Probabilistic selection of high-redshift quasars Mortlock, Daniel J.; Patel, Mitesh; Warren, Stephen J. ...
Monthly notices of the Royal Astronomical Society,
01/2012, Volume:
419, Issue:
1
Journal Article
Bone morphogenetic protein 4 (Bmp4) is a multi-functional, developmentally regulated gene that is essential for mouse development, as most Bmp4-null mouse embyros die at the onset of gastrulation and ...fail to develop mesoderm. Little is known about the transcriptional regulation of Bmp4. To identify potential long-range cis-regulatory elements that direct its complex spatiotemporal expression patterns, we surveyed the mouse Bmp4 locus using two overlapping bacterial artificial chromosome (BAC) reporter transgenes. Our findings indicate that tissue-specific cis-regulatory elements reside greater than 28 kb 5' or 3' to the mouse Bmp4 transcription unit. In addition, comparative analyses identified three noncoding evolutionarily conserved regions (ECRs), spaced around the gene and conserved from mammals to fish, that are maintained in a syntenic group across vertebrates. Deletion of one of these conserved sequences (ECR2) from a BAC transgene revealed a tissue-specific requirement for ECR2 in driving Bmp4 expression in extraembryonic and embryonic mesoderm. Furthermore, a 467 bp mouse sequence containing ECR2 reproducibly directed lacZ minigene expression in mesoderm. Taken together, this shows that an ancient, mesoderm-specific cis-regulatory element resides nearly 50 kb 5' to mouse Bmp4.
A defect in the blue sensitive mechanism has been reported in certain ocular and systemic diseases. For example, tritanopic colour vision defects and changes to the S‐cone electroretinogram (ERG) ...have been demonstrated in glaucoma and diabetes mellitus. Electrophysiological methods of eliciting the S‐cone ERG, however, often result in considerable L‐ and M‐cone intrusion. We report the findings of a study employing the silent substitution S‐cone ERG technique, which is thought to represent an almost pure S‐cone signal, and the L'Anthony desaturated D15 colour vision test in subjects with Type 1 or 2 diabetes mellitus with no or minimal background retinopathy. The results of this study show a significantly increased S‐cone ERG b‐wave implicit time and significantly worse colour vision in those with background retinopathy compared with those with no diabetic retinopathy. This suggests that S‐cone pathway dysfunction may be responsible for the deterioration in colour vision found in diabetes mellitus.
Several tentative associations between high-energy neutrinos and astrophysical sources have been recently reported, but a conclusive identification of these potential neutrino emitters remains ...challenging. We explore the use of Monte Carlo simulations of source populations to gain deeper insight into the physical implications of proposed individual source--neutrino associations. In particular, we focus on the IC170922A--TXS~0506+056 observation. Assuming a null model, we find a 7.6\% chance of mistakenly identifying coincidences between \(\gamma\)-ray flares from blazars and neutrino alerts in 10-year surveys. We confirm that a blazar--neutrino connection based on the \(\gamma\)-ray flux is required to find a low chance coincidence probability and, therefore, a significant IC170922A--TXS~0506+056 association. We then assume this blazar--neutrino connection for the whole population and find that the ratio of neutrino to \(\gamma\)-ray fluxes must be \(\lesssim 10^{-2}\) in order not to overproduce the total number of neutrino alerts seen by IceCube. For the IC170922A--TXS~0506+056 association to make sense, we must either accept this low flux ratio or suppose that only some rare sub-population of blazars is capable of high-energy neutrino production. For example, if we consider neutrino production only in blazar flares, we expect the flux ratio of between \(10^{-3}\) and \(10^{-1}\) to be consistent with a single coincident observation of a neutrino alert and flaring \(\gamma\)-ray blazar. These constraints should be interpreted in the context of the likelihood models used to find the IC170922A--TXS~0506+056 association, which assumes a fixed power-law neutrino spectrum of \(E^{-2.13}\) for all blazars.
Bone morphogenetic protein 4 (
Bmp4
) is a multi-functional, developmentally regulated gene that is essential for mouse development, as most
Bmp4
-null mouse embyros die at the onset of gastrulation ...and fail to develop mesoderm. Little is known about the transcriptional regulation of
Bmp4
. To identify potential long-range
cis
-regulatory elements that direct its complex spatiotemporal expression patterns, we surveyed the mouse
Bmp4
locus using two overlapping bacterial artificial chromosome (BAC) reporter transgenes. Our findings indicate that tissue-specific
cis
-regulatory elements reside greater than 28 kilobases 5’ or 3’ to the mouse
Bmp4
transcription unit. In addition, comparative analyses identified three noncoding evolutionarily conserved regions (ECRs), spaced around the gene and conserved from mammals to fish, that are maintained in a syntenic group across vertebrates. Deletion of one of these conserved sequences (ECR2) from a BAC transgene revealed a tissue-specific requirement for ECR2 in driving
Bmp4
expression in extraembryonic and embryonic mesoderm. Furthermore, a 467 bp mouse sequence containing ECR2 reproducibly directed
lacZ
minigene expression in mesoderm. Taken together, this shows an ancient, mesoderm-specific
cis
-regulatory element resides nearly 50 kilobases 5’ to mouse
Bmp4
.
Following the detection of a gravitational microlensing high-magnification event (HME) in Q2237+0305A, attempts have been made to place limits on the dimensions of the quasar continuum source. The ...analyses have studied either the observed event magnitude or the event duration. The latter approach has been hampered by lack of knowledge about the transverse velocity of the lensing galaxy. We obtain both upper and lower statistical limits on the size of the continuum source from the observed HME using determinations of transverse velocity obtained from the published monitoring data. Our calculations take account of the caustic orientation as well as the component of the caustic velocity that results from stellar proper motions. Our determination of the source size relies on an estimated duration of 52 d for the HME, and so will be refined when more HMEs are observed. We find that the upper and lower limits on the magnified region of the R-band continuum source are 6×1015 and 2×1013 cm, respectively (99 per cent confidence). Through consideration of the joint probability for source size and mean microlens mass we find that the mean mass lies between ∼0.01 and ∼1 M⊙ (95 per cent confidence).
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