the reaction mechanism which leads to the excitation of these states
in nuclei, as well as the better microscopic understanding of their properties.
The Coulomb mechanism of the excitation of single and double giant resonances
in heavy ion collision at different projectile energies is discussed in
details. A contribution of the nuclear excitation to the total cross section of
the reaction is also considered. The Coulomb excitation of double resonances is
described within both, the second-order perturbation theory approach and in
coupled-channels calculation. The properties of single and double resonances
are considered within the phenomenologic harmonic vibrator model and
microscopic quasiparticle-RPA approach. For the last we use the
Quasiparticle-Phonon Model (QPM) the basic ideas and formalism of which are
presented. The QPM predictions of the DGDR properties (energy centroids,
widths, strength distributions, anharmonicities and excitation cross sections)
are compared to predictions of harmonic vibrator model, results of other
microscopic calculations and experimental data available.Comment: 98 pages, 43 figures, to be published in Phys. Re
Multifactorial modeling of impairment of evoked gamma range oscillations in schizophrenia
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Despite a significant increase in efforts to identify biomarkers and endophenotypic measures of psychiatric illnesses, only a very limited amount of computational models of these markers and measures has been implemented so far. Moreover, existing computational models dealing with biomarkers typically only examine one possible mechanism in isolation, disregarding the possibility that other combinations of model parameters might produce the same network behavior (what has been termed “multifactoriality”). In this study we describe a step toward a computational instantiation of an endophenotypic finding for schizophrenia, namely the impairment of evoked auditory gamma and beta oscillations in schizophrenia. We explore the multifactorial nature of this impairment using an established model of primary auditory cortex, by performing an extensive search of the parameter space. We find that single network parameters contain only little information about whether the network will show impaired gamma entrainment and that different regions in the parameter space yield similar network level oscillation abnormalities. These regions in the parameter space, however, show strong differences in the underlying network dynamics. To sum up, we present a first step toward an in silico instantiation of an important biomarker of schizophrenia, which has great potential for the identification and study of disease mechanisms and for understanding of existing treatments and development of novel ones.Peer reviewedFinal Published versio
Essential roles of three enhancer sites in σ54-dependent transcription by the nitric oxide sensing regulatory protein NorR
The bacterial activator protein NorR binds to enhancer-like elements, upstream of the promoter site, and activates σ54-dependent transcription of genes that encode nitric oxide detoxifying enzymes (NorVW), in response to NO stress. Unique to the norVW promoter in Escherichia coli is the presence of three enhancer sites associated with a binding site for σ54-RNA polymerase. Here we show that all three sites are required for NorR-dependent catalysis of open complex formation by σ54-RNAP holoenzyme (Eσ54). We demonstrate that this is essentially due to the need for all three enhancers for maximal ATPase activity of NorR, energy from which is used to remodel the closed Eσ54 complex and allow melting of the promoter DNA. We also find that site-specific DNA binding per se promotes oligomerisation but the DNA flanking the three sites is needed to further stabilise the functional higher order oligomer of NorR at the enhancers
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